Entubulation repair with protein additives increases the maximum nerve gap distance successfully bridged with tubular prostheses

The major objective of the experiments reported in this paper was to test the hypothesis that the maximum distance that peripheral nervous system (PNS) axons can regenerate through a tubular prosthesis may be increased by specific modifications to the internal environment of the prosthesis. The sciatic nerve of adult male rats was transected and proximal and distal nerve stumps were sutured into a silicone tube 20-25 mm in length. The silicone tubes were implanted empty, or the lumen was filled with collagen or a laminin-containing gel. Following 4-16 weeks survival time animals were sacrificed and the contents of the silicone tubes were processed for histological identification of myelinated and unmyelinated axons. All of the tubes with additives, but one of the initially empty tubes, displayed a regenerated nerve cable within the tube. Retrograde labeling studies were carried out to prove that some of the axons present in the regenerated nerve cables arose from primary motor and sensory neurons. These results show that specific modifications to the microenvironment of regenerating PNS axons can affect the success or failure of tubular prostheses for nerve repair.