Ionflux: A Microfluidic Approach to Ensemble Recording and Block of Whole-Cell Current from Voltage-Gated Ion Channels

Abstract

Automated patch clamp (APC) addresses a need for high throughput screening of chemical entities altering ion channel function. Systems that can produce pharmacologically relevant data rapidly and consistently find considerable utility in the pharmaceutical industry, but also increasingly in academic laboratories. Here we present data obtained with a novel APC platform utilizing a well-plate microfluidic design. Unlike existing devices, the IonFlux system incorporates no internal robotic liquid handling, and features continuous recording from cell ensembles during rapid solution switches with a bench-top footprint resembling a conventional plate reader.True whole cell voltage clamp was applied to linear arrays of up-to thirty cells in parallel, utilizing fully-featured 16 or 64 channel voltage-clamp amplifiers under computer control. Laminar flow of solutions in a microfluidic network delivered cells in suspension to the recording sites and enabled fast exchange of bathing solutions via an electro-pneumatic interface, on either 96 or 384 well-plate formats. Electrophysiological characterization was achieved for KV 2.1 and hERG potassium channels, and examples of NaV sodium channels. Our results show the voltage-dependence of these currents and their block by pharmacological agents. The recordings also demonstrate the potential for microfluidics-enabled, exceptionally fast superfusion and washout of candidate drugs. Incorporation of multiple experiments per well-plate enables many investigations to be performed in parallel, especially if multiple compounds are applied to each individual cell ensemble recording array. Data on recording success rates, throughput and assay reproducibility show that high throughput experiments can be performed with enhanced reliability.