Many phenotypic cell-based assays are limited to 384-well formats due to the challenges of liquid handling, and the need for consistency during microplate washing and media change steps. Use of expensive assay formats in 384 format impacts the number of compounds that can be screened through such assays.
To address these challenges, Plant explains how the BlueCatBio centrifugal plate washer integrates centrifugal emptying with the individual addition of up to four separate solutions for complex phenotypic assays. The achievement of near zero residual volume by using centrifugation rather than aspiration is enabling for 1536-well formats. Typically phenotypic imaging assays are limited to 384-well formats due to the need for consistent washing steps after fixation and staining. To miniaturize to a 1536-well format the centrifugal plate washer is used to perform washing cycles. Similar high-throughput screening (HTS) quality metrics are obtained in 1536 formats compared to that obtained in the original HTS using 384 format.
The Corning Epic system is a label-free detection system that uses resonant waveguide grating to measure the drug-induced response of cells using dynamic mass redistribution (DMR). DMR is measured by the refraction of light from a biosensor integral to an Epic plate, but the cost of these high value plates has limited the use of this technology at scale. To enable its use in HTS, Dr. Plant hasdeveloped a 1536 format assay, but many challenges are encountered throughout this process.
When using smaller assay volumes, lengthy incubations at 37oC can result in issues with evaporation leading to edge effects. These are often more apparent when scaling up to larger batches of plates. Testing various types of plate seals shows that edge effects are dramatically reduced.
Successful conversion of complex phenotypic assays to 1536-well formats results in up to a 50 percent reduction in cell number requirements and approximately a four-fold reduction in time taken to perform a full HTS screening campaign. It also allows screening of expensive assay formats and cell types in high-content phenotypic HTS screens.
Scientist, AstraZeneca Pharmaceuticals, Macclesfield, United Kingdom
Having obtained her BSc in Biochemistry at the University of Manchester UK, Helen Plant has worked in the pharmaceutical industry for 23 years. Dr. Plant is an experienced drug-discovery bioscientist, working in the fields of Biochemical & Cell Assay Development, High Throughput Screening and Laboratory Automation. Helen Plant has been employed in her current role since 2009 as a senior research scientist within the AstraZeneca Global High Throughput Screening centre, with a responsibility for delivering screening data to a global internal & external customer base.
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