Hepair Of Nerve Gaps With Acellular Nerve Scaffolds Extracted By Detergents

Peripheral nerve defects may occur frequently both hi war and peace periods, which can result in serious motor and sensory disabilities of the injured extremities. The autologous nerve grafting is still the standard method to repair a nerve gap clinically. For the reason that new sensory disturbance is unavoidable when an autologous cutaneous nerve having been harvested, it is very important to develop a new effective material instead of autologous nerve graft to repair the nerve defects.In this paper, a new developed biomaterial called acellular nerve scaffolds (ANS) was evaluated using morphometry combining with neurophisiological technique to show the efficacy of nerve regeneration when bridging an allogenic nerve gap alone or enhanced by exogenous bFGF. Also the possibility of ANS to repair a xenogeneic nerve defect was explored. There are six parts of work asfollows.1. An improved chemical procedure was utilized to obtain acellular nerve scaffolds of the rabbit tibial nerve. The extracted ANSs were quite good in physical character and easy to be handled as being transplanted. Histology and immunohistochemistry were used to evaluate the results of extracting procedure, which showed that it is cell free in an acellular nerve constituted by numerous parallel lamina tubes.2.The aim of part two was to evaluate the effectiveness of acellular allogeneic nerve graft to bridge peripheral nerve defects. Various length of rabbit tibial nerve gaps were repaired by 1 cm, 2cm and 3 cm long acellular nerve scaffolds respectively and the nerve regeneration was evaluated by functional measurement combining with morphological observation. Nerve defects were successfully repaired with functional recovery in all experimental groups twenty weeks postoperatively. The results of nerve regeneration in the 1 cm-group and the 2cm-group were satisfactory; however, in the 3 cm-group nerve regeneration was inferior to autologous nerve grafting.3.The early mechanism of promoting effect by bFGF on nerve regeneration following ANS grafting was explored, and the effects of various concentration of bFGF on axon growth were compared. Immunohistochemistry staining of neurofilament-160 and S-100 was used to show the length of axonal growth and Schwann cell infiltration 10 days after the surgery. The average distance of regenerated nerve fibers in the high dose groups (lOOOAU/ml and 500 AU/ml ) was longer than that in the normal saline control group; but there was no difference between the low dose groups (250 AU/ml and 100 AU/ml) and thecontrol group.4.The purpose of this part was to evaluate whether exogenous bFGF enhanced the long term effect of nerve regeneration after nerve repair with ANSs extracted by detergent. In the experimental group 3 cm long allogeneic ANSs were used to bridge the rabbit tibial nerve defects, and 1ml of 500 IU bFGF solution was given from the second day after surgery with the schedule once per day for 2 weeks and twice a week for another 6 weeks. In the control group normal saline solution was given as the same course as in the experimental group. The functional recovery and the maturity of regenerated myelinated nerve fibers in the experimental group were markedly superior to that in the control group in 20 weeks after surgery. So, it seems that allogeneic ANSs combining with exogenous some growth factors might be an alternative of autologous nerve grafting to bridge nerve defects.5. The aim was to explore the possibility of using xenogeneic acellular nerve scaffolds to bridge peripheral nerve defects. Two kinds of ANS, extracted from either a fresh rabbit tibial nerve or a predegenerated one, were transplanted to bridge 15 mm rat sciatic nerve gaps. Rats treated with orthotopic transplantation and unrepaired ones were as control respectively. Six months after the grafting, functional recovery was evaluated by gait analysis, pinch test, morphological and morphometric analysis. The sciatic nerve function index (SFI) was -30.7%?.8% in rats treated with xenogeneic acellular nerve,...