The way to improve peripheral nerve regeneration has been devotedly studied by the researchers. Using the nerve conduits to bridge axonotmesis has been proven as a practical repairing method. The nerve conduits made of biodegradable materials can avoid a second surgery to remove the non-degradable conduits. Therefore, the subjects become popular research area. Among the biodegradable materials, gelatin derived from collagen posses the characteristic of lower antigenicity and better biocompatibility. Genipin extracted from the Chinese herb-Gardenia jasminoides Ellis is a natural substance and low-cytotoxic cross-linking agent.
In the presented study, biodegradable genipin-cross-linked gelatin conduits (GGCs) and highly permeable genipin-cross-linked gelatin conduits (PGGCs) were fabricated for next assays. GGC, PGGC and non-degradable silicone tubes were all to be evaluated of the capability of bridging a 10mm gap within the sciatic nerve of the Sprague-Dawley rat. The expression of GAP43, synapsin I and TGF-β1 was also compared in this study. Overall gross examination of the GGCs and the PGGCs after 8 weeks of post implantation revealed 100％ of nerve formation in the tubes, and the silicone tubes only demonstrated 54％, respectively. The histological study further showed that the regenerated nerve area in the silicone tubes was the greatest. Abundant scar tissues surrounding the regenerated nerves were obviously observed in the PGGCs and GGCs. Coordinately, these nerves also showed apparent expression of TGF-β1 than that in the non-degradable silicone tubes. In addition, the regenerated nerves in the PGGCs demonstrated relatively the characteristic of more maturity and had much more expression of GAP43 than those in the GGCs. These data suggested that the PGGCs could offer effective aids for regenerating nerves compared with the GGCs. Compared with the regenerated nerves in the silicone tubes, the nerves in the PGGCs expressed high levels of GAP43 and had better regeneration ability. However, considering the impedance of scar tissue at the nerve repairing site, the silicone tubes expressed high levels of synapsin I, which implied better nerve terminal maturation.
