Modeling Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy with Patient-Specific iPSCs

Abstract

Cellular reprogramming of somatic cells from cardiac patients to induced pluripotent stem cells (iPSCs) enables in vitro modeling of human genetic disorders for pathogenic investigations and therapeutic screens. However, using iPSC-derived cardiomyocytes (iPSC-CMs) to model an adult-onset heart disease remains challenging due to the uncertainty regarding the ability of relatively immature iPSC-CMs to fully recapitulate adult disease phenotypes. Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy characterized by pathological fibrofatty infiltration and cardiomyocyte (CM) loss predominantly in the right ventricle (RV), leading to life-threatening ventricular arrhythmias. Over 50 % of affected individuals have desmosome gene mutations, most commonly in PKP2 encoding plakophilin-2. The median age at presentation of ARVD is 26–30 years. We used Yamanaka’s pluripotent factors to generate iPSC lines from two ARVD patients with PKP2 mutations. We first developed a method to induce metabolic maturation of iPSC-CMs and showed that induction of adult-like/fatty acid dominant energetics from an embryonic/glycolytic state is essential to model an adult-onset cardiac disease using patient-specific iPSC-CMs. Furthermore, we demonstrate that coactivation of normal peroxisome proliferator-activated receptor-alpha (PPARα) and abnormal PPARγ pathways led to aggressive lipogenesis, elevated apoptosis, and defective intracellular calcium handling in ARVD iPSC-CMs, recapitulating the pathological signatures of ARVD. PPARγ antagonists rescued all ARVD pathological phenotypes and reactive oxygen species (ROS) scavengers curtailed CM apoptosis in our ARVD in vitro model. Thus, using this model, we revealed novel pathogenic insights that metabolic derangement in an adult-like metabolic milieu underlies ARVD pathologies, enabling us to test novel disease-modifying therapeutic strategies.