Artificial implants for the regeneration of peripheral nerves

Abstract

Axonal regeneration is possible in the pe­ripheral nervous system. Therefore, nerve le­sions can be cured by suturing the dissoci­ated nerve stumps or by grafting an autol­ogous nerve. Since nerve transplantations cause a sensory deficit at the donor site, it is desirable to develop artificial implants for nerve regeneration. Artificial implants have to promote and guide axonal growth, the migration of Schwann cells and must not cause inflammation. Hollow tubes as nerve bridges are already used in the clinic. However, with these it is not possible to achieve nerve re­generation over distances much longer than 30 mm. For this purpose, a number of natural and synthetic materials have already been tested. Biocompatible tubes are being developed which contain orientated fibers or gels with longitudinal channels. In addition, artificial guidance materials are endowed with specific biological functions. Most frequently, extracellular matrix proteins or synthet­ic peptides that activate integrin receptors are coupled to the materials. Other approach­es use gradients of neurotrophins or incorporate living cells. In the long run, a major goal of research is to develop cell-free artificial implants which allow a similar degree of regen­eration as is possible with autologous nerve transplants.