Stem Cells From Human Exfoliated Deciduous Teeth Relieve Trigeminal Neuralgia In Rats

Objective: Neuropathic pain(NP)is a common clinical chronic pain.Patients can experience pain abnormalities and sleep or mental disorders,which affects the quality of life seriously.Trigeminal Neuralgia(TN)is a common NP that occurs in one or more areas innervated by the trigeminal nerve.It is a sudden,severe,and very short painful attack that occurs repeatedly.The pathogenesis of TN is very intricate.Current conventional drugs and surgical treatments make limited effort for pain relief.Stem cells from human exfoliated deciduous teeth(SHED)are odontogenic stem cells derived from deciduous teeth.SHED are easy to obtain non-invasively.Moreover,the incidence of immune rejection is low.Studies have shown that SHED have neuroprotective and immunomodulatory effects,which may have potential therapeutic effects for TN.In this study,a model of chronic compression injury of infraorbital nerve was established.The changes of mechanical pain threshold were observed before and after local transplantation of SHED.The impact of SHED transplantation on local inflammatory cell infiltration in ligated nerve was measured.The distribution of local SHED transplantation was traced.Whether the levels of immune-related factors CXCR5 and IL-21 mRNA is regulated in the trigeminal ganglion(TG)was investigated.Therefore,the possible mechanism of pain relief of TN by SHED transplantation was tentatively explored,which provides a new direction for the treatment of TN.Method: 1、Primary SHED were isolated and cultured.The stem cell surface markers were detected by flow cytometry.The multidirectional differentiation ability of SHED was measured.2、The model of TN induced by infraorbital nerve ligation was established.Von Frey filaments were used to measure the mechanical threshold in rats before and 1,3,5,and 7 days after nerve ligation.3、The effect of local SHED transplantation on the mechanical threshold was measured with Von Frey filaments before transplantation and 3,5,7 days after transplantation.4、The changes of inflammation reaction around the nerve before and after SHED transplantation were observed.5、The distribution of SHED after local transplantation was observed by immunofluorescence.6、The relative levels of CXCR5 and IL-21 mRNA in TG in the nerve ligation group and sham group were detected.7、The relative levels of CXCR5 and IL-21 mRNA in TG caused by SHED transplantation were detected.Results: 1、SHED was successfully isolated and extracted.The cells showed a spindle-shaped adherent growth.Flow cytometry detected that SHED expressed mesenchymal stem cell surface markers CD73 and CD105,but hematopoietic stem cell surface markers CD34 and CD45 were negatively expressed.SHED present neronal and osteogenic differentiation.2、The model of infraorbital nerve ligation was successfully established.The mechanical thresholds were significantly decreased 1,3,5 and 7 days after operation(P<0.01).3、In the SHED group,the mechanical thresholds were significantly increased 1,3,5 and 7 days after the transplantation(P<0.05).In the control group,the mechanical pain threshold did not change significantly(P>0.05).Compared with control group,the mechanical threshold was significantly increased 3,5 and 7 days after transplantation in the SHED group(P<0.01).4 、 The number of leukocytes recruited in the trigeminal nerve was significantly increased in the ligation group compared with the sham group.Inflammatory cell infiltration was decreased after local transplantation of SHED.5、SHED can be distributed in the ipsilateral TG.6、After nerve ligation,the levels of CXCR5 and IL-21 mRNA in the TG were increased.Compared with the sham group,the levels of CXCR5 mRNA and IL-21 mRNA were significantly up-regulated in the operation group at the 7 day after ligation(P<0.001,P=0.002).7、Compared with the control group,the levels of CXCR5 mRNA and IL-21 mRNA were significantly inhibited in the SHED group at 7 days after transplantation(P<0.001,P=0.006).Conclusion: In the trigeminal neuralgia model,local transplantation of SHED can improve the mechanical threshold.The possible mechanism of SHED alleviating trigeminal neuralgia is related to reducing the infiltration of inflammatory cells around the injured nerve and down-regulating the levels of CXCR5 and IL-21 mRNA in TG.