Induced peripheral nerve regeneration using scaffolds

In the United States more than 200 000 people per year are treated for severe peripheral nerve injuries that require surgical intervention. Functional recovery of motor and sensory capability is limited after autografting, the most common surgical intervention for severe peripheral nerve injuries. The process of peripheral nerve regeneration has been studied extensively in a variety of animal models using a tubular conduit. This model has been used to generate a large base of data from a wide variety of experimental devices; however, this data has not been analyzed comparatively due to a lack of standardization of experimental conditions, assays, and reported measures of the quality of regeneration. As a result, progress in understanding conditions for optimal nerve regeneration has been stunted and the optimal characteristics for such an implant have not been identified. So while tubulation repair of a transected peripheral nerve presents an attractive alternative to autograft, it has not yet shown the ability to satisfactorily restore lost function. In this article, we provide an overview of mammalian wound healing following severe injury, the physiology of the peripheral nervous system, the standardized wound models used to study peripheral nerve regeneration, and the critical axon elongation criteria and how it can be used to directly compare results from dissimilar studies. We complete this review article with a description of the critical features of tubular implants used to induce peripheral nerve regeneration that can be optimized in order to improve the quality of regeneration.