A High Throughput Microfluidic Approach Enables Fast Exchange of Solutions and Ligand Gated Ion Channel Recording from Cell Ensembles

Abstract

Electrophysiology is the preferred technique for characterizing ion channel function and kinetics. It is the most functionally pertinent assay for screening in terms of information content. High throughput pharmaceutical screens often use a population patch approach, which eliminates cell-to cell variability of single cell recordings. However, currently available population patch platforms have key shortcomings such as a) the inability for fast exchange of solutions, b) the inability to apply multiple compounds to the same ensemble of cells, and c) the inability to record fast desensitizing channels.Here we present novel data showing that by using a microfluidic network design along with population patch recording we are able to overcome these obstacles. We validated our system using cells expressing voltage-gated channels in ensembles of up to 30 cells under voltage clamp. Moreover, these results showed that there is fast compound application (<100ms). The time course of compound application was confirmed using fluorescent indicators and biological reporters, such as GABA-A expressing cells. These data also validated our ability to record from fast desensitizing ligand gated ion channels without appreciable desensitization. We compared the time course of solution exchange with and without a protective layer technique and additionally characterized application of multiple compounds to the same ensemble of cells. In conclusion, the novel microfluidic approach allows for the fast exchange of compounds and facilitates the recording of fast activating voltage and ligand-gated channels.