Prevention of death of axotomized hypoglossal neurones and promotion of regeneration by chitin grafting

1. Chitin is known to promote skin wound healing. In this study, chitin, pr epared from Zuwai crab shell, was used as a bridge between the proximal and distal stumps of cut hypoglossal nerves in shrews. We compared the effects of chitin on the regeneration of transected right hypoglossal nerve axons, with those of porcine dermis, bovine dermal aterocollagen, and autologous nerve bundles. 2. To assess the survival of neurones, the size of neuronal cell body: and number of motoneurones were determined in the absence of any bridged materi al and in the presence of porcine dermis, bovine dermal aterocollagen, chit in, or autologous nerve bundles as a bridge. 3. Our results revealed a significantly better outcome in chitin and autolo gous nerve bridged groups; the size of neuronal cell body and number of hyp oglossal neurones were higher than in the other groups. Chitin also enhance d the regeneration of neurones; the number of horseradish peroxide positive neurones indicative of repaired axonal processes was significantly higher in chitin and autologous nerve-bridged groups than in other groups. 4. Our results demonstrated that the use of chitin sheet or autograft succe ssfully prevented the death of severed neurones and promoted the regenerati on of the lesioned nerve. Although the mechanisms underlying the effects of chitin are still unknown, chitin seems to be a potentially useful biocompa tible material for nerve repair and regeneration.