1. business and industrial
2. business operations
3. business plans

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Table of Contents
Welcome Message from the Director of IBBME
3
Llewellyn-Thomas Visiting Scientist
7
Innovation in Emerging Fields of Research Speaker
8
Table of Podium Presentations
9
Table of Biomaterials, Tissue Engineering and Regenerative Medicine Abstracts
10
Table of Nanotechnology, Molecular Imaging and Systems Biology Abstracts
12
Table of Neural, Sensory Systems and Rehabilitation Abstracts
13
Table of Engineering in a Clinical Setting and Clinical Engineering Abstracts
14
Podium Presentation Abstracts
15
Biomaterials, Tissue Engineering and Regenerative Medicine
Poster Presentation Abstracts
29
Nanotechnology, Molecular Imaging and Systems Biology
Poster Presentation Abstracts
59
Neural, Sensory Systems and Rehabilitation
Poster Presentation Abstracts
71
Engineering in a Clinical Setting and Clinical Engineering
Poster Presentation Abstracts
83
Chestnut Residence Map
91
Acknowledgments 92
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Event Schedule
8:00 am –
8:45 am
Registration, Continental Breakfast - SECOND FLOOR LOBBY AND COLONY BALLROOM WEST
Chestnut Residence and Conference Centre, University of Toronto
8:45 am –
9:00 am
Welcome and Introductions - COLONY BALLROOM EAST STAGE
Professor Christopher Yip, Director of IBBME
9:00 am –
10:00 am
Edward Llewellyn-Thomas Distinguished Lecture - COLONY BALLROOM EAST STAGE
Dr. Ed Boyden, Massachussetts Institute of Technology
10:00 am –
11:15 am
Student Podium Presentations Session 1 - COLONY BALLROOM EAST STAGE
1. A digital microfluidic pseudo-chemostat for on-line culture and analysis of microorganisms - Nooman S.
Mufti
2. Reflex neuromodulation of bladder function elicited by posterior tibial nerve stimulation in anesthetized
rats - Mario Kovacevic
3. Efficient low dose x-ray CT reconstruction through sparsity-based MAP modeling - SayedMasoud
Hashemi Amroabadi
4. Identification of novel proteins in Dreissena bugensis: the quagga mussel - David Rees
11:15 am –
12:15 pm
Student Poster Presentations Session 1
Engineering in a Clinical Setting & Clinical Engineering; Nanotechnology, Molecular Imaging & Systems
Biology - ARMOURY SUITE
Neural, Sensory Systems & Rehabilitation- LOMBARDI SUITE
Biomaterials, Tissue Engineering & Regenerative Medicine - GIOVANNI ROOM
12:15 pm –
12:45 pm
Lightning Round Presentations - COLONY BALLROOM EAST STAGE
1. The role of niche architecture and stiffness on aged muscle stem cell self-renewal - Richard Cheng
2. Dual Focal Spot Dose Painting for precision preclinical radiobiological investigations - James Stewart
3. Development of a FRET-based biosensor to measure intracellular NADPH levels in beta-cells - William
Cameron
4. Comparison of techniques for classifying patients with schizophrenia from healthy controls based on
cortical thickness - Julie Winterburn
12:45 pm –
1:45 pm
Lunch - COLONY BALLROOM WEST
Posters are available for viewing at this time
1:45 pm –
2:45 pm
Innovation in Emerging Fields of Research Keynote - COLONY BALLROOM EAST STAGE
Dr. Hai-Ling Margaret Cheng, The Hospital for Sick Children
2:45 pm –
3:45 pm
Student Poster Presentations Session 2
Engineering in a Clinical Setting & Clinical Engineering; Nanotechnology, Molecular Imaging & Systems
Biology - ARMOURY SUITE
Neural, Sensory Systems & Rehabilitation - LOMBARDI SUITE
Biomaterials, Tissue Engineering & Regenerative Medicine - GIOVANNI ROOM
3:45 pm –
5:00 pm
Student Podium Presentations Session 2 - COLONY BALLROOM EAST STAGE
1. Workflow analysis identifies key barriers in femoral IM nailing - Hamid Ebrahim
2. Closed-loop controlled neuroprosthesis design with optimized FES parameters to minimize muscle
fatigue - Hossein Rouhan
3. A peptide modified hydrogel therapy for acute myocardial infarction - Lewis Reis
4. Using quantitative fluorescence microscopy to investigate the role of fibroblast growth factor receptor 5
(FGFR5) in pancreatic beta-cells - Pamuditha Silva
5:00 pm –
5:10 pm
Closing remarks
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Welcome Message from the Director of IBBME
Professor Christopher Yip, Ph.D.
Director, Institute for Biomaterials and Biomedical Engineering
Professor Christopher Yip became Director of IBBME on July 1, 2013.
Professor Yip joined the University of Toronto in 1997 after completing his PhD in Chemical Engineering at the University of Minnesota in
1996. He spent one year as a post-doctoral fellow at Eli Lilly and Company in Indianapolis. He received his undergraduate degree in Chemical Engineering from the University of Toronto in 1988 and worked
for Dupont Canada for 3 years before starting his graduate work at
Minnesota.
Professor Yip’s research interests are quite diverse, but are focused on
the development and application of super-resolution combinatorial
microscopies for functional cellular and molecular imaging of molecular assemblies, structures, and dynamics. Recent projects include
studies of peptide and protein-membrane interactions in the context
of neurodegenerative diseases and the design of novel antimicrobial
agents, membrane receptor self-association and its implications for
cell signaling in the context of both infection and cancer, as well as
multi-colour super-resolution and light sheet microscopy. Professor
Yip currently serves on the Institute Advisory Board for the Institute of
Genetics at CIHR, was the past Section Co-Chair of the NSERC Evaluation Group for Materials and Chemical Engineering, and is a standing
member on the NIH Biophysics of Neural Systems Study Section.
To All IBBME Scientific Day Participants,
It is with great pleasure that I welcome you to the 2014 IBBME Scientific Day. This is the 30th anniversary of a uniquely
student-led initiative to showcase the exceptional research activities in IBBME. I am always inspired and indeed captivated by the breadth and depth of the diverse and highly interdisciplinary projects that are underway in the Institute.
From fundamental studies of stem cell biology through to novel imaging modalities and technologies, new diagnostic
tools, and assistive devices and healthcare technologies, our students are making an impact in all aspects of biomedical engineering. Scientific Day is a chance for the IBBME community and its supporters to celebrate the Institute’s
rich heritage of collaborations and collegiality, and to recognize the outstanding achievements of our researchers and
students. I would like to express my sincerest gratitude for the hard work of BESA and the Scientific Day Organizing
Committee for putting together an exciting schedule of talks, including our keynote speakers, and helping to continue
to grow a rich tradition of engagement by our graduate students in the mission of IBBME. I would also like to thank
Sandra Walker, Erin Vollick, and the rest of the IBBME staff for helping provide administrative support for Scientific Day.
May today’s events inspire you in your own research quest and who knows, your next idea may just come from the next
talk or poster at this year’s Scientific Day.
Christopher Yip, Ph.D.
Director, IBBME
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Dear Members of the IBBME Community,
We are very excited to welcome you to this year’s Institute of Biomaterials and Biomedical Engineering Scientific Day.
2014 marks the 30th anniversary of this annual symposium, a day in which the whole IBBME community comes together
to learn from each other, and to hopefully spark the kinds of connections across disciplines that make research in
biomedical engineering so fascinating.
This year’s E. Llewellyn-Thomas Distinguished Lecturer, Dr. Ed Boyden, is a shining example of the cross-disciplinary
nature of biomedical research. His work at the Massachussetts Institute of Technology focuses on understanding
and manipulating brain circuits, and has led to tools ranging from genetically engineered light-activated proteins to
neuroprosthetics, and from neurorobotics for precise and detailed brain imaging to 3D engineered neural tissues. Dr.
Boyden has been recognized by, among others, the Grete Lundbeck European Brain Research Foundation, the National
Institutes of Health, the New York Stem Cell Foundation, the Society for Neuroscience, the World Economic Forum and
TED. It is our honour and pleasure to welcome him to 2014 IBBME Scientific Day.
We are also pleased to welcome Dr. Hai-Ling Margaret Cheng from the Hospital for Sick Children as our 2014 Innovation
in Emerging Fields of Research Keynote speaker. Dr. Cheng’s research focuses on developing quantitative magnetic
resonance imaging. Her advanced imaging technologies are likely to have a large impact on both the clinic and the
development of improved engineered tissues.
Furthermore, today showcases the research at IBBME in 12 oral presentations and 58 poster presentations. Scientific
Day aims to promote scientific discourse across the community; we encourage you to explore the posters, attend the
podium presentations and to meet and engage in dialogue with others within and outside of your own field.
Lastly, we would like to thank the Abstract Review Committee and the Presentation Evaluation committee for
volunteering their time to ensure the success of this event. We also wish to thank the staff at the Institute for their
invaluable support from start to finish.
Since its inception thirty years ago, Scientific Day has served both as forum to display the Institute’s academic and
scientific excellence, and as an annual opportunity for the community as a whole to come together, mingle, and
celebrate another year of progress and successes. This year is no different, and we hope you will find 2014 Scientific Day
stimulating and exciting.
Sincerely,
IBBME 2014 Scientific Day Organizing Committee
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Dear IBBME Scientific Day Attendees,
Hello and welcome! The year 2014 represents an important milestone: the 30th anniversary of the Institute’s internal
conference, IBBME Scientific Day! Scientific Day gives students a fantastic medium to showcase their work and
celebrate their triumphs with the IBBME community. We’re glad you’ve joined us.
The ongoing success of Scientific Day is a testament to the engagement and enthusiasm of the IBBME student initiative.
Over the past three decades, the event has grown and gained momentum to become a multi-day event that well over
half the student body participates in. For many students, Scientific Day is the first opportunity they have to present
their research to a public audience. Accordingly, Scientific Day offers a supportive environment for students to hone
their communication skills though ‘selling’ and defending their work, and making their research accessible to people
outside of their field. It also develops interpersonal skills, crucial for developing synergy between researchers for future
collaborations.
This year, Scientific Day will include the second installation of Career Day, a unique professional event catered to
students in Biomedical and Clinical Engineering. The goal of Career Day is to assist students in traversing the (often
troublesome) gap between graduate school and their careers through multiple events with industry partners and fellow
academics.
On behalf of the BESA Executive of 2013-2014, I want to thank you for your participation. Scientific Day offers a special
sample of some of the highest caliber work at the Institution and we are proud that you have chosen to take part.
Mingle, ask questions, and enjoy – we hope you leave Scientific Day inspired.
Regards,
David J. Rees
President, Biomedical Engineering Student Association (BESA)
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Edward Llewellyn-Thomas
B.Sc., M.D., CM FRSC (1918-1984)
Professor Edward Llewellyn-Thomas joined the University of Toronto as a part-time lecturer in Pharmacology
in 1959 and became a full-time member of the Faculty in 1963, and here pursued his research in pharmacology
and biomedical engineering. He was appointed as the first Associate Director of the Institute of Biomedical
Electronics that had been established in 1962 under the direction of Professor Norman Moody. In this capacity he
provided a direct link to the Faculty of Medicine, as well as, to the many associated medical research groups in
the surrounding hospitals. These were responsible for establishing new interdisciplinary research projects for the
Institute staff and graduate students.
In April 1984, Dr. Walter Zingg organized the Institute’s first Scientific Day. Professor Edward Llewellyn-Thomas
gave the keynote address to open the scientific sessions. Sadly, he passed away in July of that year. Several days
following this unfortunate incident, Dean Lowy of Medicine and Dean Slemon of Applied Science and Engineering
appointed a committee to consider a fitting memorial for Professor Llewellyn-Thomas, a physician, writer and
educator. Hence, the Edward Llewellyn-Thomas Lecture was established in his memory.
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Llewellyn-Thomas Visiting Scientist
Ed Boyden, Ph.D.
Ed Boyden is Associate Professor of Biological Engineering and Brain and Cognitive
Sciences, at the MIT Media Lab and the MIT McGovern Institute. He leads the
Synthetic Neurobiology Group, which develops tools for analyzing and engineering
the circuits of the brain. These technologies, created often in interdisciplinary
collaborations, include ‘optogenetic’ tools, which enable the activation and silencing
of neural circuit elements with light, 3-D microfabricated neural interfaces that
enable control and readout of neural activity, and robotic methods for automatically
recording intracellular neural activity and performing single-cell analyses in the
living brain. He has launched an award-winning series of classes at MIT that teach
principles of neuroengineering, starting with basic principles of how to control and
observe neural functions, and culminating with strategies for launching companies
in the nascent neurotechnology space. He also co-directs the MIT Center for
Neurobiological Engineering, which aims to develop new tools to accelerate
neuroscience progress.
Amongst other recognitions, he has received the Jacob Heskel Gabbay Award (2013), the Grete Lundbeck European
“Brain” Prize, the largest brain research prize in the world (2013), the Perl/UNC Neuroscience Prize (2011), the A F Harvey Prize (2011), and the Society for Neuroscience Research Award for Innovation in Neuroscience (RAIN) Prize (2007).
He has also received the NIH Director’s Pioneer Award (2013), the NIH Director’s Transformative Research Award (twice,
2012 and 2013), and the NIH Director’s New Innovator Award (2007), as well as the New York Stem Cell FoundationRobertson Investigator Award (2011) and the the Paul Allen Distinguished Investigator Award in Neuroscience (2010).
He was also named to the World Economic Forum Young Scientist list (2013), the Wired Smart List “50 People Who Will
Change the World” (2012), the Technology Review World’s “Top 35 Innovators under Age 35” list (2006), and his work was
included in Nature Methods “Method of the Year” in 2010.
His group has hosted hundreds of visitors to learn how to use neurotechnologies, and he also regularly teaches at
summer courses and workshops in neuroscience, as well as delivering lectures to the broader public at TED and at the
World Economic Forum. Ed received his Ph.D. in neurosciences from Stanford University as a Hertz Fellow, where he
discovered that the molecular mechanisms used to store a memory are determined by the content to be learned. Before
that, he received three degrees in electrical engineering, computer science, and physics from MIT. He has contributed
to over 300 peer-reviewed papers, current or pending patents, and articles, and has given over 240 invited talks on his
group’s work.
The brain is a complex, densely wired circuit made out of heterogeneous cells, which vary in their shapes, molecular
composition, and patterns of connectivity. In order to help discover how neural circuits implement brain functions, and
how these computations go awry in brain disorders, we invent technologies to enable the scalable, systematic observation and control of biological structures and processes in the living brain. We have developed genetically-encoded
reagents that, when expressed in specific neuron types in the nervous system, enable their electrical activities to be
precisely driven or silenced in response to millisecond timescale pulses of light. I will give an overview of these “optogenetic” tools, adapted from natural photosensory and photosynthetic proteins, and discuss new tools we are developing, including molecules with novel color sensitivities (e.g., Chrimson, Jaws) and other unique capabilities (e.g., Chronos).
We are also developing optogenetic tools that enable activation of endogenous protein and signaling pathways (e.g.,
lumitoxins). Often working in interdisciplinary collaborations, we have developed microfabricated hardware to enable
complex and distributed neural circuits to be controlled and observed in a fully 3-D fashion, as well as robots that can
automatically record neurons intracellularly and integratively in live brain, and strategies for building 3-D brain circuits
in vitro. These tools are in widespread use to enable systematic analysis of neural circuit functions, are also opening up
new frontiers on the understanding and treatment of brain disorders, and may serve as components of new platforms
for diagnosing and treating brain disease.
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Innovation in Emerging Fields of Research Speaker
Hai-Ling Margaret Cheng, PhD
Dr. Hai-Ling Margaret Cheng received her B.Sc. and M.Sc. degrees in
Electrical and Computer Engineering from the University of Calgary and
her Ph.D. degree in Medical Biophysics from the University of Toronto. Prior
to her Ph.D. studies, she spent two years in industry working on real-time
synthetic aperture radar development for Canadian defense surveillance
aircrafts. She is currently a Scientist at the Hospital for Sick Children and an
Assistant Professor at the University of Toronto in the Department of Medical
Biophysics, Leslie Dan Faculty of Pharmacy, and the Institute of Biomaterials
and Biomedical Engineering. Dr. Cheng’s research focuses on developing
quantitative magnetic resonance imaging technology for advanced
applications in cancer and tissue engineering, with an emphasis on imaging
and measuring events at the physiological, cellular, and molecular level.
Beyond Disease Diagnosis: Magnetic Resonance Imaging in Tissue Engineering and Regenerative Medicine
Magnetic resonance imaging (MRI) allows non-invasive, high-resolution whole-body visualization of tissues deep
inside living organisms without subjecting them to ionizing radiation. It is a firmly established medical imaging
modality and is preferred for demonstrating pathological alterations in many diseases because of its exquisite softtissue contrast. Exploration of MRI methods beyond the conventional realm of disease diagnosis is emerging, and
one very promising area is its application to tissue engineering and regenerative medicine. The role of MRI in this
setting is to enable and accelerate the development of viable tissue engineering techniques for creating functional
tissues and organs. The vision is for MRI to fulfill an important existing gap, which is the ability to quantitatively
assess and monitor in vivo the efficacy of tissue-engineering strategies through all stages of regeneration, from initial
cell attachment to long-term integration and function of tissue-engineered constructs. In this seminar I will describe
recent progress in the application of MRI to tissue engineering and our own research in this area. Specifically, I will
describe new technologies we are currently developing to advance MRI for tissue engineering and regenerative
medicine at the functional, cellular, and molecular level.
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Podium Presentations
A digital microfluidic pseudo-chemostat for on-line culture and analysis of microorganisms
Nooman S. Mufti, Sam H. Au, Steve C. C. Shih, Aaron R. Wheeler
Reflex neuromodulation of bladder function elicited by posterior tibial nerve stimulation in
anesthetized rats
Mario Kovacevic, Paul Yoo
16
17
Efficient low dose X-ray CT reconstruction through sparsity-based MAP modeling
SayedMasoud Hashemi Amroabadi, Richard S.C. Cobbold, Narinder S. Paul
18
Identification of novel proteins in Dreissena bugensis: the quagga mussel
David Rees, Arash Hanifi, Joseph Manion, Eli Sone
19
Workflow analysis identifies key barriers in femoral IM nailing
Hamid Ebrahimi, Albert Yee, Emily Seto, Cari Whyne
20
Using quantitative fluorescence microscopy to investigate the role of fibroblast growth factor
receptor 5 (FGFR5) in pancreatic beta-cells
Pamuditha Silva, Dawn Kilkenny, Jonathan Rocheleau
21
22
A peptide modified hydrogel therapy for acute myocardial infarction
Lewis Reis, Loraine Chiu, Jun Wu, Nicole Feric, Carol Laschinger, Abdul Momen,
Ren-Ke Li, Milica Radisic
Closed-loop controlled neuroprosthesis design with optimized FES parameters to minimize
muscle fatigue
Hossein Rouhani; Karen Elena Rodriguez; Kei Masani; Milos R. Popovic
23
The role of niche architecture and stiffness on aged muscle stem cell self-renewal
Richard Cheng, Penney Gilbert
24
Dual focal spot dose painting for precision preclinical radiobiological investigations
James Stewart, Patricia Lindsay, David Jaffray
25
Development of a FRET-based biosensor to measure intracellular NADPH levels in beta-cells
William Cameron, Pamuditha Silva, Jonathan Rocheleau
26
Comparison of techniques for classifying patients with schizophrenia from healthy controls
based on cortical thickness
Julie Winterburn, Nikhil Bhagwat, Aristotle Voineskos, Mallar Chakravarty
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27
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biomaterials, tissue engineering and regenerative medicine
Biomaterials, Tissue Engineering and Regenerative
Medicine Poster Presentations
Combining cyclic mechanical strain and monocyte co-culture enhances collagen production
and vascular smooth muscle cell infiltration into a porous degradable polyurethane scaffold
Kyle Battiston, Rosalind Labow, Craig Simmons, J. Paul Santerre
30
Bioengineering articular cartilage from passaged human chondrocytes using a defined serum
free media
Vanessa Bianchi, Rita Kandel
31
Blood compatibility of degradable polar hydrophobic ionic polyurethane (D-PHI) designed for
blood contact application
Kathryne Brockman, Jayachandran Kizhakkedathu, J. Paul Santerre
32
One-step formation of heterogeneous soft material tubes
Mark Jeronimo, Haotian Chen, Arianna McAllister, Zahra Barikbin, Axel Günther
33
Characterization of endothelial (HUVEC)-gingival fibroblasts co-cultures in perfused
degradable/polar/hydrophobic/ionic polyurethane (D-PHI) scaffolds
Jane W.C. Cheung, Devika Jain, Christopher A.G. McCulloch, J. Paul Santerre
34
Identifying human salivary esterase activity on dental resins and its use to evaluate the
biodegradation of antimicrobial derived composite resins
Yasaman Delaviz, Kuihua Cai, Michael Banh, Michael Laschuk, Meilin Yang, J. Paul Santerre
35
Superficial zone chondrocytes regulate deep zone matrix mineralization by modulating
polyphosphate accumulation through a soluble factor
Elizabeth Delve, Sadat Bromand, Jean-Philippe St Pierre, Marc Grynpas, Rita Kandel
36
Prevention of thrombogenesis from whole human blood on plastic polymer by ultrathin
monoethylene glycol silane adlayer
Kiril Fedorov, Christophe Blaszykowski, Sonia Sheikh, Micheal Thompson
37
Novel adhesive proteins from freshwater zebra mussels
Arash Hanifi, Joseph G Manion, David J Rees, ED Sone
The effect of model salivary esterase and MMP inhibition on the resin-dentin interfacial
degradation and its relationship with adaptation mechanisms of cariogenic bacteria
Bo Huang, Dennis Cvitkovitch, Paul Santerre, Yoav Finer
38
39
Mechanosensitivity of Versican expression by inner and outer annulus fibrosus cells
Jonathan Iu, J. Paul Santerre, Rita Kandel
40
Development of a combinatorial search algorithm for optimizing stem cell culture conditions
Michelle Kim, Julie Audet
41
Manipulating extracellular matrix control of collagen biomineralization
Alexander Lausch, Eli Sone
42
Microdamage and mechanical loading have an interactive effect on remodeling signals
produced by osteocyte
Chao Liu, Xiaoqing Zhang, Michael Wu, Lidan You
43
The Planar Cell Polarity signalling pathway protein Vangl1 depends on external cues to
affect the collective migration of endothelial cells
Camila Londono, Alison McGuigan
44
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Conditioned medium from osteocyte-like cells exposed to mechanical loadingat tracts
breast cancer cells
Yu-Heng Ma, Lidan You
45
46
Mechanics of collagen matrices from perspective of adherent cells
Hamid Mohammadi, Paul Janmey, Christopher McCulloch
47
Designing an elastic scaffold with shape-memory for functional tissue delivery
Miles Montgomery, Boyang Zhang, Milica Radisic
48
ContextExplorer: exposing spatial organization of phenotypic heterogeneity in human
pluripotent stem cell colonies
Joel E.E. Ostblom, Emanuel J.P. Nazareth, Peter W. Zandstra
49
The role of Toll-Like Receptors in cardiac regeneration mediated by human bone marrow-derived
mesenchymal stromal cells (MSCs).
