Construction of type Ⅰ collagen nerve conduit and its mechanism of action in reconstruction of median nerve injury of the forearm / 中国组织工程研究

ABSTRACT

BACKGROUND: Type I collagen is a polymer material that has good biocompatibility and good cell affinity, and can degrade under certain conditions. It can also develop good mechanical properties after cross-linking, but it is less reported in the reconstruction of the injured median nerve of the forearm. OBJECTIVE: To explore the preparation method of type I collagen nerve conduit and its mechanism in the reconstruction following median nerve injury in the forearm. METHODS: A total of 40 Sprague-Dawley rats were selected from the Medical Animal Experimental Center, the Affiliated Hospital of Guizhou Medical University, 10 of which were randomly selected as sham surgery group. The remaining 30 rats were used to establish a rat model of median nerve injury in the forearm by laser-induced photochemical reaction. After successful modeling, the model rats were randomly divided into positive control group (n=10), type I collagen group (n=10) and autologous nerve group (n=10). The sham surgery group was routinely fed and did not participate in the modeling; the positive control group did not take special treatment after the successful modeling; the type I collagen group was subjected to bridging with type I collagen nerve conduit; and the autologous nerve group was subjected to bridging with autologous nerve. The repair effects were compared among groups. RESULTS AND CONCLUSION: (1) Under the inverted microscope, the type I collagen was loosely arranged before cross-linking, and it had honeycomb-shaped irregular pores with the pore size of 10-100 μm and the porosity of 20-200 μm, and the pore interstitial was relatively thin. After cross-linking, the type I collagen was densely arranged, the collagen fibers could form relatively regular pores with the pore size of 50-100 μm and the porosity of 20-200 μm, the interstitial mass was thickened, and the spatial structure changed significantly. (2) After 4, 8 and 12 weeks of repair, the scores on the Minnesota Manual Dexterity Test in the type I collagen and autologous nerve groups were significantly lower than those in the positive control group (P < 0.05) and higher than those in the sham surgery group (P < 0.05). (3) At 12 weeks after repair, there was no significant difference in amplitude and latency between the type I collagen group and the autologous nerve group (P> 0.05), but the amplitude and latency in both groups were significantly higher than those in the positive control group (P < 0.05). (4) At 12 weeks after repair, the nerve injury site surrounded by necrotic tissues was visible in the positive control group; no injury was found in the autologous nerve group, and the surrounding necrotic area decreased, indicating good recovery; no injury was shown by toluidine blue staining in the type II collagen group, indicating good recovery. Overall, the type I collagen nerve conduit can be successfully prepared by the self-made mold, and it can be used for the reconstruction following median nerve injury in the rat forearm, helping nerve repair.