Abstract 211: Substrate Elasticity Impacts Duchenne Muscular Dystrophy Cardiomyopathy Progression

Abstract

Duchenne Muscular Dystrophy (DMD) is a X-link disease affecting ~1:3500 boys per year and culminating with heart failure in early adulthood. DMD results from >200 possible genetic mutations on dystrophin. The lack of dystrophin disrupts the anchoring of the cell sarcomere to the extracellular matrix (ECM), affecting the cardiac contraction. With disease progression, in an attempt to mitigate the subcellular defects, the tissue stiffness and ECM composition remodel in association with a dilated cardiomyopathy phenotype and fibrosis. Our hypothesis is that disease progression is accelerating because of this remodelling, through a positive feedback loop involving multiple mechanosensing pathways. Here, we use a single-cell assay platform to model the effect of fibrotic remodelling in DMD. This platform allows measuring the force production of single human-derived pluripotent stem cell (hiPSC) cardiomyocytes (CMs). The substrate stiffness can be controlled to match that of healthy (~10kPa) or fibrotic (~35kPa) tissue. In addition, single iPSC-CMs are patterned in an elongated 1:7 aspect ratio using microcontact printing of ECM protein. This enhances their intracellular structural maturity towards a more mature adult phenotype. This renders our in-vitro model more representative of the human pathology and greatly improves our measurements standardization. Our results show that single iPSC-CMs with DMD mutations have a dramatically reduced ability to produce force on stiffer substrates compared to their isogenic control. This loss of contractile function correlates with an increase in reactive oxygen species (ROS) and mitochondria dysfunction, as well as with other markers of stress response and cellular senescence.We are asking how the remodeling of the ECM stiffness and composition is signaled from the outside-in and affects the progression of the disease phenotype. The further development of our platform and approach will allow for more accurate in-vitro modeling of cardiac diseases and greatly increase our understanding of the underlying biophysics of mechanosensing.