Split-sciatic nerve surgery: A new microsurgical model in experimental nerve repair.

Abstract

Sciatic experimental surgery in rat often leads to hindlimb autophagy, with considerable ethical and research issues. In this work, the distal part of the sciatic nerve was split following the natural bifurcation between tibial and peroneal branches, before applying regenerative stem cells in a fibrin conduit on the peroneal segment. The new microsurgical model was tested in terms of animal morbidity and consistency of research outcomes, particularly comparing to the standard total sciatic axotomy procedure. After dissection of sciatic the nerve, the tibial and peroneal fibres were split upwards and a total axotomy was performed in the peroneal side. The 1 cm nerve gap between the proximal sciatic nerve and peroneal nerve was crossed using fibrin conduits. The tibial nerve was not included. Experimental groups involved either empty or fibrin conduit seeded with Schwann cell-like differentiated adipose derived stem cells (dASC) (Fib + dASC). Autografts and sham rats were used as controls (total n = 20). At 12 weeks post-implantation, an extensive histomorphometric analysis was performed. Functional aspects of regeneration were analysed by walking track analysis. No major autophagy occurred using the split-sciatic technique. A detailed histomorphometric analysis showed consistent results with previous literature using fibrin conduits in a full sciatic axotomy experimental setting. Walking track analysis reflected the histological regeneration pattern, displaying superior regeneration in both autograft and dASC groups. Split-Sciatic nerve surgery reduced animal morbidity, while being representative of the whole nerve as regeneration outcomes were consistent with previous data obtained on the whole sciatic nerve. The decreased autophagy rate allowed for a more efficient functional evaluation.