| Background and Purpose Bone marrow mesenchymal stem cells(BMSCs)transplantation has a good therapeutic effect on various diseases caused by ischemia or reperfusion injury.BMSCs are a small group of non-hematopoietic adult stem cells with multi-lineage differentiation potential and self-renewal ability.They can maintain a stable immunophenotype and multi-lineage differentiation potential for multiple generations in vitro.Mesenchymstem cells(MSCs)themselves have the advantage of low immunogenicity.Previous studies have shown that BMSCs can reduce intestinal Ischemia Reperfusion injury(I/R),but the specific mechanism is still unclear.Intestinal mucosal barrier function is another important function in addition to digestion and absorption.The intact intestinal mucosal barrier can effectively block the translocation of intestinal parasitic bacteria and their toxins to extra-intestinal tissues and organs,and prevent the body from being damaged by endogenous microorganisms and their toxins.Intestinal I/R injury is an inflammatory reaction in nature,which is commonly seen in abdominal aortic aneurysm surgery,small bowel transplantation,cardiopulmonary bypass,strangulation hernia and neonatal necrotizing enterocolitis.Several studies exploring strategies to prevent intestinal I/R injury have been successfully applied to mitigate intestinal I/R injury in animal models.The aim of this study is to investigate the effect of BMSCs on the immune function of intestinal mucosal microenvironment after I/R injury.Methods Twenty adult Sprague-Dawley(SD)rats were randomly assigned to a treatment or a control group.All the rats underwent superior mesenteric artery clamping and unclamping.In the treatment group,BMSCs were implanted into the intestine of ten rats by direct submucosal injection whereas the other ten rats in the control group were injected with the same volume of saline.On the fourth and seventh day after BMSCs transplantation,intestinal samples were examined for the CD4(CD4-positive T-lymphocytes)/ CD8(CD8-positive T-lymphocytes)ratio of the bowel mucosa via flow cytometry,and for the level of Interleukin-2(IL-2),Interleukin-4(IL-4)and Interleukin-6(IL-6)via ELISA.Paneth cell counts and Secretory Immunoglobulin A(SIg A)level were examined via immunohistochemical(IHC)analysis.Real time PCR(RT-PCR)was used to detect the expression levels of tumor necrosis factor-α(TNF-α)and trypsinogen(Protease Serine 2,PRSS2)genes.White blood cell(WBC)count was measured by manual counting under the microscope.Results The CD4/CD8 ratio of the treatment group was significantly lower than that of the control group.The concentrations of IL-2 and IL-6 in the treatment group were lower than those in the control group,and the level of IL-4 showed opposite results compared with the control group.After BMSCs transplantation,the number of Paneth cells in the intestinal mucosa increased significantly,while the level of SIg A in the intestinal mucosa decreased significantly.The expression levels of TNF-α and PRSS2 in the intestinal mucosa of the treatment group were significantly lower than those of the control group.The white blood cell count in the treatment group was significantly lower than that in the control group.The percentages of CD4-positive and CD8-positive T cells in the control group were significantly lower on the 7th day than on the 4th day.There were no significant differences in IL-2,4,and 6 levels,CD4/CD8 ratio,WBC count,and PRSS2 and TNF-α gene expression levels between the two groups.The percentages of CD4 + and CD8 + T cells and the expression levels of PRSS2 and TNF-α mrna on the7 th day in the treatment group were significantly higher than those before treatment(p <0.05).The levels of IL-2,4,6,CD4/CD8 ratio and WBC count were not significantly different between the two groups.Conclusion According to our trial results,we identified immune-relevant molecular changes that may explain the mechanism of BMSCs transplantation efficacy in alleviating rat intestinal immune-barrier after I/R.Based on our experimental results,we found immune-related molecular changes in intestinal mucosa tissues and explained the mechanism by which BMSCs transplantation restored the intestinal immune barrier after I/R in rats.The normal recovery process of intestinal mucosal immune barrier after I/R and the recovery process of BMSCs treatment were obtained by measuring the inflammatory immune indexes at different stages. |
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