Iran Rashedi, Xing-Hua Wang, Sowmya Viswanathan, Milica Radisic, Armand Keating
50
51
Developing an in vitro model of the interface between the annulus-cartilage endplate
Elisabeth Rok, J. Paul Santerre, Rita Kandel
The effect of simulated human salivary enzymes and matrix metalloproteinase (MMP)
inhibition on the degradation and fracture toughness of the self-etched resin-dentin interface
Kyle Serkies, Laura Tam, Grace De Souza, Yoav Finer
52
A compartmental probabilistic model of heterogeneity in reprogramming to pluripotency
Nika Shakiba, Wenlian Qiao, Carl A. White, Ayako Yachie-Kinoshita, Peter D. Tonge,
Andras Nagy, Peter W. Zandstra
53
The development of a shape memory polymer blend foam for biomedical and clinical applications
Janice Song, Ijya Srivastava, Jennifer Kowalski, Hani Naguib
54
Enhancement of nerve regeneration through neural allografts and after delayed repair
with controlled release of neurotrophic factors
Kasra Tajdaran, Matthew D Wood, Molly S. Shoichet, Tessa Gordon, Gregory H Borschel
55
Characterization and validation of a 3D PEG-NB screening platform for improved MSC
based heart valve tissue engineering
Jenna Usprech, Craig Simmons
56
In vitro degradation and physical characterization of antimicrobial electrospun scaffolds
with aligned fibers
Meghan Wright, Meilin Yang, Paul Santerre
57
Automated multidimensional image analysis reveals a role for Abl in embryonic wound repair
Teresa Zulueta-Coarasa, Rodrigo Fernandez-Gonzalez
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58
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biomaterials, tissue engineering and regenerative medicine
A microfluidic system to study the interractions of bone cells during mechanical stimulation
Kevin Middleton, Lidan You
Nanotechnology, Molecular Imaging and Systems
Biology Poster Presentations
nanotechnology, molecular imaging and systems biology
Wavelength modulated differential photoacoustic spectroscopy (WM-DPAS) for ultrasensitive
quantitative hemoglobin concentration and oxygenation monitoring in soft tissues
Sung soo (Sean) Choi Choi, Bahman Lashkari, Xinxin Guo, Andreas Mandelis
60
Colloidal drug formulations can explain “bell-shaped” concentration-response curves
Ahil Ganesh, Shawn Owen, Allison Doak, Lyudmila Nedyalkova, Christopher McLaughlin,
Brian Shoichet, Molly Shoichet
61
Cytoskeletal dynamics and coordinated cell behaviors during Drosophila embryonic wound repair
Anna Kobb, Rodrigo Fernandez-Gonzalez
62
Engineering red blood cell progenitors with an inducible self renewal gene to achieve
creater proliferative potential
Steven Mayers, Julie Audet
63
Characterizing transcription factories between stem cells and differentiated cells with
super-resolution localization microscopy
Nafiseh Rafiei, Amir Mazouchi, Joshua N. Milstein
64
CT landmark-based semi-automated mesh morphing and mapping techniques: generation
of patient specific models of the human pelvis without segmentation
Zoryana Salo, Maarten Beek, David Wright, Cari Whyne
65
The role of ligand density and size in mediating quantum dot nuclear transport
Peter S. Tang, Sarmitha Sathiamoorthy, Lindsay Lustig, Romina Ponzielli, Ichiro Inamoto,
Linda Penn, Jumi Shin, Warren C.W. Chan
Structural studies of septin protein assemblies by direct stochastic optical reconstruction
microscopy
Adriano Vissa, Theodore Pham, William S. Trimble, Peter K. Kim, Christopher M. Yip
66
67
Quantifying cell division orientation during axis elongation in Drosophila
Rodrigo Fernandez-Gonzalez, Michael Wang
68
Mechanical tension and actin polymerization during axis elongation in Drosophila
Jessica Yu, Rodrigo Fernandez-Gonzalez
69
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Neural, Sensory Systems and Rehabilitation Poster
Presentations
Multi-segment kinematic assessment of human trunk sensitivity to skin artifacts
Sara Ayatollahzadeh, Hossein Rouhani, Richard Preuss, Kei Masani, Milos R. Popovic
72
Detecting intentional muscle activity through Mechanomyogram signal in the presence of
dyskinetic movements
Marcela Correa Villada, Tom Chau
73
An artificial sensory-feedback system to improve obstacle avoidance of individuals with lower-limb
amputations
Juan Francisco Morales Gonzalez, Jan Andrysek
74
75
Investigating online three-class transcranial doppler ultrasound based brain computer interface
Anuja Goyal, Tom Chau
76
Designing everyday technologies for the home: views from people with Alzheimer’s disease
Tizneem Jiancaro, Alex Mihailidis
77
MoveEasy Pole Kit: A practical device for safer in-home mobility
Vicki Komisar, Emily C King, T Daniel Smyth, Andrew J Hart, Geoff R Fernie
78
A novel EEG-based feature clustering algorithm for detection of changes in mental state
Andrew Myrden, Tom Chau
79
Using mechanomyography as a biofeedback tool for altering gait dynamics in the rehabilitation of
pediatric spinal cord injuries
Katherine Plewa, Tom Chau
80
81
Synchronization in heterogeneous neural networks
Omid Talakoub, Milos R Popovic, Willy Wong
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neural, sensory systems and rehabilitation
Validated finite element model of a peripheral nerve
Purbasha Garai, José Zariffa
Engineering in a Clinical Setting and Clinical
Engineering Poster Presentations
engineering in a clinical setting and clinical engineering
Magnetic resonance imaging and X-ray fusion for cardiac resynchronization therapy
Jinwoo Choi, Graham Wright
Adoption of insulin pumps and continuous glucose monitors: patient perceptions
of utility and usability
Isabelle Dutil, Melanie Yeung, Holly Tschirhart, Bruce Perkins, Patricia Trbovich,
Linda Gonder-Frederick, Joseph Cafazzo
Enhancing the decoding of functional intention in children and youth with severe disabilities
through a systematic apparel-based investigation of involuntary motion
Amanda Fleury, Tom Chau, Ryan Hung
84
85
86
A wearable computer vision system for monitoring hand use at home
Jirapat Likitlersuang, José Zariffa
87
Analysis of force distribution on upper body limbs during ambulation with crutches
Emma Rogers, Jan Andrysek
88
Applying ecological interface design to improve a radiation therapy interface.
Ashleigh Shier, Eduardo Mujica, Joseph Cafazzo
89
Application of medical body area networks to reduce blood pressure in ambulatory settings
Akib Uddin, Kevin Tallevi, Kevin Armor, John Li, Rob Nolan, Joseph Cafazzo
90
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Podium Presentation Abstracts
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IBBME
A digital microfluidic pseudo-chemostat for on-line
culture and analysis of microorganisms
Nooman S. Mufti1,2, Sam H. Au1,2, Steve C. C. Shih3, Aaron R. Wheeler1,2,4
Institute for Biomaterials and Biomedical Engineering, University of Toronto; 2Donnelly Centre for Cellular
and Biomolecular Research; 3Sandia National Laboratories, New Mexico; 4Department of Chemistry,
University of Toronto
nanotechnology, molecular imaging and systems biology
1
Microfluidic bioreactors are invaluable tools for cell viability assays in the pharmaceutical industry, analyzing
culture conditions for bioprocessing of industrially relevant chemicals such as biofuels from algae, and for
assessing the phenotypes of genetically modified strains of microorganisms on-chip. Unlike conventional
microchannel based bioreactors, which often require a complex network of valves, mixers and optical systems,
digital microfluidics (DMF) has the unique advantage of allowing the culture and manipulation of discrete
microliter size droplets of cells via programmable electrostatic actuation. We previously developed an integrated
DMF bioreactor for the culture and density analysis of Bacteria, Algae and Yeast cells (the “BAY” microbioreactor).
The system allowed culture of microorganisms for up to 5 days with automated mixing and temperature control. A
significant drawback of this system was a requirement that the device had to be removed from the incubator and
manually inserted into a benchtop absorbance measurement system, resulting in temperature fluctuations and
substantial evaporation.
Here, we introduce an integrated an on-chip sensor comprising of an LED light source and inexpensive
photodiode detector which enables on-line absorbance measurements without the need for offline analysis with
bulky, expensive detectors. In contrast to typical absorbance systems, we have introduced a reflectance based
light path configuration in which light is obliquely reflected off of metal electrodes to increase the path length by
a factor of 2.8, thereby greatly improving sensitivity. To demonstrate the utility of this sensor, we have interfaced
it with a DMF platform for the growth of yeast cultures with automated long-term mixing. The addition of this
sensor enables fully automated control over S. cerevisiae yeast populations, serving as a pseudo-chemostat.
Real-time cell density measurements were recorded with one-second resolution and cells were detectable at
levels as low as 0.3 optical density (OD), which is comparable or better than benchtop analyzers. In addition, an
arduino control board was integrated to wirelessly transmit pertinent information about the culture conditions
to Bluetooth-enabled Android phones. These results demonstrate DMF as a potentially useful tool for automated
control of microorganism density and growth with off-site wireless monitoring of experimental progress. We
have recently incorporated on-chip feedback control of cell density and aim to add sensors to allow online
quantification of fluorescently labeled cellular products. Exciting applications could include studying antibiotic
drug resistance in bacteria with concomitant screening of anti-microbial peptides, studying protein-protein or
drug interactions in yeast on-chip and screening libraries of RNAis for overproducing metabolites such as lipids
and proteins in algae and bacteria.
-16-
Reflex neuromodulation of bladder function elicited
by posterior tibial nerve stimulation in anesthetized
rats
Mario Kovacevic1, Paul Yoo1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Electrical and
Computer Engineering, University of Toronto
1
In 11 adult rats (150-300g, Sprague-Dawley) anesthetized IP with a urethane, the bladder was instrumented
with suprapubic catheter to both infuse saline and measure bladder pressure. A stimulating bipolar nerve cuff
electrode was implanted on the posterior tibial nerve and a pair of insulated stainless steel wires was injected
para-urethrally to measure the external urethral sphincter (EUS) muscle activity. The bladder was continuously
infused with saline (rate = 0.05-0.16 ml/min) to generate periodic bladder contractions, which were confirmed
by rapid sustained increases in bladder pressure, concomitant EUS activity, and fluid leak through the urethral
meatus. The experimental protocol involved both baseline (no stimulation) and PTNS (continuous electrical nerve
stimulation throughout a single bladder fill) trials. The parameters of each PTNS trial were randomly varied:
frequency (1 Hz to 50 Hz), and amplitude (6 times the threshold for foot twitch).
Our data shows that we were able to achieve significant bladder inhibition during 5Hz and 10Hz PTNS, reducing
the frequency of contractions by an average of 26.5±11.0% and 45.5±11.6%, respectively. We also observed a
significant post-stimulation effect after 5Hz stimulation, during which bladder contraction frequency was
reduced by an average of 37.7±13.9% from baseline. Finally, we were able to show, for the first time, an excitatory
effect on reflex bladder activity during and after 50Hz stimulation.
-17-
scientific2014
day
IBBME
neural, sensory systems and rehabilitation
Overactive bladder (OAB) is a chronic disorder characterized by frequent and sudden urges to urinate. Although
posterior tibial nerve stimulation (PTNS) has recently emerged as a potentially effective long-term treatment
option, the neural mechanism(s) underlying this bladder-inhibitory pathway remains unknown. The objective of
this study was to investigate the role of PTN afferents in reflexively modulating bladder function.
Efficient low dose X-ray CT reconstruction through
sparsity-based MAP modeling
Sayed Masoud Hashemi Amroabadi1,2, Richard S.C. Cobbold1, Narinder S. Paul1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2University Health Network;
Department of Medical Imaging, University of Toronto
engineering in a clinical setting and clinical engineering
1
3
Purpose: Conventional Iterative Reconstruction (IR) and Compressed Sensing (CS)-based methods increase
the image quality and decrease the noise effect using noise, image, and CT system statistical models. These
algorithms (e.g. VEO from GE) are very time consuming. Hybrid techniques have been developed to gain lower
computational load with some benefits of MBIR (e.g. AIDR3D from Toshiba, and ASiR from GE). However, there is
no evidence of lesion detectability improvement in sub-mSv CT imaging using hybrid algorithms. We report the
early results of a prospective trial to examine the effectiveness of our proposed fast CS-based CT reconstruction
to reduce the effective dose due to lung nodules and coronary plaques CT follow ups.
Materials and methods: An anthropomorphic chest phantom (Kyoto Kagaku N1, Kyoto, Japan) and a coronary
plaque phantom, which is built in our lab and mimics soft, hard, and mixed plaques with different sizes, were
scanned with a 320-detector CT scanner (Aquilion ONE, Toshiba Medical Systems, Otawara, Japan) using 5 tube
current levels (ranged from 25 mA to 500 mA) at 120 kV, 1sec rotation time (1200 projection angles), and pitch
factor of 0.64. Images are reconstructed with standard filtered back projection (FBP) and the proposed CS-based
method from different projections numbers; and the images are compared for each setting. A reviewer evaluated
the images qualitatively (on a scale of 1-10), providing separate scores for the overall image and individual
appearance of plaques and nodules.
Results: Subjective quality ratings of the images reconstructed by our proposed method from 256 projections
(~1/5 of full projections set) was not statistically different form the images reconstructed by FBP from full dataset.
In addition, images reconstructed from full dataset by the proposed method have significantly higher contrast to
noise ratio (CNR), compared to the images reconstructed by FBP.
Conclusion: Using the proposed method, on a typical desktop computer, a 512×512 CT image is reconstructed in
approximately 30sec (compared to few hours required by MBIR methods) with almost the same diagnostic quality
as FBP with ~70% lower radiation.
Clinical Relevance: Our proposed method may be among the first statistical modeling based CT reconstruction
methods with computational complexity within the realm of what could be clinically relevant today.
-18-
Identification of novel proteins in Dreissena
bugensis: the quagga mussel
David Rees1, Arash Hanifi1, Joseph Manion2, Eli Sone1, 2, 3
The European freshwater mollusk Dreissena bugensis (quagga mussel) was introduced to the Great Lakes in the
1980s and have since spread rapidly throughout eastern North America. Quagga mussels adhere to a plethora
of surfaces underwater via the byssus: a non-living protein ‘anchor’, however, the molecular mechanism of
adhesion has not been characterized. We propose to reveal the proteins that freshwater mussels utilize to adhere
underwater and to use these proteins to create peptide mimics for medical and dental applications. There is
a gap in the scientific knowledge: current synthetic adhesives have fallen short for medical applications, often
failing in wet environments, or are toxic. The byssus sticks to a variety of substrates with different properties; this
versatility could be applied to attach different human tissues such as bone, muscle, and skin. Our goal is to create
novel bioadhesive mimicking the quagga mussel adhesive proteins.
Quagga mussels were induced to secrete fresh byssal material, which was isolated using a novel processing
protocol. Soluble byssal proteins were identified and separated using polyacrylamide gel electrophoresis
(PAGE). Four proteins observed correspond with previously identified proteins: Dreissena bugensis foot
proteins 0-3 (Dbfp0-3). The most prominent gel bands, 6kDa, 7kDa, 15kDa and 30kDa were clipped from the
gel, trypsin digested, and analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). De
novo sequencing was used to determine the amino acid sequences of the fragments. Analysis revealed peptide
sequences unique to each band that may represent adhesion protein motifs. To examine plaque interface-specific
proteins, presumably adhesive proteins, plaques were freshly deposited on PVC, then isolated by dissolving the
PVC, and fixing the plaques upturned in gelatin. The exposed interface was analyzed using matrix assisted laser
desorption ionization time-of-flight (MALDI) mass spectrometry. Plaques were also deposited directly onto a
MALDI sample plate and shaved clean with razor leaving behind the plaque ‘footprint’ for MALDI probing. Spectra
of freshly induced threads/plaques were also taken. A series of 6-8kDa proteins were observed in both thread
and plaque spectra, suggesting a shared structural role. One protein 8.1kDa protein appears solely in the plaque,
and a 4.3kDa protein has a higher relative intensity compared to threads. Furthermore, the spectra suggest the
8.1kDa protein is present at the adhesive interface. To determine protein sequence information, next-generation
RNA-sequencing was used to create a cDNA library of the quagga mussel foot transcriptome, containing >200,000
transcripts. Using LC-MS/MS with our cDNA library, we now have the ability to determine the complete primary
structure of the adhesive proteins. This lays the groundwork for investigating the protein’s corresponding
mechanism of adhesion as a blueprint to develop new synthetic bioadhesives.
-19-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Materials
Science and Engineering, University of Toronto; 3Faculty of Dentistry, University of Toronto
1
Workflow analysis identifies key barriers in femoral
IM nailing
Hamid Ebrahimi1,2, Albert Yee1,2,3, Emily Seto4, Cari Whyne1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Holland Musculoskeletal
Program, Sunnybrook Research Institute; 3Division of Orthopaedics, Department of Surgery, University of
Toronto; 4Centre for Global eHealth Innovatio
engineering in a clinical setting and clinical engineering
1
Introduction: Intramedullary (IM) nailing is the standard of care for adult lower extremity long bone fracture
stabilization. Development of a surgical workflow for this type of surgery is critical to identify barriers and
required technologies/methodologies to optimize the surgical process. The primary aim of this study is to
model the surgical workflow for IM nailing and identify the surgical challenges that impede the process. It is
hypothesized that femoral fracture reduction represents the most challenging step in IM nailing due to 3D
malalignment.
Methods: Semi-structured face-to-face interviews were conducted to identify: 1- the surgical procedure,
2- surgical challenges, 3- adapted surgical techniques when encountering current challenges. Eight surgeons
with varying levels of experience from community and teaching hospitals were included. Seven IM nailing
surgeries were observed to gather additional information on similarities and differences in surgical procedures.
The total time for completing each step of the procedure and the use of fluoroscopy were recorded. A surgical
workflow model was developed by considering all variations of surgical interventions for IM nailing. Challenges
encountered, potential areas of improvements and adapted surgical techniques were identified.
Results: An 11 step workflow associated with IM nailing of femoral fractures was generated based on interviews
and observations. Provisional reduction was identified as the most challenging step (by 6/8 surgeons), consistent
with the surgical observations. Less experienced surgeons also identified challenges with entry point selection. In
both steps, 3D alignment was the critical barrier. Utilization of repeated 2D fluoroscopy without any connectivity
between sequential images to guide reorientation was observed to cause great frustration and be a consistent
impediment to 3D positioning of the guidewire for entry point and femoral fragment realignment.
Conclusion: Workflow analysis has identified 2 critical steps in the IM nailing process both of which are
dependent on 3D intraoperative alignment. These findings have important implications to guide technological
improvements and competency based training.
-20-
Using quantitative fluorescence microscopy to
investigate the role of fibroblast growth factor
receptor 5 (FGFR5) in pancreatic beta-cells
Pamuditha Silva1, Dawn Kilkenny1, Jonathan Rocheleau1, 2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Physiology,
University of Toronto
1
-21-
scientific2014
day
IBBME
nanotechnology, molecular imaging and systems biology
Type II diabetes, a metabolic syndrome that affects over 250 million people worldwide, is characterized by the
inability of pancreatic beta-cells to produce, process and/or secrete insulin, an endocrine hormone critical for
glucose homeostasis. The combined adverse effects of high glucose and free fatty acids on beta-cell survival
(glucolipotoxicity) are considered a major cause of type II diabetes. Beta-cell function and survival is tightly
regulated by extracellular stimuli that are translated into intracellular signaling events via membrane proteins
such fibroblast growth factor tyrosine kinase receptors (FGFRs) that are known to influence beta-cell metabolism,
insulin processing and survival. Fibroblast growth factor receptor 5 (FGFR5; R5) is a newly discovered member of
this protein family currently thought to function as a decoy receptor to down-regulate canonical FGFR signaling
in lieu of its lack of catalytic tyrosine kinase domains common to all other FGFRs. We have previously shown that
R5 expression in the murine pancreatic beta-TC3 cell line increased insulin secretion, adhesion to collagen type
IV and laminin, and activation of intracellular MAPK signaling. We have engineered multiple protein constructs
of wild-type and mutant R5 tagged to spectrally diverse fluorescent proteins in order to use quantitative
fluorescence microscopy to identify receptor localization at insulin secretory granules and the plasma membrane.
Because we have identified R5 association with the MAPK pathway regulator SHP-1 at insulin secretory granules,
our current focus is to identify other signaling molecules that interact with the unique R5 C-terminus, in
particular Src family kinases (SFKs). SFKs are key intracellular molecules known to interact with FGF receptors to
affect downstream signaling events in response to extracellular stimuli. We hypothesize that direct interaction
between R5 and SFK regulates beta-cell survival and intracellular signaling. Preliminary immunofluorescence
studies reveal strong co-localization between R5 and SFK at the beta-cell plasma membrane. Interestingly, ligand
(FGF2)-stimulated activation of SFK was only observed in beta-cells overexpressing R5. By examining levels
of cleaved caspase-3 as a measure of beta-cell survival during stress (palmitate treatment), our data suggests
that FGF2 treatment improves beta-cell survival when R5 is overexpressed. Using multi-parametric advanced
quantitative fluorescence microscopy, we are examining the dynamics and distribution of R5 in live beta-cells
with the goal of characterizing the relationship between R5 with SHP-1, SFKs and canonical FGF receptors.
Ultimately, these results will contribute towards development of novel therapeutics to treat diabetes.
A peptide modified hydrogel therapy for acute
myocardial infarction
biomaterials, tissue engineering and regenerative medicine
Lewis Reis1,2, Loraine Chiu1,2, Jun Wu2,4,, Nicole Feric1,2, Carol Laschinger1,2, Abdul Momen2,,
Ren-Ke Li2,4,, Milica Radisic1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Chemical
Engineering and Applied Chemistry, University of Toronto; 3Division of Cardiovascular Surgery, Department
of Surgery, University of Toronto; 4Toronto General Research Institute, University Health Network
1
Introduction: Myocardial infarction (MI) results in the death of cardiomyocytes (CM) followed by scar formation
and pathological remodeling of the heart. Myocardium does not regenerate and this presents an urgent need for
therapies to renew damaged muscle and restore heart morphology and function, or maintain both after infarct.
To address this many groups have been focused on developing biomaterials, and more specifically hydrogels, for
direct delivery of components to the heart for treatment of MI. We propose that chitosan conjugated with the
angiopoietin-1 derived peptide, QHREDGS, and mixed with collagen I forms a thermo-responsive hydrogel suited
for the amelioration of negative post-infarct cardiac remodeling.
