Experimental study on promoting the regeneration of rat sciatic nerve using slow-release FK506-eluting peripheral nerve stent

Design and construction of biocompatible tissue-engineered stents for long segment peripheral nerve regeneration has become a significant research topic. However, in the early of damaged, the immigration and aggregation of inflammatory cells and factors can induce a secondary nerve injury and peroxide damage to the injured nerves, which in turn can result in severe neuronal apoptosis. The use of immunosuppressant in the injury site can reduce the inflammatory reactions and secondary injury, and build a conducive microenvironment for nerve regeneration. In this study, we prepared tissue-engineering peripheral nerve stent using FK506, where the release of fk506 into the periphery after microsphere degradation still needs to pass through the stent wall. Such double effect of slow-release significantly reduced the burst release and prolonged the full release to 17 days. In our rat model of repairing a 20 mm sciatic nerve defect, 3 months after the surgery, the SFI and electrophysiological testing results of the ipsilateral side in group 1(FK506+PLGA+Stent) showed no significant difference from those in the autologous nerve grafting group. Morphological results also indicated that in terms of either the number of regenerated axons or the degree of myelin maturity, the regeneration outcome in group 1 was close to that in autologous nerve grafting group and significantly superior over that in the group 2(Only Stent). The slow-release FK506-eluting stent introduced in this study is easy for clinical application and provides a new experimental evidence of promoting peripheral nerve regeneration with tissue-engineering methods.