Immunogenicity and regenerative potential of acellular nerve allografts to repair peripheral nerve in rats and rabbits

This study describes the ability of acellular nerve allografts (genetically different) to repair injured peripheral nerve in rats and rabbits. We recently reported the regeneration supporting potential and immunogenicity of acellular nerve allografts in rats⁷. The present study extends our previous work and quantitates the extent of axonal regeneration through various nerve grafts in rats. In addition, the use of longer nerve grafts to repair rabbit peripheral nerve is described. Inbred strains of Fischer and Buffalo rats and New Zealand white and Dutch rabbits were used. Acellular grafts were prepared by repeated freezing and thawing of in situ degenerated nerves. Nonfrozen predegenerated nerves were used as cellular grafts for comparison. Nerve isografts (genetically identical) were also performed. The graft length was 2.0 cm in rats and 4.0 cm in rabbits. In both rats and rabbits the cellular isografts showed the most rapid regeneration and target muscle innervation. The cellular allografts were invariably rejected and only showed limited regeneration. In contrast, acellular allografts, in spite of their mild immunogenicity, allowed significant regeneration through them. It is concluded that acellular nerve allografts are capable of supporting axonal regeneration because of their reduced immunogenicity, and thus can be used to bridge nerve gaps after nerve injury.