Materials & Methods: The development and optimization of the QHREDGS-chitosan-collagen hydrogel used
in this work was previously described. Current work has focused on hydrogel injection into the MI zone of
adult Lewis rats subjected to a left anterior descending coronary artery ligation procedure to mimic acute MI.
Injection of 50µL of the developed hydrogel (QHG213-H), Control gel (gel with no peptide), or PBS into three spots
surrounding the MI zone was done immediately following ligation.
Results: Tracking of DyLight-800 labelled hydrogel showed sustained presence up to two weeks in the heart,
and subsequent chitosan staining of excised heart sections showed clearance by three weeks post injection.
Echocardiography revealed peptide modified hydrogel significantly maintained cardiac function post MI
compared to Control hydrogel and PBS injection. Pressure-volume analysis showed similar results with QHG213-H
hydrogel yielding significantly improved ejection fraction, preload recruitable stroke work, and end systolic
pressure volume relationship compared to both Control gel and PBS groups. Cardiac morphology quantification
revealed scar thickness and scar area fraction were significantly improved with QHG213-H gel compared to the
other two groups. Cardiac troponin T staining revealed a significantly higher proportion of healthy CMs in the MI
zone of peptide-gel treated animals. RT-qPCR and CM attachment assays has implicated integrin subunit β1 as
the binding site for CM to QHREDGS, is sufficient for activation of survival gene BCL-2, deactivation of apoptotic
gene CASP-9, and up-regulation of inflammation genes IL-6 and IL1-β.
Conclusions: Further work must still be done to definitively determine the mechanism by which improvement
is occurring, and specifically determine the conjugate α-integrin subunit. However, the developed hydrogel has
shown the ability to be injected and localize within the beating heart, has an in vivo lifespan appropriate for the
acute phase of cardiac remodeling, and shows promising cardiac functional and morphological maintenance after
acute MI.
-22-
Closed-loop controlled neuroprosthesis design
with optimized FES parameters to minimize muscle
fatigue
Hossein Rouhani1,2; Karen Elena Rodriguez1,2; Kei Masani1,2; Milos R. Popovic1,2
Rehabilitation Engineering Laboratory, Institute of Biomaterials and Biomedical Engineering, University
of Toronto; 2Rehabilitation Engineering Laboratory, Toronto Rehabilitation Institute, University Health
Network
1
Methods: For this purpose, we measured the generated ankle torque of three individuals with different levels (3×3)
of pulse duration (150, 300, 450 micro-second) and pulse amplitude (40, 50, 60 mA) of the biphasic, asymmetric,
balanced rectangular pulse wave, applied to ankle plantarflexor muscles. We calculated the maximum torque
and two muscle fatigue measures (i.e., fatigue time and torque time integral) during three-minute of continuous
FES. Then, we interpolated the obtained muscle fatigue measures and maximum torque over the range of pulse
duration and amplitude. For each level of the generated maximum torque, we chose the pulse duration and
amplitude combination that resulted in the minimum muscle fatigue among all combinations that resulted in such
a maximum torque level.
Results: The fatigue performance of the left and right ankle plantarflexors was similar for each subject, even when
measurements of the left and right ankles were done on different days (median correlation coefficient was over
0.95 for all subjects and parameter levels). This indicated that the obtained choice of pulse duration and pulse
amplitude could be later used in clinical applications. The fatigue performance did not show high inter-subject
repeatability with median coefficient of multiple correlations of 0.71 over all pulse duration and pulse amplitude
levels and all subjects. This suggests that the results obtained for one individual cannot necessarily be applied to
another individual. Finally, the optimal choices of pulse duration and pulse amplitude were not necessarily similar
when obtained based on fatigue time and torque time integral measures.
Conclusion: We suggested an algorithm to empirically obtain the generated torque and muscle fatigue measures
based on pulse duration and pulse amplitude of rectangular FES pulses. In order to generate each level of an
ankle joint torque, we found optimum choices of pulse duration and pulse amplitude combinations that resulted
in the minimum muscle fatigue among all combinations. In order to design neuroprostheses with optimal muscle
fatigue performance, we suggest modulating the pulse duration and pulse amplitude along the line formed by the
calculated optimal choices to obtain different torque levels. Similar algorithm to optimize FES pulse shapes can be
applied for other muscles in design of variety of neuroprostheses.
-23-
scientific2014
day
IBBME
neural, sensory systems and rehabilitation
Background and Aims: Design of neuroprostheses for individuals with spinal cord injury is confined by rapid
onset of muscle fatigue in response to functional electrical stimulation (FES). We introduced an algorithm to
choose optimal pulse shape parameters for FES pulse that attained certain levels of muscle force for longer time
periods and resulted in minimal muscle fatigue.
The role of niche architecture and stiffness on aged
muscle stem cell self-renewal
biomaterials, tissue engineering and regenerative medicine
Richard Cheng1, Penney Gilbert1
Institute of Biomaterials and Biomedical Engineering, University of Toronto
1
Muscle stem cells (MuSCs), also known as satellite cells, reside in a specialized location, or ‘niche’, between the
basal lamina and the sarcolemma of muscle fibers. Upon injury MuSCs are ‘activated’ and undergo self-renewal
divisions to produce daughter cells that repair the damaged tissue and repopulate the niche. As humans age,
skeletal muscle regenerative potential is diminished and studies indicate this is due in part to changes in the
biochemical (growth factors, cytokines and receptor ligands) composition of the muscle stem cell niche. Our
recent studies showed that substrate stiffness, a biophysical niche cue, integrates with biochemical cues to
rejuvenate aged MuSC self-renewal in culture. This observation indicates that biophysical features of the stem
cell niche might constitute a novel therapeutic target to restore regenerative potential to aged skeletal muscle
tissue in vivo. By carefully comparing immunostained young and aged mouse skeletal muscle tissue sections, we
identified previously undocumented features of the MuSC niche that transform with age. MuSCs in young muscle
tissue preferentially reside in an architecturally distinct niche at the apex of myofibres whereas MuSCs in aged
tissue are at the edge of myofibres. Furthermore, we find that aged MuSCs reside in a niche that contains thick
bundles of aligned collagen, which was not seen in the young MuSC niche, indicating that the MuSC niche stiffens
with age in nonrandom patterns that coincide with position. In this research project we will use culture and in
vivo studies to investigate the hypothesis that aged MuSC niche architecture and stiffness contribute to reduced
aged MuSC self-renewal and regenerative potential. This knowledge will be strategic for the development of drugs
that control endogenous MuSC activity in predictable ways to stimulate aged muscle regeneration. Ultimately,
we aim to develop a novel stem cell targeted therapy to maintain skeletal muscle strength in the aging Canadian
population.
-24-
Dual focal spot dose painting for precision
preclinical radiobiological investigations
James Stewart1, 2, Patricia Lindsay2, 3, David Jaffray1, 2, 3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Radiation Medicine Program,
Princess Margaret Cancer Centre; 3Department of Radiation Oncology, University of Toronto
1
To this end, two-dimensional dose kernel primitives were empirically measured for the small and large x-ray focal
spots on a recently developed small animal irradiator using a 1 mm diameter fixed circular collimator. Compared
to the large x-ray focal spot, the small focal spot delivers dose at a lower rate, but with a sharper dose gradient.
As such, the small focal spot is analogous to a fine “dose brush” used to paint highly heterogeneous regions of
radiation dose, with the thick focal spot “dose brush” used to paint more homogeneous dose regions at a quicker
rate. More specifically, the measured dose kernels were used in an optimization framework which segmented an
arbitrary prescribed dose into low- and high- heterogeneous regions for optimization and delivery by the large
and small focal spots, respectively. For each region, the method then determined an optimal set of animal stage
positions and beam-on times.
The method was demonstrated by optimizing a bullseye pattern consisting of 0.75 mm radius circular target and
0.5 and 1.0 mm wide rings alternating between 0 and 2 Gy. Compared to a large focal spot technique, the dual
focal spot technique improved the optimized dose distribution: 69.2% of the optimized dose was within 0.5 Gy of
the intended dose for the large focal spot, compared to 80.6% for the dual focal spot method. The dual focal spot
design required 14.0 minutes of optimization, and will require 178.3 minutes for automated delivery.
The dual focal spot optimization and delivery framework is a novel option for delivering conformal and
heterogeneous dose distributions at the preclinical level and provides a new experimental option for millimetre
scale preclinical dose painting.
-25-
scientific2014
day
IBBME
engineering in a clinical setting and clinical engineering
Of the 187,600 Canadians that received a cancer diagnosis last year, approximately 113,000 were prescribed
external beam radiotherapy during the course of their disease management. In general, the goal of this treatment
is to deliver a tumour ablating dose of radiation using high energy x-rays, while minimizing the dose received by
healthy tissues surrounding the tumour. Recent engineering advances have focused on shaping the high dose
region to the three-dimensional tumour target; however, interest in redistributing dose within the tumor has
emerged as an attractive option to improve clinical outcomes. In such a manner, higher radiation doses could
be delivered to radioresistant tumour subvolumes. Preclinical testing this efficacy of this hypothesis is currently
limited by the lack of techniques to deliver dose at the millimetre scale and sub-millimetre accuracy demanded by
small animal tumour models. The purpose of this work was to develop an optimization method based on a dualfocal spot x-ray beam design to deliver highly heterogeneous dose distributions for preclinical research.
Development of a FRET-based biosensor to measure
intracellular NADPH levels in beta-cells
William Cameron1, Pamuditha Silva1, Jonathan Rocheleau1
Institute of Biomaterials and Biomedical Engineering, University of Toronto
nanotechnology, molecular imaging and systems biology
1
Type 2 diabetes (T2D) affects over 2.5 million Canadians at an estimated annual cost of 12 billion dollars. Betacell failure is at the heart of the disease, which is strongly linked to diet-induced obesity and develops through
the long-term exposure to high levels of glucose and free fatty acids (FFA). A consequence of this metabolic
state - known as glucolipotoxicity – is the increased production of reactive oxygen species (ROS) within the cell,
largely as a byproduct of the electron transport chain in the mitochondria. The cell’s main defence against ROS
is glutathione, which is maintained in both the cytosol and mitochondria by independent pools of Nicotinamide
adenine dinucleotide phosphate (NADPH). NADPH also plays a crucial role in other aspects of beta-cell function,
such as fatty-acid synthesis and insulin secretion. In Type 2 Diabetes (T2D), the systems that maintain adequate
NADPH levels become overwhelmed by glucolipotoxic-induced ROS, leading to cellular dysfunction or apoptosis.
As a result, understanding how NADPH-producing pathways are affected by glucolipotoxicity is crucial to an
understanding of the disease.
Despite its importance to beta-cell function, NADPH-specific pathways have been understudied due to limitations
in current measurement techniques. For example, autofluorescence cannot distinguish between NADPH and its
sister cofactor NADH, while assay-based techniques are specific for NADPH, but lack the temporal and spatial
resolution required to capture fast metabolic responses. A new sensor based on Förster resonance energy
transfer (FRET) has therefore been developed to address these issues. It is based on the Glucose-6-Phosphate
enzyme and is designed to use changes in fluorescent anisotropy to track changes in cellular NADPH levels.
Our sensor has been confirmed to be enzymatically inactive, reversible, and responds within physiological
conditions. Furthermore, our sensor is also able use targeting sequences to image specific organelles such as the
mitochondria with a sub-micrometer, second-scale resolution. Finally, our sensor acts to demonstrate a novel use
of homo-FRET for cellular imaging and highlights one of homo-FRET’s key advantages in its capacity for multiparametric imaging. Compared to existing hetero-FRET sensors, our sensor required a smaller spectral width and
has been tuned for a range of colours in the red to blue spectrum to maximize its compatibility with existing dyes.
As a sample application, our sensor was used to examine the effect of glucolipotoxicity on beta TC3 cells. Our
results showed that both cytoplasmic and mitochondrial pools of NADPH were depleted in response to elevated
ROS (>1uM H202); however, only the mitochondrial supply of NADPH was significantly affected by elevated fat or
glucolipotoxicity. If confirmed in islets, these results support the theory that mitochondrial dysfunction is at the
core of beta-cell failure and provide the basis for a more comprehensive investigation.
-26-
Comparison of techniques for classifying patients
with schizophrenia from healthy controls based on
cortical thickness
Julie Winterburn1,2, Nikhil Bhagwat1,2, Aristotle Voineskos1,3, Mallar Chakravarty1,2,3
Kimel Family Translational Imaging Genetics Research Laboratory, Research Imaging Centre, Centre for
Addiction and Mental Health; 2Institute of Biomaterials and Biomedical Engineering, University of Toronto;
3
Department of Psychiatry, University of Toronto
1
Statement of Methods: T1-weighted images from 191 subjects (103 HC, 88 SZ; age 18-59, mean 35.8) were acquired
on a 1.5T MR scanner. Cortical thicknesses at 81924 vertices were calculated using the CIVET pipeline (Montreal
Neurological Institute, McGill University). A naïve Bayes (NB) classifier was applied both before and after
dimensionally reducing the data with a principal component analysis and validation was performed by splitting
the data into training (70%) and test (30%) subsets. Additionally, a logistic regression (LR) was applied to the
reduced dataset; validation was performed using 100 rounds of bootstrapping.
Summary of Results: The NB classifier using thicknesses at all vertices correctly classified 64.2% of subjects in
the training dataset, and 70.2% in the test dataset. The top 14 principal components each explained >1% of the
variance in the data, and cumulatively explained 59.1% of the data’s variance. On the reduced dataset, NB correctly
classified 56.1% correctly. An LR model on the reduced dataset (R2=0.20, p<0.01) had an average accuracy of 79.7%
across validation rounds.
Statement of Conclusions Reached: Our results indicate that LR on dimensionally-reduced vertex-wise cortical
thickness data offers a predictive power competitive with results reported in the literature. We believe we can
further improve our classification rate significantly by exploring other classification techniques and including
additional brain regions. An understanding of the most effective classifier may offer insight into the disease
mechanism of schizophrenia, and can be extended to other disease populations.
-27-
scientific2014
day
IBBME
neural, sensory systems and rehabilitation
Purpose of Study: Machine learning algorithms can be used to automatically identify individuals suffering from
different neuropsychiatric disorders. The outcome of such algorithms may eventually aid in clinical diagnosis
or even improve our understanding of different disease features. Techniques that have been applied to the
classification of schizophrenia patients from healthy controls using structural magnetic resonance (MR) imaging
demonstrate 70-90% accuracy. However, it is difficult to compare results from multiple studies, as different
subject sets, algorithms, and brain regions are used. As such, we performed multiple classification techniques on a
single dataset to determine which method is best suited for this task.
-28-
Poster Presentation Abstracts
-29-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Biomaterials, Tissue Engineering and Regenerative
Medicine
Combining cyclic mechanical strain and monocyte
co-culture enhances collagen production and
vascular smooth muscle cell infiltration into a
porous degradable polyurethane scaffold
biomaterials, tissue engineering and regenerative medicine
Kyle Battiston1 , Rosalind Labow2, Craig Simmons1,3, J. Paul Santerre1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Division of Cardiac Surgery,
University of Ottawa Heart Institute, Ottawa; 3Faculty of Dentistry, University of Toronto
1
Introduction: Strategies for tissue engineering a vascular graft aim to promote cell growth, obtain a uniform cell
distribution, and to promote the contractile phenotypic state of the vascular smooth muscle cell (VSMC).
Biomechanical stress is an important regulator of VSMC function and has been shown to significantly enhance
VSMC growth and migration. Another important regulator of VSMC function in vivo is the monocyte/
macrophage, which have been shown to be positive contributors to vascular graft remodeling depending on their
activation state within the M1/M2 spectrum. VSMC-monocyte co-culture strategies are thus an attractive option
for regulating VSMC response on biomaterial scaffolds.
Methods: D-PHI scaffolds were prepared as previously reported. The resulting scaffolds were seeded with
monocytes isolated from the whole blood of healthy volunteers (University of Toronto ethics approval #22203),
human coronary artery smooth muscle cells (VSMCs, Lonza, CC-2583) or monocytes and VSMCs in co-culture
(2:1 monocyte:VSMC). Seeded scaffolds were cultured for up to 4 weeks under static conditions, or cultured
under dynamic conditions (10% strain, 1 Hz). The cells within the scaffold were analyzed for total DNA mass,
cellular infiltration (H&E), ECM production (OH-Pro and GAG quantification), as well as monocyte/macrophage
polarization (immunofluorescence [IF] for CD80, CD86 [M1 markers] vs. CD163, CD206 [M2 markers]).
Results: After 4 weeks of culture on D-PHI scaffolds, the VSMC-monocyte co-culture supported an increase in
DNA mass relative to the sum of VSMC and monocyte monocultures for both static (6636±1249 vs. 4545±827 ng/
scaffold) and dynamic (6522±1497 vs. 4564±660 ng/scaffold) conditions. H&E analysis indicated greater cellular
infiltration into scaffolds with the combination of co-culture and biomechanical stimulation. The combined
co-culture-dynamic condition resulted in the greatest amount of collagen content in scaffolds after 4 weeks vs.
monocultures, while co-culture enhanced GAG content vs. monoculture conditions (p<0.05), with no effects of
dynamic vs. static culture. IF analysis of M1/M2 marker expression indicated no change in the ratio of CD80/
CD163 or CD86/CD206 over time, suggesting no shift towards pro-inflammatory macrophage polarization over
the 4 weeks of culture. The management of inflammation is a common challenge of many traditional synthetic
biomaterials, such as PLGA.
Conclusions: The combination of biomechanical stimulation and monocyte co-culture supported enhanced
cellular infiltration into porous D-PHI scaffolds while also promoting enhanced collagen production relative to
static co-culture conditions. This study supports the importance of combining co-culture strategies with dynamic
bioreactor systems as a means to enhance cell and tissue growth for tissue engineering strategies.
Acknowledgements: CIHR grant #230762, Cell Signals (Battiston), Ontario Graduate Scholarship (Battiston).
-30-
Bioengineering articular cartilage from passaged
human chondrocytes using a defined serum free
media
Vanessa Bianchi1, Rita Kandel1,2
Introduction: Osteoarthritis (OA) is characterized by the loss of extracellular matrix (ECM) in articular cartilage.
As currently there are no disease modifying drugs to treat OA, most people suffer with pain and limited mobility
until the disease progresses sufficiently to warrant a joint replacement. These prostheses have a limited lifespan
and so it is not an optimal treatment. An alternative approach is to resurface focal disease by implanting
bioengineered cartilage. However, this is limited by the requirement for a large number of cells. Culturing of
primary chondrocytes in monolayer for cell number expansion leads to loss of phenotype and the ability to
produce ECM, hindering the bioengineering process. Recently we have identified conditions for redifferentiating
passaged bovine chondrocytes in 3D culture, using media supplementation alone to produce bioengineered
articular cartilage rich in ECM. However this system was not able to produce robust tissue when passaged human
OA chondrocytes were used. This may be due to the fact that diseased chondrocytes lose the ability to produce
sufficient levels of growth factors required for matrix remodeling. The hypothesis of this study is that the addition
of transforming growth factor beta (TGFβ) to our defined serum free culture system will promote the production
and deposition of ECM in bioengineered cartilage from passaged human OA chondrocytes, producing tissues that
resemble native cartilage.
Methods: Second passage (P2) human OA chondrocytes were seeded onto Millicell® inserts (12mm) with 2 x 106
cells per insert. Cells were cultured serum free in DMEM high glucose media supplemented with varying
concentrations of TGFβ1 or 3 for two weeks, at which point the tissues were harvested, examined histologically
and matrix components quantified.
Results: Passaged human OA chondrocytes formed cartilage tissue rich in ECM containing more collagens and
proteoglycans, major macromolecules of cartilage, in the presence of 10ng TGFβ3 compared to untreated tissues
and to tissues treated with 10ng TGFβ1 reproducibly.
Conclusions: Passaged human chondrocytes have the potential to form cartilage tissue when grown in media
supplemented with TGFβ3. Further studies will elucidate how TGFβ3 modulates the chondrogenic phenotype.
Characterization of the tissue and comparison to native articular cartilage will be performed to determine if it is
suitable to use for cartilage repair.
-31-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Pathology and
Laboratory Medicine, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital and University of
Toronto
1
Blood compatibility of degradable polar
hydrophobic ionic polyurethane (D-PHI) designed
for blood contact application
biomaterials, tissue engineering and regenerative medicine
Kathryne Brockman1, Jayachandran Kizhakkedathu2,3, J. Paul Santerre1, 4,5
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Chemistry,
University of British Columbia; 3Department of Pathology and Laboratory Medicine and Centre for Blood
Research, University of British Columbia; 4Faculty of Dentistry, University of Toronto; 5Department of
1
Chemical Engineering and Applied Chemistry, University of Toronto
Introduction: Cardiovascular disease is a major cause of death in Canada, often requiring bypass graft surgery, for
which there is a lack of suitable small diameter grafts. Degradable polar hydrophobic ionic polyurethane (D-PHI)
has been developed for small diameter vascular graft applications, and it shows mechanical properties similar to
that of natural vessels and a reduced pro-inflammatory cell response. The current work will use in vitro methods
to assess the blood compatibility of D-PHI.
Methods: D-PHI was prepared as films and particles generated from scaffolds. Particles were ground from
scaffolds and sieved to an average particle size of 80.5 ± 28.6 μm, then suspended in HEPES buffered saline
solution (pH=7.4) by sonication to a concentration of 50 g/L. Coagulation in whole blood was assessed by
thromboelastography (TEG) analysis wherein D-PHI suspension (HEPES as control) was mixed with fresh whole
human blood (protocol approved by UBC’s clinical ethics board) or platelet poor plasma (PPP) and added to a
TEG cup at 37°C. The TEG measures the kinetics of blood coagulation. The intrinsic and extrinsic pathways of
the coagulation cascade were evaluated by activated partial thromboplastin time (APTT) and dilute prothrombin
time (PT) assays, respectively. These assays mix PPP with D-PHI suspension and reagents and measure clotting
time with a coagulometer. The total complement consumption was measured by a hemolytic assay (CH50 sheep
erythrocyte lysis assay). Platelet activation and adhesion were assessed by the expression of CD62P on the surface
of platelets by flow cytometry and SEM analysis of surface adhered platelets, respectively. Hemolysis in the
presence of D-PHI particle suspension was also measured.
Results: TEG studies demonstrate a statistically significant decrease in coagulation time (CT) for D-PHI in whole
blood when compared to the control sample; however, no significant change in CT is seen when in PPP. The CT
for D-PHI is significantly longer for APTT and significantly shorter for PT compared to control. There is no
significant change in hemolysis, or activation of complement or platelets compared to control.
Discussion: The results suggest a slightly increased potential for thrombus generation in whole blood exposed to
D-PHI when compared to whole blood under control. Since initiation in PPP, intrinsic pathway activation,
complement activation, platelet activation and adhesion, and hemolysis are negligible; it is suggested that the
plasma proteins, platelets, and red blood cells are not predominantly responsible for the decreased CT in whole
blood upon exposure to D-PHI. This leads to the hypothesis that white blood cells (WBCs) may be playing a role
in these findings. However, samples were assessed under static blood conditions with no flow, yet thrombosis is
affected by flow. Therefore, future studies will specifically investigate platelet, WBCs, and RBC response under
physiologically relevant shear flow rates.
