P35 Adaptation of a phenotypic screening assay to incorporate 384-well plates: opening the door to high-throughput screening

Abstract Introduction and aims High-throughput screening has significantly impacted drug discovery by increasing speed of experiments and reducing reagent and sample costs. We have previously developed several screening assays to measure myofibroblast inhibition via quantification of α-smooth muscle actin (α-SMA) expression, in a 96-well format. Currently, there are no drugs for the treatment of hypertrophic scarring, a major side-effect of burn injuries that occurs by myofibroblast transformation, leaving a huge gap in this sector. The aim for this project was to adapt our current assay for use in 384-well microplates. Methods Human primary dermal fibroblasts were transformed to myofibroblasts using 10 ng mL−1 transforming growth factor (TGF)-β1. α-SMA expression was measured using the In-Cell enzyme-linked immunosorbent assay method, with cell viability measured using DRAQ5 nuclear staining. Assay accuracy and reliability was determined by calculating the robust z-factor, with guidelines set to an average score over 0.5, with a minimum score per plate above 0.4. To further validate the assay, concentration-response curves (CRCs) for the drug vehicle [dimethyl sulfoxide (DMSO)] and our tool compound (SB-505124) were constructed at varying concentrations, in coincubation with TGF-β1. Results Optimization of well metrics was performed, producing an average robust z-factor of 0.52, confirming the assay Results are reliable and reproducible. The DMSO CRC produced no significant drop in cell viability at concentrations that are expected to be used in the screening of compounds. Our tool compound (SB-505124) produced a concentration-dependant curve for the inhibition of myofibroblast transformation. Conclusions A 384-well assay has been designed, tested and validated for the determination of myofibroblast transformation in human primary dermal fibroblasts. The assay has been shown to deliver an average robust z-factor of above 0.5, it contains a positive control and is compatible with compounds stored in up to 100% DMSO.