Fig. 1.

Single high dose of etoposide induces arrhythmic beating and cytotoxicity in hiPSC-CMs. a Schematic representation and experimental setup of the in vitro cardiotoxicity test model. For functional studies, the synchronously beating hiPSC-CMs in the E-plate Cardio 96 were exposed to ETP (single high-dose exposure) for 48 h. After exposure, the ETP was washed out and the cells were further incubated for 48 h. The effects of ETP on hPSC-CMs functional characteristics were monitored by the xCELLigence RTCA Cardio system. For qRT-PCR studies, RNA from ETP-treated and untreated control cells were harvested at day 2. b–e Functional studies of ETP-treated hiPSC-CMs. The representative graphs display, b normalized CI values showing ETP-induced cytotoxicity (n = 3, error bars represent ± SEM), c % beating rate alterations induced by single dose of ETP in hiPSC-CMs (n = 3, error bars represent ± SEM) (t test, *p < 0.05, **p < 0.01, ***p < 0.001), d representative 12 s beating traces of hiPSC-CMs before, during and after the ETP treatment, e normalized amplitude showing significant drop after ETP treatment (n = 3, error bars = ± SEM) (t test, *p < 0.05, **p < 0.01, ***p < 0.001). f ETP-induced cytotoxicity was assessed by LDH leakage assay. The graph shows % cytotoxicity induced by ETP compared to untreated control (n = 3, error bars represent ± SEM) (t test, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001)