Comparative transcriptomic analysis of dermal wound healing reveals de novo skeletal muscle regeneration in Acomys cahirinus

The African spiny mouse, Acomys spp., is capable of scar-free dermal wound healing. Here, we have performed a comprehensive analysis of gene expression throughout wound healing following full-thickness excisional dermal wounds in both Acomys cahirinus and Mus musculus. Additionally, we provide an annotated, de novo transcriptome assembly of A. cahirinus skin and skin wounds. Using a novel computational comparative RNA-Seq approach along with pathway and co-expression analyses, we identify enrichment of regeneration associated genes as well as upregulation of genes directly related to muscle development or function. Our RT-qPCR data reveals induction of the myogenic regulatory factors, as well as upregulation of embryonic myosin, starting between days 14 and 18 post-wounding in A. cahirinus. In contrast, the myogenic regulatory factors remain downregulated, embryonic myosin is only modestly upregulated, and no new muscle fibers of the panniculus carnosus are generated in M. musculus wounds. Additionally, we show that Col6a1, a key component of the satellite cell niche, is upregulated in A. cahirinus compared to M. musculus. Our data also demonstrate that the macrophage profile and inflammatory response is different between species, with A. cahirinus expressing significantly higher levels of parallel to 10. We also demonstrate differential expression of the upstream regulators Wnt7a, Wnt2 and Wnt6 during wound healing. Our analyses demonstrate that A. cahirinus is capable of de novo skeletal muscle regeneration of the panniculus carnosus following removal of the extracellular matrix. We believe this study represents the first detailed analysis of de novo skeletal muscle regeneration observed in an adult mammal.