Gene therapy in peripheral nerve reconstruction approaches.

Gene transfer to a transected peripheral nerve or avulsed nerve root is discussed to be helpful where neurosurgical peripheral nerve reconstruction alone will not result in full recovery of function. Axonal regeneration is supposed to be facilitated by this new therapeutic approach via delivery of specific regeneration promoting molecules as well as survival proteins for the injured sensory and motor neurons. Therefore gene therapy aims in long-term and site-specific delivery of those neurotrophic factors. This paper reviews methods and perspectives for gene therapy to promote functional recovery of severely injured and thereafter reconstructed peripheral nerves. Experimental in vivo and ex vivo gene therapy approaches are reported by different groups. In vivo gene therapy generally uses direct injection of cDNA vectors to injured peripheral nerves. Ex vivo gene therapy is based on the isolation of autologous cells followed by genetic modification of these cells in vitro and re-transplantation of the modified cells to the patient as part of tissue engineered nerve transplants. Vectors of different origin are published to be suitable for peripheral nerve gene therapy and this review discusses the different strategies with regard to their efficiency in gene transfer, their risks and their potential relevance for clinical application.