Cyclophosphamide Combined with Bone Marrow Mesenchymal Stromal Cells Protects against Bleomycin-induced Lung Fibrosis in Mice

Introduction. To examine the effects and possible mechanism of the immunosuppressant agent cyclophosphamide (CP) combined with bone marrow mesenchymal stromal cells (BM-MSCs) on bleomycin induced lung fibrosis in mice. Methods. BM-MSCs labeled with red fluorescence protein (RFP) from male Friend virus B-type(FVB) mice were cultured in vitro. Pulmonary fibrosis(PF) was induced in female wild type FVB mice and mice were randomly divided into five groups: control, model, CP, BM-MSCs, and BM-MSCs+ CP. Pathological changes and distribution of RFP (+) BMSC in lung tissue were observed and hydroxyproline (Hyp) content in the lungs was measured. Changes in TGF-beta mRNA, PDGF mRNA, and SDF-1mRNA expression in lung tissue were measured. Results. PF and Hyp levels in the BM-MSCs and BM-MSCs+ CP groups were significantly alleviated (p<0.01) compared to the model group. The RFP (+) cells were distributed in the periphery of the alveolar space and endomembrane of bronchus. Hyp levels were reduced in the BM-MSCs+ CP group compared to the BM-MSCs group (p<0.05). TGF-beta and PDGF levels in the BM-MSCs and BM-MSCs+ CP groups were higher than in the control or model group (p<0.05). SDF-1 level in the CP group showed no significant differences compared to the control group, in the other groups were higher than in the control group (p<0.05) and in the BM-MSCs+ CP group was lower than in the BM-MSCs group (p<0.05). Conclusion. It was concluded that CP alone does not improve PF and may be harmful. In contrast, combined application of BM-MSCs with CP provided better protection against PF and may serve as an effective therapy.