A platform for assessing pro- and anti-arrhythmic effects of drugs based on isogenic human iPSC-derived cardiomyocytes

Cardiotoxicity is an unexpected side effect of drugs and a major cause of drug failure in preclinical and clinical phases of drug discovery. Some drugs bind to the cardiac hERG ion channel and cause a prolongation of the heart QT interval, inducing arrhythmias that can eventually lead to sudden cardiac death. Notably, individuals with inherited long QT syndrome (LQTS) are more prone to develop drug-induced arrhythmia. We previously showed that the LUF7346 allosteric modulator can shorten the QT interval in vitro in LQTS human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). Our aim is to establish a drug-screening platform based on healthy and diseased hiPSC-CM to i) identify molecules with hERG allosteric modulator activity and ii) assess drug pro- and anti- arrhythmic effects. We used two isogenic hiPSC lines: one representing a severe form of LQTS, called Jervell and Lange-Nielsen syndrome (JLNS), carrying a homozygous mutation in the cardiac ion channel KCNQ1 gene, and its isogenic wild-type line, that we generated with CRISPR/Cas9 technology. Both lines were differentiated into cardiomyocytes and their electrophysiological properties were evaluated by multi-electrode array (MEA) recording of spontaneous beating activity and by patch clamp. JLNS hiPSC- CM action potential (AP) duration was prolonged compared to the isogenic wild type line. We then optimized seeding and recording conditions in 96-well MEA plates. Finally, we used a novel integrated system based on fluorescent dyes to simultaneously measure AP, calcium transient, and contraction upon application of the reference compound LUF7346. This platform can identify active molecules able to shorten AP. Our approach will provide evidence for the value of using hiPSC-CM in preclinical drug testing.