Chapter 9: Artificial scaffolds for peripheral nerve reconstruction.

Posttraumatic peripheral nerve repair is one of the major challenges in restorative medicine and microsurgery. Despite the recent progresses in the field of tissue engineering, functional recovery after severe nerve lesions is generally partial and unsatisfactory. Autograft is still the best method to treat peripheral nerve lesions, although it has several drawbacks and does not allow complete functional recovery. Full recovery of nerve functionality could ideally be achieved by proper guiding axon regeneration toward the original target tissues, through the use of purposely engineered artificial nerve guidance channels (NGCs). In the last decade, artificial NGCs have been produced using a variety of both natural and synthetic, biodegradable and nonbiodegradable polymers. Several techniques have been developed to obtain porous and nonporous NGCs and to realize and incorporate bioactive fillers for NGCs. Some of the developed products have been approved for clinical applications. Many other NGC typologies have been object of interest and are currently under investigation. The current trend of nerve tissue engineering is the realization of biomimetic NGCs, providing chemotactic, topological, and haptotactic signalling to cells, respectively by surface functionalization with cell binding domains, the use of internal-oriented matrices/fibres and the sustained release of neurotrophic factors. The present contribution provides a balanced integration of the most recent achievements of tissue engineering in the field of peripheral nerve repair. By an accurate evaluation of the status of research, the review delineates the most promising directions to which research should address for consistent progress in the field of peripheral nerve repair.