Abstract 17241: Modeling Arrhythmogenic Right Ventricular Cardiomyopathy with Human Induced Pluripotent Stem Cells
Introduction: The study of inherited cardiac disorders has been hampered by lack of human in vitro models. This problem may be overcome by the recent derivation of patient-specific cardiomyocytes from human induced pluripotent stem cells (hiPSC). Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a leading cause of sudden cardiac death in young adults. ARVC is caused by mutations in desmosomal proteins and results in myocardial fibro-fatty accumulation. We aimed to establish a hiPSC in vitro model of ARVC. We hypothesize that the patient-specific cardiomyocytes will recapitulate the disease phenotype and provide novel mechanistic insights into the disease.
Methods and Results: hiPSC were generated from a patient with plakophilin2 (PKP2) mutation and compared to control hiPSC. The hiPSC exhibited characteristic reprogramming properties and were coaxed to differentiate into the cardiac lineage. Temporal gene expression pattern and immunostainings confirmed the cardiac-phenotype of the differentiating ARVC-cardiomyocytes. Multielectrode array recordings showed the development of a functional cardiac syncytium with chronotropic responses to adrenergic and cholinergic stimuli. Real-time PCR revealed a 69%±5% decrease in PKP2 levels. 3D immunostaining studies revealed reduced PKP2 signal density in the ARVC cardiomyocytes (2.2%±0.6% vs. 9.5%±3.6%, p<0.05) as well as a trend towards cytosolic translocation of plakoglobin. Electron microscopy demonstrated widened and distorted desmosomes in the diseased cells (internal width: 32±2.3nm vs. 24±3.8nm, p<0.05; maximal external width: 171±12nm vs. 101±5nm, p<0.001, n=50) which remarkably correlated with the presence of lipid droplets within the cardiomyocytes (AUC=0.84, 95% CI, 0.73 - 0.94, n=50). Exposure to metabolic and contractile stress augmented lipid accumulation and desmosomal distortion of the ARVC-cardiomyocytes exclusively.
Conclusions: The generated hiPSC cardiomyocyte model was shown to recapitulate ARVC phenotype in the dish, confirm and provide novel insights into disease mechanisms (showing a correlation between desmosomal abnormalities and intracellular lipid accumulation) and identify potential disease triggers (metabolic and contractile stress).
- © 2012 by American Heart Association, Inc.