Repair of sciatic nerve defect in rats by polyethylene glycol modified polylactic acid nerve conduit scaffold

  Background  Tissue engineering is promising to replace autogenous nerve transplantation and has become a new method to repair peripheral nerve defects. Tissue scaffold nerve conduit is one of the three elements of tissue engineering, and the improved method of tissue scaffold nerve conduit is the current research hotspot.

  Objective  To prepare poly (ethylene glycol) (polyethylene glycol, PEG) modified polylactic acid (poly lactic acid, PLA) nerve conduit scaffold for nerve repair and regeneration and evaluate its biological characteristics.

  Methods  PLA nerve conduit was prepared by solvent volatilization method. Polyethylene glycol diacrylate (PEGDA), was synthesized by acyl chloride esterification of PEG with acryloyl chloride. The inner wall of polyethylene glycol diacrylate was modified by PEGDA. The microscopic morphology was observed by electron microscope. The proliferation of rat nerve Schwann cell RSC96 in polyethylene glycol modified poly (lactic acid) nerve conduit (PEG-PLA) pretreatment medium was detected by CCK-8 experiment. Thirty SD rats were randomly divided into autogenous nerve graft(ANG) group, poly (ethylene glycol) modified poly (lactic acid) nerve conduit (PEG-PLA) group, and poly (lactic acid) nerve conduit (PLA) group , with 10 rats in each group. The rat model of sciatic nerve 10 mm defect was repaired with autogenous nerve graft, PEG-PLA conduit, and PLA conduit, respectively. Gross observation was performed after operation, nerve regeneration speed was evaluated at 2 weeks after operation, gait analysis was performed at 4, 8 and 12 weeks after operation, sciatic nerve function index was measured. At 12 weeks after operation, samples were taken for histological evaluation of regenerated nerve, wet weight recovery rate of gastrocnemius muscle and histological examination.

  Results  Scanning electron microscope showed that the inner wall of the PEG-PLA nerve conduit was loose and well arranged, and the proliferation of RSC96 cells was not inhibited after the nerve conduit was co-cultured with RSC96 cells, suggesting that the biocompatibility of the nerve conduit was good. At 2 weeks after operation, the results of immunofluorescence staining showed that the axon regeneration in the PEG-PLA group was better than that in the PLA group and lower than that in the ANG group. At 12 weeks after operation, the gait analysis, gastrocnemius muscle wet weight recovery rate and Masson staining in PEG-PLA group were superior to those in PLA nerve catheter group, which was closer to the repair outcome of autogenous nerve transplantation.

  Conclusion  Poly (ethylene glycol) modified polylactic acid nerve conduit has good histocompatibility and can improve the effect of nerve regeneration.