MMP‐10 Is Required for Efficient Muscle Regeneration in Mouse Models of Injury and Muscular Dystrophy

Matrix metalloproteinases (MMPs), a family of endopeptidases that are involved in the degradation of extracellular matrix components, have been implicated in skeletal muscle regeneration. Among the MMPs, MMP‐2 and MMP‐9 are upregulated in Duchenne muscular dystrophy (DMD), a fatal X‐linked muscle disorder. However, inhibition or overexpression of specific MMPs in a mouse model of DMD ( mdx ) has yielded mixed results regarding disease progression, depending on the MMP studied. Here, we have examined the role of MMP‐10 in muscle regeneration during injury and muscular dystrophy. We found that skeletal muscle increases MMP‐10 protein expression in response to damage (notexin) or disease ( mdx mice), suggesting its role in muscle regeneration. In addition, we found that MMP‐10‐deficient muscles displayed impaired recruitment of endothelial cells, reduced levels of extracellular matrix proteins, diminished collagen deposition, and decreased fiber size, which collectively contributed to delayed muscle regeneration after injury. Also, MMP‐10 knockout in mdx mice led to a deteriorated dystrophic phenotype. Moreover, MMP‐10 mRNA silencing in injured muscles (wild‐type and mdx ) reduced muscle regeneration, while addition of recombinant human MMP‐10 accelerated muscle repair, suggesting that MMP‐10 is required for efficient muscle regeneration. Furthermore, our data suggest that MMP‐10‐mediated muscle repair is associated with VEGF/Akt signaling. Thus, our findings indicate that MMP‐10 is critical for skeletal muscle maintenance and regeneration during injury and disease. S tem C ells 2014;32:447–461