Enhanced nerve regeneration through a bilayered chitosan tube: the effect of introduction of glycine spacer into the CYIGSR sequence.

We have developed a novel bilayered chitosan tube that comprises an outer layer of chitosan film and an inner layer of chitosan nonwoven nano/microfiber mesh. The tube is fabricated with an electrospinning method. We characterized the microstructure and mechanical properties of this material. We introduced glycine spacers into the CYIGSR sequence, domain of laminin-1 that enhances Schwann cells migration and attachment, as well as neural outgrowth, resulting in the amino acid sequences CGGYIGSR and CGGGGGGYIGSR. These peptides were covalently bound to the nano/microfiber mesh surface of the chitosan tube to examine the effects of peptide mobility on nerve regeneration. Scaffolds constructed from these bilayered chitosan tubes were grafted to bridge injured sciatic nerve. Isografting was performed as a control. These scaffolds were removed 5 and 10 weeks after implantation for histological analysis. Nerve regeneration into chitosan tubes, on which the CGGGGGGYIGSR peptide was immobilized, exhibited efficacy similar to that of the isograft and represent a promising candidate for promoting peripheral nerve repair.