Adipose-Derived Stem Cells Enhance Axonal Regeneration through Cross-Facial Nerve Grafting in a Rat Model of Facial Paralysis

Background: Cross-face nerve grafting combined with functional muscle transplantation has become the standard in reconstructing an emotionally controlled smile in complete irreversible facial palsy. However, the efficacy of this procedure depends on the ability of regenerating axons to breach two nerve coaptations and reinnervate endplates in denervated muscle. The current study tested the hypothesis that adipose-derived stem cells would enhance axonal regeneration through a cross-facial nerve graft and thereby enhance recovery of the facial nerve function. Methods: Twelve rats underwent transection of the right facial nerve, and cross-facial nerve grafting using the sciatic nerve as an interpositional graft, with coaptations to the ipsilateral and contralateral buccal branches, was carried out. Rats were divided equally into two groups: a grafted but nontreated control group and a grafted and adipose-derived stem cell-treated group. Three months after surgery, biometric and electrophysiologic assessments of vibrissae movements were performed. Histologically, the spectra of fiber density, myelin sheath thickness, fiber diameter, and g ratio of the nerve were analyzed. Immunohistochemical staining was performed for the evaluation of acetylcholine in the neuromuscular junctions. Results: The data from the biometric and electrophysiologic analysis of vibrissae movements, immunohistochemical analysis, and histologic assessment of the nerve showed that adipose-derived stem cells significantly enhanced axonal regeneration through the graft. Conclusion: These observations suggest that adipose-derived stem cells could be a clinically translatable route toward new methods to enhance recovery after cross-facial nerve grafting.