Current status and future prospects of artificial nerves: The future of artificial nerves as nerve connectors

Abstract

　Previous studies have suggested that utilizing a nerve conduit as a connector may provide outcomes that are equivalent to, or even better than direct suture repair. Therefore, the present study investigated the underlying mechanisms of nerve regeneration through a short gap encapsulated in a conduit comparing with conventional direct suture repair.
　To observe the axonal growth after the repair serially, we used Thy1 yellow fluorescent protein 16 transgenic mice, all of whose axon fibers constitutively express fluorescence. The sciatic nerve of each mouse was transected and two weeks later, two types of repairs were performed: 1) direct epineural suture (DR) and 2) repair using an artificial nerve made by polyglycolic acid conduit as a nerve connector (CR) . Axonal growth after the repair was monitored by serial in vivo imaging and gene expression at the repair site was also analyzed by qRTPCR. In addition, Histomorphometric measurements were evaluated and functional recovery was checked by calculating the area of anterior tibialis muscle and using the von Frey filament test. The gene expression at the repair site showed that while almost all the neurotrophic marker increased up to Week 1 and did not continue thereafter, SOX10, NTF3, and NGF in CR continued to show significant increases throughout the observation period. Moreover, although sensory recovery was faster in DR, the quality of regenerated axons and also recovery of the muscle fiber were significantly better in CR compared with that of DR. Our research found that, although slow, repair using a nerve connector would provide a favorable environment for the continuous increase of neurotrophins, leading to a better functional recovery.