Effect Of Microencapsulated Schwann Cell Transplantation On Neuropathic Pain Mediated By P2X2/3 Receptor In Rats

Objective:Pain is a great danger to human health.Neuropathic pain caused by peripheral nerve injury is a kind of chronic pain that is difficult to cure in clinical practice.People have been devoted to the study of neuropathic pain mechanism and drug development.Previous studies have shown that Schwann cells(SCs)transplantation is one of the most promising cells to promote neural repair.Our lab observed the therapeutic effects of microencapsulated Schwann cells transplantation in rats with neuropathic pain,and investigated the effects and mechanisms that mediated by P2X2/3 receptors in dorsal root ganglion(DRG).Methods:1.Cultured rat Schwann cells(SCs)were cultured by subculture,and the microencapsulated SCs were made by microencapsulation technology.2.The chronic constiction injury(CCI)rats were used as the neuropathic pain model.3.The rats were randomly assigned into four groups : sham group(Sham);chronic constriction injury group(CCI);CCI rats treated with schwann cells group(CCI +SCs);CCI rats treated with microencapsulated schwann cells group(CCI + MC-SCs).4.We assessed mechanical withdrawal threshold(MWT)and thermal withdrawal latency(TWL)in the rat models before the surgery and in the 2nd?4th?6th?8th?10th?12th and 14 th days after surgery.5.Ultrastructural changes in the injured sciatic nerve were assessed using transmission electron microscopy.6.The expressions of P2X2/3 receptors in L4-5 dorsal root ganglia of different groups were detected by Double-label immunofluorescence 14 th days after surgery.7.We determined P2X2/3mRNA expression and protein level changes in the L4-5 DRG using quantitative real-time polymerase change reaction technology and Western blotting analysis.Results: 1.CCI group showed lower MWT and TWL than Sham group from the1 st day to the 14 th days after surgery(p < 0.01);CCI + MC-SCs and CCI + SCs group showed higher MWT and TWL than CCI group(p < 0.01);CCI + MC-SCs group showed higher MWT and TWL than CCI + SCs group(p < 0.05).2.The sciatic nerve myelin sheath of the Sham group was dense,uniform in structure,regular inmorphology and clear in morphology.In the CCI group,the sciatic nerve fibers were completely separated from the myelin sheath.In the CCI + SCs group,some neurons had lower mitochondria.The number of axons shrinks,while the thickness of the myelin sheath is uniform in the CCI + MC-SCs group,the myelin fibers are abundant,and the myelin sheath is occasionally loose.3.After the 14 th days of surgery,the Double-label immunofluorescence results that the expressed cells of P2X2/3 in CCT exhibited more intense staining than Sham(p < 0.01);CCI + MC-SCs and CCI + SCs were lower than CCI(p < 0.01);and CCI + MC-SCs was lower than CCI + SCs(p <0.05).4.The P2X2/3 mRNA expression was higher in CCI group than in Sham group(p < 0.01).The expression levels of P2X2/3 mRNA in CCI + SCs/MC-SCs groups were lower than that in CCI group((p < 0.01),and the expression levels of P2X2/3mRNA in the CCI + MC-SCs group was lower than that in the CCI + SCs group(p <0.05).5.The optical density values for P2X2/3 protein expression were increased in CCI group when compared to Sham group(p < 0.01).The expression levels of P2X2/3 protein in CCI + SCs/MC-SCs groups were lower than that in CCI group(p <0.01).In addition,the expression level of P2X2/3 protein in CCI + MC-SCs group was lower than that in CCI + SCs group(p < 0.05).Conclusions: Microencapsulated Schwann cell transplantation probably inhibit P2X2/3 receptor-mediated Neuropathic pain in the dorsal Root ganglion of CCI Rats.