-32-
One-step formation of heterogeneous soft material
tubes
Mark Jeronimo1, Haotian Chen1, Arianna McAllister1, Zahra Barikbin1, Axel Günther1
Institute of Biomaterials and Biomedical Engineering, University of Toronto;
We present a method that allows homogeneous and heterogeneous soft materials to be continuously defined
in one single step. Biopolymer solutions are introduced to a microfluidic device, distributed in a feature layer,
radially fed to a common outlet at the device center to form a concentric complex fluid and, upon crosslinking, a
hydrogel tube at the device exit. This approach allows for the controlled and continuous extrusion of tubes with
tailored diameters, thicknesses, compositions as well as programmable mechanical and chemical properties.
Techniques of reversible fixation and perfusion of these tubes are also developed.
Soft material tubes play essential roles in the vascular systems from plants to humans, as well as in almost every
internal organ. Such structures are often characterized by a structure and composition that are highly
directionally dependent. There has been significant interest in the continuous formation of soft material fibers
and tubes using microfluidic platforms. The presented approaches are limited in diameter and thickness range
and so far lack the critical ability of providing for spatial heterogeneity. An additional inconvenience is that these
device architectures are incompliant with standard (planar) fabrication processes. Multilayered microfluidic devices with individually addressable biopolymer and inner and outer fluid stream
carrying a cross-linker were designed and fabricated using standard soft lithography. The devices enable the
continuous vertical extrusion of biopolymer tubes through a focusing confinement and into a liquid-filled
reservoir. Cross-linking is initiated at the device exit, so the spatial organization defined by the fluid flows is
retained in the final soft material. By altering the configuration of the biopolymer outlets, multiple biopolymer
materials can be incorporated to form heterogeneous tubes with controllably non-uniform cross-sections.
Using the presented platform, meter-long perfusable homogeneous and heterogeneous tubes of varying
composition were routinely produced. Dynamic control of the tube geometry (inner diameter, outer diameter and
wall thickness) is dictated by the relative flow rates of the inner flow, the biopolymer flow, and the outer flow. The
dimensions of the tube were consistent with the predictions from an analytical model. The system is compliant
with a wide range of operating conditions and allowed the outer diameter to vary between 750µm to 2300µm and
wall thickness between 60µm and 420µm. Heterogeneous tubes were obtained by spotting different materials
and extruding multilayer tubes. As-formed tubes were reversibly interfaced and liquid perfused with a second
microfluidic device using a vacuum channel network.
Our strategy enables a continuous format for the high-throughput formation of soft hydrogel tubes with dynamic
control over geometry and composition. We envision the formation of perfusable tube assemblies and bulk
materials with stimulus responsive material properties.
-33-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
1
Characterization of endothelial (HUVEC)-gingival
fibroblasts co-cultures in perfused degradable/
polar/hydrophobic/ionic polyurethane (D-PHI)
scaffolds
biomaterials, tissue engineering and regenerative medicine
Jane W.C. Cheung1, Devika Jain1, Christopher A.G. McCulloch2, J. Paul Santerre1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Faculty of Dentistry,
University of Toronto
1
Background: Periodontal diseases affect nearly 50% of North Americans 30 years and older. For restoration of
lost periodontium, polyurethane hydrogels (D-PHI) could be used for regenerative procedures and they have been
shown to elicit less inflammatory response post-implantation. Perfused D-PHI scaffolds enhanced the
proliferation of human gingival fibroblasts (HGFs) and collagen production. Co-cultures of endothelial cells with
fibroblasts in synthetic materials can support capillary formation however the culture medium and cell seeding
ratio must be optimized for each unique cell source and culture environment.
Objective: To investigate the effect of culture medium and cell seeding ratio in HUVEC-HGF co-cultures in a
perfused scaffold with respect to promoting growth, capillary formation, and angiogenic factor production.
Methods: A mixture of HGF-1 cells and HUVECs (1:1) was seeded into D-PHI scaffolds for 24 hrs, which were then
cultured in a perfusion bioreactor for 28 days. The samples were either cultured in a 50/50 mix of DMEM and
F-12 K medium (by vol.), or in DMEM only. For investigating the effect of seeding ratio, a mixture of both cell types
at ratios 2:1, 1:1, or 1:2 (HUVEC:HGF) was seeded and cultured under flow for 28 days. DNA content and metabolic
activity were measured. The production of angiogenic factors (VEGF, TGF-β1, FGF-2) was measured by ELISAs.
The presence of capillary formation was assessed using immunofluorescence.
Results and Discussion: DNA content in the co-culture with the 50/50 mix medium showed a significant 3.1-fold
increase in cell population over 28 days (p<0.01) while the DMEM condition showed a 1.6-fold increase.
Immunofluorescence indicated that networks of HUVECs were only observed in the 50/50 condition. In addition,
VEGF and FGF-2 levels increased significantly (relative to D0) only in the 50/50 condition. Based on cell seeding
ratio, DNA and WST-1 data suggest that the number of HGFs should be greater than that of HUVECs during initial
seeding to achieve greater cell proliferation. A ratio of 1:2 resulted in greater metabolic activity at D28 than the
other two ratios. TGF-β1 production was significantly greater for the 1:2 ratio, suggesting that the increased
number of HGFs may have upregulated TGF-β1. Conclusion: HUVEC-HGF co-culture in perfused D-PHI scaffolds
with a 50/50 mix of media (by vol.) and greater fibroblast proportion exhibit enhanced growth, early signs of
angiogenesis, and increased angiogenic factor production.
-34-
Identifying human salivary esterase activity
on dental resins and its use to evaluate the
biodegradation of antimicrobial derived composite
resins
Yasaman Delaviz1, Kuihua Cai2, Michael Banh2, Michael Laschuk2, Meilin Yang2 , J. Paul Santerre1,2
Composite resins used as dental restorative materials experience biochemical breakdown in the oral cavity.
Marginal breakdown is responsible for more than 50% of restoration replacements and involves salivary enzyme
activity (generated by cells and bacteria), which can degrade the resin and enable bacteria to promote
demineralization of the tooth surface at the tooth and restorative interface. To overcome this challenge, this
research aims to use a pro-biochemical approach where antimicrobial action will be generated upon degradation
of composites by salivary enzymes, releasing the antibiotic Ciprofloxacin (CF) as a byproduct.
Objectives: The main objective is to study the degradation of the novel antimicrobial polymers with model salivary
enzyme solutions. Methods: To establish an understanding of salivary esterase activity, fractions of high esterase
activity were collected from human whole saliva and separated by gel electrophoresis. Proteins suspected of
esterase activity were analyzed by mass spectrometry (MS). Commercially available proteins, similar to the
salivary proteins identified by MS were used to replicate the enzymatic complexes and confirm their degradation
activity with respect to Bisphenol A-glycidylmethacrylate (BisGMA). The antimicrobial monomers are synthesized
following previously established carbodiimide chemistry, and they are subsequently reacted via chain growth
polymerization. CF is used as starting material and light-curing chemistry is incorporated using methacrylic
acid or 2-hydroxyethyl methacrylate (HEMA), yielding divinyl monomers that can cross-link upon curing. These
monomers are combined with BisGMA and HEMA in different ratios, polymerized and assessed for physical
properties, including gel content, degree of swelling and polymerization. Initial biodegradation studies of the
cured resins are carried out using cholesterol esterase (CE) and pseudocholinesterase (PCE) to model aspects
of the salivary enzymes. Over a period of one month, aliquots are removed and degradation by-products are
quantified using a high performance liquid chromatography.
Results: Commercially available albumin and α-amylase are both able to degrade BisGMA, and showed activity
that could in part be modeled by CE and PCE. The ability of albumin to degrade BisGMA is enhanced when
forming a complex with Zn-α2-glycoprotein and under slightly basic conditions. Two monomers were
successfully synthesized and characterized by nuclear magnetic resonance and MS with overall yields greater
than 55%. Initial experiments suggest successful polymerization of these monomers in the presence of BisGMA
and HEMA. Both monomers were stable up to one week in the presence of CE activity, and on-going work is now
investigating the biodegradation of the cured resins.
Acknowledgment: NSERC Discovery Grant #360520.
-35-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Faculty of Dentistry,
University of Toronto
Superficial zone chondrocytes regulate deep zone
matrix mineralization by modulating polyphosphate
accumulation through a soluble factor
biomaterials, tissue engineering and regenerative medicine
Elizabeth Delve1,2, Sadat Bromand1,2, Jean-Philippe St Pierre2,3, Marc Grynpas1,2, Rita Kandel1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Lunenfeld-Tannenbaum Research Institute; 3Department of Materials Science and Engineering, University of Toronto; 4Pathology and
Laboratory Medicine Mt Sinai
1
Background: Articular cartilage is an avascular connective tissue that forms the surface of synovial joints. This
tissue absorbs and distributes forces applied to the joint while permitting low friction articulation. It fulfills these
functions through a complex depth-dependent zonal architecture characterized by a distinct matrix composition
and organization. Osteoarthritis is a degenerative disease that disrupts the zonal architecture, with loss of the
superficial zone (SZ) of cartilage being one of the earliest changes, followed by progressive matrix loss and
mineralization. Understanding the role of the SZ in regulating articular cartilage homeostasis may provide insight
into potential therapeutic interventions to delay the onset or progression of OA.
Hypothesis: SZ chondrocytes (SZC) regulate mineralization in cartilage formed by deep zone chondrocytes (DZC)
by modulating polyphosphate levels through a soluble factor(s). Methods: An in vitro co-culture system was
developed to investigate the role of SZC on mineralization and polyphosphate accumulation in cartilage formed by
DZC. Conditioned media (CM) studies were performed to determine if the factor was a soluble protein. RT-PCR
and immunocytochemistry identified a putative protein and recombinant protein/specific inhibitor studies were
performed to confirm the role of the identified protein in matrix mineralization.
Results: Co-culture of cartilage formed by DZC with SZC resulted in significantly less mineralization and more
polyphosphate accumulation, compared to co-culture with DZC. Treatment of cartilage formed by DZC with
SZCM resulted in significantly less mineralization; and trypsin digestion and heat treatment inactivated the SZCM
rescuing mineralization. FGF-18 gene expression was significantly higher in the SZ compared to the DZ and was
identified in the cultures used to generate the CM. Treatment with recombinant FGF-18 inhibited mineralization,
and supplementing the SZCM with an FGF receptor inhibitor rescued mineralization.
Conclusion: SZC release a soluble factor, potentially FGF-18, which inhibits mineralization in cartilage formed by
DZC and correlates with increased polyphosphate accumulation.
-36-
Prevention of thrombogenesis from whole human
blood on plastic polymer by ultrathin monoethylene
glycol silane adlayer
Kiril Fedorov1, Christophe Blaszykowski2, Sonia Sheikh3, Micheal Thompson1,2,3
Introduction: Currently large number of medical equipment components undergoing contact with biological
fluids are made out of polymer based materials. Continuous contact with biological fluids results in protein
fouling on the polymer surfaces. Several of these plastics are currently used in many medial applications including
poly(ethylene terephthalate) (PET), Polycarbonate (PC), polyvinyl chloride(PVC), polypropylene (POP), Poly(methyl
methacrylate)(PMMA) and polyurethane(PUR).
Methods: Prior to the modification the polymers have been treated with air plasma to allow formation surface
hydroxyl groups for film adhesion. The treated polymers have been characterized using: Contact angle
goniometry (CAG), Attenuated total reflectance infrared spectroscopy (ATR-IR) spectroscopy and x-ray
photoelectron spectroscopy (XPS). The finished surface was analysed using fluorescence microscopy for
thrombus formation. Whole blood with no heparin adedd was used for thrombus formation analysis on the
polymer surface.
Results: The surface energy had confirmed the changes corresponding to coating head groups ranging from
~ 25 mJ/cm2 uncoated surface to ~ 40+ mJ/cm2 final coating stage for both polymers. Using ATR-IR analysis both
of the films have reported Si and F based bonds. The results for XPS have confirmed significant changes in
surface composition of C, O, Si and F atoms proportional to the composition of the film. Film has been
successfully deposited on: PET, PC, POP, PVC, POP and PMMA. When tested the film successful reduced
thrombus formation using whole blood on PC at shear rate of 1000 s-1 by > 97% compared to untreated PC.
Conclusions: The film was successfully deposited on the surfaces of all polymers. The film was successful in
significantly reducing the thrombus formation on PC. In future other shear rates and more materials will be
tested coated with the film.
-37-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Econous Systems Inc.; 3Department of Chemistry, University of Toronto
1
Novel adhesive proteins from freshwater zebra
mussels
biomaterials, tissue engineering and regenerative medicine
Arash Hanifi1, Joseph G Manion1, David J Rees1, ED Sone1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Materials
Science and Engineering, University of Toronto 3Faculty of Dentistry, University of Toronto.
1
For the past 30 years several types of bioadhesive materials have been used in clinical applications for tissue
healing and regeneration purposes. However, there have been complications with their poor adhesion, toxicity of
biodegradation side products, and mechanical properties mismatch with the surrounding tissue. The freshwater
zebra mussel (Dreissena polymorpha) presents underwater adhesion properties that can be used to overcome
the current challenges of synthetic adhesives in aqueous environment. The mussel anchors itself to the substrate
by means of a proteinaceous structure called byssus, which is secreted by foot organ and composed of series
of threads connected to an adhesive plaque. Although the marine mussel adhesion has been correlated to 3,4
dihydroxyphenylalanine (DOPA)-rich proteins, the adhesion mechanism of freshwater mussel is not completely
understood. It has been shown that the mussel attachment is mediated by a uniform layer on the plaque footprint.
MALDI mass spectroscopic spatial analysis on byssus-substrate interface revealed the presence of low-molecular
weight proteins at the mussel footprint that are not contained in the plaque bulk. Therefore, the aim of this study
was to identify the highly specialized low-molecular weight byssal proteins that play a key role in underwater
adhesion of zebra mussel to the substrate. Twenty freshly induced threads/plaques were extracted in a basic
extraction buffer using an improved extraction and purification protocol. Samples were homogenized on ice,
sonicated, and centrifuged. The supernatant (soluble extract) was then washed, concentrated, and separated by
gel electrophoresis. The gels were then stained to visualize portion bands. Protein gel bands at 6, 7, and 14 KDa
were trypsin digested and analyzed by LC-MS/MS. Mass spectrometry spectra were searched against a zebra
mussel cDNA library using Peaks to determine expressed sequence tags (ESTs). ESTs were then evaluated for;
hydroxylation of tyrosine to locate possible DOPA sites, signal peptides, and sequence alignments. Then, ESTs
with the -logP greater than 100 and peptide coverage greater than 20% were selected for following analysis.
Among protein sequences a total of 16 unique EST families were obtained. Amino acid sequence of each of EST
family was aligned against known zebra mussel proteins. Of these, five represented completely novel proteins and
eight represented new variant of known proteins. According to MALDI mass spectrometry experiments, these low
molecular weight novel proteins are the most likely candidates responsible for the zebra mussel adhesion to
substrates. Specific parts of EST families will be used to synthesize bioadhesive peptides, which will be tested by
atomic force microscopy to evaluate their adhesive properties. The results of this work will serve as the
groundwork for freshwater mussel inspired synthetic adhesive peptides.
-38-
The effect of model salivary esterase and
MMP inhibition on the resin-dentin interfacial
degradation and its relationship with adaptation
mechanisms of cariogenic bacteria
Bo Huang1,2, Dennis Cvitkovitch1, Paul Santerre1,2, Yoav Finer1
Background: Resin composite restorations are currently the most prevalent restorative materials in dentistry
with more than 166 million procedures annually in the USA. About 70% of the procedures are replacements
for previous restorations. The high prevalence of secondary caries along the resin-dentin interface limits the
lifetime of resin-based restorations. Current findings indicate that this interface loses its integrity with time due
to the combined degradation effects of exposed collagen fibrils in dentin by intrinsic matrix metalloproteinases
(MMPs), and the hydrolysis of resinous components in both adhesives and resin composites catalyzed by salivary
esterases. As a result, the compromised interface allows ingress of cariogenic bacteria like Streptococcus mutans
(S. mutans), a major species that contributes to the initiation and progression of secondary caries. Furthermore,
the by-products from resin degradation modulate bacterial growth and virulence gene expression.
Objectives: 1. to investigate the combined effects of MMP inhibitor (galardin), different adhesive systems and
traditional composite resin on interfacial integrity by measuring bacterial penetration along the interface; 2. to
examine the effect of resin composite degradation product, bis-hydroxy-propoxy-phenyl-propane (BisHPPP), on
the gene expression of a putative esterase (SMU_118c), in S. mutans UA159. Material and Methods: Resin-dentin
specimens were prepared from traditional resin composite bonded to human dentin using total-etch or self-etch
adhesive with or without the application of an MMP inhibitor (galardin) to the interface (N=3/group). Specimens
were incubated in PBS or simulated human salivary esterase (SHSE) (37°C, pH=7.0) for 30 days. Post-incubation,
specimens were suspended in a continuous media biofilm fermenter to form biofilm over the resin-dentin
interfaces. Bacterial ingress along the interface was measured by confocal laser scanning microscopy and image
processing software (IMARIS, Bitplane). Fluorescence In Situ Hybridization (FISH) was used to assess the effect of
different concentrations of BisHPPP on gene expression of SMU_118c.
Results: Total-etch specimens treated with galardin showed less bacterial microleakage vs. non-treated
specimens after incubation for 30 days in either SHSE or PBS (p<0.05). There was no significant difference
in bacterial ingress between SHSE-incubated and PBS-Incubated groups for both adhesive systems. FISH
demonstrated the up-regulation of the putative esterase SMU_118c in response to increased concentrations of
the resin composite and the adhesive biodegradation product, BisHPPP.
Conclusion: Galardin has inhibitory effect on interfacial degradation of total-etch adhesive and preserves the
interfacial integrity. The feasibility of the non-invasive non-disruptive FISH-based method has been demonstrated
for assessment of gene expression within intact biofilms.
-39-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Faculty of Dentistry, University of Toronto; 2Institute of Biomaterials and Biomedical Engineering,
University of Toronto
1
Mechanosensitivity of Versican expression by inner
and outer annulus fibrosus cells
biomaterials, tissue engineering and regenerative medicine
Jonathan Iu1, J. Paul Santerre1, Rita Kandel2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2The Lunenfeld-Tanenbaum
Research Institute, Mount Sinai Hospital, Toronto
1
The mature annulus fibrosus (AF) surrounds the nucleus pulposus (NP) and is composed of angle ply lamellae.
The inner lamellae contain type II collagen, aggrecan and versican. Progressing towards the outer lamellae, the
amount of aggrecan and type II collagen decreases as type I collagen increases and veriscan localizes to the
interlamellar septae and translamellar crossbridges. This differential organization of the extracellular matrix
(ECM) results in inner (IAF) and outer (OAF) zones (Fig. 1). Although the function of versican in the IVD is unknown,
it has been shown to have a role in mechanical function. Given the load distribution in the disc, it may be that
versican expression is mechanosensitive. Aligned nanofibrous polycarbonate urethane (PU) membranes support
the accumulation of appropriate ECM molecules by IAF and OAF cells. On PU membranes, type II collagen and
versican are accumulated by IAF cells, while OAF cells accumulate type I collagen and lower levels of versican
compared to IAF cells making it a good in vitro model to study AF tissue metabolism. The objective of this study is
to determine if versican expression and accumulation by IAF and OAF cells cultured on PU membranes is
mechanosensitive.
Aligned nanofibrous PU membranes were formed by electrospinning and placed in a specially designed holder.
OAF and IAF tissues were dissected from bovine caudal discs and their corresponding OAF and IAF cells were
isolated by sequential enzymatic digestion and seeded onto PU membranes. On day 7 of culture, the membranes
were subjected to uniaxial, confined cyclic compressive loading of 2, 4 or 6 kPa per membrane using a
mechanical stimulator (MACH-1) at 1 Hz for 1800 cycles through a 4% agarose plug. Control samples were
manipulated identically, but did not experience any stimulation. Results were analyzed by gene expression,
immunostaining and immunoblot.
Versican is mechanosensitive in IAF cultures as loading increased versican gene and proteoglycan accumulation.
Interestingly only the V0 isoform was responsive to loading. OAF cells showed increased versican gene expression
with mechanical loading but this did not result in increased proteoglycan accumulation. Western blot analysis
and confocal imaging showed discrepant results as the former showed maximal versican accumulation at 4kPa
compared to 6kPa by confocal imaging. The antibodies used detected different epitopes (αGAG vs G1 domains
respectively). The G1 and αGAG domains of versican are adjacent to one another in the V0 isoform. The G1 domain
binds to hyaluronan via link protein. As there are cleavage sites between these two domains that are susceptible
to proteolysis by enzymes such as ADAMTS-1 and -4, it is possible that at 6 kPa these proteases are activated, and
that versican lost its αGAG domain but retained the G1 domain. Further studies are required to address how
versican is processed by IAF cells following mechanical loading.
-40-
Development of a combinatorial search algorithm
for optimizing stem cell culture conditions
Michelle Kim1, Julie Audet1
Institute of Biomaterials and Biomedical Engineering, University of Toronto
The ability to accurately manipulate stem and progenitor (“precursor”) cell cultures has become critical with the
increasing interest of novel cell-based therapies. Efficiently optimizing cell culture systems is challenging due to
the complexity generated by numerous factors in various dose combinations, non-linear cell response, interacting
factors, and donor-to-donor variability. The conventional experimental approach to identify an optimal condition
is by factorial design which is costly and unrealistic as the number of experiments (N) increases exponentially
(N=k^n), dependent on the number of factors (n) and dose levels (k). A strategy to efficiently identify the optimal
conditions for precursor cell expansion would facilitate the production of precursor cell populations and the
discovery of potentially more effective complex conditions. This study proposes the development of a
combinatorial search algorithm to optimize culture conditions for precursor cell expansion based on direct
measurement of cellular response. Preliminary algorithms based on the combinatorial approach integrating
aspects from conventional search methodologies have been developed and assessed using simulated
hematopoietic stem cell culture data inspired by experimental findings, consisting of 5 factors over 5 dose levels
including an inhibitory factor and a pair of interacting factors. A deterministic algorithm required testing of a
similar number (~33) of combinations as in a central composite design experiment but inter-experimental
controls resulted in additional experimental cost, reducing efficiency. A purely stochastic algorithm struggled to
recognize and respond to effects of interacting factors and was unable to converge to an optimal condition. In
both cases, increasing variability simulated in the data posed a challenge to an efficient optimization process. To
address these limitations, a differential evolution-based algorithm is being developed to enable the algorithm to
accommodate the high degree of complexity of an expansion culture system resulting from factor interactions
and the non-linearity in factor effects. The algorithm will aim to address the inter-experimental variability
associated with cell culture data as part of the decision-making process of the algorithm. Such algorithm will
provide a robust optimization process that efficiently identifies the optimal culture condition of precursor
expansion culture systems, facilitating the development and translation of precursor cell-based applications in
research and industry.
