The Effects And Correlated Mechanism Of Bone Marrow-derived Mesenchymal Stem Cells On The Bleomycin-induced Pulmonary Fibrosis In Mice

Objective: To explore the effects of bone marrow-derived mesenchymal stem cells on bleomycin-induced pulmonary fibrosis in mice and to study the mechanism of its effects.Methods: Bone marrow derived BMSCs were harvested from male C57BL/6J mice in vitro,cultured into culture flasks with medium and expanded to the fourth passage for the experiments.60 C57BL/6J mice were randomly divided into 3 groups with 20 of each group: negative control group (Group P),positive control group (Group B),mesenchymal stem cells transplanting group(group B+M) .Group P were instilled with 50μL PBS via trachea discission.Group B and group B+M were made as pulmonary fibrosis models by intratracheal instillation of bleomycin(5μg/g, 50μL).After 6 hours, the suspension of BMSCs were injected into mice via the tail vein of B+M group with a concentration of 1×107/mL,200ul.Five mice were sacrificed at days 3,7, 14, 28 after modeling in batch. The bronchoalveolar lavage fluid were acquired for IFN-γ,IL-4 concentration analysis.Lung tissues were restored to analyze the pathological changes,HE staining,HYP content;The RNA of lung tissue was extracted for TGF-β1mRNA,IFN-γmRNA,IL-4mRNA detecting.The DNA of lung tissue was extracted for the detection sry gene.Results: 1. the pathological changes:compared with groupB,at 7th and 14th ,the pulmonary inflammation of group B+M were decreased obviously;at 28th,the fibrosis extent of group B+M were decreased obviously.2.lung coefficient:at each time point, lung coefficient of group B were all higher than group P;but group B+M were obviously lower than group B.3.The content of HYP:At the 3rd and 7th,the HYP content in each group were nearly the same.There were no disparity between group P and B+M at 14th , at 28th ,the HYP content were higher than group P,but lower than the group B,the disparity were obviously.4.The expression of TGF-β1mRNA:at each time point, the TGF-β1mRNA of groupB and B+M were expressed more than group P,but the TGF-β1mRNA of group B+M were less than group B at the last 3 time points.5.sry gene:At each time point,we can detected the sry gene in each mice. 6. The expression of IFN-γmRNA,L-4mRNA: the IFN-γmRNA and IL-4mRNA of group B and B+M were expressed more than group P,but IFN-γmRNA of B+M were less than group B at the last 3 time points,and theIL-4mRNA of group B+M less than group B at the last 2 time points;Compared the ratio of IL-4mRNA/IFN-γmRNA, group B+M were lower than group B at the last 2 time points.7.the concentration of IFN-γ,IL-4 of BALF:at each time point,the concentration of IFN-γand IL-4of group B and B+M were higher than group P,at the last 3 time points,the concengtration of IFN-γof group B+M were lower than group B; and the concengtration of IL-4 of group B+M were lower than group B at each time point. Compared the ratio of IL-4/IFN-γ, group B+M were higher than group B at the 3rd,14th,28th, and less than group Bat 7th,14th,28th(7th,14th:P〈0.05;28th P=0.05).Conclusion:1.Doner-derived BMSCs can arrive to the injured lung and can existence for a long time.2. Doner-derived BMSCs can decrease alveolitis and pulmonary fibrosis in mice with bleomycin-induced pulmonary fibrosis.3. the mechanism might be related to its reversion for the unbalance of Th1/Th2 cytokine.4. Doner-derived BMSCs may inhibit the expression of TGF-β1mRNA while arrived at the injured lung,so as to decrease pulmonary fibrosis.