Immune Intervention Effect Of UC-MSCs On ALI Induced By Sepsis

Objective:The rat model of sepsis was prepared by cecal ligation perforation.The percentage of CD4~+T lymphocytes,percentage of Th1/Th2,CD4~+T lymphocyte apoptosis,plasma inflammatory factors and HE staining of lung tissue were observed in sepsis rats.To investigate the immune intervention effect of human umbilical cord mesenchymal stem cells(UC-MSCs)on acute lung injury(ALI)induced by sepsis.Methods:208 SD rats were divided into normal control group(n=8),sham operation group(n=40),septic model group(n=80),MSCs treatment group(n=80)The The sepsis model was established by cecal ligation perforation(CLP).In the MSCs treatment group,the third generation of UC-MSCs(2×10~6)1 mL was injected intraperitoneally at 1 h after the model establishment.The sham operation group and the septic model group were given the same amount of normal saline.Sham operation group,septic model group,MSCs treatment group were taken 8,16,16,observed in each group 72h survival rate.The percentage of CD4~+T lymphocytes,Th1/Th2 and the percentage of CD4~+T lymphocyte apoptosis in whole blood cells were measured by flow cytometry(FACS)at 12,24,48 and 72 hours after the model.tumor necrosis factor-?(TNF-?),high migration rate family protein 1(HMGB1)and interleukin-10(IL-10)in plasma were measured by enzyme-linked immunosorbent assay(ELISA).The lung tissue was stained with HE.Results:There was no considerable difference in the survival rate between the septic model group and the stem cell treatment group(P>0.05).The percentage of CD4~+T lymphocytes and Th1/Th2 ratio in the septic model group were significantly higher than those in the sham operation group(P<0.01),the results have been reduced with the extension of time,and decreased significantly at 48 and 72 hours compared with the sham operation group(P<0.01).Plasma inflammatory factor levels were significantly higher at 12 hours after CLP than in sham operation group(P<0.01).TNF-?and IL-10 were decreased at 48 hours after CLP,but the levels of HMGB1 continues to rise to 72 hours.Compared with the septic model group,the percentage of CD4~+T lymphocytes 12?24 hours after operation,the Th1/Th2 ratio at12,24 and 48 hours after operation,and the levels of TNF-??HMGB1 at 12,24,48and 72hours after operation were significantly decreased(P<0.01).The percentage of IL-10 in 12,24,48 and 72 hours after operation was significantly increased(P<0.01),and the percentage of CD4~+T cell apoptosis was decreased at 12 and 24 hours after operation(P<0.05),and significantly lower than that of septic model group at 48 and72 hours(P<0.01).septic model group compared with the sham operation group HE staining showed that:with the advance of time,septic model group lung normal alveolar gradually disappeared and merged into different sizes of pulmonary bullae,a large number of inflammatory cell infiltration,pulmonary hemorrhage,pulmonary interstitial edema,Alveolar septum significantly thickened.Compared with Septic model group,HE staining of lung tissue in stem cell treatment group suggested that:The alveolar size of the stem cells treated group was more than that of the mean,inflammatory cell infiltration,intrapulmonary hemorrhage,interstitial edema and alveolar septal thickening.were significantly reduced.Conclusions:1?UC-MSCs did not improve the 72h survival rate of sepsis rats.2?UC-MSCs can reduce the early inflammation of sepsis early to improve the early sepsis to promote the immune imbalance.3?UC-MSCs can inhibit sepsis-induced lymphocyte apoptosis,to avoid excessive reduction of lymphocytes caused by decreased immunity.4?UC-MSCs can reduce the degree of lung injury caused by sepsis.