Magnetically aligned collagen gel filling a collagen nerve guide improves peripheral nerve regeneration

Bioresorbable collagen nerve guides filled with either magnetically aligned type I collagen gel or control collagen gel were implanted into 4- or 6-mm surgical gaps created in the sciatic nerve of mice and explanted 30 and 60 days postoperation (dpo) for histological and immunohistochemical evaluati on. The hypothesis was that contact guidance of regenerating axons and/or i nvading nonneuronal cells to the longitudinally aligned collagen fibrils wo uld improve nerve regeneration. The criterion for regeneration was observat ion of regenerating myelinated fibers distal to the nerve guide. Consistent with previous studies showing poor regeneration in 6-mm gaps at 60 dpo wit h entubulation repair, only one of six mice exhibited regeneration with con trol collagen gel. In contrast, four of four mice exhibited regeneration wi th magnetically aligned collagen gel, including the appearance of nerve fas cicle formation. The numbers of myelinated fibers were less than the uninju red nerve in all groups, however, which may have been due to rapid resorpti on of the nerve guides. An attempt to increase the stability of the collage n gel, and thereby the directional information presented by the aligned col lagen fibrils, by crosslinking the collagen with ribose before implantation proved detrimental for regeneration. (C) 1999 Academic Press.