Rehabilitation Of Distal Anastomotic Stoma Promoting Axon Regeneration After Nerve Graft

It is one of the difficult problems left unsolved in surgical field to repair the peripheral nerve defect.Although many scholars have investigated a lot on xenogenous nerve graft, heterogenous nerve graft, alternating autologous biological tissue and tissue-engineered bioartificial nerve to repair nerve defect, autologous nerve graft has always been the first consideration for nerve restorative procedure in clinic. However, the healing efficacy of autologous nerve graft is still not so satisfactory, especially long nerve graft. Blood supply of long nerve graft, surrounding scar tissue and axons stepping over two anastomotic stomata influence the nerve regeneration are concentrated on by many scholars. But if there were the differences between the impacts from distal and proximal anastomotic stoma on nerve regeneration, how are the effects on regenerated axon growing through distal anastomotic stoma of re-anastomosis after selective excision of distal anastomotic stoma according to the speed of nerve regeneration? How will affect the function of sensory and motor neurons after selective excision of distal anastomotic stoma? These are still rare all over the world on these studies.Purposes:The distal anastomotic stoma after nerve graft was excised and re- anastomsed, then we observed whether hyperplasia of scar tissue could be suppressed and the growth through distal anastomotic stoma of regenerated axon could be promoted. Meanwhile, functional status of axons was observed which had grown to distal anastomotic stoma to see whether axonal growth promotion could be aroused again by sensory and motor neurons.Methods:Sciatic nerve graft in situ was built on Wistar mouse. The mice were grouped randomly into sham operation group (nerve exposed only), control group (nerve graft in situ) and experimental group (excision and repair distal anastomotic stoma 8 weeks after nerve graft). Nerve tissue of distal anastomotic stoma, corresponding spinal cord and dorsal root ganglion were excised in different time spots. Immunohistochemical methods were used to test the expression changes of collagen type I and III ,which could obtain the condition of hyperplastic scar tissue in distal anastomotic stoma. The changes of AChE, ACP and BDNF in sensory and motor neurons after re-anatomsis were detected by immunohistochemical methods, Rt-PCR and western blot .These changes could identify the state of axon regeneration and scar tissue and the influences on partical function of corresponding sensory and motor neurons.Results:1. There was no significant variation in expression of collagen type I and III in control group and experimental group 4 weeks after the re-anastomosis and 8 weeks later. It was lower in experimental group compared with control group.2. AChE and ACP leading to impaired reaction of motor neuron still existed after re-anastomosis in experimental group. There was significant deviation of AChE expression in experimental group than that of control group from 7th to 28th day (P<0.01).There was significant deviation of ACP expression in experimental group lower than control group from 7th to 56th day (P<0.01)3. After the re-anastomosis, there was a BDNF expression peak in spinal cord and dorsal root ganglion in 14th day and the deviation was significant between control group and experimental group(P<0.01).The expression went down gradually after 42th day .At 56th day, BDNF expression is still higher than that of control group (P<0.01).Conclusions:1. Re-anastomosis after selective excision of distal anastomotic stoma strongly suppresses hyperplasia of scar tissue and is helpful to stimulate axon growing throu- gh distal anas- tomotic stoma.2. Although there is still enzyme changes caused by selective excision in motor neurons,but the injury degree is obviously less than that caused by previous injury.3. Capability of promoting axon regeneration is aroused and enhanced in sensory and motor neurons after the re-anastomosis. 4. According to the speed of peripheral nerve regeneration, re-anastomosis after selective excision of distal anastomotic stoma could suppress hyperplasia of scar tissue and promote regenerative axon growing through distal anastomotic stoma preferably. It could stimulate efficiently the grown axons which have reached distal anastomotic stoma, which could evoke functional status of promoting axon growth in the correlated sensory and motor neurons once more.