Nerve Conduit Enhancement with Vomeronasal Organ Improves Rat Sciatic Functional Index in a Segmental Nerve Defect Model

Abstract

Segmental nerve loss presents a challenge to the reconstructive surgeon. Collagen nerve conduits are one strategy for reconstruction of segmental defects, but no conduit-based reconstructive strategy has been as successful as autograft reconstruction. We hypothesized that collagen nerve conduits used to bridge segmental sciatic nerve defects may be enhanced by grafting with vomeronasal organ (VNO), owing to this tissue’s capacity for regeneration. Fourteen rats underwent resection of a 1.0 cm segment of sciatic nerve. Seven rats underwent reconstruction of the defect using a commercially available collagen nerve conduit. Seven rats underwent reconstruction using conduit filled with fresh VNO allograft. An additional seven rats underwent transection and direct epineural repair. Fourteen weeks postoperatively, all animals underwent calculation of sciatic functional index (SFI) via walking track analysis. After sacrifice, tissues were processed for histomorphometric analysis, including axon quantification and axon density. All reconstructed nerves were in continuity at sacrifice. At 14 weeks, the mean SFI was significantly higher in the vomeronasal organ-enhanced (VNOE) group and epineural repair (ER) group than the conduit-only (CO) group. `SFI was equivalent between VNOE and ER groups. Axon density was greater in the VNOE and ER groups than the CO group. Axon density was equivalent between VNOE and ER groups. In conclusion, this rat sciatic nerve segmental defect model achieved greater functional recovery and axon density using collagen nerve conduits filled with a pluripotent neuroepithelium relative to reconstruction with an empty conduit. These results suggest a promising strategy for repair of segmental peripheral nerve defects.