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Acellular nerve allografts can help preserve normal nerve structure and extracellular matrix composition. These allografts have low immunogenicity and are more readily available than autologous nerves for the repair of long-segment peripheral nerve defects. In this study, we repaired a 40-mm ulnar nerve defect in rhesus monkeys with tissue-engineered peripheral nerve, and compared the outcome with that of autograft. The graft was prepared using a chemical extract from adult rhesus monkeys and seeded with allogeneic Schwann cells. Pathomorphology, electromyogram and immunohistochemistry findings revealed the absence of palmar erosion or ulcers, and that the morphology and elasticity of the hypothenar eminence were normal 5 months postoperatively. There were no significant differences in the mean peak compound muscle action potential, the mean nerve conduction velocity, or the number of neurofilaments between the experimental and control groups. However, outcome was significantly better in the experimental group than in the blank group. These findings suggest that chemically extracted allogeneic nerve seeded with autologous Schwann cells can repair 40-mm ulnar nerve defects in the rhesus monkey. The outcomes are similar to those obtained with autologous nerve graft.

Little consensus exists regarding which decellularization technique best removes the cellular components while maintaining structural integrity. We aimed to identify the most efficient and safest decellularization method by combining previously established chemical (detergent based) and biological (nuclease based) methods in a systematic manner. Sixty sciatic nerves were harvested from Sprague-Dawley rats and prepared in 120 nerve fragments with 1-cm length. Nerve fragments were randomly divided into six groups and decellularized with six different methods: A, nonionic detergent + amphoteric detergent; B, nonionic detergent + anionic detergent; C, anionic detergent + amphoteric detergent; D, nonionic detergent + nuclease; E, amphoteric detergent + nuclease; and F, anionic detergent + nuclease. The remaining cellular components were evaluated with H&E, DAPI, and S-100 immunohistochemical staining, and DNA content was measured in each sample. The remaining extracellular matrix (ECM) integrity was evaluated with H&E, Masson's trichrome, periodic acid-Schiff, Luxol fast blue, and laminin immunohistochemical staining, and collagen content was measured in each sample. The amphoteric detergent + nuclease method was the best protocol for both cell removal and ECM preservation. In the in vivo study, the nerve allograft that was decellularized with amphoteric detergent + nuclease showed an inferior recovery rate based on the tibialis anterior muscle weight to autograft, but considerable recovery was observed. In conclusion, among the possible systematic combinations of detergent- and nuclease-based methods, the combination of amphoteric detergent and nuclease is currently the most suitable for nerve decellularization in terms of adequate cell removal and sufficient preservation of the ECM., (© 2019 John Wiley & Sons, Ltd.)

Acellular nerve allografts can help preserve normal nerve structure and extracellular matrix composition. These allografts have low immunogenicity and are more readily available than autologous nerves for the repair of long-segment peripheral nerve defects. In this study, we repaired a 40-mm ulnar nerve defect in rhesus monkeys with tissue-engineered peripheral nerve, and compared the outcome with that of autograft. The graft was prepared using a chemical extract from adult rhesus monkeys and seeded with allogeneic Schwann cells. Pathomorphology, electromyogram and immunohistochemistry findings revealed the absence of palmar erosion or ulcers, and that the morphology and elasticity of the hypothenar eminence were normal 5 months postoperatively. There were no significant differences in the mean peak compound muscle action potential, the mean nerve conduction velocity, or the number of neurofilaments between the experimental and control groups. However, outcome was significantly better in the experimental group than in the blank group. These findings suggest that chemically extracted allogeneic nerve seeded with autologous Schwann cells can repair 40-mm ulnar nerve defects in the rhesus monkey. The outcomes are similar to those obtained with autologous nerve graft., Competing Interests: Conflicts of Interest: None declared.

This study developed a human acellular nerve graft (hANG) as an alternative to autogenous nerve and reports on its safety and efficacy. There were two groups comprised of 72 patients that received digital nerve repair with hANG (test) and 81 that received conventional direct tension-free suture repair of the nerve defect (control). The efficacy of the treatment was evaluated by static 2-point discrimination (s2PD) and Semmes-Weinstein monofilament testing. Safety was evaluated by local wound response and laboratory testing. Mean age of patients in the test group was 33.0 ± 11.1 years (range 18-61 years) and in the control group 36.9 ± 13.4 years (range 15-77 years) (p = 0.0470). Mean time from injury to repair in the test group was 23.7 ± 52 days (range 0-200 days) and in the control group 1.5 ± 10.4 days (range 0-91 days) (p = 0.0005). Mean length of nerve graft was 1.80 ± 0.82 cm (range 1-5 cm). All surgeries were performed successfully and without complications. The excellent and good rate of s2PD in the test group was 65.28% and 95% CI was 51.98-78.93%. s2PD in the test group improved over time and average distance was 12.81 ± 5.99 mm at 6 months postoperatively. No serious adverse or product-related events were reported. These results indicate that hANG is a safe and effective for the repair of nerve defects of 1-5 cm in size., (© 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.)