Functional and molecular effects of TNF-α on human iPSC-derived cardiomyocytes.

Proinflammatory molecule tumor necrosis factor alpha (TNF-α) is predominantly elevated in cytokine storm as well as worsening cardiac function. Here we model the molecular and functional effects of TNF-α in cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSC). We found that treatment of hiPSC-CMs with TNF-α increased reactive oxygen species (ROS) and caspase 3/7 activity and caused cell death and apoptosis. TNF-α treatment also resulted in dysregulation of cardiomyocyte function with respect to the increased abnormal calcium handling, calcium wave propagation between cells and excitation-contraction coupling. We also uncovered significant changes in gene expression and protein localization caused by TNF-α treatment. Notably, TNF-α treatment altered the expression of ion channels, dysregulated cadherins, and affected the localization of gap-junction protein connexin-43. In addition, TNF-α treatment up-regulated IL-32 (a human specific cytokine, not present in rodents and an inducer of TNF-α) and IL-34 and down-regulated glutamate receptors and cardiomyocyte contractile proteins. These findings provide insights into the molecular and functional consequences from the exposure of human cardiomyocytes to TNF-α. Our study provides a model to incorporate inflammatory factors into hiPSC-CM-based studies to evaluate mechanistic aspects of heart disease.