[Morphologic research on PDLLA/NGF-controlled release conduit promoting peripheral nerve regeneration].

OBJECTIVE: To establish an animal model for repairing the sciatic nerve defect with a biodegradable poly D,L-lactic acid/nerve growth factor (PDLLA/NGF) that can control the release conduit in rats and to observe an effect of the conduit on the sciatic nerve regeneration. METHODS: The PDLLA conduit and the PDLLA/NGF-controlled release conduit (NGF 450 U per conduit) were made with the solvent-volatilization method. Forty male SD rats were randomly and equally divided into 4 groups. The middle segments (10 mm) of the sciatic nerves of the rats were excised and were then repaired with the sciatic nerve autograft (Group A), with the PDLLA conduit (Group B), with the PDLLA conduit and an injection of NGF (30 U) into the conduit (Group C), and with the PDLLA/NGF controlled-release conduit (Group D), respectively, with the 10-mm nerve defect left behind. Three months after operation, the morphologic parameters of the nerve regeneration were observed and evaluated under light microscope and electron microscope, and the image analysis was also made. RESULTS: Three months after operation, porous adherence between the conduit and the surrounding tissues could be observed. The conduit presented a partial biodegradation but still remained intact in the outline and the proximal nerve regenerated through the conduit cavity. Based on the histological observation, the quantity, uniformity, and maturity of the nerve fiber regeneration in Groups A and D were better than those in Groups B and C. The image analysis indicated that there were no significant differences in the nerve fiber diameter, axon diameter or myelin thickness between Group A and Group D (P > 0.05). However, all the parameters in Groups A and D were better than those in Groups B and C (P < 0.05). CONCLUSION: The PDLLA/NGF-controlled release conduit can effectively promote the sciatic nerve regeneration of rats. Its morphological index is similar to that of the nerve autograft.