Enhanced cardiotoxicity assessment through propagation pattern analysis using HD-CMOS-MEA in hiPSC-derived cardiomyocytes

Cardiotoxicity is a common reason for drug discontinuation in new drug development. The in vitro microelectrode array (MEA) method using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is expected to be an alternative to animal experiments, but hiPSC-CMs cannot mature sufficiently in two-dimensional culture. In addition, the evaluation method of MEA is mainly based on the field potential duration (FPD) as an index, and the mechanism of action based on conduction velocity and propagation pattern has not been predicted. This research aims to construct an evaluation method focusing on conduction velocity and propagation pattern as indices for MEA. To enable detailed analysis, hiPSC-CMs were measured using a high-density (HD)-CMOS-MEA with 236,880-microelectrodes instead of conventional MEA. Pharmacological tests used compounds and concentrations undetectable by conventional MEA, measuring extracellular potentials for 14 compounds, including negative controls. The HD-CMOS-MEA can record a single cell with dozens of electrodes. Seventeen parameters were established for the propagation pattern, including the number of origins, origin position fluctuation, propagation velocity, and propagation area. A specific increase in origins was detected with isoproterenol, an adrenergic β1 receptor agonist. A decrease in propagation velocity was observed with mexiletine, a Na channel inhibitor. A decrease in propagation area was detected with E4031, a hERG potassium channel inhibitor. Furthermore, differences in conduction velocity and propagation pattern based on the mechanism of action of each compound were revealed, suggesting that cardiotoxicity evaluation using CMOS-MEA may capture differences in channel activity for each concentration of compounds with multiple actions with high sensitivity. Additionally, a decrease in propagation area and propagation velocity was detected 24 h after exposure to 0.1 μM doxorubicin, which exhibits cardiotoxicity when administered chronically. Cardiotoxicity evaluation using CMOS-MEA demonstrated that cardiotoxicity could be detected at lower concentrations and shorter durations of chronic administration compared to conventional cardiotoxicity evaluations. This indicates that cardiotoxicity evaluation using HD-CMOS-MEA may detect cardiotoxicity risks that could not be identified by conventional MEA analysis, based on new parameters. This underscores the potential use of imaging technology in drug discovery and compound toxicity evaluation.