ObjectiveTo compare the capability of optimized acellular(OA) allograft and xenograft reparing rat sciatic nerve defect by observing the immunological rejection, early functional recovery and nerve regeneration in the adult rats, which had been made a 1.0cm long gap in the continuity of the sciatic nerve.MethodsThe right sciatic nerve of adult Sprague-Dawley(SD) rats were exposed and 1.0cm long segment of the nerves were removed and repaired by fresh rabbit nerve and autofrafts, OA rat and rabbit nerve. After 1 and 3 months respectively,sciatic functional index (SFI),electrophysiological and histology studies were detected to evaluate immunological rejection,early functional recovery and nerve regeneration. ResultsThe immunological rejection, functional recovery and nerve regeneration in OA xenografts were compared with that in OA allografts, autografts and fresh allografts. One month after the surgery, the levels of CD8+ T cells and macrophages that infiltrated the grafts,the SFI and the axon density at the midpoints of them were similar within OA grafts and autografts(P ＞ 0.05),but all statistically distinguishable from fresh allografts(P ＜ 0.05).And better results were got after 2 months(P ＜ 0.05).ConclusionsThe results imply that OA xenografts is as good as OA allografts,which can be immunologically tolerated and that the removal of cellular material and preservation of the matrix are beneficial for promoting regeneration and functional recovery through an OA procedure.And this gives another promising option to repair peripheral nerve defect.