Characterization of Cultured Cardiomyocytes Derived from Human Induced Pluripotent Stem Cell for Quantitative Studies of Ca²⁺ Transport

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) are a promising experimental model of human myocardium for drug development and studies on cardiac pathophysiology, although their immature phenotype may limit their application. This study aimed at characterizing this model regarding Ca²⁺ transport by systems involved in cardiac relaxation. Ca²⁺ transients were recorded under different conditions of selective inhibition of these systems in hiPSC-CM from different batches, cultivated for different periods. The results indicate: (a) a pattern of interaction among Ca²⁺ transporters similar to that previously seen in neonatal rat myocardium, i.e., a greater impact of inhibiting the Na⁺-Ca²⁺ exchanger than impairing sarcoplasmic reticulum Ca²⁺ accumulation; (b) prolonging hiPSC-CM culture from 2 to 3 weeks did not result in further maturation of Ca²⁺ transport; (c) although data are comparable in cells from the same batch, the significant interbatch variation observed indicates the need of sampling several batches for reliable results and conclusions.