Synergistic Effects of Acetyl-L-Carnitine and Adipose-Derived Stromal Cells on Improving Regenerative Capacity of Acellular Nerve Allograft in Sciatic Nerve Defect

The combination of decellularized nerve allograft and adipose-derived stromal cells (ASCs) represents a good alternative to nerve autograft for bridging peripheral nerve defects by providing physical guidance and biologic cues. However, the regeneration outcome of acellular nerve allograft (ANA) is often inferior to autograft. Therefore, we hypothesized that acetyl-L-carnitine (ALCAR) treatment and implantation of ASC-embedded ANA would work synergistically to promote nerve regeneration. Seventy rats were randomly allocated into seven experimental groups (n = 10), including the healthy control group, sham surgery group, autograft group, ANA group, ANA + ASCs group, ANA + ALCAR group (50 mg/kg for 2 weeks), and ANA + ASCs + ALCAR (50 mg/kg for 2 weeks) group. All grafts were implanted to bridge long-gap (10-mm) sciatic nerve defects. Functional, electrophysiological, and morphologic analysis was conducted during the experimental period. We found that ALCAR potentiated the survival and retention of transplanted ASCs and upregulated the expression of neurotrophic factor mRNAs in transplanted grafts. Sixteen weeks following implantation in the rat, the ANA supplemented by ASCs was capable of supporting reinnervation across a 10-mm sciatic nerve gap, with results close to that of the autografts in terms of functional, electrophysiological, and histologic assessments. Results demonstrated that ALCAR treatment improved regenerative effects of ANA combined with ASCs on reconstruction of a 10-mm sciatic nerve defect in rat comparable to those of autograft.