Engineered exosomes improve myocardial cell membrane integrity and heart function in dystrophic cardiomyopathy

BACKGROUND: Duchenne muscular dystrophy (DMD)-associated cardiomyopathy is a leading causes of premature death, yet treatment options remain limited. In this study, we developed the easily accessible engineered exosomes for treatment of DMD-associated cardiomyopathy and explored the underlying mechanisms in DmdΔ4 mice, a model harboring hot spot mutation in the dystrophin gene. METHODS: DmdΔ4 mice and their cardiomyopathy phenotype were confirmed by Sanger sequencing, pathological staining, flow cytometry, immunoblotting, single-cell sequencing and echocardiographic analysis. Engineered exosomes, exosomes- cardiac homing peptide (Exo-CHP), were synthesised and characterised by click chemistry and miRNA sequence, separately. The targeted ability and the therapeutic effects of Exo-CHP were studied in vitro and in vivo. Primary cardiomyocytes were used to study the underlying mechanism of Exo-CHP. RESULTS: DmdΔ4 mice showed an obvious cardiomyopathy-associated phenotype. Exo-CHP can target myocardium and mitigate pathological progression of cardiomyopathy in DmdΔ4 mice. The therapeutic effects of intravenously delivered Exo-CHP significantly reduced myocardial inflammation, fibrosis and improved the mice's cardiac function. The rescue effects were mediated through the regulation of gene expression at the transcriptomic level, prevention of dystrophin protein complex degradation, and inhibition of intracellular calcium influx and calpain protease activity. The miR-21 knockdown Exo-CHP can counteract the protective effects of Exo-CHP on the calcium content and membrane integrity of primary DmdΔ4-derived cardiomyocytes. CONCLUSIONS: Our study demonstrated the feasibility, efficacy and the possible mechanism of mesenchymal stromal cell-derived engineered exosomes, positioning them as a potential cell-free intervention for DMD-associated cardiomyopathy.