Studying arrhythmogenic right ventricular dysplasia with patient-specific iPSCs.
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 screens. 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 ventricle, 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 years. We used previously published methods to generate iPSC lines from fibroblasts of two patients with ARVD/C and PKP2 mutations. Mutant PKP2 iPSC-CMs demonstrate abnormal plakoglobin nuclear translocation and decreased β-catenin activity 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.
Del E. Webb Neuroscience, Aging & Stem Cell Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA.
Changsung
C
Kim
Johnson
J
Wong
Jianyan
J
Wen
Shirong
S
Wang
Cheng
C
Wang
Sean
S
Spiering
Natalia G
NG
Kan
Sonia
S
Forcales
Pier Lorenzo
PL
Puri
Teresa C
TC
Leone
Joseph E
JE
Marine
Hugh
H
Calkins
Daniel P
DP
Kelly
Daniel P
DP
Judge
Huei-Sheng Vincent
HS
Chen
D021581:Active Transport, Cell Nucleus; D017668:Age of Onset; D017209:Apoptosis / Q000235:genetics; D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D065150:Cellular Reprogramming; D003470:Culture Media / Q000494:pharmacology; D058732:Embryoid Bodies / Q000187:drug effects / Q000502:physiology; D004734:Energy Metabolism / Q000235:genetics; D005227:Fatty Acids / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism / Q000473:pathology*; D050155:Lipogenesis / Q000235:genetics; D008954:Models, Biological; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000473:pathology; D047493:PPAR alpha / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism; D010641:Phenotype; D051191:Plakophilins / Q000235:genetics; D013997:Time Factors; D051176:beta Catenin / Q000378:metabolism
D003470:Culture Media; D005227:Fatty Acids; C495337:PKP2 protein, human; D047493:PPAR alpha; D047495:PPAR gamma; D051191:Plakophilins; D051176:beta Catenin; D005947:Glucose