Project Summary/Abstract The long-term objective of this study is to develop gene therapies that treat Duchenne muscular dystrophy (DMD) cardiomyopathy. DMD cardiomyopathy, characterized by ventricular chamber enlargement and thinning of the ventricular wall, ultimately leads to heart failure. Pathogenic features of DMD cardiomyocytes include contractile dysfunction, poor calcium handling, elevated reactive oxygen species, telomere shortening, and premature cell death. When a large number of cells die in the heart, scar tissue forms, increasing the stiffness of the heart. Although there are treatments available to alleviate symptoms of dilated cardiomyopathy, there are currently no therapies to prevent or delay the onset of this disease. Smaller versions of dystrophin amenable to gene therapy have shown promise to treat DMD-associated severe skeletal muscle wasting; however, surprisingly little is known about their effects in treating heart failure. This research plan will leverage bioengineered hydrogels of tunable stiffness, human induced pluripotent stem cells (iPSCs) with dystrophin mutations, and biochemical techniques to determine if full-length dystrophin can rescue DMD cardiomyocytes from their pathogenic demise. During the K01 award period, Dr. Asuka Eguchi will train under the mentorship of Dr. Helen Blau, an expert on DMD. By engineering hydrogels that mimic stiff, diseased heart tissue, Dr. Eguchi will be able to measure parameters of contraction in cardiomyocytes differentiated from DMD iPSCs. Aim 1 will test if full-length dystrophin can rescue DMD cardiomyocytes from contractile deficits, aberrant calcium handling, and premature cell death. Aim 2 will determine if split vector or lipid nanoparticle approaches can deliver full-length dystrophin to cardiomyocytes. Aim 3 will test whether this gene therapy strategy to deliver full-length dystrophin can delay the onset of DMD cardiomyopathy in a mouse model. Gene therapy approaches targeting the root cause of disease, the lack of dystrophin, is critical for extending lifespan and improving the quality of life of DMD patients. The career development plan is designed to enable Dr. Eguchi to successfully transition to a career as independent investigator. Her scientific advisory committee consist of Dr. Beth Pruitt, a bioengineer with expertise in traction force microscopy, Dr. Joseph Wu, an expert on cardiovascular disease modeling, and Dr. Daniel Bernstein, a pediatric cardiologist. Collectively, these collaborators will help Dr. Eguchi develop skills at the interface of bioengineering, cell biology, and biochemistry to launch an independent research program in cardiovascular research.