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Use of Cold-Preserved Allografts Seeded with Autologous Schwann Cells in the Treatment of a Long-Gap Peripheral Nerve Injury

Background: Limitations in autogenous tissue have inspired the study of alternative materials for repair of complex peripheral nerve injuries. Cadaveric allografts are one potential reconstructive material, but their use requires systemic immunosuppression. Cold preservation (≥7 weeks) renders allografts devoid of antigens, but these acellular substrates generally fail in supporting regeneration beyond 3 cm. In this study, the authors evaluated the reconstruction of extensive nonhuman primate peripheral nerve defects using 7-week cold-preserved allografts repopulated with cultured autologous Schwann cells. Methods: Ten outbred Macaca fascicularis primates were paired based on maximal genetic disparity as measured by similarity index assay. A total of 14 ulnar nerve defects measuring 6 cm were successfully reconstructed using autografts (n = 5), fresh allografts (n = 2), cold-preserved allografts (n = 3), or cold-preserved allografts seeded with autogenous Schwann cells (n = 4). Recipient immunoreactivity was evaluated by means of enzyme-linked immunosorbent spot assay, and nerves were harvested at 6 months for histologic and histomorphometric analysis. Results: Cytokine production in response to cold-preserved allografts and cold-preserved allografts seeded with autologous Schwann cells was similar to that observed for autografts. Schwann cell–repopulated cold-preserved grafts demonstrated significantly enhanced fiber counts, nerve density, and percentage nerve (p < 0.05) compared with unseeded cold-preserved grafts at 6 months after reconstruction. Conclusions: Cold-preserved allografts seeded with autologous Schwann cells were well-tolerated in unrelated recipients and supported significant regeneration across 6-cm peripheral nerve defects. Use of cold-preserved allogeneic nerve tissue supplemented with autogenous Schwann cells poses a potentially safe and effective alternative to the use of autologous tissue in the reconstruction of extensive nerve injuries.