-41-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
1
Manipulating extracellular matrix control of
collagen biomineralization
biomaterials, tissue engineering and regenerative medicine
Alexander Lausch1, Eli Sone1, 2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Material Science and Engineering, University of Toronto
1
Biomineralization is the controlled deposition of mineral within an organic matrix. In vertebrates, most body
fluids (blood plasma, saliva, enamel fluid etc.) are supersaturated with respect to hydroxyapatite, and as such,
different collagenous tissues mineralize to form the mineralized connective tissues of bone, dentin and
cementum. However, not all collagenous tissues mineralize. Collagen biomineralization is a complex process and
the controlling factors, at the molecular level, are not well understood.
The extracellular matrix (ECM) is known to play an important role in mineral deposition. Specifically,
macromolecular components such as phosphoproteins and glycosaminoglycans are thought to control mineral
deposition and growth. In vitro models of collagen biomineralization have provided limited conclusions as to the
role of certain non-collagenous proteins (NCPs). The literature is rich with contradictions as to whether specific
proteins act as inhibitors or promoters of mineralization. We require better, more physiologically relevant, models
of collagen biomineralization, in which to probe in vivo control over biomineralization.
We employ mouse periodontium, the set of tissues involved in tooth anchorage, as a model of collagen
biomineralization. When thin sections of demineralized periodontium, showing bone, ligament, cementum and
dentin, are exposed to solutions supersaturated with respect to hydroxyapatite they mineralize with near-native
selectivity. Naturally mineralized tissues, such as bone, dentin and cementum, mineralize, leaving the ligament
unmineralized. This shows us that the ECM is capable of controlling mineral deposition with a high degree of
fidelity. Selected area diffraction shows that, with the use of soluble additives, we can achieve oriented
hydroxyapatite, as is found in vivo.
We are currently working to elucidate the mechanisms involved in the selective mineralization demonstrated in
our model. We use different extraction techniques, such as GuHCl and different enzymes to selectively remove
specific portions of the ECM. Specifically we are interested in the role of total NCPs, glycosaminoglycans, and
phosphorylation. We remineralize digested tissues to observe the effect the removal of these ECM components
has on remineralization. We show that cementum is particularly sensitive to ECM composition and following the
removal of NCPs it does not remineralize within experimental parameters, similar to the ligament. Surprisingly,
the ligament does not seem to be affected by any of the treatments. This suggests that in our model, the
promotion of mineralization is more important than inhibition.
A better understanding of the controlling mechanisms in biomineralization is required for the development of
treatments for mineralization diseases such as periodontitis, and heart valve calcification.
-42-
Microdamage and mechanical loading have an
interactive effect on remodeling signals produced
by osteocyte
Chao Liu1, Xiaoqing Zhang2, Michael Wu3, Lidan You1,4
Introduction: Microdamage in bone triggers remodeling with resorption and bone formation along the damage
site. However the cellular mechanism of the sensing of microdamage as well as the signaling to guide the repair
process is not well understood. Osteocytes are cells distributed throughout the bone. They have been observed
to be physically damaged by microdamage. Interestingly, microdamage-induced remodeling requires mechanical
loading in vivo. Since osteocytes are the mechanosensors of bone, they could react to mechanical loading at the
same time to microdamage. We hypothesize that osteocyte damaged by physical trauma similar to microdamage
would produce increased levels of remodeling-related molecules; and this response is mechanically regulated.
Methods: Osteocyte cell model: MLO-Y4 cells cultured (2.5% FBS/CS, 1% Pen/Strap) on glass slides.
Microdamage model: Cells were damaged by tungsten needles (1 µm tip) mounted on a frame with horizontally
travel, and adjustment of vertical position. The cell culture was damage to have ~15% dead cells. Cell damage was
assessed with Trypan Blue and Live/Dead assay.
Fluid shear stress treatment: parallel flow chambers were used to apply fluid shear stress to the cells. The flow
was oscillatory with sinusoidal profile at frequency of 1 Hz, and applied peak shear stress of 2 Pa to the cells for 1
hr.
Gene quantification: Total RNA was isolated from MLO-Y4 cells. Reverse transcription and real-time PCR was
used to measure IL-6, TNFα, COX-2, RANKL, and OPG mRNA levels, normalized to 18s.
Results: Significant number of dead cells was observed near the damage sites, ranges from 1-10 µm. COX-2 and
VEGF mRNA levels increased 24 hrs after cell damage. Other measured mRNA levels was not changed. Concurrent
fluid shear stress and physical damage induced higher COX-2 and VEGF mRNA level than the effect from each
individual stimulus.
Discussion: Using the cell damage system described here, the dead cell percentage relative to the distance to
damage site resembles fatigue loading in vivo. Microdamage has a time-dependent effect in osteocyte expression
of inflammatory and angiogenic genes. But osteocytes are not responsible for the changes in RANKL, OPG, IL-6,
TNF-α that were observed in fatigue damaged bone in vivo.
Significance: This study introduced a system that is able to induce sub-cellular damage. This study showed that
cellular mechanism in targeted bone remodeling to microdamage includes altered inflammatory and angiogenic
gene expression levels in osteocytes; and this response is sensitive to mechanical loading.
-43-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Division of Engineering
Science, University of Toronto; 3Department of Laboratory Medicine and Pathobiology, University of
Toronto; 4Department of Mechanical and Industrial Engineering, University of Toronto
1
The Planar Cell Polarity signalling pathway protein
Vangl1 depends on external cues to affect the
collective migration of endothelial cells
biomaterials, tissue engineering and regenerative medicine
Camila Londono1, Alison McGuigan1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Chemical Engineering and
Applied Chemistry, University of Toronto
1
The planar cell polarity (PCP) signalling pathway is well-known for enabling global organization of cells within the
Drosophila wing and for coordinating convergent extension movements during development. It has also been
implicated in coordinating collective cell migration in a number of specific systems. However, little is known
about how the PCP pathway actually influences cellular behaviour in a coordinated manner in a variety of
contexts. One theory is that the PCP pathway reinforces external cues to affect individual cells rather than
creating global coordinating signals. The purpose of this project is to study the synergy between PCP signalling
and external polarization cues in the context of collective endothelial cell migration. We chose to overexpress
and knockdown the PCP protein Van gogh-like1 (Vangl1) because its only known roles are in the PCP pathway, and
because it is the only homologue expressed in human umbilical vein endothelial cells (HUVEC). Our results show
that neither overexpression nor knockdown of Vangl1 affect the migratory properties of cells within undamaged
confluent monolayers or of sparsely seeded single cells, but that Vangl1 expression levels correlate with wound
closure rate in a scratch wound assay. This indicates that the environmental cues (eg. cell polarization and
elongation into wound site, free space, cellular damage) present in the wound healing assay are necessary for a
Vangl1 endothelial cell migration phenotype. We tracked cells at the wound edge and farther within the wound
and found that Vangl1 cells do not move earlier or faster than their wild-type counterparts, but that their motion
is more directed towards the wound. In view of that, we used a microgroove system to test whether cell
elongation is sufficient to enhance migration of Vangl1-overexpressing cells in confluent monolayers, and found
no changes in migratory properties. We also used a barrier method to determine the importance of cellular
damage to the PCP phenotype. Our results highlight the importance of environmental context to Planar Cell
Polarity signalling, and demonstrate that cells must be polarized for Vangl1 expression levels to affect their
migratory behaviour.
-44-
Conditioned medium from osteocyte-like cells
exposed to mechanical loading attracts breast
cancer cells
Yu-Heng Ma1, Lidan You1,2
Bone metastases, the spread of cancer from the primary site to bone, are common complications of many types
of cancers, with only 20% of patients alive five years after the discovery of bone metastases. It is estimated that
69% of patients died from breast cancer have developed bone metastases and that 350,000 people in the United
States die annually from bone metastases. Cancer cells have such destructive impact on bones due to their ability
to alter the bone remodeling process, leading to bone lesions. Yet, information on the relationship between bone
metastases and the key regulator of bone remodeling – osteocytes – is limited. Since osteocytes are characterized
as the mechanosensors of the bone that signals to reduce bone resorption in response to mechanical loading, this
study focuses on the effect of this response on bone metastasis development. This was done by exposing MLO-Y4
osteocyte-like cells to mechanical loading in the form of oscillatory fluid flow and culture MDA-MB-231 breast
cancer cells in the medium extracted from these flow experiments (conditioned medium; CM). MC3T3 osteoblasts
are used in this study as controls due to their known interaction with cancer cells. Migration of MDA-MB-231
cells towards the CM was assayed with Transwell assay. Viability of MDA-MB-231 cells in the presence of CM
was measured with trypan blue, apoptosis with APOPercentage, and proliferation with CyQuant. It was observed
that significantly more MDA-MB-231 cells migrated towards CM from MLO-Y4 cells with exposure to flow in
comparison to CM from MLO-Y4 cells not exposed to flow. The same trend was not shown in flow experiments
with MC3T3 nor in the control group of glass slides with no cells. Furthermore, the number of MDA-MB-231 cells
that migrated in conditioned medium from MLO-Y4 cells with exposure to flow was greater than conditioned
medium from all the other groups. The current data, although still with limited sample size, show no significant
difference between MDA-MB-231 cells viability, proliferation, and apoptosis rate cultured between any two
groups. However, there were trends (p-value<0.15) suggesting higher viability and lower apoptosis rate of MDAMB-231 cells in conditioned medium from MLO-Y4 cells exposed to flow in comparison to no flow. This suggests
that osteocytes subjected to mechanical loading can promote metastases. This gives insight on the potential
effects of exercises on patients suffering from cancers and further investigation on potential factors may provide
potential targets for bone metastases.
-45-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Mechanical and Industrial
Engineering, University of Toronto
1
A microfluidic system to study the interractions of
bone cells during mechanical stimulation
biomaterials, tissue engineering and regenerative medicine
Kevin Middleton1, Lidan You1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Mechanical
and Industrial Engineering, University of Toronto
1
Introduction: Most bone diseases are characterized by a disparity between bone loss and bone formation due to
an imbalance in osteoclast and osteoblast activity. Bone has long been known to be able to remodel, a process that
involves both osteoclasts and osteoblasts, to accommodate the loads under which it is placed; however, the
underlying mechanisms that link mechanical stress and bone remodeling have yet to be fully elucidated. A
third cell, the osteocyte, is an ideal candidate for driving mechanically stimulated bone remodeling because it
is a known mechanotransducer and is thoroughly distributed and well connected throughout the bone matrix.
However, current in vitro studies fail to elucidate the direct and dynamic effect of bone cell signaling in terms of
remodeling. Because of this, we have developed a microfluidic system to test the hypothesis that mechanically
unloaded osteocytes promote osteoclast precursor migration and differentiation.
Methods: A 2-channel microfluidic device was fabricated using PDMS. The channel dimensions are both 60µm
high, 1mm wide and 16mm long and are separated by 200µm long and 50µm wide high resistance side channels
to prevent cross-channel fluid flow while allowing for signal diffusion. To test the device, RAW 264.7 cells were
seeded into one of the channels at a cell density of 300k cells/ml while the other channel contained either a
control RAW cell media or media supplemented with 50ng/ml of RANKL. Over the course of 1 week the cells were
exposed to a perfusion flow of 1µl/min and were imaged daily to investigate cell migration and differentiation. At
the end of the week, the cells were TRAP stained to validate osteoclastogenesis.
Results: COMSOL modeling we performed on our system suggested that large proteins would be able to diffuse
through the side channel. This was validated when it was observed that precursor cell densities increased
preferentially closer to the RANKL channel. Similarly, multinucleated osteoclasts formed preferentially within the
vicinity of the RANKL channel as opposed to further along the width of the channel. For future studies we will use
a modified 3-channel system and seed in RAW cells between MLO-Y4 cells that are exposed to non-stimulatory
perfusion flow on one side, and 1Pa fluid flow on the other side. This will cause a mechanically induced chemical
gradient across the central channel so we can directly observe the dynamic effects of osteocyte-osteoclast
cross-talk.
-46-
Mechanics of collagen matrices from perspective of
adherent cells
Hamid Mohammadi1, Paul Janmey2, Christopher McCulloch1
The mechanical properties of extracellular matrices influence the ability of cells to sense and respond to
environmental cues but the impact of the inelastic properties of collagen gels and the effect of a rigid
underlying foundation on mechanosensation are not well-defined. We examined cellular mechanosensing by
measurement of projected cell area and collagen remodeling behavior of fibroblasts on thin attached gels
supported by a rigid foundation or floating collagen gels supported at their edges by nylon grids. Cells on
attached collagen gels showed no difference of surface area when plated on 1 or 3mg/ml collagen while the
surface area of cells on floating gels was ~40% less on 1mg/ml gels than 3mg/ml gels. Pericellular collagen fibers
were compacted and aligned by cells similarly on 1 or 3 mg/ml attached collagen gels. In contrast, collagen fibers
were 40% more aligned and compacted on 1mg/ml floating gels than 3mg/ml floating gels. Measurements of
compressive indentation showed that attached and floating collagen gels subjected to slow indentation (1μm/
min; similar rate as cell-mediated compaction) exhibited >5 fold larger irreversible deformation than fast
indentation (1 or 15μm/sec). While attached gels (1 or 3mg/ml) exhibited similar irreversible deformations at slow
indentations, floating gels of 1mg/ml exhibited ~30% more irreversible deformation than 3mg/ml collagen gels.
These data indicate that at the slow compaction rates exhibited by fibroblasts, the inelastic responses of collagen
gels, collagen concentration and the presence of an underlying foundation are important determinants of cellular
mechanosensation.
-47-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Matrix Dynamics Group, University of Toronto; 2Institute for Medicine and Engineering, University of
Pennsylvania
1
Designing an elastic scaffold with shape-memory
for functional tissue delivery
biomaterials, tissue engineering and regenerative medicine
Miles Montgomery1,2, Boyang Zhang1,2, Milica Radisic1,2
Chemical Engineering and Applied Chemistry, University of Toronto; 2Institute of Biomaterials and Biomedical Engineering, University of Toronto
1
This project revolves around developing a functional tissue patch that can be delivered in a minimally invasive
manner. The concept is that this tissue would possess the capability of deforming to fit through a small diameter
needle and regain its original shape once injected. A potential application that we envision is placing this patch
over an ischemic region of the heart to remuscularize and revascularize to reduce overall damage. An optimal
design has been identified with both shape-memory and anisotropic mechanical properties matching the rat
myocardium. Cardiomyocytes have successfully been cultured on the scaffolds and injected through a 1mm
orifice with minimal tissue damage. A novel photocrosslinkable bioadhesive has been synthesized that could be
used to adhere a patch onto the surface of a heart. Success of the proposed research would be the first
demonstration of minimally invasive functional tissue delivery.
-48-
ContextExplorer: exposing spatial organization of
phenotypic heterogeneity in human pluripotent
stem cell colonies
Joel E.E. Ostblom1, Emanuel J.P. Nazareth1, Peter W. Zandstra1
A growing body of evidence highlights population context as a major contributor to cellular phenotype and
heterogeneity within cell populations. This phenotypic heterogeneity can strongly influence experimental
outcomes, as has been shown in both mouse and human pluripotent stem cells (PSCs). However, the emergence
of spatial heterogeneity is poorly studied and may contain novel insights to microenvironmentally regulated cell
fate control mechanisms relevant to the stem cell niche in vivo. Given the strong relationship between population
context and cellular phenotype, we believe accessibility to user friendly software to measure
microenvironmental factors is paramount. To address this, we have developed ContextExplorer (CE), a standalone
application for post-processing data from cell image analysis software, with a focus on measuring population
context dependent variables, such as a cell’s position within a colony and its number of neighbors.
CE is open source, cross-platform compatible and has its full functionality accessible through a graphical user
interface. It identifies colonies in both patterned and unpatterned wells based on cell density, with filters for
marker intensity, colony size and shape. Both cell level (position, local cell density, etc.), colony level (colony size,
shape, etc.) and well level (media condition, total cell number, etc.) parameters are quantified for each cell. CE can
be used to expose correlations between these factors through a number of output analytics: superimposition of
colony images within the same condition, robustness measurements between conditions, scatter plot matrices of
measured parameters vs cellular phenotypes and quality pattern fidelity.
Analysis of patterned colony data has revealed cells at different developmental stages to display spatially
organized patterns of protein expression. The pluripotency markers Oct4 and Sox2 show the highest expression
at the center of human PSC colonies, and expression gradually decreases towards the colony border. By
classifying cells into three groups depending on their position within the colony (“center”, “ring” and “edge”), the
differences in protein expression between the three groups can be quantified. The Sox2 expression is on average
is 93 % higher in the center compared to along the edges of the colony and 36 % higher than among cells located
in a ring surrounding the center. Oct4 expression is 41 % higher in the center versus at the perimeter and 12 %
higher compared to the ring group. The phenomena of colony organization appears generalizable, as under other
conditions we observe similar phenotypic patterns. In conclusion, by using CE to analyze data from patterned
human PSC colonies, we observe spatial heterogeneity in expression of key pluripotency markers, which seem to
be organized in a population context dependent pattern of gradually decreasing expression towards the edge of
the colony.
-49-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto
1
The role of Toll-Like Receptors in cardiac
regeneration mediated by human bone marrowderived mesenchymal stromal cells (MSCs).
biomaterials, tissue engineering and regenerative medicine
Iran Rashedi1,2, Xing-Hua Wang2, Sowmya Viswanathan2, Milica Radisic1, Armand Keating1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Cell Therapy Program, Princess Margaret Cancer Centre, University Health Network
1
Mesenchymal Stromal Cells (MSCs) are promising candidates for cell therapy and tissue regeneration due to
several properties including immunomodulatory/anti-inflammatory effects. Toll-like receptors (TLRs), known for
their role in innate immunity, are expressed by various cell types and are involved in the pathogenesis of
cardiovascular diseases. Several TLRs are highly expressed on hMSCs and can affect their differentiation,
migration, immunosuppressive and therapeutic properties. The results of studies on the role of TLRs in cardiac
tissue regeneration, however, are limited and inconsistent. We previously showed that the capacity of human
MSCs to express cardiac-specific proteins was enhanced in cells cultured on collagen scaffolds (3D) versus grown
on culture plates (2D). We also showed that the capacity of hMSCs to undergo cardiac lineage reprogramming
was not affected by activation of TLR2-4. Here, we investigated the effect of TLR2-4 on the immune properties of
hMSC and remodeling of extra cellular matrix (ECM). We grew non-activated and TLR-activated hMSCs in 2D and
3D cultures as well as with or without co-culture with rat neonatal cardiomyocytes (rCM). We showed
differential expression of various cytokines including IL6, IL8, IP10 and RANTES in hMSCs cultured in 2D versus
3D with reduced cytokine production by hMSCs cultured on collagen scaffolds. Co-culturing with rCMs, however,
did not affect the cytokine production by hMSCs. IDO mRNA up-regulated only after TLR4 activation and was
significantly lower in 3D-cutlured hMSCs as well. In co-culture with human peripheral blood mononuclear
cells (PBMCs), 3D-cultured hMSCs did not affect the proliferation of PBMCs even after treatment with TLR4specific ligand (LPS) and interferon gamma whereas 2D-cultured hMSCs suppressed the proliferation of PBMC
by more than 50%. Our data also showed that 2D-cultured hMSCs decreased the viability of PBMCs whereas in
3D-cultured hMSCs, only TLR4-activated hMSCs decreased the viability of PBMCs although not as significantly as
their 2D counterparts. Our data showed down-regulation of Notch receptor and ligands in 3D-cultured hMSCs.
We also showed differential expression of several trophic factors including IGF, BMP4, Activin-A and VEGF in 2Dversus 3D-cultured hMSCs. We did not find any difference in the expression of ECM markers by rCMs co-cultured
with hMSCs, TLR-activated or not. In summary, we showed that TLR activation affects the immune phenotype of
hMSCs in a culture-dependent manner. Our data suggest that reduced response to TLR activation in 3D-cultured
hMSCs is a result of down-regulation of Notch signaling. Our data suggest that ECM remodeling and TLRmediated cardiac regeneration by hMSCs needs to be investigated in the context of tissue injury. Our
observations have implication for cardiac regeneration mediated by TLR-activated hMSCs and the search for
more effective MSC subsets.
-50-
Developing an in vitro model of the interface
between the annulus- cartilage endplate
Elisabeth Rok1, J. Paul Santerre1,2, Rita Kandel3
Purpose: Although biological disc replacement is an area of intense investigation, little is known about how
integration will occur upon implantation. The purpose of this study was to generate an in vitro model of the outer
annulus fibrosus (OAF)/ cartilage endplate (CEP) interface to investigate if integration can happen and to
characterize the interface.
Methods: Deep zone chondrocytes were isolated from bovine articular cartilage and grown on membrane
inserts to form cartilage tissue (CEP). OAF cells were isolated from bovine caudal spine and seeded on
multilayered nanofibrous polycarbonate urethane (PU-ADO) scaffolds. A 3-dimensional model of the OAF-CEP
interface was created by contact co-culture of these tissues. Tissue was analyzed histologically and biochemically.
Results: AF cells were seen between and within layers of the PU-ADO scaffold, aligned parallel to the nanofibers.
Chondrocytes formed mineralizing cartilage. These tissues when placed in co-culture and fused to form an in
vitro model of the AF-CEP. Calcific deposits and alkaline phosphatase activity (ALPa) were observed in the
chondroid region. Significantly more proteoglycans and collagen was accumulated at the interface as compared
to independently cultured AF tissues. The spatial organization of collagen type II, versican, decorin and mineral in
the interface model was similar to the in vivo bovine interface and differed from the distribution observed when
these tissues were grown alone.
Conclusion: This study demonstrated that AF tissue and cartilage can form an interface model in contact coculture. Additional studies are ongoing to further characterize this interface to better understand the tissue
engineering process.
-51-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Faculty of Dentistry,
University of Toronto; 3Bioengineering of Skeletal Tissues Team, Lunenfeld Tannenbaum Research Institute,
Mount Sinai Hospital
1
The effect of simulated human salivary enzymes
and matrix metalloproteinase (MMP) inhibition on
the degradation and fracture toughness of the selfetched resin-dentin interface
biomaterials, tissue engineering and regenerative medicine
Kyle Serkies1, Laura Tam2, Grace De Souza2, Yoav Finer1,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Restorative Dentistry, Faculty of Dentistry, University of Toronto; 3Faculty of Dentistry, University of Toronto
1
Background: Human salivary and bacterial esterases catalyze the hydrolytic degradation of ester bonds within
the methacrylate-based monomers of resin composites and adhesives. Degradation of the resin-dentin interface
compromises its structural integrity and allows for ingress of cariogenic bacteria and the formation of biofilms
within the interface, increasing the risk for recurrent caries, a major reason for restoration failure. Autodegradation of the dentin’s collagen fibers by intrinsic matrix metalloproteinases (MMPs) further contribute to
interfacial degradation.
