Study On Using PLGA Three-dimensional Conduit To Repair Rat's Peripheral Nerve Defect

Objective: To study the feasibility of using a new type of PLGA three-dimensional nerve conduit containing varies of microfilaments in repairing rat's peripheral nerve defect, observe the role of microfilaments as guide-fibers and their influence on nerve regeneration in vivo when their quantities are diversity, provide theory foundation and experiment experience for further study of ideal artificial nerves.Methods: New absorbable three-dimensional nerve conduits were made with the biomaterial named PLGA(85:15). Firstly, we used this absorbing material to prepare to be three-dimensional tubiform , which containing varies of microfilaments, and the tubal wall had many micropores; Then 40 adult SD rats were randomly divided into 4 groups(n=10), which sciatic nerves were resected 12mm by operations. All those sciatic nerve defects were repaired using the three-dimensional nerve conduits. Group A: PLGA nerve conduit; group B: PLGA nerve conduit containing 20 microfilaments; group C: PLGA nerve conduit containing 40 microfilaments; group D: nervous autograft (control group). Except group D, the nerve conduits of all groups were filled with o.3ml mixed liquor of laminin and never growth factor. The left-behind legs of all rats were operated as experiment side, the right ones were contrast side. After operation, movement of hindlimb, hindlimb's retraction after being pricked by needle and ulcer in claw's palm were normally observed. To evaluate the repair result, special assessments were performed including histology, EMG testing, image analysis and weighing of triceps muscle of calf 12 weeks after operation. The data of four groups was statistically analyzed by group F test.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 and D than in group A and C; 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 and D than in group A and C. Compared to group A and C, the regeneration nerve conduction velocity and the weighing of triceps muscle of calf were showed better in group B and D(P<0.05). However, there was no significance of atrophy of triceps muscle between group B and D(P>0.05). Under light microscope and electron microscope, we also discovered that there were significance of nerve fiber diameter, thickness of myelin sheath, and fiber density in group B and D from those in group A and C (P<0.05). Furthermore, image analysis suggested the group B and D had the nerve regeneration better than group A and C in quantity of nerve fiber, thickness of myelin sheath, and nerve fiber diameter (P<0.05).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 conduct rat's sciatic nerve regeneration and repair 12mm nerve defect effectively, which can be considered as an ideal nerve conduit;2. Microfilaments in nerve conduit can promote rat's sciatic nervous regeneration, and the number of microfilaments probably influence nerve regeneration, which restrain it instead when excessively.