Duchenne muscular dystrophy (DMD) is a degenerative lethal, X-linked disease of skeletal and cardiac muscles caused by mutations in the
dystrophin gene.
Cell therapy using different cell types, including mesenchymal stromal cells (MSCs), has been considered as a potential approach for the treatment of DMD. MSCs can be obtained from autologous sources such as bone marrow and adipose tissues or from allogeneic placenta and umbilical cord. The safety and therapeutic impact of these cells has been demonstrated in pre-clinical and clinical studies and their functions are attributed to paracrine effects that are mediated by secreted
cytokines and extracellular vesicles. Here, we studied the
therapeutic effects of placenta-derived MSCs (PL-MSCs) and their secreted exosomes using mouse and human myoblasts from healthy controls, Duchenne patients and mdx mice. Treatment of myoblasts with
conditioned medium or exosomes secreted by PL-MSCs increased the differentiation of these cells and decreased the expression of fibrogenic genes in DMD patient myoblasts. In addition, these treatments also increased the expression of
utrophin in these cells. Using a quantitative miR-29c reporter, we demonstrated that the PL-MSC effects were partly mediated by the transfer of exosomal miR-29c. Intramuscular
transplantation of PL-MSCs in mdx mice resulted in decreased
creatine kinase levels. PL-MSCs significantly decreased the expression of TGF-β and the level of
fibrosis in the diaphragm and cardiac muscles, inhibited
inflammation and increased
utrophin expression. In vivo imaging analyses using MSCs labeled with
gold nanoparticles or
fluorescent dyes demonstrated localization of the cells in the muscle tissues up to 3 weeks post treatment. Altogether, these results demonstrate that PL-MSCs and their secreted exosomes have important clinical applications in
cell therapy of DMD partly via the targeted delivery of exosomal miR-29c.