Abstract P1118: Engineering A Patient-specific Heart On A Chip Model Of Hypoplastic Left Heart Syndrome

Hypoplastic Left Heart Syndrome (HLHS) is the most expensive congenital cardiac disease and is characterized by underdevelopment of the left side of the heart. The surgical intervention leads to the developmentally disadvantaged right ventricle performing systemic circulation. As such, a subset of HLHS patients develops progressive heart failure that results in limited transplant-free survival. There are no animal models to study the molecular and functional properties of HLHS cardiomyocytes, limiting our understanding of disease mechanisms and human genotype-phenotype relationships. To address this, we are creating a physiologically and functionally relevant ”heart on a chip” model of HLHS hiPSC-derived cardiomyocytes (CMs). Induced Pluripotent Stem Cells (iPSCs) were derived from cord blood mononuclear cells isolated from the umbilical cord blood from 8 antenatally diagnosed HLHS children at birth. Control (iPSCs) from 3 healthy subjects were derived from peripheral blood mononuclear cells. We then differentiated ventricular CMs from these iPSCs using StemDiff ventricular CM kit. We observed HLHS iPSCs formed ~50% fewer CMs compared to healthy controls. We studied calcium handling by iPSC-CMs with Fluo-4 fluorescent calcium dye in HLHS and Healthy iPSC-CMs. We observed that calcium transients in HLHS-CMs have half the beat rate, 1.4 times longer rise time to rise, 1.5 times higher time constant (Tau), compared to Healthy CMs, suggesting that HLHS CMs have dysfunctional calcium handling compared to healthy CMs. Our results demonstrate that in an in vitro model of iPSC-derived CM, HLHS patient CMs demonstrate reduced formation and defective calcium handling, which may potentially explain the pathogenesis of heart failure in HLHS patients. In ongoing experiments, we are evaluating diastolic and systolic stress generation in these cells. We will also establish the underlying molecular mechanisms of functional defects in HLHS CMs and screen potential drug therapies for single-ventricle patients.