Changsung Kim1, JohnsonWong1, Jianyan Wen1,2, ShirongWang1, ChengWang1, Sean Spiering3, Natalia G. Kan3, Sonia Forcales3, Pier Lorenzo Puri3,4, Teresa C. Leone5, Joseph E. Marine6, Hugh Calkins6, Daniel P. Kelly5, Daniel P. Judge6 & Huei-Sheng Vincent Chen1,7,*
1Del E. Webb Neuroscience, Aging & Stem Cell Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA. 2Department of Cardiovascular Surgery, China-Japan Friendship Hospital, Beijing 100029, China. 3Muscle Regeneration and Development Program, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA. 4Dulbecco Telethon Institute, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy. 5Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute, Orlando, Florida 32827, USA. 6Department of Medicine/ Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA. 7Department of Medicine/Cardiology, University of California-San Diego, San Diego, California, 92103, USA.
*Correspondence to: Huei-Sheng Vincent Chen
Cellular reprogramming of somatic cells to patient-specific induced pluripotent stem cells (iPSCs) enables in vitro modelling of human genetic disorders for pathogenic investigations and therapeutic screens1-7. However, using iPSC-derived cardiomyocytes (iPSC-CMs) to model an adult-onset heart disease remains challenging owing to the uncertainty regarding the ability of relatively immature iPSC-CMs to fully recapitulate adult disease phenotypes. Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited heart disease characterized by pathological fatty infiltration and cardiomyocyte loss predominantly in the right ventricle8, which is associated with life-threatening ventricular arrhythmias. Over 50% of affected individuals have desmosome gene mutations, most commonly in PKP2, encoding plakophilin-2 (ref. 9). The median age at presentation of ARVD/C is 26 years8. We used previously published methods1, 10 to generate iPSC lines from fibroblasts of two patients with ARVD/C and PKP2 mutations11, 12. Mutant PKP2 iPSC-CMs demonstrate abnormal plakoglobin nuclear translocation and decreased β-catenin activity13 in cardiogenic conditions; yet, these abnormal features are insufficient to reproduce the pathological phenotypes of ARVD/C in standard cardiogenic conditions. Here we show that induction of adult-like metabolic energetics from an embryonic/glycolytic state and abnormal peroxisome proliferator-activated receptor gamma (PPAR-γ) activation underlie the pathogenesis of ARVD/C. By co-activating normal PPAR-alpha-dependent metabolism and abnormal PPAR-γ pathway in beating embryoid bodies (EBs) with defined media, we established an efficient ARVD/C in vitro model within 2 months. This model manifests exaggerated lipogenesis and apoptosis in mutant PKP2 iPSC-CMs. iPSC-CMs with a homozygous PKP2 mutation also had calcium-handling deficits. Our study is the first to demonstrate that induction of adult-like metabolism has a critical role in establishing an adult-onset disease model using patient-specific iPSCs. Using this model, we revealed crucial pathogenic insights that metabolic derangement in adult-like metabolic milieu underlies ARVD/C pathologies, enabling us to propose novel disease-modifying therapeutic strategies.