Study On The Composite And Its Properties Used In Repairing Peripheral Nerve Defect

A kind of composite conduit based on poly(DL-lactide) was investigated to repair nerve defect. This kind of composite conduit with good degradation and good drug release property was prepared by a solvent volatilization method using poly(DL-lactide), phosphate and nerve growth factor.The pH value, weight and SEM of pure PDLLA and its composite with β -TCP and HA were observed during the degradation in 20 weeks in vitro to study the most suitable composite for repairing nerve defect. The results showed that both HA and β -TCP had significant inhibitory effects on the degradation of the composite and the pH value of circumstance. In view of the degradation speed of the composite matching the nerve restoring speed and the particle size of HA and β -TCP prepared by current technique, the never conduit was selected as composite of PDLLA and HA.The study on the preparation process and condition of the composite nerve conduit shows that HA was added to PDLLA in the scale of 5% by the ultrasonic dispersal technique and the conduit could be prepared by a solvent volatilization method using ethyl acetate as solvent under 20 ℃.The pH value, weight and NGF release rate of the composite nerve conduit with different NGF content were observed during the degradation in 20 weeks in vitro. The results show that both HA particles and the content of NGF have significant inhibitory effects on the degradation of the composite while the content of NGF also have important effects on the release property of the conduit. The release rate which rised up to maximum matched the nerve restoring speed.Each rat underwent right sciatic nerve transection and kept a 10mm nerve defect, then these defects were repaired by using pure PDLLA conduits and composite conduits. Function repair of sciatic nerve regeneration was evaluated at 3m and 6m following operation by using gross observation, triceps weight, electrophysiological, histological and axon morphologic assessment of the outcome of nerve regeneration. The results showed that NGF of composition conduit may repair the sciatic nerve in a dose-dependent manner. Suitable dosage of NGF can promote nerve regeneration Thesuitable dose of NGF in composition conduit is about 400-500U. The SEM pictures showed that the degradation in vivo and in vitro were almost in the same way. This conclusion can provide an important foundation for the clinical study.