Objective: To assess the effect of simulated human salivary esterases (SHSE) and MMP inhibition on the
biostability and fracture toughness (FT) of the self-etched resin-dentin interface.
Materials and Methods: Mini short-rod FT specimens (N=10/group) containing a resin composite (Z250) bonded
to human dentin using a self-etch adhesive (EasyBond) were prepared with and without application of the MMP
inhibitor (galardin). Specimens were non-incubated or incubated in either phosphate buffered saline (PBS) or
SHSE for 7, 30, or 90 days. Incubation media was analyzed by high performance liquid chromatography (HPLC) for
the presence of a BisGMA-derived degradation product, Bis-hydroxy-propoxy-phenyl-propane (BisHPPP); FT data
was obtained using a Universal Testing Machine (Instron); and fractographic analysis was performed by scanning
electron microscopy and the image processing software ImageJ. Statistical analysis was performed by ANOVA and
Tukey HSD tests.
Results: There was no difference in FT for the different incubation periods and conditions (PBS vs. SHSE; galardin
vs. no galardin). The amount of BisHPPP was higher for specimens incubated with SHSE vs. PBS (p<0.05).
Specimens incubated for 30 and 90 days, regardless of incubation condition, failed more frequently in the resin
bulk vs. a mixed failure in the resin bulk and resin-dentin interface as seen in the 0 and 7 day groups (p<0.05).
Conclusions: Initial HPLC results confirm that SHSE significantly accelerates the biochemical degradation of
self-etched resin-dentin specimens. The more frequent occurrence of 30 and 90 day incubated specimens failing
in the resin bulk vs. resin-dentin interface and the lack of significant change in FT suggest that degradation of the
composite resin is more dominant than degradation of the interface, at least at these early time periods. Longer
incubation periods are required to correlate these effects with the restoration’s clinical performance.
Grant: CIHR-MOP115113.
-52-
A compartmental probabilistic model of
heterogeneity in reprogramming to pluripotency
Nika Shakiba1, Wenlian Qiao1, Carl A. White1, Ayako Yachie-Kinoshita1, Peter D. Tonge2, Andras
Nagy2, Peter W. Zandstra1,3
Induced Pluripotent Stem (iPS) cells are pluripotent stem cells generated through a somewhat poorly-defined
multi-step process. A better understanding of the cellular dynamics in reprogramming to pluripotency could
impact their suitability for regenerative medicine applications. It has been suggested that cells experience unique
latencies when reprogramming (Hanna et al., Nature, 2009), thus resulting in a heterogeneous mixture of cells
positioned at differing reprogramming stages. An investigation of the existence and kinetics of emerging
subpopulations in the reprogramming pool is necessary. Here, two complementary mathematical models are used
to examine this heterogeneity. Firstly, deconvolution strategies are used to predict the cellular composition of the
reprogramming population. This analysis suggests the contribution of a distinct and uncharacterized “partially
reprogrammed” subpopulation. Subsequent validation via flow cytometry is used to characterize the emergence
of this predicted subpopulation. Next, a compartmental, probabilistic model of reprogramming aims to elucidate
the kinetics of these heterogeneous populations and models reprogramming as a process in which unspecialized
cells transition between “partially reprogrammed” stages to reach a final iPS cell state. This model is applied to
time course data collected from the reprogramming of secondary MEF DOX-inducible cells. Using a genetic
algorithm, the model predicts experimentally inaccessible parameters of the system. Subsequent application of
these system parameters to single cell simulations allows for analysis of stochastic cell behaviour, thereby
explaining experimental variability. Thus, the complementary modeling strategies introduced here describe the
emergence and dynamics of intermediate reprogramming stages, allowing these subpopulations to be targeted
experimentally for further analysis.
-53-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Samuel Lunenfeld Research
Institute, Toronto; 3McEwen Centre for Regenerative Medicine, Toronto
1
The development of a shape memory polymer blend
foam for biomedical and clinical applications
biomaterials, tissue engineering and regenerative medicine
Janice Song1, Ijya Srivastava2, Jennifer Kowalski2, Hani Naguib1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Materials
Science and Engineering, University of Toronto; 3Department of Industrial and Mechanical Engineering,
University of Toronto
1
Shape memory polymers (SMP) are a class of stimuli-responsive materials that are able to respond to external
stimulus such as heat by altering their shape. Bio-compatible SMPs have a number of advantages over static
materials and are being studied extensively for biomedical and clinical applications (such as stents and scaffolds).
Previous studies have shown that polymer blends have improved mechanical properties compared to pure
polymers. In this study, the mechanical and thermo-mechanical (shape memory) properties of thermoplastic
polyurethane (TPU) and poly-lactic acid (PLA) SMP blends were characterized; the compositions studied were
80/20, 65/35, and 50/50 TPU/PLA. The TPU/PLA bio-compatible SMP blend was fabricated with melt-blending
and compression molding. The glass transition temperature (Tg) of the SMP blends was determined with a
differential scanning calorimeter (DSC). The mechanical properties studied were the stress-strain behavior,
tensile strength, and elastic modulus; and the thermo-mechanical (or shape memory) properties studied were the
shape fixity rate (Rf), shape recovery rate (Rr), response time, and the effect of recovery temperature on Rr. The
morphology of the polymers was characterized with a scanning electron microscope (SEM). In addition, porous
TPU/PLA SMP blends were fabricated with a gas-foaming technique; and the morphology of the porous
structure of these SMPs foams were characterized with scanning electron microscopy (SEM). The porous 80/20
PLA/TPU SMP blend was found to have the highest tensile strength, toughness and percentage extension, as well
as the lowest density and uniform pore structure in the micron and submicron scale. The porous 80/20 TPU/
PLA SMP blend may be further developed for specific biomedical and clinical applications where a combination of
high tensile strength, toughness, and low density are required.
-54-
Enhancement of nerve regeneration through neural
allografts and after delayed repair with controlled
release of neurotrophic factors
Kasra Tajdaran*1,2, Matthew D Wood1,2, Molly S. Shoichet1,2, Tessa Gordon2,3, Gregory H Borschel1,2,3
Despite the substantial improvement of microsurgical techniques for nerve repair, recovery after nerve injury
in the peripheral nervous system (PNS) is usually incomplete. Delays in treatment further compromise recovery
because of the diminished capability of neurons to regenerate their axons to their end-organs and reduced
neurotrophic factor availability from the progressively denervated Schwann cells in the growth pathway of the
distal nerve stump. The condition is exacerbated after placement of grafts to bridge nerve gaps, a common
practice in human nerve repair and modifications are required to obtain better regeneration using nerve grafts.
Recently, surgeons have been using acellular nerve grafts to bridge nerve gaps in humans, but these grafts lack
neurotrophic factors and therefore do not support regeneration to the same extent as autografts. Application of
exogenous neurotrophic factors such as glial cell line derived neurotrophic factor (GDNF) was shown to have a
positive effect on neuron survival and axon regeneration under conditions where endogenous supplies decline
with time. Our group has developed a drug delivery system, composed of drug-loaded poly(lactic-co-glycolic
acid) (PLGA) microspheres (MS) embedded in a fibrin gel, which serves to localize the microspheres around the
nerve injury site and allows sustained drug release.
We hypothesize that microspheres will deliver sufficient quantities of GDNF to promote axon regeneration
following delayed nerve repair and through a nerve graft. Our objective is to develop and optimize a clinically
applicable biodegradable delivery system to enhance PNS regeneration. In order to determine whether delivery
of GDNF from MSs enhances PNS regeneration, common peroneal (CP) nerves in rats are transected and ligated
to muscle for 2 months to chronically axotomize neurons and denervate Schwann cells. The denervated stumps
are then directly repaired with the implantation of a drug delivery system containing GDNF encapsulated MSs at
the repair site. Another experimental group will undergo transection and immediate grafting of a CP nerve gap
using an acellular nerve graft, while the drug delivery system will be placed around the injured CP nerves and the
allografts. We expect that GDNF will indeed enhance axon regeneration. Results from this project will provide a
mean of improving nerve allografts with MS-delivered neurotrophic factors, which can lead to an improvement in
“off the shelf” alternatives in the current management of severe nerve injuries.
-55-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Division of Plastic and
Reconstructive Surgery, The Hospital for Sick Children; 3Division of Plastic and Reconstructive Surgery,
Department of Surgery, University of Toronto
1
Characterization and validation of a 3D PEG-NB
screening platform for improved MSC based heart
valve tissue engineering
biomaterials, tissue engineering and regenerative medicine
Jenna Usprech1, Craig Simmons1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Mechanical and Industrial
Engineering, University of Toronto
1
Background: Substrate properties (physical and biochemical) as well as external mechanical and soluble
chemical cues are important microenvironmental factors for directing the differentiation of bone marrow
mesenchymal stromal cells (bmMSCs) in vitro. In recent years, microculture platforms have been developed to
apply select combinations of these factors in 2D for the purpose of heart valve tissue engineering. However, the
integration of environmental factors in 3D culture has yet to be appropriately considered, despite being necessary
for functional valve tissue development.
Objectives: To characterize and validate a 3D screening platform that enables the combinatorial assessment of
chemical and stiffness factors affecting bmMSC viability, morphology and differentiation to a valve phenotype.
Methods: Human bmMSCs were encapsulated in 4 – 11 wt% (5 – 30 kPa) polyethylene glycol norbornene
(PEG-NB) hydrogels and were cultured for 1 week. Viability and morphology of bmMSCs were assessed as a
function of polymer wt% and RGD concentration using factorial design of experiments. Separately, the effect of
polymer wt% on the promotion of a valve phenotype (indicated by enhanced α-SMA staining) was investigated by
supplementing media with 5 ng/mL TGF-β1 for 1 week.
Results: Factorial central composite designs were able to effectively model the viability and morphology
responses, demonstrating an optimal wt% and RGD concentration for maximal viability and spread morphology.
The intensity of α-SMA staining was observed to significantly increase 2.2 and 1.3 fold in response to TGF-β1
treatment in 7.5 and 10.3 wt% PEG-NB gels, respectively.
Significance: This study highlights the characterization of a novel platform with which to culture bmMSCs in a
more physiological, 3D simulated valve environment. This generalizable approach and platform could be
extended to other tissues types for broader impact.
-56-
In vitro degradation and physical characterization
of antimicrobial electrospun scaffolds with aligned
fibers
Meghan Wright1, Meilin Yang2, Paul Santerre1,2
Background: Electrospun scaffolds may be used to create tissue engineered constructs for the regeneration of
the gingival connective tissues that are destroyed during the progression of periodontal disease. However, the
use of a synthetic material in the infectious oral environment has the potential to lead to a biomaterial-associated
infection.
Objective: To incorporate a proprietary antimicrobial polymer containing ciprofloxacin (CF) into aligned
electrospun nanofiber scaffolds and characterize the scaffolds’ properties. It is hypothesized that the
antimicrobial polymer will promote a uniform distribution of drug in the scaffolds such that as the antimicrobial
polymer and scaffold degrade by hydrolysis, there will be a sustained release of antibiotic.
Methods: The antimicrobial polymer was incorporated into degradable polyurethane via blend electrospinning
at concentrations corresponding to 7 and 15wt% CF with respect to the polyurethane. Scaffolds with 15wt% CF
HCl were also fabricated. The fiber morphology was investigated using scanning electron microscopy (SEM), and
the distribution of CF in the fibers was imaged using confocal light microscopy. Scaffold physical properties were
characterized via attenuated total reflectance Fourier transform IR spectroscopy (ATR-FTIR), differential
scanning calorimetry (DSC), and tensile testing. Scaffold degradation and antimicrobial release studies were
carried out in an in vitro chemical hydrolysis model.
Results: There was greater surface roughness on the fibers of scaffolds made with CF HCl when compared
to scaffolds with antimicrobial polymer. Antimicrobial polymer scaffolds showed a uniform distribution of CF
throughout the fibers, while scaffolds with CF HCl showed aggregated CF in the fibers and on the surface of the
fibers in clumps. Hydrogen bonding between the polyurethane and CF molecules yielded significant changes in
inter-urethane hydrogen bonding surface chemistry (p < 0.05), however there was no detectable change in the
scaffold microstructure. The tensile strength and elastic modulus of the scaffolds were not significantly altered
relative to the control scaffold. At 7 days, the 7wt% scaffolds had a cumulative release of 7.37 ± 0.87% of the total
loaded antimicrobial polymer, while the 15wt% scaffolds had released 80.19 ± 11.94% (n = 3 ± SD). The scaffolds
with 15wt% CF HCl released 96.14 ± 9.83% of the loaded antimicrobial within 1 hour, while the scaffolds with
15wt% antimicrobial in polymeric form had released 24.27 ± 3.59%.
Conclusions: Preliminary results reveal that the release of antimicrobial containing compounds is highly
dependent on the form (polymeric molecule or non-polymeric CF HCl), and on the concentration loaded into the
fibers.
Acknowledgements: Interface Biologics Inc. for consulting support on polymer characterization. NSERC Synergy
grant #430828. NSERC CGS M. Milligan Scholarship.
-57-
scientific2014
day
IBBME
biomaterials, tissue engineering and regenerative medicine
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Faculty of Dentistry,
University of Toronto
1
Automated multidimensional image analysis reveals
a role for Abl in embryonic wound repair
biomaterials, tissue engineering and regenerative medicine
Teresa Zulueta-Coarasa1, Rodrigo Fernandez-Gonzalez1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Cell and
Systems Biology, University of Toronto; 3Developmental and Stem Cell Biology Program, The Hospital for
Sick Children, Toronto
1
The embryonic epidermis displays a remarkable ability to rapidly repair wounds with no scarring, by contrast
with adult wound healing, which is slow and often leads to scar formation. Embryonic wound repair is driven by
the redistribution of cytoskeletal and junctional proteins around the wound. However, the molecular mechanisms
that regulate this protein redistribution are not well understood. The conserved nature of the molecular
rearrangements associated with embryonic wound repair has allowed the use of model organisms, such as
Drosophila, to screen for factors implicated in wound closure. However, genetic screens have been limited by the
use of manual analysis methods. We introduce MEDUSA, a novel image analysis tool for the automated
quantification of wound closure and molecular dynamics from time-lapse confocal microscopy data. We use
snakes, an algorithm in which a contour evolves on an image to minimize an energy related to its curvature and
the local image intensity. The contour stops in areas where large intensity changes occur, such as the wound
margin. We used Dijkstra’s method to refine the results of snakes by finding the brightest path that connects
consecutive contour points. The final contour was used to initialize the snakes algorithm in the next time point.
We validate our algorithm quantifying wound closure dynamics in Drosophila embryos, and we show that the
results of our automated analysis are comparable to manual delineation and tracking of the wounds, while
significantly reducing the processing time. We apply MEDUSA to identify GFP-fused molecules that localize
around epidermal wounds in Drosophila embryos. We find that the conserved non-receptor tyrosine kinase
Abelson contributes to rapid embryonic wound closure. We demonstrate that Abelson plays a role in the
redistribution of the junctional protein β-catenin at the wound margin during embryonic wound repair. We
propose that Abelson can regulate adhesion dynamics during wound repair 1) through tyrosine phosphorylation
to promote β-catenin turnover and the disassembly of junctions between wounded and adjacent cells; and 2)
regulating actin organization around the wound to promote contractile forces and growth of mechanosensitive
cadherin-catenin complexes at discrete points of contact between cells adjacent to the wound.
-58-
Poster Presentation Abstracts
-59-
scientific2014
day
IBBME
nanotechnology, molecular imaging and systems biology
Nanotechnology, Molecular Imaging and Systems Biology
Wavelength modulated differential photoacoustic
spectroscopy (WM-DPAS) for ultrasensitive
quantitative hemoglobin concentration and
oxygenation monitoring in soft tissues
Sung soo (Sean) Choi Choi1, Bahman Lashkari2, Xinxin Guo2, Andreas Mandelis1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Mechanical
and Industrial Engineering, University of Toronto
nanotechnology, molecular imaging and systems biology
1
In the field of medical diagnostics, biomedical photoacoustic (PA) imaging is a non-invasive hybrid opticalultrasonic imaging modality. Due to the unique hybrid capability of optical and acoustic imaging, PA imaging
has risen to the frontiers of medical diagnostic procedures such as human breast cancer detection. While
conventional PA imaging has been mainly carried out by a high-power pulsed laser, an alternative technology,
Frequency Domain Biophotoacoustic Radar (FD-PAR) is under intensive development. It utilizes a continuous
wave optical source with the laser intensity modulated by a frequency-swept (chirped) waveform for acoustic
wave generation. The small amplitude of the generated acoustic wave is significantly compensated by increased
signal-to-noise ratio by several orders of magnitude using matched-filter correlation processing in a way similar
to radar systems.
The current study introduces a novel FD-PAR modality for ultra-sensitive characterization of functional
information for breast cancer imaging. Wavelength-modulated differential PA spectroscopy (WM-DPAS) detection
has been developed to address angiogenesis and hypoxia monitoring, two well-known benchmarks of breast
tumor formation. Based on WM-DPAS theory, this modality efficiently suppresses background absorptions
and is expected to detect very small changes in total hemoglobin concentration and oxygenation levels,
therefore identifying pre-malignant tumors before they are anatomically apparent. Preliminary single-ended
laser experimental results were compared to a developed theoretical formalism. More extended differential
measurements using two wavelength-modulated lasers (~680nm and ~800nm) are being investigated and will
be reported for the sensitive assessment of the total hemoglobin concentration and oxygenation level, thus
indicating the health state of the biological tissues.
-60-
Colloidal drug formulations can explain “bellshaped” concentration-response curves
Ahil Ganesh1,2, Shawn Owen1,2, Allison Doak3, Lyudmila Nedyalkova3, Christopher McLaughlin1,2,
Brian Shoichet3,4, Molly Shoichet1,2,4
Department of Chemical Engineering and Applied Chemistry, University of Toronto; 2Institute of
Biomaterials and Biomedical Engineering, University of Toronto; 3Department of Pharmaceutical
Chemistry, University of California-San Francisco; 4Department of Chemistry, University of Toronto
1
To help determine a mechanism for the loss of cytotoxic activity in colloidal formulations, we studied the diffusion
of colloidal and monomeric formulations of Evans blue dye across cell membranes. Evans blue dye monomers
are able to diffuse into healthy cells while dye colloids are excluded. However, upon membrane permeabilization
both colloidal and monomeric formulations are able to diffuse into cells. This suggests that the loss of activity in
colloidal formulations is due to colloids being physically unable to enter cells.
Just as colloids introduce false-positive signals in high-throughput screening, they can introduce false-negative
results in cellular assays. Being aware of this artifact, the introduction of small amounts of detergent can break up
colloids and return agents to an active state.
The authors are grateful for the funding provided by the U.S. National Institutes of Health and the Natural
Sciences and Engineering Research Council of Canada.
-61-
scientific2014
day
IBBME
nanotechnology, molecular imaging and systems biology
Many hydrophobic small molecule drug candidates have been found to form colloids at micromolar
concentrations, with diameters ranging from 100-1000 nm. These colloids bind proteins to their surface leading
to nonspecific enzyme inhibition and false-positives in the high-throughput drug discovery process. Colloid
formation is governed by the critical aggregation concentration (CAC). Below the CAC, the compound exists as
free drug monomers while above the CAC these monomers aggregate into colloids. This process is reversible and
the addition of nonionic detergents, such as polysorbate 80, can disrupt colloid formation.
We have shown that a number of clinically approved anticancer drugs form colloidal aggregates. Drug colloids
have been found to form in both normal cell culture media and other biological media such as simulated gastric
and intestinal fluids. Here, we studied three clinically approved anticancer drugs that form colloids: fulvestrant,
sorafenib and crizotinib. We demonstrate that in colloidal formulations these drugs lose their cytotoxic activity.
These colloid-forming compounds exhibit bell-shaped concentration-response curves, losing their activity at
concentrations greater than their respective CACs. However, in monomeric formulations they are active, leading
to typical sigmoidal concentration-response curves.
Cytoskeletal dynamics and coordinated cell
behaviors during Drosophila embryonic wound
repair
Anna Kobb1,2, Rodrigo Fernandez-Gonzalez1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2The Hospital for Sick
Children; 3Cell and Systems Biology, University of Toronto
nanotechnology, molecular imaging and systems biology
1
Cell coordination is critical in tissue assembly and repair and has been implicated in metastasis. Embryonic
wound repair is a conserved morphogenetic process in which the cells adjacent to the wound coordinate their
migratory behaviors. Cells adjacent to an embryonic wound accumulate filamentous actin and the motor protein
non-muscle myosin II at the interface with the wounded cells. This results in the assembly of a contractile,
supracellular, cable-like structure around the wound that acts as a purse string to drive wound repair. However,
the mechanisms by which actin and myosin are recruited to the wound margin are not well understood. We
are using ultraviolet laser ablation to create wounds in the Drosophila embryonic epidermis, and Fluorescence
Recovery After Photobleaching (FRAP) to quantify protein dynamics at the wound margin during purse string
assembly and contraction. Using these methods I found that myosin is stabilized at the wound margin, as shown
by increased recovery time compared to myosin in cell interfaces away from the wound. In addition, as the
purse string contracts, myosin fluorescence increases significantly, suggesting that the purse string contracts
by condensation. We are using genetic and molecular manipulations to identify novel regulators of actomyosin
purse string assembly. Understanding the mechanisms of actomyosin purse string assembly will contribute to
the understanding of coordinated cell behavior, and may provide strategies for the pharmacological treatment of
metastatic disease.
-62-
Engineering red blood cell progenitors with an
inducible self renewal gene to achieve creater
proliferative potential
Steven Mayers1,2, Julie Audet1,3
Institute for Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Chemical
Engineering and Applied Chemistry, University of Toronto; 3Faculty of Medicine, University of Toronto
1
-63-
scientific2014
day
IBBME
nanotechnology, molecular imaging and systems biology
The ability to manufacture red blood cells (RBCs) for clinical blood transfusions would benefit patients and blood
donors worldwide. Currently most RBC transfusion units come from donor blood which has variable supply, and
can have pathogens. Being able to produce RBCs in vitro would allow for well characterized universal donor type
RBC units to be available in hospitals and clinics under any demand situation without the need for donations.
Recent progress has shown that RBCs can be produced from their respective progenitor cells in vitro, and also
from their more primitive stem cell sources. These approaches have fallen short from clinical application due to
limited proliferation of progenitors and low efficiencies of sequential differentiation steps from stem cells. To
achieve an economically viable production process, an integrated inducible transcription factor that stimulates
controlled proliferation of RBC progenitors is being explored. In this approach extensive proliferation of RBC
progenitor cells occurs before terminal differentiation into RBCs. The genetic engineering of the progenitor
cells is achieved using non-replicating lentiviruses engineered to deliver an inducible gene expression system
to primary cells. Applying genetic engineering to control cell proliferation is particularly applicable to RBC
production since the RBC progenitor cell extrudes it’s nucleus during terminal differentiation removing the
integrated transgene and the ability to proliferate. This process for producing RBCs would be efficient, scalable
and suitable for clinical translation.
