A modular method for high-throughput measurement of ion channel currents in cardiac myocytes

The patch-clamp technique offers unparalleled insight into the electrical and biophysical behavior of excitable cells. However, it is a slow and low-throughput method that typically requires cells to be measured one by one. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are regularly subjected to this technique to unravel the molecular mechanisms of cardiac diseases. Their use in direct patient treatment and successful drug development has been limited due to the lack of applicable high-throughput patch-clamp methods suited to successful hiPSC-CM measurement. Here we present a protocol employing a patch-clamp robot that addresses these limitations by using planar patch-clamp technology. We outline how to collect and handle hiPSC-CM for these experiments, along with optimized patch-clamp protocols for direct functional measurement of major cardiac ion channels including K_ir2.1, Na_V1.5, Ca_V1.2, K_v11.1 and K_ir3.1/3.4. We further explain how the liquid-handling properties of this setup allow multiple patch-clamp protocols to be combined in sequence while the cell remains in whole-cell configuration. This allows for over a hundred-fold increase in functional data acquisition. These procedures can be carried out within 1 d by both skilled and non-electrophysiologists; however, some experience in cell culture and handling is required. Overall, this protocol enhances fast and reliable functional characterization of hiPSCl-CM and may increase their applicability for rapid and safe drug development.