Local administration of neurotrophic growth factor in subcutaneous siliconchambers enhances the regeneration of the sensory component of the rat sciatic nerve

An experimental model for local administration of neurotrophic growth facto r (NGF) in peripheral nerve lesions is tested. The model consists of a subc utaneous reservoir connected to the sciatic nerve neurorrhaphy. The right s ciatic nerves were exposed, severed, and repaired at a level 1.5 cm proxima l to their trifurcation. Then, a dome-shaped silicone reservoir connected t o the proximal end of a silicone tube was placed subcutaneously in the dors um of the experimental animal. The distal end of the connecting tube was lo cated in the nerve neurorrhaphy. Two experimental groups were made: Group A (n = 90) received daily doses of a solution containing NGF-7S during the f irst 4 weeks after surgery and a single weekly dose thereafter. Within this group, three subgroups of 30 rats each were made: A-4 sacrificed 4 weeks a fter surgery, A-8 sacrificed after 8 weeks, and A-12 after 12 weeks. Group B (n = 90) received the same vehicle solution without NGF under the same sc hedule and volume as in Group A. Three subgroups were also made as in Group A depending on the survival period. in order to locate the neurons in the dorsal root ganglia, the retrograde tracer horseradish peroxidase was admin istered at the proximal stump of the sciatic nerve (tibialis branch), which was severed 1 cm distal to the sciatic trifurcation. In respect of the non operated side, the percentage between the number of dorsal root ganglia neu rons in the NGF-treated group was significantly higher than in the control group (P < 0.001). These results demonstrate that percutaneous administrati on of multiple doses of NGF in this model enhances sensory nerve regenerati on after sciatic lesions evaluated by horseradish peroxidase labeling of do rsal root ganglia neurons. (C) 1999 Wiley-Liss, Inc.