TGFB1 and pulmonary fibrosis: Intravenously injected MSC-Exos attenuated pulmonary vascular remodeling and lung fibrosis by down-regulating the gene expression of β-catenin, cyclin D1 and TGF-β1 and by enhancing expression of Wnt5a and BMPR2 (Bone Morphogenetic Protein Receptor Type 2) [36].