High throughput methods for broad electrophysiological characterization of human induced pluripotent stem cell derived cardiomyocytes

Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) offer a promising, renewable source for the study of cardiac physiology. Quantification of key iPSC-CM ion channel function is traditionally done using the patch-clamp technique, a complex and low throughput method. This methodological bottleneck often hinders the practical application of iPSC-CM in drug testing, cardiac disease modelling and the generation of patient specific therapies. 

This work presents a novel protocol to increase the throughput of key cardiac ion channel measurements in iPSC-CM using an automated patch clamp device. Such a device allows for the simultaneous measurement of hundreds of cells under identical conditions over short experimental periods. Furthermore, automated liquid handling capabilities allow for solution exchange in both the bath and pipette compartments during an experiment allowing for the sequential measurement of multiple ion channel types in the same cell. We outline solution compositions and voltage protocols for rapid and direct measurement of cardiac ion channels: Na_V1.5, Ca_V1.2, K_v11.1, Kir2.1 and Kir3.1/3.4 in iPSC-CM. Assessment of drug effects on these channels is easily implemented in the modular voltage protocol sequences. Application of the muscarinic receptor agonist Carbachol (2 µm) functions as a useful iPSC-CM phenotype detector, revealing the presence or absence of Kir3.1/3.4 channels, which are only expressed in atrial cardiomyocytes.

This protocol allows for an integrated and efficient method which applies voltage-clamp approaches in a way that increases the throughput of data acquisition while relying on familiar patch-clamp principles. This may lead to faster and more reliable investigations of hiPSC-CM physiology therefore enhancing their applicability for drug development and personalised medicine.