Mechanism Of Immunomodulation Effect Of MSCs On Recovery From Facial Nerve Injury

Background and objectives:Facial nerve injury might be caused by trauma or surgery,and results in changes of patient’s face and related functions.Now we use microsurgical techniques to restore its continuity,but functional recovery is not satisfied.Recent studies have shown that there is interaction between the immune system and the nervous system.CD4+T cell-mediated adaptive immune response plays an important role in protecting facial motor neurons after facial nerve injury.At the same time,a large number of studies have shown that stem cells in the peripheral nerve repair process can protect the nerve and promote axon regeneration.The immune regulation function of stem cells has become an important research direction.This study will explored the mechanism of immunomodulation effect of SDBMSCs in recovery from facial nerve injury,especially the regulation of Th17,and the protective effect on motor neurons in the facial nerve nucleus.Methods:This study was divided into four parts:(1)Observed the morphology and growth of SDBMSCs in vitro,and selected cells suitable for injection after facial nerve injury.(2)Detected the levels of TGF-β1 IL-6,HGF,iNOS and PGE2 in supernatant by ELISA after culturing 72h respectively in 4 groups(Blank,SDBMSCs,FN,FN + SDBMSCs).(3)Established the rat model of facial nerve injury/no injury and SDBMSCs injection/PBS injection,and compared the proportion of Th17 in bilateral lymph nodes of different experimental groups.(4)Established the rat model of SDBMSCs injection/PBS injection,and compared the apoptotic index of motor neurons in the bilateral facial nucleus on the 21st day after operation by Tunel apoptosis staining.Results:P3.P4 SDBMSCs are homogeneous,have the ability to proliferate and generate in vitro.SDBMSCs could secrete high levels of IL-6,HGF,PGE2,iNOS and TGF-β1.On the 9th day after operation,the percentage of Th17 in SDBMSCs(+)group was lower than that in SDBMSCs(-)(P<0.05).On the 21st day after operation,the apoptotic index in SDBMSCs(+)group was significantly lower than that in SDBMSCs(-)group.Conclusions:P4 SDBMSCs are suitable for local injection in the experiment.SDBMSCs have the ability to independently secrete high levels of IL-6,HGF,PGE2,iNOS and TGF-β1.Local injection of SDBMSCs at FN lesion site could significantly reduce the proportion of Th17 in the lateral lymph nodes,and protect FMN in the facial nucleus.