Innervation of an engineered muscle graft for reconstruction of muscle defects

Abstract

Autologous muscle flaps are commonly used to reconstruct defects that involve muscle impairment. To maintain viability and functionality of these flaps, they must be properly vascularized and innervated. Tissue-engineered muscles could potentially replace autologous muscle tissue, but still require establishment of sufficient innervation to ensure functionality. In this study, we explored the possibility of innervating engineered muscle grafts transplanted to an abdominal wall defect in mice, by transferring the native femoral nerve to the graft. Six weeks posttransplantation, nerve conduction studies and electromyography demonstrated increased innervation in engineered grafts neurotized with the femoral nerve, as compared to non-neurotized grafts. Histologic assessments revealed axonal penetration and formation of neuromuscular junctions within the grafts. The innervation process described here may advance the fabrication of a fully functional engineered muscle graft that will be of utility in clinical settings.

Innervation: the missing link for biofabricated tissues and organs

“…Surgical rerouting of adjacent host nerves toward an implanted tissueengineered construct can be a potential method to achieve targeted innervation. Indeed, neurotization has been applied to innervate engineered muscle grafts fabricated by seeding a triculture of endothelial cells, fibroblasts, and myoblasts on porous scaffolds of poly-L-lactic acid (PLLA) and poly (lactic-co-glycolic acid) (PLGA) 152 . After myotube assembly in vitro for 7-14 days, the scaffolds were transplanted into an abdominal wall defect in mice and sutured to the isolated femoral nerve to provide innervation ( Fig.…”

“…2e), serving as additional confirmation of innervation. Despite the need for more research into creating sophisticated and mature engineered tissues, neurotization as a strategy to promote graft innervation is aided by its well established nature in reconstructive surgery 152 .…”

“…e Neuromuscular junctions in the grafts were stained for acetylcholine receptors (AChR; red) and synapses (synaptophysin; green). (Reprinted with permission from Kaufman and Kaplan et al 152 ; Copyright John Wiley & Sons). f, g Diagrams of examples of traditional strategies for promoting peripheral nerve regeneration using nerve guidance conduits modified to deliver neurotrophic/growth factors or cells using biomaterial-based delivery methods.…”

Stem Cell-Based and Tissue Engineering Approaches for Skeletal Muscle Repair

“…Multiple groups have since utilized C2C12 to produce muscle constructs in vitro by various tissue engineering techniques (Engler et al 2004;Costantini et al 2017;Zhang and Guo 2017;Kang et al 2016). Furthermore, C2C12 has also been incorporated into engineered muscle constructs to replace muscle tissue in vivo (Levenberg et al 2005;Koffler et al 2011;Kaufman et al 2019). While these studies provided the experimental framework to engineer skeletal muscle cells, C2C12 is an immortalized cell line which is physiologically distinct from normal myogenic cells, necessitating usage of physiologically relevant and therapeutically acceptable primary cells (Yaffe and Saxel 1977;Morgan et al 1992;Wernig et al 1991).…”

Prevascularized Scaffolds Bearing Human Dental Pulp Stem Cells for Treating Complete Spinal Cord Injury

“…In previous work, we engineered vascular networks on biocompatible and biodegradable poly(l-lactic acid)(PLLA)/polylacticglycolic acid (PLGA) scaffolds, using a coculture of endothelial cells and support cells. [5,[27][28][29][30] We hypothesized that, apart from neurotrophic factors secretion, DPSCs could support cocultured endothelial cells to develop vessel networks on the PLLA/PLGA scaffolds. The implantation of these prevascularized constructs would be suitable for treating SCI.…”