Chitosan tubes enriched with fresh skeletal muscle fibers for delayed repair of peripheral nerve defects

Nerve regeneration after delayed nerve repair is often unsuccessful. Indeed, the expression of genes associated with regeneration, including neurotrophic and gliotrophic factors, is drastically reduced in the distal stump of chronically transected nerves; moreover, Schwann cells undergo atrophy, losing their ability to sustain regeneration. In the present study, to provide a three-dimensional environment and trophic factors supporting Schwann cell activity and axon re-growth, we combined the use of an effective conduit(a chitosan tube) with a promising intraluminal structure(fresh longitudinal skeletal muscle fibers). This enriched conduit was used to repair a 10-mm rat median nerve gap after 3-month delay and functional and morphometrical analyses were performed 4 months after nerve reconstruction. Our data show that the enriched chitosan conduit is as effective as the hollow chitosan conduit in promoting nerve regeneration,and its efficacy is not statistically different from the autograft, considered the "gold standard" technique for nerve reconstruction. Since hollow tubes not always lead to good results after long defects(> 20 mm), we believe that the conduit enriched with fresh muscle fibers could be a promising strategy to repair longer gaps, as muscle fibers create a favorable three-dimensional environment and release trophic factors. All procedures were approved by the Bioethical Committee of the University of Torino and by the Italian Ministry of Health(approval number: 864/2016/PR) on September 14, 2016.

Emerging issues in peripheral nerve repair

It is today widely acknowledged that nerve repair is now more than a matter of perfect microsurgical reconstruction only and that, to further improve clinical outcome, the involvement of different scientific disciplines is required. This evolving reconstructive/regenerative approach is based on the interdisciplinary and integrated pillars of tissue engineering such as reconstructive microsurgery, transplantation and biomaterials. In this paper, some of the most promising innovations for the tissue engineering of nerves, emerging from basic science investigation, are critically overviewed with special focus on those approaches that appear today to be more suitable for clinical translation.

Nerve transfers in distal forearm and in the hand

Nerve transfers were used,originally,to restore shoulder and elbow function in brachial plexus lesions.This concept has been developed over the years and applied to distal nerve injuries in which lower functionality was expected because of the gap between the injury site and the target muscle.The aim of this review is to describe nerve transfers in the distal forearm and hand for isolated lesions of the median,ulnar and radial nerves.The different advantages achieved by transposition of a functional nerve stump near the effector muscle have opened up new options for the management of nerve lesions.Some of these alternatives have only been recently reported and a few are exclusively case reports.