Mechanism Of Bone Marrow Mesenchymal Stem Cell Derived Exosomes To Improve Ulcerative Colitis

Objectives: Ulcerative colitis(UC)is a chronic non-specific inflammation of the colon and rectum.The pathogenesis is not clear,and the treatment is still challenging.Bone marrow mesenchymal stem cell-derived exosomes(BMSC-Exos)mediate a variety of biological functions and may be the main paracrine mechanism for communication between stem cells and injured cells.The molecular mechanism of BMSC-Exos in the treatment of UC is still unclear.Therefore,this thesis studied the therapeutic effect of BMSC-Exos on UC through animal and cell level experiments,and explored the molecular mechanism involved,so as to provide new ideas and treatment basis for clinical treatment of UC.Methods:In this thesis,the molecular mechanisms underlying the improvement of ulcerative colitis by BMSC-Exos were investigated at the animal and cellular levels.First,a UC mouse model was established and treated with BMSC-Exos.The physiological state of mice was observed and recorded.Hematoxylin-eosin staining(H&E)was used to detect the pathological changes under the microscope.The expression of proinflammatory cytokines in colon tissue of mice was detected by Quantitative Real-time PCR(q PCR)and Western blot(WB).Serum proinflammatory cytokines were measured by enzyme-linked immunosorbent assay(ELISA).FHC cells and NCM460 cells were cultured,lipopolysaccharide(LPS)was used to construct an inflammatory cell model,BMSC-Exos was used for intervention,and cell proliferation was detected by CCK-8 and Ed U staining.Cell apoptosis was detected by flow cytometry.Western blot was used to detect the expression of apoptosis-related proteins.ELISA was used to detect the secretion of proinflammatory cytokines.NCM460 cells were further cultured,and intestinal epithelial inflammatory cell model was constructed by LPS.BMSC-Exos were intervened,and transcriptome sequencing was used to detect differential genes.Go analysis and Pathway analysis were performed on the differentially expressed genes.Results:1.The body weight of mice in UC group was significantly decreased,the DAI score was significantly increased,and the colon length was significantly shortened compared with the control group.The colon histological score of mice was significantly increased.The expression of proinflammatory cytokines in colon tissue and serum was significantly increased.After BMSC-Exos intervention,the body weight of mice increased significantly,the DAI score decreased significantly,and the colon length increased significantly.The infiltration of inflammatory cells in colon tissue was significantly reduced.The expression of proinflammatory cytokines in colon tissue and serum was significantly reduced.2.In vitro cell models,LPS significantly inhibited the proliferation of FHC and NCM460 cells,promoted apoptosis,and induced the expression of apoptosis-related proteins and inflammatory factors.After BMSC-Exos intervention,the proliferation ability of FHC and NCM460 cells was significantly increased,the LPS-mediated apoptosis was inhibited,and the expression of LPS-induced apoptotic proteins and pro-inflammatory cytokines was antagonised.3.A total of 245 differential genes were identified by transcriptomic sequencing,and the differential genes were mainly involved in the biological functions of microtubule binding,microtubule movement and NF-κB,tyrosine metabolism,ECM receptor interaction and other signaling pathways.Conclusions: BMSC-Exos can inhibit intestinal epithelial cell apoptosis and inflammatory response to improve UC,which is potentially related to NF-κB,tyrosine metabolism,ECM receptor interaction and other signaling pathways.