A human cardiomyocyte-based cellular model mimicking cardiac ischemia

Ischemic heart disease, the most common form of heart disease worldwide, is caused by a lack of oxygen and nutrients in the heart due to the narrowing of coronary arteries. Research in this field is mostly limited to animal models, but the development of cellular models could significantly accelerate the discovery of novel therapeutic molecules to protect cardiomyocytes from ischemic stress. To address this limitation, this study focused on developing an in vitro model of ischemic stress using human cardiomyocytes derived from induced pluripotent stem cells. After differentiating induced pluripotent stem cells into cardiomyocytes, the cells, cultured either in monolayers or as a spheroid, were exposed to an ischemic environment characterized by oxygen and nutrient deprivation. Specifically, we reduced the oxygen concentration to 1% using a hypoxia chamber and the glucose concentration to 65 mg/L to trigger the onset of cardiac ischemia. Twenty-four hours later, the stressed cardiomyocytes were treated with tumor necrosis factor alpha (TNF-α, 20 ng/mL) and interleukin 6 (IL-6, 20 ng/mL) to also mimic the inflammatory environment. The cells were then analyzed at various timepoints following exposure to ischemic stress. Our results showed that this novel ischemia model induces progressive cellular toxicity characterized by increased apoptosis, double-stranded DNA breaks, and overall cell death. These effects are accompanied by mitochondrial and metabolic dysfunction, loss of cardiomyocyte contractile function, and numerous morphological alterations, including reduced cell and nuclei size and disorganization of the α-actinin network. In conclusion, our results highlight that this model offers a valuable platform for understanding the mechanistic underpinnings of cardiomyocyte ischemic stress and holds promise for screening novel therapeutic molecules aimed at protecting cardiomyocytes. Furthermore, by reducing reliance on animal models, it adheres to the reduction, replacement, and refinement (3Rs) ethical principles.<b>NEW & NOTEWORTHY</b> In this study, we developed a novel in vitro model of cardiac ischemia using cardiomyocytes derived from induced pluripotent stem cells. Cells were exposed to oxygen and nutrient deprivation, followed by proinflammatory cytokines to mimic postischemic inflammation. This approach reproduces key features of ischemic injury, including mitochondrial dysfunction, impaired contractility, and morphological changes. The model provides a valuable tool for studying cardiac pathophysiology and testing therapeutic strategies while reducing reliance on animal models.