Effects of a laminin peptide (YIGSR) immobilized on crab‐tendon chitosan tubes on nerve regeneration

Abstract

Thiolated and nonthiolated hydroxyapatite-coated crab-tendon chitosan (t-chitosan/HAp-SH and t-chitosan/HAp, respectively) tubes, both alone and conjugated with CDPGYIGSR (YIGSR) peptide, were compared, in order to determine their biocompatibility and efficacy as nerve conduits. YIGSR peptide was adsorbed on the t-chitosan/HAp (HAp) tubes, and covalently bound on the t-chitosan/HAp-SH (HAp-SH) tubes (Y/HAp and Y/HAp-SH tubes, respectively). HAp, HAp-SH, Y/HAp, or Y/HAp-SH tubes measuring 15 mm were bridge grafted into the sciatic nerve of SD rats. Grafting of 15-mm-long Type I atelocollagen tubes and isografting of sciatic nerves were also carried out (N = 6 in each group). After 12 weeks, evoked muscle action potentials were recorded to calculate the terminal latency quotient. Histological observation and analysis of myelinated axons were also carried out. Nerve-tissue regeneration did not occur directly on the tubes' surfaces in the YIGSR peptide-unconjugated groups. Transplantation of YIGSR-conjugated tubes, however, gave rise to regenerated nerve tissue attached to thin layers of epineurium-like structure formed on the inner-tube surface. Histological and electrophysiological analyses suggested that although thiolation retards nerve-tissue regeneration, adsorbed YIGSR, and, to a lesser extent, peptide that had been covalently bound onto the tube surfaces, enhance nerve regeneration, promoting sprouting from the proximal nerve stump and bridging of regenerated axons throughout the tube.