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High Throughput, High Content Screening ‐ Automa6ng the Pipeline
Rajarshi Guha, Ph.D. NIH Center for Transla:onal Therapeu:cs
San Francisco, January 2010
Merging Screening Technologies
• Lead iden:fica:on • Single (few) read outs • High‐throughput • Moderate data volumes
• Phenotypic profiling • Mul:ple parameters • Moderate throughput • Very large data volumes
High throughput screening High content screening
• We’d like to combine the technologies, to obtain rich high‐resolu:on data at high speed
• Is this feasible? What are the trade‐offs?
Merging Screening Technologies
• A simple solu:on is to run a HTS & HCS as separate, primary & secondary screens
• Alterna:vely – Wells to Cells – Integrate HTS & HCS in a single screen using a combined plaYorm for robo:cs & real :me automated HTS analy:cs
– Selec%ve imaging of interes%ng wells
Wells to Cells Workflow
• Sequen:al qHTS using laser scanning cytometry followed by high‐res microscopy
• Unit of work is a plate series • The same aliquot is analyzed by both techniques
• A message based system
• The key is deciding which wells go through the workflow
DecisionAnalytics
Inactive
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Log[Compound], MLog[Compound], M
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Active
-9 -8 -7 -6 -5 -4
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Object segmentation
Parameters selection
Thresholds definition
Raw data Images
Curve class, AC50, Efficacy
Morphological properties, localization
HTS Laser Scanning Cytometry
Population Definition
Population distribution
Curve class, AC50, Efficacy
Selective HCSMicroscopy
Normalization
Correction
Fitting
Curve classification
Response Curve Calculation
Object segmentation
Parameters selection
Thresholds definition
Population Definition
Objects characterization
Normalization
Correction
Fitting
Curve classification
Response Curve Calculation
qHTS Database
9 8 7 6 5 4
0
75
- 0
25
0
Log[Compound], M
5
-
-
- - - - - -10-
)%(
ytivit
cA
Selected
wells
HTS HCS
SAR
Confirmation
Acquisition Client
Integrated Chemical
Genomics Client
Informa:cs Pla<orm
• Advanced correc:on and normaliza:on methods
• Sophis:cated curve fi]ng algorithm
• Good performance, allows paralleliza:on of the en:re workflow
InCell Layout File
Why Messaging?
• A messaging architecture allows for significant flexibility – Persistent, can be kept for process tracking, repor:ng
– Asynchronous, allows individual components of the workflow to proceed at their own pace
– Modular, new components can be introduced at any :me without redesigning the whole workflow
• We employ Oracle AQ, but any message queue can be employed
qHTS & Curve Classes
• Heuris:c assessment of the significance of a concentra:on response curve
• Prior valida:on screens allow us to decide which types of curves should be selected
Inac%ve
Ac%ve
Inconclusive
Well Selec:on Criteria
• Generally, pre‐determined (from valida:on assays)
• Selec:on criteria implemented as Java code – Easy to adapt for different assays – Currently only makes use of the :tra:on curve parameters
– Could easily involve • Chemical structure • Enrichments • Predic:ve models
Well to Cells Assays
• Cell cycle, cell transloca:on, DNA repreplica:on
• All assays run against LOPAC1280 • Consistency between cytometry & microscopy is measured by the R2 between log AC50’s – Cell cycle, 0.94 – 0.96 – Cell transloca:on, 0.66 – 0.94 – DNA rereplica:on, s:ll in progress
Cell Transloca:on Example Hits
Data Access & Browsing
• In development • An integrated tool to manage and disseminate data relevant to chemical genomics
• A consistent/simple interface to register/import, browse, search, and annotate data
• An effec:ve tool for confirma:on of HTS and/or HCS data
Handling Mul:ple Pla<orms
• Current examples employ InCell hardware • We also use Molecular Devices hardware
• As a result we have two orthogonal image stores / databases
• Need to integrate them – Support seamless data browsing across mul:ple screens irrespec:ve of imaging plaYorm used
– Support analy:cs external to vendor code
Image Stores & REST
• We use the file‐system based image store op:on for MetaXpress
• Allows us to repurpose it to store InCell images
• Custom Python code to load InCell images into the store and meta‐data into an Oracle DB
A Unified Interface
• A client sees a single, simple interface to screening image data
• Transparently extract image data via the MetaXpress database or via custom code
• Currently the interface address image serving
• Unified metadata interface in the works
h;p://host/rest/protocol/plate/well/image
Trade‐offs & Opportuni:es
• Automa:on reduces the ability to handle unforeseen errors – Dispense errors and other plate problems – Well selec:on based on curve classes may need to be modified on the fly
• Well selec:on does not consider SAR – Wells are selected independently of each other – If we could model SAR on the fly (or from valida:on screens), we’d select mul:ple wells, to obtain posi:ve and nega6ve results
Conclusions
• Automated mul:‐stage screening is a leap forward – Saves money and :me – Requires good analy:cs to be robust to on‐the‐fly errors
• Integra:on at all layers (data / image store, data types) is key to making sense out of the data
• Would be nice to have clean vendor API’s!
Acknowledgments
• Doug Auld • Jim Inglese
• Ronald Johnson • Sam Michael
• Trung Nguyen • Steve Titus • Jennifer Wichterman