Abnormal action potential and calcium handling in Δ3–7 hiPSC-CMs
(A) Representative traces of the calcium transient of spontaneous beating in WT, Δ3–9, and Δ3–7 hiPSC-CMs on day 55. (B and C) Beating rate (B) and SD of inter-beat intervals (C) of spontaneous beating in single cells (n = 70, 55, 56 for WT, Δ3–9, Δ3–7, respectively). (D–G) ASAP2s imaging of a single-layered hiPSC-CMs sheet at 1/3 Hz field pacing. Representative traces of voltage (D), -(F-F0)/F0 of voltage (E), rise time (F), and APD60 (G) (n = 13, 12, 13 for WT, Δ3–9, Δ3–7, respectively). (H–K) R-CaMP1.07 imaging of a single-layered hiPSC-CMs sheet at 1/3 Hz field pacing. Representative traces of the calcium transient in the single-layered hiPSC-CMs sheet at 1/3 Hz field pacing (H), -(F-F0)/F0 (I), time to peak (J), and FWHM (K) (n = 13, 13, 12 for WT, Δ3–9, Δ3–7, respectively). F/F0, fluorescence (F) normalized to baseline fluorescence (F0). Data are presented as mean ± SEM. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.005, ∗∗∗∗p < 0.001.