Abstract 18056: Modeling Duchenne Muscular Dystrophy (DMD) Cardiomyopathy Using Patient-specific Induced Pluripotent Stem Cell-derived Cardiomyocytes

Abstract

Introduction: DMD is the most common muscular dystrophy and is characterized by the absence of dystrophin. Cardiomyopathy and associated arrhythmias have emerged as a leading cause of death in DMD. Hypothesis: We hypothesized that the pathophysiology of DMD cardiomyopathy can be modeled using DMD hiPSC-derived cardiomyocytes (CM), which can be interrogated at the cellular and molecular level. Methods: Dermal fibroblasts were obtained from patients with genetically confirmed DMD and healthy controls and reprogrammed to hiPSC using human reprogramming transcription factors. DMD and control hiPSC lines were differentiated to CMs using a directed differentiation protocol. Functional analysis including wheat-germ agglutinin co-immunoprecipitation and calcium handling was performed at d60. Results: DMD hiPSCs demonstrated DYSTROPHIN exon mutations consistent with patient mutations. DMD and control hiPSCs differentiated to beating, electrically coupled CM sheets. Quantitative western blot analysis for dystroglycan complex (DGC) components and novel cardiac DGC proteins Cryab and Cypher demonstrated expression of the majority of DGC and novel cardiac DGC proteins at d60 of differentiation in control hiPSC-derived CM. Dystrophin and DGC proteins including novel cardiac DGC proteins are associated with the DGC in all control hiPSC CM at d60. DMD hiPSC-derived CM have absence of dystrophin and a disrupted DGC. We identified that cypher is absent in DMD hiPSC CM and validated this in human DMD left ventricular tissue. Calcium imaging demonstrated significantly abnormal calcium transients in DMD hiPSC-derived CM correlating to arrhythmias. Conclusion: Our results suggest that the control hiPSC-derived CMs have a largely nucleated DGC at d60 including novel cardiac DGC associated proteins. DMD hiPSCs have the hallmark absence of dystrophin and a disrupted DGC. The phenotype of increased arrhythmias in DMD patients is also reflected in DMD hiPSC CM. DMD hiPSC-derived CMs can be used as a model for investigation of DMD cardiomyopathy and further evaluation of the molecular and physiologic phenotype of DMD hiPSC cardiomyocytes will serve as a platform for testing current therapies and developing novel therapies for patients with DMD cardiomyopathy.