Effects of Nerve Growth Factor, Insulin- Like Growth Factor-I and Collagen Gel on Peripheral Nerve Channel: Sensory, Functional and Regeneration Through Piezoelectric Electrophysiologicalal Study

Purpose: The limited availability of donor sites for nerve grafts continues to stimulate research toward finding suitable alternatives. Material and Methods: In the following study, the effects of direct administration of Nerve Growth Factor (NGF), Insulin - Like Growth Factor - I (IGF-I) , or / and collagen gel into Polyvinylidene Fluride (PVDF) gap was tested in a rat sciatic nerve model. A 1-cm segment of the left, sciatic nerve in Sprague-Dawely rats was resected, and the gap was then bridged using the following methods: Group I (NGF+ IGF-I, n=12): a PVDF tube filled with NGF (100ng) and IGF-I (100ng) in 0.3ml phosphate buffered saline or PBS; Group II (collagen gel, n=12): a PVDF tube filled with collagen gel (diluted at 1.28 mg/ml in PBS); Group III (NGF+ IGF-I +Collagen gel, n=12): a PVDF filled with NGF (100ng), IGF-I (100ng) and Collagen gel (1.28 mg/ml) in PBS; Group IV (Autograft ,n=12); and Group V (sham operation, n-12). All the animals were evaluated at 7, 21, 35, 49, 60 and 90 days after operation by sensory testing and Sciatic Functional Index (SFI) and at 90 days by electrophysiological testing. Results: At 35 days, sensory testing showed that latency to a noxious stimulus in Group III (5.86±2.1, sec) was significantly lower than that in Group I (9.24±2.7, sec) and Group 11(1l.98±3.11, sec) , which indicated that sensory recovery was superior in the rats receiving NGF, IGF-I and collagen gel (P<0.005). The mean latency of rats in Group IV was 7.47±2.21 sec, but the difference between the latencies of Groups III and IV did not reach statistical significance. At 90days, there was no difference in sensory testing between the groups. SFI in groups III (-66±5.6) and IV (-68.1±6.1) was superior to that in Groups I (-73.1±8.9) and II (74.8±7.11) at 60 days after operation (P<0.001). Mean Motor Nerve Conduction Velocities (MNCV) were 24±1.63m/sec, 19.7±4.3m/sec, 32±4.47 m/sec and 29.6±5.07m/sec in groups I, II, III, and IV, respectively. The difference between groups I, III and IV was not statistically significant, but the MNCV of group 11was significantly lower than that of group III and IV (P<0.002). Conclusion: The positive effects of NGF, IGF-I and collagen gel on the regeneration of nerve through a PVDF channel seen in this study suggest that it may be useful for the treatment of peripheral nerve injuries.