Human Engineered Heart Tissues as an In Vitro Model of Duchenne Muscular Dystrophy

Abstract

Cardiomyopathy is the leading cause of death for patients with Duchenne muscular dystrophy (DMD), a severe, degenerative muscular disorder. This disease results from the lack of functional dystrophin, a protein that localizes to the plasma membrane of cardiomyocytes to form a mechanically strong link between the extracellular matrix and the intracellular cytoskeleton, and its absence has detrimental effects on contractile, calcium, and metabolic regulation. The development of novel treatments for DMD has been hampered by the shortcomings of commonly used animal models to replicate all aspects of the disease, prompting the need for human in vitro models of dystrophic cardiomyopathy for preclinical studies. To date, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been an invaluable source with which to study DMD, as they have been shown to replicate many relevant disease phenotypes. However, the utility of hiPSC-CMs is limited by their relative immaturity and the biological irrelevance of traditional two-dimensional cell culture. To address these shortcomings, we have developed engineered heart tissues (EHTs) from dystrophic hiPSC-CMs as an in vitro, preclinical model of DMD. This EHT model better mimics the native cardiac microenvironment, providing extracellular matrix cues of a relevant stiffness, cell-cell communication, and uniaxial force development promoting proper cellular alignment and hypertrophy. We have shown that dystrophic EHTs present relevant functional deficiencies, including decreased contractile performance and altered calcium transients. Additionally, we have demonstrated the ability of a miniaturized EHT platform to evaluate the efficiency and cardioprotective effect of novel microdystrophin gene therapies for DMD. Through the studies described herein, we have validated the promise of three-dimensional engineered cardiac tissues as a preclinical screening model of dystrophic cardiomyopathy.