title: Modeling of arrhythmogenic right ventricular cardiomyopathy with human induced pluripotent stem cells.
abstract: BACKGROUND
  Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary heart muscle disorder resulting from desmosomal protein mutations. ARVC is characterized pathologically by fibrofatty infiltration and clinically by arrhythmias and sudden cardiac death. We aimed to establish a patient-/disease-specific human induced pluripotent stem cell (hiPSC) model of ARVC.
  
  
  RESULTS
  Dermal fibroblasts were obtained from 2 patients with ARVC with plakophilin-2 (PKP2) mutations, reprogrammed to generate hiPSCs, coaxed to differentiate into cardiomyocytes (CMs), and then compared with healthy control hiPSC-derived CMs (hiPSC-CMs). Real-time polymerase chain reaction showed a significant decrease in the expression of PKP2 in the ARVC-hiPSC-CMs. Immunostainings revealed reduced densities of PKP2, the associated desmosomal protein plakoglobin, and the gap-junction protein connexin-43. Electrophysiological assessment demonstrated prolonged field potential rise time in the ARVC-hiPSC-CMs. Transmission electron microscopy identified widened and distorted desmosomes in the ARVC-hiPSC-CMs. Clusters of lipid droplets were identified in the ARVC-CMs that displayed the more severe desmosomal pathology. This finding was associated with upregulation of the proadipogenic transcription factor peroxisome proliferator-activated receptor-γ. Exposure of the cells to apidogenic stimuli augmented desmosomal distortion and lipid accumulation. The latter phenomenon was prevented by application of a specific inhibitor of glycogen synthase kinase 3β (6-bromoindirubin-3'-oxime).
  
  
  CONCLUSIONS
  This study highlights the unique potential of the hiPSC technology for modeling inherited cardiac disorders in general and ARVC specifically. The hiPSC-CMs were demonstrated to recapitulate the ARVC phenotype in the dish, provide mechanistic insights into early disease pathogenesis, and provide a unique platform for drug discovery and testing in this disorder.
authors.affiliation: Sohnis Family Research Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Oren
authors.initials: O
authors.lastname: Caspi
authors.forename: Irit
authors.initials: I
authors.lastname: Huber
authors.forename: Amira
authors.initials: A
authors.lastname: Gepstein
authors.forename: Gil
authors.initials: G
authors.lastname: Arbel
authors.forename: Leonid
authors.initials: L
authors.lastname: Maizels
authors.forename: Monther
authors.initials: M
authors.lastname: Boulos
authors.forename: Lior
authors.initials: L
authors.lastname: Gepstein
mesh_terms: D017209:Apoptosis; D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D002454:Cell Differentiation; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism; D020405:Dermis / Q000378:metabolism / Q000473:pathology; D003896:Desmosomes / Q000187:drug effects / Q000378:metabolism; D004562:Electrocardiography; D005347:Fibroblasts / Q000378:metabolism* / Q000502:physiology; D015870:Gene Expression; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors; D006801:Humans; D007150:Immunohistochemistry; D007211:Indoles / Q000494:pharmacology; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism* / Q000502:physiology; D046529:Microscopy, Electron, Transmission; D008955:Models, Cardiovascular; D009154:Mutation; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D010091:Oximes / Q000494:pharmacology; D051191:Plakophilins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051185:gamma Catenin / Q000378:metabolism
chemical_list: C483321:6-bromoindirubin-3'-oxime; D018031:Connexin 43; D007211:Indoles; D010091:Oximes; C495337:PKP2 protein, human; D051191:Plakophilins; D051185:gamma Catenin; D038362:Glycogen Synthase Kinase 3
keywords: arrhythmogenic right ventricular dysplasia; lipids; myocytes, cardiac; stem cells