The modulation of calcium and chloride channels induces cardiomyocytes from human pluripotent stem cells

Ion channels play a crucial role in cardiac functions, and their activities exhibit dynamic changes during heart development. However, the precise function of ion channels in human heart development remains elusive. In this study, we utilized human embryonic stem cells (hESCs) as a model to mimic the process of human embryonic heart development. During hESCs differentiation into cardiomyocytes, we observed differential expression of ion channel genes, including upregulation of ryanodine receptor 2 (RYR2), which encodes a calcium release channel. Subsequently, we discovered that Suramin, an activator of RyR2, efficiently promoted cardiac differentiation even in the absence of conventional WNT inhibitors. Furthermore, various modulators targeting sodium channels, potassium channels or chloride channels were examined under chemically defined conditions during cardiac differentiation. We found that DIDS, a chloride transport inhibitor, also enhanced hESCs differentiation into cardiomyocytes. Both Suramin and DIDS partially inhibited WNT signaling pathway, and RYR2 knockdown attenuated cardiac differentiation induced by WNT inhibitor treatment, or Suramin or DIDS administration. The resulting cardiomyocytes induced by these ion modulators exhibited specific expression patterns of cardiac genes and displayed typical electrophysiological signals. Notably, compared to WNT inhibitor treatment group, both Suramin and DIDS led to increased generation of atrial-like cardiomyocytes suggesting their potential as alternative inducers for specific cardiomyocyte lineage commitment during human cardiomyocyte induction processes. This study demonstrates that regulation of ion channels plays a crucial role in determining the fate of cardiac cells, providing an effective approach for inducing cardiomyocytes from hPSCs and highlighting their critical involvement in human heart development.