Chronic Exposure to Testosterone Increases Expression of Transient Outward Current in Human Induced Pluripotent Stem Cell (hiPSC)-Derived Cardiomyocytes (CM)

Arrhythmia Mechanisms in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

ABSTRACT

Despite major efforts by clinicians and researchers, cardiac arrhythmia remains a leading cause of morbidity and mortality in the world. Experimental work has relied on combining high-throughput strategies with standard molecular and electrophysiological studies, which are, to a great extent, based on the use of animal models. Because this poses major challenges for translation, the progress in the development of novel antiarrhythmic agents and clinical care has been mostly disappointing. Recently, the advent of human induced pluripotent stem cell-derived cardiomyocytes has opened new avenues for both basic cardiac research and drug discovery; now, there is an unlimited source of cardiomyocytes of human origin, both from healthy individuals and patients with cardiac diseases. Understanding arrhythmic mechanisms is one of the main use cases of human induced pluripotent stem cell-derived cardiomyocytes, in addition to pharmacological cardiotoxicity and efficacy testing, in vitro disease modeling, developing patient-specific models and personalized drugs, and regenerative medicine. Here, we review the advances that the human induced pluripotent stem cell-derived-based modeling systems have brought so far regarding the understanding of both arrhythmogenic triggers and substrates, while also briefly speculating about the possibilities in the future.

Cellular and ionic basis of J-wave syndromes

J-wave syndromes are disorders of ventricular repolarization characterized by prominent J waves on the ECG and have the potential to predispose affected individuals to lethal ventricular arrhythmias. These disorders share a common cellular mechanism with prominent Ito in ventricular epicardium. This current causes transmural dispersion of repolarization and the generation of phase 2 reentry, leading to short-coupled extrasystoles and VF. Several autonomic, chemical, and hormonal factors modulate Ito and are therefore vital in attenuating or increasing the arrhythmic potential of these syndromes. Future research should focus on evaluating the arrhythmogenic potential of patients with pathogenic genotypes and/or J waves and no history of VF.