Characterizing transcription factories between stem
cells and differentiated cells with super- resolution
localization microscopy
Nafiseh Rafiei1,2, Amir Mazouchi2, Joshua N. Milstein1,2
Institute for Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Chemical
and Physical Sciences, University of Toronto Mississauga
nanotechnology, molecular imaging and systems biology
1
A stem cell has the potential to transform into almost any cell type found in the body. One of the great challenges
of modern biomedical engineering is to understand how differential RNA transcription determines the fate of
stem cells, so that this fate can be controllably altered and/or engineered. There is strong evidence suggesting
that genes migrate to preassembled subnuclear units called transcription factories that are essentially clusters
of active RNA Polymerase II and other transcriptional components. The estimated size of a transcription factory
varies between 40-200 nm, which is beyond the reaches of conventional light microscopy. In this study, we
will quantitatively map, count and measure the size of the active transcription factories in mouse embryonic
stem cells and correlate these results with observations in differentiated cell lines. In conjunction with
immunofluorescence labeling, we use direct stochastic optical reconstruction microscopy (dSTORM), which can
circumvent the diffraction limit and resolve fine structures as small as ~20 nm.
-64-
CT landmark-based semi-automated mesh
morphing and mapping techniques: generation of
patient specific models of the human pelvis without
segmentation
Zoryana Salo1, Maarten Beek2, David Wright2, Cari Whyne2
Institute of Biomaterials and Biomedical Engineering, Univeristy of Toronto; 2Sunnybrook Research
Institute
1
Method: Traditional methods were used to create two CT based specimen-specific pelvic FE models which served
as the source mesh and target model respectively. To generate a specimen specific FE model of the target pelvis
using the new technique, the source mesh was morphed to landmarks placed directly onto the target CT scan.
Landmark placement was applied initially based on the work of Boulay et al. 2006 and subsequently optimized
to reduce the number of landmarks required. Ligamentous and cartilaginous structures morphed along with the
skeletal elements in the model. The morphed model was further refined through mesh mapping in which surface
nodes were moved until they reached a set threshold intensity value. The source model, target model (generated
using traditional segmentation and meshing techniques), and auto morphed/mapped target model were all
loaded through the fifth lumbar vertebra to 345 N in axial compression. The two FE models (target and morphed/
mapped) were solved using non-linear static FE analysis (Abaqus). Strains generated in the morphed/mapped
model were compared to the traditionally segmented target model, as well as to experimental data.
Results: The new CT based morphing/mapping technique efficiently generated a specimen-specific pelvic FE
model that was able to recreate the target model strain patterns. The algorithm required approximately an hour
to complete on a standard PC. A voxel-wise paired t-test demonstrated that all axial and shear strains between
the target and morphed/mapped models were not significantly different (t<1.96, p>0.05 for all). The strains
obtained from the morphed/mapped model correlated well (R2 = 0.95) with experimental strains.
Conclusion: A landmark-based semi-automated mesh morphing and mapping method was successfully applied
to geometrically reconfigure a specimen-specific pelvic source mesh onto a target CT scan to generate a
new specimen-specific FE model without any segmentation of the target CT data set. The application of semi
automated morphing and mapping techniques to complex skeletal structures will considerably enhance the
capability of generating multiple specimen-specific FE models that can produce clinically relevant information
about the pelvis and other multifaceted skeletal structures.
-65-
scientific2014
day
IBBME
nanotechnology, molecular imaging and systems biology
Purpose: The complex geometric, material property and loading conditions of the pelvis motivates the use of
advanced computational modeling methods (finite element (FE) analysis) to describe its behaviour. Generating
an FE model of the human pelvis has been a labour intensive process requiring a high level of user intervention
and time (segmentation, surface generation, meshing and optimization). This study presents a new landmarkbased semi-automated mesh morphing and mapping algorithm to generate specimen-specific FE models of the
human pelvis directly from specimen-specific CT scans without the use of segmentation and validates it against
experimental data.
The role of ligand density and size in mediating
quantum dot nuclear transport
Peter S. Tang1, Sarmitha Sathiamoorthy2, Lindsay Lustig3, Romina Ponzielli3, Ichiro Inamoto2,
Linda Penn3, Jumi Shin2, Warren C.W. Chan1
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of Chemistry,
University of Toronto; 3Department of Medical Biophysics, University of Toronto
nanotechnology, molecular imaging and systems biology
1
There is a tremendous interest in studying the effects of the physico-chemical properties of nanomaterials on
cellular uptake, toxicity, and exocytosis. These findings provide the foundation to design safer and more effective
nanoparticles for clinical applications. However, an understanding of the effects of these properties on subcellular transport, accumulation and distribution remains limited. Here, the present study investigates the effects
of surface density and particle size of semiconductor quantum dots on cellular uptake as well as nuclear transport
kinetics, retention, and accumulation. The current work illustrates that cellular uptake and nuclear accumulation
of nanoparticles depends on surface density of the nuclear localization signal (NLS) peptides, but the nuclear
transport reaches a plateau at 20% surface NLS density in as little as 30 minutes. These intracellular nanoparticles
have no effects on cell viability up to 72 hours post treatment. These findings will set a foundation for engineering
more sophisticated nanoparticle systems for imaging and manipulating genetic targets in the nucleus.
-66-
Structural studies of septin protein assemblies by
direct stochastic optical reconstruction microscopy
Adriano Vissa1,2, Theodore Pham1, William S. Trimble1, Peter K. Kim1, Christopher M. Yip1,2,3
Department of Biochemistry, University of Toronto; 2 Department of Chemical Engineering and Applied
Chemistry, University of Toronto; 3Institute of Biomaterials and Biomedical Engineering, University of
Toronto
1
-67-
scientific2014
day
IBBME
nanotechnology, molecular imaging and systems biology
Septins belong to a family of GTP-binding proteins that are thought to have various functions in mammalian cells
including acting as scaffolds for protein recruitment, forming diffusion barriers in primary cilia, and participating
in cytokinesis. These proteins, sometimes referred to as the fourth cytoskeletal component in part due to
their colocalization with F-actin, assemble into homo- and hetero-oligomers such as the SEPT7-SEPT6-SEPT2
complex. This complex has been shown to form the symmetrically arranged hexamer SEPT7-SEPT6-SEPT2SEPT2-SEPT6-SEPT7, with recent evidence pointing to the association of SEPT 9 at either end of the hexamer.
These filamentous building blocks are thought to form higher-order assemblies such as bundles and upon
actin depolymerisation, dissociate from actin to form characteristic ring structures. The organizational motif
by which this assembly takes place is not currently well understood. To address this question, we use dSTORM
(direct Stochastic Optical Reconstruction Microscopy), a single molecule localization-based approach to resolve
diffraction-limited fluorescent signals in both space and time, with a theoretical lateral resolution of 20 nm and
axial resolution of 50-70 nm. We report here the development and implementation of the dSTORM imaging
technique on a combinatorial TIRF/confocal/AFM platform. Two-colour dSTORM imaging was performed
by labelling F-actin/SEPT2 and SEPT2/SETP9 in human fibroblast cells using ATTO 488 and AlexaFluor 647,
with and without the presence of an actin depolymerising drug. The combinatorial diversity and higher-order
structural assembly of septins are likely directly related to their specialized cytoskeletal functions and versatility.
Therefore, a molecular scale investigation of the structural complexities of these proteins could lead to a better
understanding of their cellular roles.
Quantifying cell division orientation during axis
elongation in Drosophila
Rodrigo Fernandez-Gonzalez1, Michael Wang2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Engineering Science,
University of Toronto
nanotechnology, molecular imaging and systems biology
1
Axis elongation is a conserved morphogenetic process in which embryos extend their head-to-tail or anteriorposterior axis. In Drosophila, axis elongation occurs in an epithelial monolayer tissue known as the germband.
During germband extension, cells intercalate along the dorsal-ventral axis, causing an anterior-posterior
elongation of the tissue. In addition, oriented cell divisions at the posterior end of the germband also contribute
to axis elongation. It has been proposed that mechanical tension along the anterior-posterior axis of the embryo
resulting from cell intercalation could orient these cell divisions, but this possibility has not been tested. Notably,
cells on the ventral side of the germband also divide during the final stages of axis elongation. We used spinning
disk confocal microscopy to image axis elongation in Drosophila embryos. We delineated cells in the ventral
region of the germband using quantitative image analysis based on the watershed algorithm, a region growing
method in which a seed in each cell is grown until it reaches the cell boundaries, Cells were manually seeded in
one time point per movie, and seeds were automatically propagated in time using the optical flow or local crosscorrelation between consecutive images. Dividing cells were detected based on the increase in cell area and cell
circularity. We found that cell divisions on the ventral side of the germband were oriented along the anteriorposterior axis of the embryo. These data suggest that oriented cell divisions on the ventral side of the germband
also contribute to axis elongation in the Drosophila embryo. We are currently using laser ablation to apply
mechanical stimuli to the dividing cells and determine whether mechanical signals contribute to cell division
orientation during axis elongation.
-68-
Mechanical tension and actin polymerization during
axis elongation in Drosophila
Jessica Yu1, Rodrigo Fernandez-Gonzalez1,2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Cell and Systems Biology,
University of Toronto; 3Hospital for Sick Children
1
We are using fluorescent markers and live imaging techniques to closely examine the dynamics at play during
new interface formation. In preliminary studies using laser ablation and particle image velocimetry, we found that
there are forces on the ends of the growing interface that actively pull the interface outwards, which may suggest
that the formation of new interfaces is an active process that directly results from mechanical tension sustained
within the growing interface. Indeed, we found that interface growth rate increases in the presence of increased
tension levels sustained within the growing interface. Previous studies have found that actin accumulates
at newly forming interfaces as they grow, and we reason that the formin Diaphanous may be mediating this
behaviour, as Diaphanous has been reported to respond to mechanical activity. We are currently using genetic
and molecular approaches to determine the role of Diaphanous in axis elongation and to define the interplay
between actin dynamics, Diaphanous activity, and mechanical tension during vertex resolution.
Characterizing the underlying mechanical principles behind morphogenetic processes such as axis elongation is
crucial for understanding animal development. Cell intercalation is important during neural tube and limb bud
elongation in vertebrates, and as such, my research will provide key findings necessary to understand animal
development and developmental disorders such as spina bifida and limb malformations.
-69-
scientific2014
day
IBBME
nanotechnology, molecular imaging and systems biology
Convergent extension (CE) is a fundamental and conserved process that occurs when a tissue elongates along one
axis and narrows along a second orthogonal axis, and is necessary during many stages of organismal development.
In Drosophila, one mode of CE existing early in embryogenesis is the elongation of the head-to-tail (anteriorposterior) axis. This process results largely from cell intercalation, in which cell-cell interfaces parallel to the
back-to-front (dorsal-ventral) axis of the animal contract to form a transitory vertex where four or more cells
meet, and subsequently resolve through the formation of new cell interfaces parallel to the anterior-posterior
axis of the animal. Vertex resolution is critical for axis elongation, but little is known about the regulation of this
process.
-70-
Poster Presentation Abstracts
-71-
scientific2014
day
IBBME
neural, sensory systems and rehabilitation
Neural, Sensory Systems and Rehabilitation
Multi-segment kinematic assessment of human
trunk sensitivity to skin artifacts
Sara Ayatollahzadeh1,2, Hossein Rouhani1,2, Richard Preuss3,4, Kei Masani1,2, Milos R. Popovic1,2
Rehabilitation Engineering Laboratory; Lyndhurst Centre, Toronto Rehabilitation Institute, University
Health Network; 2Institute of Biomaterials and Biomedical Engineering, University of Toronto; 3School of
Physical and Occupational Therapy, McGill University; 4The Constance Lethbridge Rehabilitation Centre
site of the Centre de Recherche Interdisciplinaire en Réadaptation (CRIR)
neural, sensory systems and rehabilitation
1
Background and aims: Kinematic assessment of the trunk based on a multi-segment trunk model is valuable in
clinical evaluations in a wide range of back pathologies and conditions, such as low back pain, scoliosis and spinal
cord injuries. Previous studies on lower-limb kinematic assessment have found that skin artifacts are the major
source of error in motion analysis. A study that investigated the role of skin artifacts in trunk motion analysis is
not yet available. We hypothesized that due to small ranges of angular displacement in the multi-segment trunk
the skin artifacts could considerably affect kinematic measurements. Our goal was to investigate the propagation
of skin artifacts to the 3D joint angles assessments in the seven-segment trunk model.
Methods: 11 healthy subjects performed trunk bending in five directions (left, anterior-left, anterior, anteriorright and right) up to 45° based on trunk movement as an inverted pendulum. Six Vicon Cameras recorded
the trajectory of 22 reflective markers placed on the trunk anatomical landmarks. We adopted a non-invasive
approach and simulated the skin artifact induced errors based on the task-related skin movements’ characteristic.
The error in the coordinate of each marker, in the maximum excursion point, was modeled as an independent
Gaussian variable and then the coordinate trajectories changed with the rate of the relative motion. The mean
and standard deviation of these variables were selected based the maximum skin movements at the point of peak
trunk motion. The simulated skin artifacts were added to original marker trajectories and the relative errors for
each joint’s range of motion (ROM) were calculated in 3D space. The relative error of each ROM was compared to
the coefficient of variation for the range of motion for the same angle for the given subject population. RESULTS:
Inter-subject variability of the joint range of motions was in the range from 25 to 60%, where the majority was
in the range around 60%. The induced errors in the sagittal, transverse and frontal planes were, <15%, <15% and
> 500%, respectively. Exception was errors in the transverse plane for sacral joints where the errors were about
100%.
Conclusions: From the above analysis we can conclude that kinematic assessments of the trunk in the sagittal and
transverse planes can be used in clinical evaluations, while the kinematic assessments in the frontal plane have
substantial errors (>500%) and should be used with caution for clinical decision making.
-72-
Detecting intentional muscle activity through
Mechanomyogram signal in the presence of
dyskinetic movements
Marcela Correa Villada1,2, Tom Chau1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Bloorview Research Institute
1
This study aims to investigate in what ways information from unwanted muscle contractions during a specific
task can be combined to enhance detection of intentional muscle activity amid dyskinetic movements. The study
will recruit a control group of healthy children as well as a group of children and youth with dyskinetic cerebral
palsy. MMG signals will be recorded during a gear shifting game where the participant will be cued to contract
the desired muscles. An MMG signal of the main agonist-antagonist pairs as well as nearby muscles involved in
the movement will be simultaneously recorded to compare the influence of each muscle in the movement. This
research will eventually allow children and youth with disabilities to use their intentional muscle contractions
to communicate and interact with their environment even in the presence of excessive undesired muscle
contractions.
-73-
scientific2014
day
IBBME
neural, sensory systems and rehabilitation
The contraction of individual motor units can be detected through the lateral movements of muscle fibers
in different muscle sites in the body. For children and youth with substantial physical disabilities, these sites
can be used as an access pathway to translate the individual’s functional intent into a functional activity.
Mechanomyogram (MMG) is a method that can be used for the study of muscle activity. However, when using
MMG with an individual who has hyperkinetic or dyskinetic movements, one of the most daunting challenges is to
locate a muscle site where the MMG signal is affected by unwanted muscle contractions that may deteriorate the
strength of the signal.
An artificial sensory-feedback system to improve
obstacle avoidance of individuals with lower-limb
amputations
Juan Francisco Morales Gonzalez1,2, Jan Andrysek1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Holland Bloorview Research
Institute
neural, sensory systems and rehabilitation
1
The current research of sensory-feedback systems in amputees tries to improve sensory-motor coordination.
Several technologies have been developed to help the users acquire information from the environment in order to
improve the use of prosthesis. In this project, a non-invasive technique suing cutaneous mechanical stimulation
is been investigated as a channel to provide feedback to the user. Studies have shown that vibrotactile stimulation
is well perceived by lower-limb amputees and can be useful in providing feedback in the upper portion of the
leg. One aspect of mobility and prosthetic function that is a common part of real-world mobility where sensory
feedback has not been investigated is in obstacle crossing and avoidance. There is evidence that individuals with
lower-limb amputations have increased failure rates in obstacle avoidance. Studies have also shown that one of
the main indicators of succesfull obstacle avoidance is foot clearance. The proposed development aims to study
the ability to control foot clearance via vibrotactile sensory feedback. The experiment will require a subject to
walk wearing a sensory device. Vibrotactile feedback based on foot clearance will be provided to the subject,
who will interpret it and try to maintain the foot clearance within a certain limit. Measurements will be taken to
determine the feasibility of foot clearance control based on vibrotactile feedback.
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Validated finite element model of a peripheral nerve
Purbasha Garai1,2, José Zariffa1,2
Toronto Rehabilitation Institute, University Health Network; 2Institute of Biomaterials and Biomedical
Engineering, University of Toronto
1
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neural, sensory systems and rehabilitation
Neurological injuries such as spinal cord injury and stroke can result in paralysis below the level of injury, making
the patients dependent on their loved ones or caregivers to perform daily tasks. Neuroprosthetic devices using
functional electrical stimulation (FES) are used to assist them in performing various tasks using the paralysed
limbs. Most existing FES are based on “open-loop” systems, in which a predefined pattern of electrical stimulation
is delivered to paralyzed muscles, causing them to contract and produce functional limb movement. In the
absence of sensory feedback, this approach cannot reproduce fine motor controls as the intact nervous system
would do, or compensate for changes in the properties of the neuromuscular system, such as fatigue. To address
these issues, closed loop FES systems are needed that use sensory information from the limb to provide feedback
signals to the FES controller. The movement could then be regulated based on sensory information extracted
by peripheral nerve electrodes. Nerve cuff electrodes can record the electrical activity of peripheral nerves but
current designs are not well suited to isolating the activity of various sensory pathways and need improvement to
get accurate feedback signals to the FES controller. To make the electrode more effective at isolating the activities
of various sensory pathways, we are proposing to construct a computational model of a peripheral nerve that
can quantitatively reproduce the electrophysiological recordings. For this purpose, we will carry out acute rat
experiments and record sensory information from the sciatic nerve using 8-channel polyimide spiral nerve cuff
electrodes, while providing mechanical stimulation to the heel and ankle. After recording, we will use histological
cross sections of nerve to construct an anatomically accurate finite element model. The model will be validated
quantitatively by adjusting its parameters until it can reproduce the averaged value of each recording from the
experiment. The realistic model can then be used for re-designing a more efficient peripheral nerve interface and
thus will facilitate the growth of closed loop FES systems.
Investigating online three-class transcranial
doppler ultrasound based brain computer
interface
Anuja Goyal1,2, Tom Chau1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Holland Bloorview Kids
Rehabilitation Hospital
neural, sensory systems and rehabilitation
1
Locked-in syndrome (LIS) is a condition in which the patient is unable to communicate verbally or move
due to paralysis but has basic cognitive functions. Brain computer interfaces (BCI) have been developed to
provide communication opportunities to LIS patients. Transcranial Doppler ultrasound (TCD) is a medical
imaging technique used to assess the blood flow of major cerebral arteries and can be used to develop a BCI. In
comparison to a resting state, cognitive activity results in an increase in cerebral blood flow velocity (CBFV) in the
major cerebral arteries. Generally in right handed individuals, verbal cognitive tasks can be performed to identify
a greater increase in blood flow in the left hemisphere in comparison to the right hemisphere and spatial tasks
result in a greater blood flow in the right hemisphere than the left hemisphere. A TCD-based BCI system was
previously implemented using verbal and spatial tasks as control signals; however, the spatial task involved a visual
cue (looking at the image of a geometric shape and identifying its match from several rotated alternatives), which
is not ideal for autonomous BCI use. Therefore, this study will investigate another right side lateralized task that
does not require a visual cue, and therefore more suitable for BCI implementation. The study will also test these
cognitive tasks as control signals in an online three-class TCD-based BCI system. Achieving these objectives will
allow for the design of a user-paced online BCI system.
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Designing everyday technologies for the home:
views from people with Alzheimer’s disease
Tizneem Jiancaro1,2, Alex Mihailidis2
Graduate Deptartment of Rehabilitation Science, University of Toronto; 2Institute of Biomaterials and
Biomedical Engineering, University of Toronto
1
Methods: Participants will engage in a ‘technology walk through’, selecting technologies in their homes they
find somewhat challenging to operate and then demonstrating use. To identify strategies and assess skills, a
modified version of the Managing Everyday Technologies Assessment, which has been previously employed in
home settings for people with dementia, will be used. To measure adoption and use characteristics, a Likert-type
survey, similar to one given to technology developers, will be orally administered. Recruitment will be conducted
via an outpatient memory clinic.
Results: Preliminary results will be presented. These will include a ranked list of observable skills, including
those considered most challenging for a user with AD; a list of common and uncommon strategies, which will be
structured within the COPE framework; and a list of characteristics that users find very important.
Implications: This new knowledge will enable developers to better understand how to tailor their designs to
suit users with AD. This study is part of a broader project to create a ‘Design Guide to support work on future
technologies for people with AD who live at home.
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scientific2014
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IBBME
neural, sensory systems and rehabilitation
Background: Despite the rising prevalence of Alzheimer’s disease (AD) in Canada and around the world, little is
known about the design of home technologies for these users. Notably, views on technology from the perspective
of those with AD are seldom considered, despite the fact that, like everyone, these individuals are also users of
everyday technologies. The objectives of this upcoming study are to assess the observable skills needed to operate
a technology; to identify the strategies employed when users are faced with technological challenges; and to rank
the importance of ‘technology adoption and use characteristics’, such as ‘usability’, ‘reliability’ and ‘self-confidence
during use’, all from the perspective of people with AD.
MoveEasy Pole Kit: A practical device for safer
in-home mobility
Vicki Komisar1,2, Emily C King1,3, T Daniel Smyth1, Andrew J Hart4, Geoff R Fernie1,2,5
Toronto Rehabilitation Institute, University Health Network; 2Institute of Biomaterials and Biomedical
Engineering, University of Toronto; 3Department of Mechanical and Industrial Engineering, University of
Toronto; 4Hart Vision Medical; 5Department of Surgery, University of Toronto
neural, sensory systems and rehabilitation
1
Rationale: There is a need to facilitate safer assisted mobility and rehabilitative exercise at home for the many
patients returning home from hospitals before they are ready to walk independently. We are addressing this
critical safety and independence issue by developing an assistive technology system, the “MoveEasy Pole Kit”, to
make it easy and affordable to install grab-poles and handrails without permanently modifying the home.
Assistive Technology Design: Our team of engineers and designers worked with potential end-users, caregivers
and clinicians to develop MoveEasy Pole Kit – a modular system of vertical pressure-fit grab-poles and clipon horizontal handrails that can provide stable mobility and exercise support on level ground or stairs. The
pressure-fit pole is easy to install and does not permanently modify the home. Pole positions and handrail heights
can be customised easily to meet the user’s needs. The handrails can also function as ‘gates’ so that rails can be
installed without blocking access to other rooms in the home, thereby helping to minimise disruption to caregiver
activities.
