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Journal of the Association for Laboratory
Automation
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SOS−−A Sample Ordering System for Delivering ''Assay-Ready'' Compound Plates for Drug Screening
C. Brideau, J. Hunter, J. Maher, S. Adam, L. J. Fortin and J. Ferentinos
Journal of Laboratory Automation 2004 9: 123
DOI: 10.1016/j.jala.2004.04.002
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Technical Brief
SOS–A Sample Ordering System for
Delivering ‘‘Assay-Ready’’ Compound
Plates for Drug Screening
C. Brideau,1* J. Hunter,2 J. Maher,2 S. Adam,1 L. J. Fortin,1 and J. Ferentinos1
1
Merck Frosst Centre for Therapeutic Research, Kirkland, Que´bec, Canada;
2
RTS Life Science International, Manchester, UK
Keywords:
compound
management,
screening,
automated
storage,
drug discovery
any bottlenecks in drug discovery have been
addressed with the advent of new assay and
instrument technologies. However, storing and
processing chemical compounds for screening remains
a challenge for many drug discovery laboratories.
Although automated storage and retrieval systems are
commercially available for medium to large collections of
chemical samples, these samples are usually stored at a
central site and are not readily accessible to satellite
research labs.
Drug discovery relies on the rapid testing of new
chemical compounds in relevant biological assays.
Therefore, newly synthesized compounds must be readily
available in various formats to biologists performing
screening assays. Until recently, our compounds were
distributed in screw cap vials to assayists who would then
manually transfer and dilute each sample in an ‘‘assayready’’ compound plate for screening. The vials would then
be managed by the individuals in an ad hoc manner.
To relieve the assayist from searching for compounds
and preparing their own assay-ready compound plates,
a newly customized compound storage system with an
ordering software application was implemented at our
research facility that eliminates these bottlenecks. The
system stores and retrieves compounds in
M
*Correspondence: C. Brideau, Biochemistry and Molecular Biology,
Merck Frosst Centre for Therapeutic Research, 16711
TransCanada Hwy., Kirkland, Quebec, Canada H9H 3L1; Phone:
+1.514.428.3360; E-mail: [email protected]
1535-5535/$30.00
Copyright
c
2004 by The Association for Laboratory Automation
doi:10.1016/j.jala.2004.04.002
1 mL-mini-tubes or microtiter plates, facilitates compound
searching by identifier or structure, orders compounds at
varying concentrations in specified wells on 96- or 384well plates, requests the addition of controls (vehicle or
reference compounds), etc. The orders are automatically
processed and delivered to the assayist the following day
for screening. An overview of our system will demonstrate
that we minimize compound waste and ensure compound
integrity and availability. ( JALA 2004;9:123–7)
INTRODUCTION
Medicinal Chemistry synthetic compounds at our
Merck Frosst Research Laboratory site have traditionally been prepared in DMSO stocks in bar coded
1 dram vials and distributed to the biologists for
screening. This was an ad hoc system where the vials
were stored in a variety locations and conditions
depending on the recipient.
Since a compound may be screened in many
biological assays, many aliquots of the solution were
prepared in several 1 dram vials containing large
dead volumes. The vials would often be misplaced
requiring a new solution to be made from the stock
powder. This resulted in increased waste in compound and time.
For each assay, the biologist is responsible for
preparing the assay compound plate for his/her
screen. Until recently, this involved searching for the
compound vials and preparing the drug plate
containing the compounds serially diluted across
columns of a 96-well plate.
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JALA
June 2004
123
Technical Brief
Figure 2. (a) Store output/input stacker area and (b) Tecan
Genesis RSP100 liquid handling system.
Figure 1. (a) 1.4 ml 2D Data Matrix coded mini-tubes with
pierceable silicone septum and (b) inside view of the Merck Frosst
automated storage and retrieval sample store.
MATERIALS AND METHODS
Automated Storage and Retrieval Store
The automated store was purchased and installed by RTS
Life Science (www.rts-group.com, UK). The cold room
was designed by Pageau Morel & Associates and the
assembly and installation was coordinated by Merck Frosst
Engineering.
124 JALA
June 2004
The system is approximately 38 feet long by 9 feet wide
and 7 feet high (Figure 1b) and is environmentally controlled
at 4 C with less than 25% relative humidity. When filled to
capacity, the store can accommodate about 1 million of 1.4
mL 2D Data Matrix coded mini-tubes (with pierceable
silicone septum) (Figure 1a) or 24,000 half deep well plates
(96-well storage plates) or 37,000 shallow plates (384-well)
containing compound solutions in DMSO.
The compounds are stored in triplicate aliquots of 200 lL
in 1.4 mL mini-tubes positioned in a 96-mini-tube rack. The
racks are placed on 6-position trays which are accessed by
the main store robot and brought to the picking station.
Upon order submission, the appropriate mini-tubes are
picked and placed into a transfer rack by the picking robot in
the picking station. The mini-tube racks are then moved by
a conveyer to the stacker area (Figure 2a) to be thawed in
one of the two Heraeus incubators which are maintained at
room temperature. Once the compounds have thawed, the
mini-tube transfer rack is then manually placed on the Tecan
Genesis RSP carousel (www.tecan-us.com, USA) for the
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Technical Brief
Figure 3. MAPS screenshot view—order titration plates, step 1:
search for available compounds.
Figure 5. MAPS screenshot view—order titration plates, step 3:
request plate type and diluent.
compound transfer to ‘‘assay-ready’’ titration plates (Figure
2b).
