Figure 6.

Viability of hypertrophic cardiomyopathy (HCM) induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) under long-term β-adrenergic activation is improved by rebalancing Ca²⁺ homeostasis. (A) Real time PCR expression profiles of key Ca²⁺ related proteins. All groups compared with Ctrl with Student’s t-test, data from two lines of Ctrl iPSC-CMs and two lines of HCM iPSC-CMs from at least two differentiation batches. (B) Western blot analysis shows increased CaMKIId activation (pThr286) in HCM iPSC-CMs compared with Ctrl iPSC-CMs, which was recovered by Ca²⁺ and late Na⁺ channel blocker treatment. All groups compared with HCM group with Student’s t-test. Data from two lines of each iPSC-CMs from at least two differentiation batches. (C and D) Long-term isoproterenol (ISO) treatment further enhanced the diastolic Ca²⁺ overload and prolonged Ca²⁺ transient decay time in HCM iPSC-CMs, which were partially rescued by Ca²⁺ and late Na⁺ channel blockers. N > 50 cells for each group. All groups compared with ISO treated HCM iPSC-CMs by one-way ANOVA (Tukey method). (E and F) Cell viability assay indicates that Ca²⁺ channel blockers partially restored viability of HCM iPSC-CMs after long-term ISO challenge. β-blockers were used as treatment control and doxorubicin was used as cell death control. All groups compared with baseline (white bar) by two-way ANOVA (Tukey method). For each group, data were generated from two different iPSC lines and two batches of differentiation.