Abstract: Objective To explore the therapeutic effects of umbilical cord mesenchymal stem cells(MSCs)on advanced pulmonary fibrosis. Methods A total of 39 male Kunming mice were randomly divided into 3 groups: normal control group(n=12, NC group), bleomycin group(n=12, PC group)and MSCs treatment group(n=15, MSCs group). On day 1, bleomycin was injected into the trachea of mice in the PC and MSCs groups, and the same amount of saline was injected into mice in the NC group. On day 21, 3 mice in the MSCs group were dissected and the other mice were injected with MSCs into the tail vein. On day 42, all mice were sacrificed. The lung wet weight, hydroxyproline and the expression of transforming growth factor beta(TGF-β)and interferon-gamma(IFN-γ)were compared among the 3 groups. Results On day 21, the alveolar texture was disordered in the MSCs group, the alveolar interval was widened, and the pulmonary interstitial fibrosis was formed. On day 42, the alveolar texture was visible in the NC group and there was no alveolar interval widening; the alveolar texture was disordered in the PC group and the interval was significantly widened; the alveolar texture was clear in the MSCs group, and the alveolar interval was widened. The PC group had significantly higher lung wet weight, hydroxyproline content and TGF-β expression than the NC group(P<0.01)and MSCs group(P<0.05). The MSCs group had significantly higher IFN-γ expression than the PC group(P<0.01), followed by the NC group(P<0.01). Conclusion MSCs can protect lung tissue, and inhibit and alleviate the formation of intermediate and late pulmonary interstitial fibrosis in mice.

Key words: Umbilical cord mesenchymal stem cells, Bleomycin, Pulmonary interstitial fibrosis, Therapeutic effect