Label-Free High-Throughput Cardiotoxicity Assays using Combined Impedance and Extracellular Field Potential Measurements

Abstract

A new trend in the industry utilizes induced pluripotent stem cells (iPSCs) for functional assays to identify cardiac pathologies and their genetic underpinnings (such as Long QT Syndrome (LQTS)), in addition to cardiotoxicity profiling of pharmaceutical compounds.The here utilized CardioExcyte® 96 system is a hybrid instrument that combines impedance readout (a correlate of cell contractility) with electric field potential recordings of the compound signal that is generated by cellular action potentials. These electrophysiological measurements are label-free and allow investigations in High Throughput format. In addition, the instrument is capable of electrical stimulation of the cellular monolayer, while the rapid acquisition rate of 1ms allows a more accurate description of signal features and nuances stemming from pharmacological effects. A dedicated software package for rapid data handling and real-time analysis is based on novel algorithms that allow a comprehensive investigation of the cellular beat signal.A broad range of cell lines was successfully validated, such as stem cell-derived cardiomyocytes from Axiogenesis (human: Cor4U®, murine: CorAt®), GE Healthcare (Cytiva), Cellectis (human, 3D-clusters: hES-CMC™) and CDI (iCell®). Furthermore, the pharmacological effects of a number of reference compounds on these cell types were evaluated and their phenotype correctly identified. For example, the effects of compounds like Blebbistatin, which blocks contraction without disrupting the electric field potential can be easily identified since it is an inhibitor of the myosin II which is mainly responsible for the contraction of cardiomyocytes, while it has no effect to the ion channels. Other compound classes like hERG inhibitors were validated as well and example data will be shown. They induce typical arrhythmia since hERG ion channels are affected.