Predicting human cardiac QT alterations and pro-arrhythmic effects of compounds with a 3D beating heart-on-chip platform

Detecting cardiac QT alterations and pro-arrhythmic effects of compounds during early stages of drug development process is still critical. Hence the development of relevant in-vitro preclinical models resembling the human heart is highly envisioned, so to effectively predict repolarization risks in humans. Here we described a human functional 3D cardiac model developed within a beating Organ-on-Chip (OoC) platform integrating fit-to-purpose assays for detecting drug-induced electrophysiological alterations in pre-clinical stages. The model, named uHeart, was developed and qualified for functional cardiotoxicity screening by following the latest International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use S7B guidelines. uHeart platform encompasses two patented technologies: i) an actuating mechanism that mechanically trains microtissues by providing a physiological uniaxial cyclic strain (i.e., 10 % stretching, 1 Hz) and ii) a system of integrated electrodes able to read electrophysiological cardiac signals (i.e., Field Potential FP). Human induced pluripotent stem cell derived cardiomyocytes (h-iPSC-CMs, iCell) and human dermal fibroblasts (h-DF), 75 %–25 % ratio, were embedded in fibrin hydrogel (125*10^6 cells/ml) and cultured for up to 10 days. Upon achievement of functional microtissues synchronously and spontaneously beating, 11 drugs listed in the Comprehensive in vitro Proarrhytmia Assay (CiPA) and affecting single or multiple cardiac ion-channels were selected to qualify the model. Drug-induced alterations were evaluated at incremental doses and by analyzing the FP morphology (i.e., beating period-BP, spike amplitude-AMP, FP-duration-FPD) and the onset of arrhythmic events. DMSO and Aspirin were used as vehicle and negative controls, respectively. Microtissues beat synchronously after 5 days, and FP signals showed the typical depolarization and re-polarization spikes. Ikr blockers (e.g., Dofetilide, Quinidine) prolonged the FPD at concentration near the Cmax. ICaL blockers (e.g., Verapamil, Nifedipine) shortened it at 5 and 50 nM respectively. Mexiletine, blocking INa, statistically decreased the AMP at 10 μM. Both Terfenadine and Dofetilide elicited arrhythmic events, matching FDA labels indications. Overall, the system showed 83.3 % sensitivity, 100 % specificity and 91.6 % accuracy in detecting FPD prolongation. DMSO (up to 0.5 % w/v) and Aspirin (up to 100 μM) did not statistically alter the repolarization time. uHeart generates functional 3D cardiac in-vitro models, predicting compound specific toxic effects at concentrations near the Cmax, thus resulting suitable to perform functional cardiotoxicity preclinical drug screening.