Adipogenic-Myogenic Signaling in Engineered Human Muscle Grafts used to Treat Volumetric Muscle Loss.

Tissue-engineered muscle grafts (TEMGs) are a promising treatment for volumetric muscle loss (VML). In this study, human myogenic progenitors (hMPs) cultured on electrospun fibrin microfiber bundles and evaluated the therapeutic potential of engineered hMP TEMGs in the treatment of murine tibialis anterior (TA) VML injuries is employed. In vitro, the hMP TEMGs express mature muscle markers by 21 days. Upon implantation into VML injuries, the hMP TEMGs enable remarkable regeneration. To further promote wound healing and myogenesis, human adipose-derived stem/stromal cells (hASCs) as fibroadipogenic progenitor (FAP)-like cells with the potential to secrete pro-regenerative cytokines are incorporated. The impact of dose and timing of seeding the hASCs on in vitro myogenesis and VML recovery using hMP-hASC TEMGs are investigated. The hASCs increase myogenesis of hMPs when co-cultured at 5% hASCs: 95% hMPs and with delayed seeding. Upon implantation into immunocompromised mice, hMP-hASC TEMGs increase cell survival, collagen IV deposition, and pro-regenerative macrophage recruitment, but result in excessive adipose tissue growth after 28 days. These data demonstrate the interactions of hASCs and hMPs enhance myogenesis in vitro but there remains a need to optimize treatments to minimize adipogenesis and promote full therapeutic recovery following VML treatment.