Decellularized scaffolds from skeletal muscle are a suitable environment for myogenesis in vivo

Background. Skeletal muscle defects arising from traumatic or pathological conditions may require surgical interventions. In our previous studies we described the interactions between a decellularized scaffold derived from a murine skeletal muscle and an isogenic mouse host. Our research is focused on the interaction of the grafted scaffold with other tissues, i.e immune and nervous systems. In addition, we aim to build off-the-shelf, transplantable constructs by culturing myogenic cells into the scaffold before transplantation. Methods. We decellularized Tibialis Anterior muscle of cadaveric origin. The decellularization process was achieved by incubation of dissected muscles in a detergent solution. To replace homologous muscles, we orthotopically transplanted decellularized scaffolds, by suturing them to the host tendon extremities following TA removal. With this approach the constructs were analyzed in regard to histocompatibility, bioactivity, degradability, toxicity in vivo at different times from transplantation. Alternatively, before transplantation the scaffolds were pre-seeded with myogenic cells in vitro. Results and conclusions. The procedure to produce acellular scaffolds from cadaveric skeletal muscles preserves the extracellular matrix and its anatomical pattern. The transplanted acellular scaffold is readily colonized by both inflammatory and myogenic stem cells, as demonstrated by the expression of stem cell markers, followed by the formation of muscle fibers. The latter show centrally located nuclei and express muscle-specific myosin. Cytofluorimetric analysis of the inflammatory cells population shows that CD45+ cells are mostly represented by macrophages, even though T lymphocytes and granulocytes are also present. So likely macrophages play a major role in acellular muscle graft integration and remodeling. Functionality of skeletal muscle is strictly dependent on myofibers spatial orientation and on innervation. Preliminary data suggest the presence of neuro-muscular junctions in the proximity of the cells that populate the grafted scaffold, suggesting the potential for re-innervation of the implant. The integration of the scaffold can likely be boosted by previous myogenic cell colonization, so we delivered satellite cells to the acellular scaffolds and noted the formation of muscle fibers into the construct in culture. Our studies show that scaffolds derived from decellularized muscles are a highly myogenic environment and may represent an innovative tool for skeletal muscle regenerative medicine.