Application of large-scale transient transfection to cell-based functional assays for ion channels and GPCRs

Despite increasing use of cell-based assays in biomedical research and drug discovery, one challenge is the adequate supply of high-quality cells expressing the target of interest. To this end, stable cell lines expressing the target are often established, maintained, and expanded in large-scale cell culture. These steps require significant investment of time and resources. Moreover, variability occurs regularly in cell yield, viability, expression, and target activities. In particular, stable expression of many targets, such as ion channels, causes toxicity, cell line degeneration, and loss of functional activity. To circumvent these problems, we utilize large-scale transient transfection (LSTT) to generate a large quantity of cells, which are cryopreserved and readily available for use in cell-based functional assays. Here we describe the application of LSTT cells to ion channel and G protein-coupled receptor (GPCR) assays in a drug discovery setting. This approach can also be applied to many other assay formats and target classes.