The custom software, named MAPS, for ordering and
arraying compounds in 96- or 384-well assay-ready compound plates was co-developed by Merck Frosst and RTS
Life Science International, PLC (www.rts-group.com, WA,
USA). Integration with Tecan’s Gemini 3.5 liquid handling
software with the RTS store database and MAPS required
a custom tray plating software to generate ‘‘Tecan worklists’’
which was developed by Traders Micro using LabViewÒ
(www.tradersmicro.com, QC, Canada).
To enable 2D bar code reading, the RVSI 2D Matrix
Scanner (Vial Reader 4000) was integrated into the system.
The external compound databases such as the Merck
Corporate Database and structure viewer ISISTM (MDL
Information Systems, www.mdli.com) were linked to
MAPS to allow compound searching via compound id or
structure.
MAPS was developed with VB/C++/Oracle Client-Server
applications and designed using Rational Unified Process
and tools. The basic features include integration with
Microsoft WindowsTM for application security, e-mail
notification of order progress, generation of reports and
importing compound lists. Graphical displays of assay
plates, HTS plates, and tube ordering were designed for ease
of use. An internal MAPS inventory database captures
compound id information (chemist, project, registration
date) and tracks sample volume, concentration, freeze-thaw
cycles, master vials, and HTS plates. The MAPS graphical
user interface (GUI) allows for the following: choose
compounds (by searching database or importing lists);
scientist username; date/time required by (am or pm);
priorities (by project); comments; define plate type (96- or
384- standardized); define minimal final volume per well;
Figure 4. MAPS screenshot view—order titration plates, step 2:
request available compounds.
Figure 6. MAPS screenshot view—order titration plates, step 4:
configure controls on titration plates.
MAPS (Montreal Automated Plating System)
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JALA June 2004 125
Technical Brief
Figure 7. MAPS screenshot view—order titration plates, step 5:
configure serial dilution parameters.
define diluent (DMSO or PBS); define number of titration
points; insert reference standard (if required on each plate);
define serial dilution factor (1/10, 1/3); define compound and
plate sequence; obtain order number.
Figure 9. MAPS screenshot view—order titration plates, step 7:
addition of reference compound serial dilution to all plates and
save as template.
The first step for scientists ordering assay-ready compound
plates is to choose the compounds for screening by either
searching in the store inventory database, importing a list or
by performing substructure searches in ISISTM. If required,
a control or standard template (already created and saved in
the database) can be chosen (Figure 3). Compounds available in the store are then displayed in a list from which the
scientist can choose for their assay (Figure 4). The next step
is to choose the plate type (i.e. density) and the diluent
required for compound titration (Figure 5). If a control
template was not chosen from the outset, the scientist can
choose which wells will contain diluent or a specific
compound for controls on the assay plate (Figure 6). By
clicking on ‘‘Next’’, the user is then guided to choose the
serial dilutions for each compound (Figures 7 and 8). The
user is prompted to enter the initial concentration (lM), the
final volume per well (lL) and the dilution factor between
wells. MAPS will automatically calculate the appropriate
transfer volumes of compound and diluent to process the
order. Addition of a reference compound can be added to the
serial dilution plate (Figure 9) and be saved for future use.
Once the first plate is completed, the subsequent plates are
added for further compound dilutions (Figure 10). Once all
compounds have been mapped to the compound titration
plate, the user then completes the order by entering the
required fields such as time and drop off location (Figure 11).
The store coordinator is notified of the new order, reviews it
in an Excel format before processing the order (Figures 12
and 13).
Figure 8. MAPS screenshot view—order titration plates, step 6:
continue to configure serial dilutions for all compounds.
Figure 10. MAPS screenshot view—order titration plates, step
8: mapping of compound dilutions to subsequent plates.
RESULTS
126 JALA
June 2004
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Technical Brief
Figure 11. MAPS screenshot view—order titration plates, step
9: submit request and obtain order number.
Upon approval by the coordinator, the orders are
submitted to the store for picking of mini-tubes. Samples
are transferred to bar-coded transport racks which are placed
on the Genesis working deck along with the bar-coded
destination titration plates. In MAPS, the Tecan worklist is
generated by clicking on the order number. By entering the
order number via the Tray Plating software, the pipetting
protocols and worklists are then transferred to Gemini 3.5.
Gemini reads the file and performs the desired transfer and
serial dilutions. The order is complete when samples are
returned to the Store.
Scientists obtain the bar-coded assay-ready compound
plates within 24 hours of the request.
Information about the compound plates (via order
number) can then be uploaded into a data analysis tool for
plate mapping and compound information.
Figure 14 illustrates the flow of samples from compound
registration by chemists to compound titration plate requests
by biologists.
Figure 13. MAPS screenshot view—order review by coordinator, step 2: review compound order details via Excel worksheet.
Figure 14. Compound processing flow chart.
CONCLUSION
Figure 12. MAPS screenshot view—order review by coordinator, step 1: review all new submitted orders.
Implementation of this new compound storage system has
resulted in the reduction of compound waste by greater than
five-fold and maintains compound integrity by storing all
samples in the same environment. The local centralization
makes compound management much more efficient and
samples are readily accessible to all scientists on an as need
basis. Multiple compound solutions from the same powder
are now captured in the MAPS database. Other benefits
include a searchable database for submitted compounds and
additional security measures allowing the restriction of
compounds to research groups. A time saving advantage
for the assayist is that freshly prepared assay-ready
compound plates are now provided for the biological assays.
Most importantly, assay performance has improved due to
the serial dilutions being performed by the same liquid
handler (fully validated for various liquid classes).
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JALA June 2004 127