Study On Using Microfilaments Diameter Of Repairing Peripheral Nerve Defect Using PLGA Three-dimensional Conduit

Objective:To study the feasibility of using a new type of PLGA three-dimensional nerve conduit containing various of microfilaments in repairing rat's peripheral nerve defect, and investigate the effect of the diameter of microfilaments on nerve regeneration, in order to provide experimental basis for further study of ideal artificial nerves.Methods:60 adult SD rats (300-350g) were randomly divided into 6 groups (n=10), whose sciatic nerves were resected 12mm. In all groups except F group nerve defects were repaired using the PLGA nerve conduit containing 20 microfilaments with different diameter (60 um,80 um,100 um,120 um,140um). The nerve conduits of all groups were filled with o.3ml laminin and never growth factor(NGF). group F:nerve autograft (control group).The left-behind legs were done as experiment sides, the right ones as control sides. To evaluate the repairing result, special assessments were performed including EMG testing, immunohistochemisty to test the number of regeneration nerves at 12 weeks after operation.Results:12 weeks after operation, all the ulcers in claw's palm were healed. The sense of pain and atrophy of triceps muscle of calf recovered better in group B,C,D and F than in group A and E; All the PLGA nerve conduits and microfilaments were degraded on the whole, the regeneration nerves succeeded passing through the gap, which were thicker in group B,C,D and F than in group A and E. Compared with group A and E, the regeneration nerve conduction velocity and the weighing of triceps muscle of calf were better in group B,C,D and F(P<0.01). However, there was no significant difference of atrophy of triceps muscle between group B,C,D and F(P>0.05). Under light microscope and electron microscope, we also discovered that there were significant difference of nerve fiber diameter, thickness of myelin sheath, and fiber density in group B,C,D and F from those in group A and E (P<0.01). Furthermore, image analysis suggested the group B,C,D and F had the nerve regeneration better than group A and E in quantity of nerve fiber, thickness of myelin sheath, and nerve fiber diameter (P<0.01).And the nerve regeneration of PLGA nerve conduit containing 20 microfilaments group was as good as that of nervous autograft group (P>0.05).Conclusion:1. The new PLGA three-dimensional nerve conduit containing 20 microfilaments can help repair 12mm nerve defect effectively, which can be considered as an ideal nerve conduit;2. The diameter of microfilaments can influence nerve regeneration, and the best diameter is 80-120um.