| Background and purposesPeripheral nerve defect is a difficult problem at present. The current gold treatment standard is autologous nerve graft, but there still exist disadvantages. Therefore, finding the substitute of the autologous nerve became the important point. Chitin and its derivatives can promote growth of the endothelial cell, regeneration of the blood vessels, scar reduction. It has become a reliable substitute carrier for the autologous nerve. However, using chitin catheter alone has limitations, because it can not promote the regeneration of Schwann cells effectively. Insulin-like growth factor (IGF-1) and Basic fibroblast growth factor (b FGF) also play important role in damaged nerve repairment. It not only promotes the regeneration of peripheral nerve, but also can increase Schwann cells proliferation and provide protection, nutrition and regeneration. the mechanism is not clear.MethodsEighty male rats were divided randomly into five groups (A, B, C, D, E). The animal model is established by removing the sciatic nerve for10mm and connecting the nerve defect by self-made chitin chamber. The chitin chamber was injected with different materials in each group isotonic saline in group A, gelatin in group B, IGF-1 in group C, b FGF in group D, combined IGF-1and b FGF in group E. At the4and8weeks after operation, the motor nerve conduction velocity (MNCV) of regenerated sciatic nerve was monitored and the specimens were collected, respectively. The special staining and S-100immuno-histochemical analysis of the specimens were performed to assess regeneration of sciatic nerves.Results1. Four weeks after the operation, General observation of samples indicate that the regenerated nerves in all of groups passed through the nerve regeneration chamber and there were regenerated blood vessels around them, Chitin catheter was not completely absorbed. Chitin catheter was completely absorbed after eight weeks, Fibrous tissue reduced significantly; there was a great amount of new capillaries.2. Electrophysiological examination of regenerated nerve showed that velocity in group E(four weeks:22.469±0.713; eight weeks:28.095±1.163) was higher than group A (four weeks:11.455±0.530; eight weeks:11.936±0.755), group B (four weeks:11.418±0.519; eight weeks:12.130±0.494), group C (four weeks:16.009±0.680; eight weeks:22.097±0.673)and group D (four weeks:16.083±1.019,eight weeks:22.618±0.863. At the fourth and eighth weeks after operation, histological results of the combined IGF-1group and bFGF group showed no evident inflammation in the defects with the exception of group E. The difference was statistically significant (P<0.05). There was no significant difference between group A and B (P>0.0167).There was no significant difference between group C and D (P>0.0167) by multiple comparisons with Bonferroni adjusted alpha level of0.0167).3. Loyezs neural staining showed that the number of nerve fiber in group E (four weeks:382.750±4.465; eight weeks:438.875±6.153) was higher than group A (four weeks:247.625±7.501; eight weeks:361.625±4.779), group B(four weeks:256.125±4.969; eight weeks:362.125±5.688), group C (four weeks:360.625±7.313; eight weeks:390.125±5.302) and group D (four weeks:355.625±5.498; eight weeks:390.125±5.988). At the fourth and eighth weeks after operation histological results of the combined IGF-1group and b FGF group showed no evident inflammation in the defects with the exception of group E. The difference was statistically significant (P<0.05). There was no significant difference between group A and B (P>0.0167). There was no significant difference between group C and D (P>0.0167) by multiple comparisons with Bonferroni adjusted alpha level of0.0167).4. S-100immuno histochemistry showed that the number of nerve fiber in group E (four weeks:508.750±12.706; eight weeks:620.250±6.666) was higher than group A (four weeks:374.375±7.873; eight weeks:417.375±5.153), group B (four weeks:376.500±9.350; eight weeks:412.375±4.181), group C (four weeks:406.625±7.140; eight weeks:474.750±5.847) and group D (four weeks:404.750±6.239; eight weeks:472.375±6.594). At the fourth and eighth weeks after operation, histological results of the combined IGF-1group and b FGF group showed no evident inflammation in the defects with the exception of group E. the difference was statistically significant (P<0.05). There was no significant difference between group A and B (P>0.0167). There was no significant difference between group C and D (P>0.0167) by multiple comparisons with Bonferroni adjusted alpha level of0.0167).Conclusions1. Insulin-like growth factor combined with chitin catheter can promote the proliferation of the Schwann cells during the nerve injury.2. Basic fibroblast growth factor combined with chitin catheter can promote the injured sciatic nerve axonal regeneration, and help its function recover.3. There is a synergistic effect of IGF-1and b FGF on promoting the regeneration of peripheral nerve. |
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