Technology Transfer: Working with industry partner Hart Vision Medical, we are developing MoveEasy Pole
Kit into a commercial product. Safety testing is complete. Pilot community installations of the vertical poles
are taking place, and trial handrail installations are forthcoming. The first generation of MoveEasy Pole Kit will
be launched later this year. Feedback from users, caregivers and therapists will guide the design of additional
components to improve usability and allow MoveEasy to facilitate a broader range of home exercises.
Significance: MoveEasy Pole Kit provides stable, customisable support for mobility and exercise. Getting up and
around is a crucial element of living independently after returning home from the hospital. By improving the
safety of transferring out of bed and walking around the home, we expect that MoveEasy will encourage users
to mobilise more frequently and independently, and take part in the exercises needed to promote effective
rehabilitation.
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A novel EEG-based feature clustering algorithm for
detection of changes in mental state
Andrew Myrden1,2, Tom Chau1, 2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Holland Bloorview Kids
Rehabilitation Hospital
1
However, current BCIs exhibit many shortcomings. Foremost among these is unstable performance. During
long-term usage, BCI accuracy typically decreases over time. It has been hypothesized that this may be related
to underlying changes in mental state. Traditional BCIs are not able to detect when the user becomes fatigued,
frustrated, or distracted. Consequently, when these changes occur, performance deteriorates accordingly. If these
underlying changes in mental state can be identified, it may be possible to use them to adapt the BCI in real-time
such that high accuracy is maintained.
Methods: Eleven able-bodied individuals took part in a research study. Each participant completed four
60-minute sessions. Within each session, participants completed a series of 80 mental tasks, split into four
categories – a rest task, a language task, an arithmetic task, and a short-term memory task. There were five
discrete difficulty levels for each non-rest task, ranging from very easy to very difficult. Following each task,
participants self-reported their perceived levels of fatigue, frustration, and attention. During each session, EEG
was used to record cortical neuronal activity at 15 different electrode locations.
A supervised learning paradigm was used to train classifiers to predict fatigue, frustration, and attention levels
from the recorded EEG data. For each task, the spectral power at each electrode location was computed within
the range from 2 to 40 Hz. A novel feature clustering algorithm was used to identify combinations of electrode
locations and frequencies that were strongly related to each other. A feature vector was then constructed for
each task by using principal component analysis to reduce the dimensionality of each cluster and concatenating
the reduced representations of each cluster together. A boosted decision tree classifier was then trained for each
participant to predict the class labels provided by the self-reported ratings.
Results: Mean classification accuracies across all participants exceeded 80% for all three mental states. These
results were comparable to previous work on fatigue detection and significantly improved on previous work on
attention detection. There are no previous studies on automatic detection of frustration for comparison.
Conclusions:These results suggest that additional investigation of EEG-based automatic mental state detection is
worthwhile. Future work will focus on combining the system developed in this study with a traditional BCI.
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scientific2014
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IBBME
neural, sensory systems and rehabilitation
Rationale: Individuals with severe physical disabilities are often unable to communicate through speech
or voluntary motion. Nevertheless, many of these individuals retain capable cognition. Numerous access
technologies have been developed to provide alternative means of communication for this population. For
example, brain-computer interfaces (BCIs) can be used to control a computer or other external device using
thoughts alone.
Using mechanomyography as a biofeedback tool for
altering gait dynamics in the rehabilitation of
pediatric spinal cord injuries
Katherine Plewa1,2, Tom Chau1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Bloorview Research Institute
neural, sensory systems and rehabilitation
1
Spinal cord injuries (SCIs) result in a loss of motor and sensory function. These injuries can be especially difficult
in the pediatric population; however, there has not been a lot of focus on pediatric rehabilitation and the effects
of using biofeedback training. Biofeedback therapy provides active information about physiological responses to
establish learned, voluntary control over those responses. Mechanomyography (MMG) is a method for measuring
muscle activation using accelerometers or microphones and has recently been introduced as an effective
biofeedback tool.
Gait is both a voluntary and automatic process, with the automatic component being governed by neural patterns
called central pattern generators. These patterns change with aging and disease, and likely with incomplete
SCIs. This study will focus on using MMG-based biofeedback as a tool to improve gait dynamics in subjects
with incomplete SCIs. First, we will measure the muscle activation patterns via MMG in healthy subjects and
incomplete SCI subjects. Comparing these gait patterns, we will establish an averaged pattern that will become
the threshold for our MMG-based biofeedback tool. This biofeedback tool will then be incorporated into a gaittraining rehabilitation program. MMG-based biofeedback is expected to improve gait dynamics in SCI patients, as
it will substitute some of the losses associated with SCI injury that hinder functional movements.
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Synchronization in heterogeneous neural networks
Omid Talakoub1,2, Milos R Popovic2,3, Willy Wong1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Department of
Electrical and Computer Engineering, University of Toronto; 3Rehabilitation Engineering
Laboratory, Toronto Rehabilitation Institute, University Health Network
1
Our simulations with this network show that the critical coupling strength (synaptic strength) at which two
networks become coherent depends separately on the dynamic of the individual oscillators (neurons) as well as
on the network topology. For example, a homogenous network synchronizes around a specific coupling strength.
On the contrary, synchronization of a heterogeneous network is gradual and starts from formation of small
clusters with coherent activity. The clusters form around the most connected oscillators. Then, the clusters grow
in size and merge as the coupling strength increases until the entire network is synchronous. In our simulations
with the model, we have found that the mean-field activity (i.e. the equivalent ‘local field potential’) of the neural
populations to be related to the coherency between them. This result illustrates the plausibility of a model
whereby a neural event opens a channel of communication between two neural networks (brain regions) allowing
the networks to synchronize together.
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scientific2014
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IBBME
neural, sensory systems and rehabilitation
The “communication through coherence” hypothesis proposes that communication across neural networks
can only take place when the oscillatory activities between different brain regions are coherent. The rhythmic
patterns of excitability across communicating networks provide a temporal window for communication because
the input-output channels of the networks are then synchronized and open at the same times. That is when their
fundamental components, neurons, are firing synchronously. A neuron can be thought of as an oscillator with a
natural frequency and phase. Here, frequency gives the firing rate of the neuron, and the phase the timing of the
spike events. The best known model using this approach is the Kuramoto model. The Kuramoto model is simple
enough to be analyzed mathematically, and provides solutions which are not trivial. In these models, the pre/
post-synaptic connections for neurons are modelled in terms of coupled oscillators. The key point of this model
is that the frequency of each oscillator can be modified through pair-wise interactions with other oscillators.
The classic Kuramoto model assumes all-to-all connections between oscillators. Effectively this means that all
neurons are connected to each other. We modified the Kuramoto model in two important ways. First, our model
uses random connections so that not every neuron is connected every other neuron. Second, since our work
involves studying the inter-relation between two networks, we set up our model as separate Kuramoto networks
with additional connections linking together these networks.
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Poster Presentation Abstracts
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scientific2014
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engineering in a clinical setting and clinical engineering
Engineering in a Clinical Setting and Clinical Engineering
Magnetic resonance imaging and X-ray fusion for
cardiac resynchronization therapy
Jinwoo Choi1,2, Graham Wright2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Sunnybrook Research
Institute; 3Department of Medical Biophysics, University of Toronto
engineering in a clinical setting and clinical engineering
1
Cardiac Resynchronization Therapy (CRT) can effectively treat Heart Failure (HF) patients who suffer from
reduced cardiac output induced by dyssynchronous ventricular contractions. However, 30% of the CRT recipients
do not respond. Recent studies show that the CRT response rate can reach 95% when the left ventricle (LV)
pacing lead is placed at the region of the latest contraction and away from the myocardial scar. Cardiac Magnetic
Resonance (CMR) Imaging can localize the latest contraction site and the regions of the myocardial scars in three
dimensions (3D). The 3D CMR data can be fused and registered to the clinical standard X-ray fluoroscopy in order
to aid in the optimal placement of the LV pacing lead. In this study, we have developed a novel 3D CMR data to 2D
X-ray image registration method for CRT procedures. We have employed the LV pacing lead as the X-ray landmark
and the coronary sinus vessel. The registration method then makes use of a guidewire simulation algorithm, the
edge based image registration technique, and X-ray C-arm tracking to register the landmarks and ensure the
correct alignment throughout the procedure.
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Adoption of insulin pumps and continuous glucose
monitors: patient perceptions of utility and usability
Isabelle Dutil1,2, Melanie Yeung2, Holly Tschirhart3, Bruce Perkins3, Patricia Trbovich1,2, Linda
Gonder-Frederick4, Joseph Cafazzo1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Centre for Global eHealth
Innovation, University Health Network; 3Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital;
4
Behavioral Medicine Center, University of Virginia Health System
1
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scientific2014
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engineering in a clinical setting and clinical engineering
As September 2012, approximately 34 million people worldwide suffer from Type 1 diabetes mellitus (T1DM). To
maintain healthy blood sugar, patients with this chronic disease are insulin dependent indefinitely. In the United
States, over 700,000 T1DM patients use a continuous subcutaneous insulin infusion therapy or insulin pump
(IP) device while approximately 150,000 T1DM patients use a continuous glucose monitor (CGM). Reported
advantages to the use of IP and CGM include tighter glycemic control and a reduction in hypoglycemic episodes.
However, despite these published clinical advantages, adoption of these diabetes technologies is not widespread.
With the development of the artificial pancreas, a closed-loop system aimed at regulating blood glucose levels
without the input of the patient, there is need for better understanding of patient barriers to adoption and
use of the two components that make up the artificial pancreas: the insulin pump and CGM. This study aims
to better understand the burden of care associated with the adoption of these devices and to understand
perceptions of the technologies through informal patient interviews and usability testing. Addressing these
barriers and understanding why patients may or may not consider these medical devices to be useful, easy to use
and trustworthy, can inform the design of new training protocols aimed at better meeting the needs of patients
preparing to adopt these diabetes technologies.
Enhancing the decoding of functional intention in
children and youth with severe disabilities through
a systematic apparel-based investigation of
involuntary motion
Amanda Fleury1,2, Tom Chau1,2, Ryan Hung2,3
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Bloorview Research Institute;
3Department of Paediatrics, University of Toronto
engineering in a clinical setting and clinical engineering
1
Many children with severe physical disabilities are effectively non-verbal and require access technologies
for communication, environmental control, and computer use. A range of solutions are available, including
mechanical switches, computer vision, and physiological sensors to facilitate inclusion and independence.
However, standard augmentative and alternative communication (AAC) technologies are often unworkable
in children who have an excess of hyperkinetic movements (HKM) due to motion artefact and frequent false
activations. The resulting ambiguity between intentional and involuntary activation leaves many without a viable
access pathway, and there currently exists no comprehensive solution.
While involuntary movements have often been dismissed as uninformative, there is evidence to suggest that in
some instances, these movements may actually express functional intent. Accelerometers and other traditional
approaches to movement monitoring are limited in that they provide only an incomplete abstraction of the body’s
motion. In addition, traditional movement monitoring can be challenging to implement in the target population,
where wires are often disconnected and sensors dislocated. Atypical body postures and physical differences
encumber the attachment of sensors sized to prototypical average bodies.
A potentially promising approach to the holistic characterization of body motion is through the use of electronic
textiles. E-textile technologies may make it possible to implement a generic solution to motion artefact, which
can be used for extended durations in naturalistic settings.
We propose a systematic investigation of the measurement of body movements using e-textiles. Measurements
may be useful in understanding HKM and in providing previously unknown information to the user, caregiver,
environment or assistive technology.
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A wearable computer vision system for monitoring
hand use at home
Jirapat Likitlersuang1,2, José Zariffa1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Toronto Rehabilitation
Institute, University Health Network; 3Edward S. Rogers Sr. Department of Electrical and Computer
Engineering, University of Toronto
1
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scientific2014
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IBBME
engineering in a clinical setting and clinical engineering
The restoration of upper limb function is usually rated as the top priority for individuals suffering from cervical
spinal cord injuries or upper extremity dysfunction following stroke. In order to develop new and effective
rehabilitation interventions as well as modify current treatments to best suit each individual’s need, it is important
to assess hand function throughout the rehabilitation process. Currently, the efficacy of these treatments is
usually measured by standardized assessments performed by a trained clinician in a controlled setting; however
there is no information collection method on these treatments in the patient’s home. Understanding how often a
patient uses their hand at home is important in assessing their level of independence. Due to the high degrees of
freedom of the human hand, creating a system that can accurately measure this abstract function is a significant
research challenge. Our approach is to develop a computer vision (CV)-based wearable camera sensor that would
allow clinicians to monitor interactions of the hand with objects in the environment outside of the laboratory.
The objective of this research is to 1) create a test dataset of recorded video that represents the activities of daily
living of the upper extremity, 2) create an algorithm that monitors interactions of the hand and objects in the
environment out of the laboratory using CV, and 3) extract information on hand manipulation including frequency
of hand use and success rate. We hypothesize that we will be able to use CV to detect interactions of the hand
with objects in the environment. To this end, 20 able-bodied participants will wear an egocentric commercially
available camera sensor over the ear and perform common object and hand interactions in a simulated home
environment, such as grasping a mug, picking up a phone, and making tea. Using this dataset as well as other
publicly available egocentric video datasets, we will investigate algorithms that analyze the visual information in
the immediate vicinity of the hand, and attempt to differentiate video segments of hands engaged in manipulating
objects from those of empty hands. The current version of the algorithm focuses on a histogram of optical flow,
which looks into the speed and direction cues of the hand in relation to the object being manipulated (e.g. the
object of interaction will have the same speed and direction of movement as the hand). The system will be
evaluated using the F-score metric by comparing with manual video annotations by trained professionals. The
algorithms will first be designed only based on recorded video and later integrated into a mobile device and
processed in real time. This system could provide an excellent framework for rehabilitation evaluation tools.
Analysis of force distribution on upper body limbs
during ambulation with crutches
Emma Rogers1,2, Jan Andrysek1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Bloorview Research Institute,
Holland Bloorview Kids Rehabilitation Hospital
engineering in a clinical setting and clinical engineering
1
Crutches provide balance and support for a variety of long-term mobility impairments as well as eliminate or
decrease load bearing during the recovery process of lower limb injuries. However, the resultant forces placed on
the upper limbs can cause pain in the arms and shoulders, and adversely affect mobility function. To gain a better
understanding of this problem, this study aims to develop a system to accurately measure the forces present on
the interaction points between the upper limb and the crutch. An array of Tekscan Flexiforce force sensors will
be placed on the crutch handles and elbow rests to determine the magnitude and location of forces on the upper
limbs. A load cell will be included in the shaft of the crutch to determine the ground reaction force throughout
the gait cycle. Using this system, comparisons will be drawn between crutch models including a standard forearm
crutch, and a forearm crutch with a damping shock absorber. The study will also evaluate the effect of differences
in terrain including flat ground at several walking speeds, going up and down a ramp, and over uneven ground.
Twelve able-bodied adult participants will complete the trial using swing-through gait. Overall, this study aims to
inform clinical practices and crutch designs to provide more effective interventions to individuals with mobility
impairments.
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Applying ecological interface design to improve a
radiation therapy interface.
Ashleigh Shier1,2, Eduardo Mujica1, Joseph Cafazzo1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Centre for Global eHealth
Innovation, University Health Network
1
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scientific2014
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IBBME
engineering in a clinical setting and clinical engineering
External beam radiation therapy (EBRT) uses linear accelerators to generate ionizing radiation to target and
damage malignant tumour tissue. The potential for radiation exposure to the surrounding healthy tissue makes
radiotherapy especially safety-critical. Technological growth in external beam radiotherapy has improved
the precision and accuracy of radiation delivery, but has also increased treatment delivery complexity. This
increased complexity in EBRT has made treatment delivery susceptible to error, specifically human error, which
has resulted in adverse events with at times severe outcomes. It is proposed that a human factors engineering
design approach for improving visualization of complex systems, ecological interface design (EID), may reduce
human errors during the complex task of radiotherapy treatment delivery by providing the user with an improved
understanding of the system, and by reducing their mental workload. This project aims to redesign a radiotherapy
monitoring and delivery interface by employing the EID method, and to evaluate whether the redesigned interface
in comparison to a current interface reduces human errors and improves patient safety.
Application of medical body area networks to
reduce blood pressure in ambulatory settings
Akib Uddin1,2, Kevin Tallevi2, Kevin Armor2, John Li2, Rob Nolan3, Joseph Cafazzo1,2
Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2Centre for Global eHealth
Innovation, University Health Network; 3Behavioural Cardiology Research Unit, University Health Network
engineering in a clinical setting and clinical engineering
1
Elevated blood pressure is a leading global risk of mortality. The primary management approaches are
lifestyle modifications and pharmaceutical treatments; however behavioural approaches offer an additional,
complementary option that focus on reducing the impact of stress from the external environment. In-clinic
delivery of Behavioural Neurocardiac Training (BNT) has been shown to stimulate and exercise the autonomic
reflexes, allowing for improved autonomic regulation, and lower blood pressure. BNT involves the training of
an entrained breathing technique with heart rate variability biofeedback. It is currently delivered in-clinic at
Toronto General Hospital and requires several large physiological monitoring tools and assistance from clinicians.
Medical Body Area Networks (MBAN) or wearable wireless sensor systems offer the ability to delivery BNT
outside of the hospital environment and potentially improving access to care. Our research team is developing
a wearable wireless battery-powered patch that uses standard Ag-AgCl electrodes to attach to the user’s chest
and collect their ECG. The device uses Bluetooth Low Energy to then transmit data to a smartphone in realtime. The smartphone coaches the user through BNT using a series of linear, structured lessons that consist of
audio narrations and interactive content. Real-time heart rate variability indices provide operant feedback and
complement the training. The MBAN BNT system will be validated in a clinical pilot study at Toronto General
Hospital on 20 subjects. It is expected that this system will offer patients a complementary treatment for stress
management and blood pressure that can be delivered at home.
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Chestnut Conference Centre Map
89 Chestnut Street
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scientific2014
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IBBME
Acknowledgments
Llewellyn- Thomas Visiting Scientist
Edward S. Boyden, Ph.D.
Associate Professor of Biological Engineering and
Brain and Cognitive Sciences, Media Lab and the
McGovern Institute, Departments of Biological
Engineering and Brain and Cognitive Sciences,
Massachusetts Institute of Technology
Co-Director, MIT Center for Neurobiological
Engineering, Massachusetts Institute of Technology
Innovation in Emerging Fields of Research Keynote
Speaker
Hai-Ling Margaret Cheng, Ph.D.
Scientist, Physiology and Experimental Medicine, The
Hospital for Sick Children
Assistant Professor, Department of Medical
Biophysics, Leslie Dan Faculty of Pharmacy and
Institute of Biomaterials and Biomedical Engineering,
University of Toronto
IBBME 2014 Scientific Day Organizing Committee
Members
Dr. Christopher Yip, Director
Carrie Laughlin, Acting Executive Assistant to the
Director
Sandra Walker, Manager of Operations
Dayle Levine, Acting Manager of Operations
Judy Gilligan, Operations Assistant
Erin Vollick, Communications Officer
Derek Boodooshingh, IT Systems Coordinator
Camila Londono, Scientific Day 2014 co-chair
Zoryana Salo, Scientific Day 2014 co-chair
Presentation Evaluation Committee
Dr. Ed Boyden - Associate Professor, Massachusetts
Institute of Technology
Dr. Hai-Ling Margaret Cheng - Assistant Professor,
The Hospital for Sick Children
Dr. Geoffrey Clarke - Research Associate, Stem Cell
Bioengineering Lab, IBBME, University of Toronto
Dr. Mike Cooke - Post-Doctoral Fellow, Shoichet
Lab, IBBME, University of Toronto
Dr. Tony Easty - Associate Professor, IBBME,
University of Toronto
Dr. Rodrigo Fernandez-Gonzalez - Assistant
Professor, IBBME, University of Toronto
Dr. Bernhard Ganss - Associate Professor, Faculty of
Dentistry, University of Toronto
Dr. Penney Gilbert - Assistant Professor, IBBME,
University of Toronto
Dr. Hans Kunov - Emeritus Faculty, IBBME,
University of Toronto
Dr. Maria Luisa López-Donaire - Post-Doctoral
Fellow, Santerre Lab, University of Toronto
Dr. Kei Masani - Assistant Professor, IBBME,
University of Toronto
Dr. Alison McGuigan - Assistant Professor, IBBME,
University of Toronto
Dr. Chris McLaughlin - Post-Doctoral Fellow,
Shoichet Lab, IBBME, University of Toronto
Dr. Josh Milstein - Assistant Professor, Department
of Physics, University of Toronto and Department of
Chemical and Physical Sciences, UTM
Dr. Maria Rodrigues - Post-Doctoral Fellow,
Department of Cell and Systems Biology, University
of Toronto
Dr. Soror Sharifpoor - Post-Doctoral Fellow,
Santerre Lab, IBBME, University of Toronto
Dr. Libero Vitiello - Visiting Scientist, University of
Toronto
Dr. Alwin Wan - Post-Doctoral Fellow, Laboratory
of Integrative Biology and Microengineered
Technologies, Department of Mechanical and
Industrial Engineering, University of Toronto
Dr. Weijia Wang - Post-Doctoral Fellow, Stem Cell
Bioengineering Lab, IBBME, University of Toronto
Dr. Laura Wells - Post-Doctoral Fellow, Sefton Lab,
IBBME, University of Toronto
Dr. Jose Zariffa - Assistant Professor, IBBME,
University of Toronto
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Marketing and Communications Committee
Tarik Attia
Neeraj Gupta
Gabrielle Lam
Sogand Namdar
Graphic Design Committee
Agnes Soos
Aileen Zhong
Abstract Booklet Committee
Elisa D’Arcangelo
Ahil Ganesh
Silvia Isabella
Aileen Zhong
Abstract Review Committee
Nikhil Bhagwat
Yasaman Delaviz
Silvia Isabella
Hoda Maleki
Julie Winterburn
IT Committee
Nikhil Bhagwat
Eric Ma
Judge Recruitment Committee
Neeraj Gupta
Eric Ma
Abstract Reviewers
Kyle Battiston
Nikhil Bhagwat
Jane Cheung
Elisa D’Arcangelo
Yasaman Delaviz
Isabelle Dutil
Nahla Elsaid
Zachary Grodzinski
Bo Huang
Silvia Isabella
Alex Lausch
Camila Londono
Hoda Maleki
Amir Manbachi
Nick Mitrousis
Miles Montgomery
Samantha Payne
James Poon
Bryan Quan
Lida Sadeghinejad
Kyle Serkies
John Soleas
Ana Viniegra
Julie Winterburn
Meghan Wright
Poster Workshop
Vicky Komisar
Rob Irish
Speaker Ambassadors
Gabrielle Lam
David Rees
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