A collagen and fibrin tube for nerve repair

A biodegradable tube consisting of alternating laminae of aldehyde and heat-treated collagen and fibrin was tested as a nerve repair device. Tubes placed around intact nerves for 3 weeks showed a high degree of biocompatibility as evidenced by the absence of reactive or toxic alterations of epineurium contacting the implant and the presence of normal perineurial and endoneurial components. Tubes used to bridge a 5 mm gap in the rat tibial nerve showed good vascularization of the collagen laminae, a well-confined nerve regenerate, and advanced resorption of the fibrin component at 3 months. One year after being used to bridge 5-12 mm gaps in the cat radial and saphenous nerves, the tubes were replaced by well-vascularized connective tissue which surrounded a dense nerve regenerate. However, inadequate stabilization of the implants by the small anchoring sutures apparently caused some of the repairs to fail. In sum, the implants appear to promote regeneration of axons across a nerve gap by providing an oriented, well-vascularized physical substrate for neurite outgrowth.