Adapting Cell-Based Assays to the High-Throughput Screening Platform: Problems Encountered and Lessons Learned

In recent years, cell-based phenotypic assays have emerged as an effective and robust addition to the array of assay technologies available for drug discovery in the high-throughput screening (HTS) arena. Previously, biochemical target-based assays have been the technology of choice. With the emergence of stem cells as a basis for a new screening technology, it is important to keep in mind the lessons that have been learned from the adaptation of existing stable cell lines onto the HTS drug discovery platform, with special consideration being given to assay miniaturization, liquid-handling complications, and instrument-introduced artifacts. We present an overview of the problems encountered with the implementation of multiple cell-based assays at the High Throughput Screening Center at Southern Research Institute as well as empirically defined effective solutions to these problems. These include examples of artifacts induced by temperature differences throughout the screening campaign, cell-plating conditions including the effect of room temperature incubation on assay consistency, DMSO carry over, and incubator-induced artifacts.