Bioengineering for nerve repair in the future

Abstract

Despite advances in many other fields in hand surgery, nerve repair has not improved substantially from the techniques for nerve repair established by Sir Sidney Sunderland during World War II. The key obstacles to repair include the accuracy of regeneration; the time required; and the lack of adequate donor nerve graft tissue for bridging a gap in a nerve, with the proper cytokines and substrate to promote regeneration without causing a defect in another site. Less than 50% of regenerating sensory or motor axons reach the correct end organ. Regeneration of motor axons is limited to approximately 12 months, after which time absorption of motor end plates occurs.Autogenous nerve grafts are in extremely limited supply, with sural nerve grafts being the primary source. Synthetic nerve grafts currently are unable to support nerve regeneration across long defects, but hold great promise. Bioengineering strategies for such grafts seek to enhance nerve regeneration by using neurotrophic factors to increase the speed of regeneration, making structural changes to improve the accuracy of repair, and incorporating cytokines, which might inhibit the re-absorption of motor end plates.