ABSTRACT
When direct repair of a severed nerve cannot be accomplished without undue tension, the standard clinical treatment remains autologous nerve grafting. Due to the limited availability of donor nerve and limited functional recovery following autografting, neural tissue engineering has focused on the development of artificial nerve guides. A nerve guide is a means of directing axonal regeneration and repair across a gap defect; the most basic objective of a nerve guide is to combine physical, chemical, and biological cues under conditions that will foster functional tissue formation. Whether fashioned from biologic or synthetic materials, the nerve guide facilitates communication between the proximal and distal ends of the nerve gap, blocks external inhibitory factors, retains neurotrophic factors at the site of regeneration, and provides physical constraints on axonal regrowth. Nerve guide technology is constantly evolving and now exists as a combination of many unique elements including scaffolds and biomimetic materials. Innovative fabrication methods have been developed and researchers are now producing biodegradable nerve guides with longitudinally aligned channels, more accurately mimicking the native nerve architecture. Multichanneled nerve guides function based on the premise that enclosing nerve stumps and spanning an intervening gap with a biomimetic scaffold create a protected, proregenerative environment. The choice of which physical, chemical, and biological cues to use is based on the properties of the nerve environment, which is critical in creating the most desirable environment for axon regeneration and subsequent return of function.
