The Therapeutic Effect Of Extracellular Vesicles Derived From Mesenchymal Stem Cells On TNBS-induced Colitis In Mice

Background: Mesenchymal stem cells(MSCs)are the multi-potential stem cells that have regenerative and immunoregulatory properties which can lead to reduction of inflammation and healing of the damaged intestine.The therapeutic effect of MSCs have been attributed to the paracrine mechanism,which could release soluble factors from stem cells.Extracellular vesicles(EVs)released as soluble factors from the stem cells surface,may play a relevant role in the damaged tissue.Methods: The colitis model of mice was induced by TNBS enema.Firstly,we evaluated the clinical parameters such as body weight,disease activity index(DAI)and histological colitis scores of mice with TNBS induced colitis.Secondly,we assessed the balance of pro-inflammatory and anti-inflammatory cytokines in TNBS-induced mice by real-time polymerase chain reaction(RT-PCR)technology and western blot assay.Then,we used the IVIS Lumina Imaging System to detect the expression of intestinal reactive oxygen species(ROS)in colitis mice,and myeloperoxidase(MPO)activity of the mice was evaluated via immunohistochemical staining.Finally,we evaluated the therapeutic efficacy of h P-MSC-derived EVs in the damaged intestinal epithelial cells(IECs),including promoting proliferation and inhibiting apoptosis by RT-PCR technology and immunohistochemical staining.Results: Injection of h P-MSCs-derived EVs alleviated the severity of colitis in mice as reflected by increasing survival rate,body weight and decreasing DAI,histological colonic damage compared to those treated with PBS.There was a decrease in the proportion of pro-inflammatory cytokines and an increase in the proportion of antiinflammatory cytokines in the intestine tissues from EVs-treated colitis mice.EVs injection also suppressed the oxidative perturbations,decreasing the activity of myeloperoxidase(MPO)and reactive oxygen species(ROS),compared with control mice.Histology analysis further confirmed that h P-MSCs-derived EVs significantly promoted the colonic epithelial cell proliferation,down regulated the expression of apoptotic protein,maintained the integrity of the intestinal epithelium and promoted mucosal healing.Conclusions: Taken together,our data demonstrated that h P-MSC-derived EVs alleviated TNBS-induced colitis through regulating the imbalance between proinflammatory and anti-inflammatory cytokines,inhibiting oxidative stress and maintaining the structure integrality of intestinal epithelial cells.These findings may provide a new theoretical basis for EVs-based treatment of IBD.