Promoting Nerve Regeneration By Secondary Surgical Renovation Of The Distal Stoma After The Rat Sciatic Nerve Autograft

The treatment of peripheral nerve defect has been one of the difficult surgical problems. Although many scholars committed to the research and application of allogeneic nerve graft, biological or non-biological non-neural tissue transplantation and tissue-engineered artificial neural transplantation to treat the long-gap nerve defect, the classical autologous nerve graft still cannot to be replaced.Although autologous nerve graft is the most effective treatment to the moderate and long peripheral nerve defects, there still is a long way to go. Many scholars believe that the main factors affect the efficacy are as follows: poor blood for the long nerve graft; the wrong direction of nerve fibers' regeneration; the muscle atrophy as to the long-time denervated and other reasons. However, there has not been study reported about whether or not the distal stoma of the long nerve graft affects the efficacy of autologous nerve graft. In theory, after autologous nerve graft, the proximal stoma can be passed in short-term, which leads to little influence to the regeneration of nerve fibers. However, while the new nerve fibers arriving the distal stoma, the scar tissue there can exert profound influence to the smooth passage of the nerve axons.Based on the theory of peripheral nerve regeneration, we put forward a hypothesis that cutting off the distal scar healing stoma, trimming two ends and anastomosing them again (renovation of the distal stoma)while the new nerve axons arriving the distal stoma will eliminate the impact of distal anastomotic scar tissue to the regeneration of nerve fibers. Also the renovation of the distal stoma will stimulate the regeneration capacity of sensory and motor neurons, at the same time, activate the nerons' anti-apoptotic signaling pathway and promote their survival.In this study, first, we build a long rat sciatic nerve defect model repaired by in situ autologous nerve graft. Then we use morphological observation of the axons to make clear whether cutting off the distal stoma, trimming two ends and anastomosing them again could promote the regeneration of nerve fibers or not. What's more we detect the GAP-43 which closely related to axonal regeneration and synaptic reconstruction and the p-S⁴⁷³-Akt which plays the role of promotion and anti-apoptotic of neuronal survival to make clear whether or not the renovation of the distal stoma could stimulate the regeneration capacity of sensory and motor neurons, activate the nerons' anti-apoptotic signaling pathway and promote their survival.We obtained results as follows. 1.16 weeks after the in situ autologous nerve graft of the rat sciatic nerve, in the proximal anastomosis the nerve axon density and diameter show no significant statistically difference (P>0.05) between the experimental group and the control group, but in the distal anastomosis the nerve axon density and diameter have significant statistically difference(P<0.01) between the experimental group and the control group, the experimental group was significantly better than the control group. 2. At different time after the nerve graft, by detecting the expression of the GAP-43 in the corresponding spinal cord motor neurons and dorsal root ganglia with immunohistochemistry and Western-blot methods, we found that the renovation of the distal stoma could significantly enhance the expression of GAP-43 in sensory and motor neurons. 3. At different time after the nerve graft, by detecting the expression of the p-S⁴⁷³-Akt in the corresponding spinal cord motor neurons and dorsal root ganglia with immunohistochemistry and Western-blot methods, we found that the renovation of the distal stoma could significantly enhance the expression of p-S⁴⁷³-Akt in sensory and motor neurons.We made conclusions of this study as follows. 1. At optimum time after the repair of nerve defect by autologous nerve graft, the renovation of the distal stoma can promote the regeneration of nerve fibers. 2. At optimum time after the repair of nerve defect by autologous nerve graft, the renovation of the distal stoma can enhance the regeneration of sensory and motor neurons. 3. At optimum time after the repair of nerve defect by autologous nerve graft, the renovation of the distal stoma can activate the nerons' anti-apoptotic signaling pathway and promote their survival.Through the experimental study, we clarified the distal stoma has a significant impact to the moderate or long nerve defect repaired by autologous nerve graft, also made clear that cutting off the distal scar healing stoma, trimming two ends and anastomosing them again play an important role in nerve regeneration. The conclusion provides an important theoretical basis to improve the clinical effect of nerve defect repaired by autologous nerve graft.