This article describes repair of peripheral nerve defect using collagen filaments instead of tubes. Many tube-shaped nerve guides induce regeneration of severed peripheral nerve axons within a limited distance. Substantial regeneration of nerve axons has not been reported without a tubular conduit. Here we show the regeneration of peripheral nerve axons along filaments of collagen without a tube. Cables of collagen filaments were grafted to repair 20-mm defects of rat sciatic nerves. Nerve autografts and collagen tubes were grafted as controls. The mean number and the mean fiber diameter of regenerated myelinated axons were approximately 4800 and 3.3 microm in the distal end of the nerve autograft at 8 weeks postoperatively while in the distal end of the collagen-filaments nerve guide, they were approximately 5500 and 2.3 microm. Collagen tubes failed to bridge the nerve defect. Histologic studies suggest that nerve axons regenerated substantially along the collagen filaments.

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This article describes a 30-mm regeneration of severed peripheral nerve axons along collagen filaments. Two thousand or 4000 31-mm-long collagen filaments were grafted to bridge a 30-mm defect of the rat sciatic nerve. A collagen tube was grafted as a control. The mean number and mean fiber diameter of regenerated myelinated axons were 330 +/- 227 and 2.7 +/- 0.9 microm in the distal end of the 2000 collagen-filaments nerve guide, and 564 +/- 275 and 2.5 +/- 1.1 microm in the distal end of the 4000 collagen-filaments nerve guide at 12 weeks postoperatively, whereas in the distal end of the collagen tube, no regenerated axon was found. These results suggest that the collagen filaments guide axons of the rat's sciatic nerve to regenerate for 30 mm and act as a scaffold for axonal regeneration. Thirty-millimeter nerve regeneration of a 1-mm-diameter rat sciatic nerve by an artificial nerve guarantees a clinical application of the implant which should be very important for patients and surgeons.