Distal airway stem cells ameliorate bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis is characterized by loss of lung epithelial cells and inexorable progression of fibrosis with no effective and approved treatments. The distal airway stem/progenitor cells (DASCs) have been shown to have potent regenerative capacity after lung injury. In this work, we aimed to define the role of mouse DASCs (mDASCs) in response to bleomycin-induced lung fibrosis in mice. The mDASCs were isolated, expanded in vitro, and labeled with GFP by lentiviral infection. The labeled mDASCs were intratracheally instilled into bleomycin-induced pulmonary fibrosis mice on day 7. Pathological change, collagen content, α-SMA expression, lung function, and mortality rate were assessed at 7, 14, and 21 days after bleomycin administration. Tissue section and direct fluorescence staining was used to show the distribution and differentiation of mDASCs in lung. The transplanted mDASCs could incorporate, proliferate, and differentiate into type I pneumocytes in bleomycin-injured lung. They also inhibited fibrogenesis by attenuating the deposition of collagen and expression of α-SMA. In addition, mDASCs improved pulmonary function and reduce mortality in bleomycin-induced pulmonary fibrosis mice. The data strongly suggest that mDASCs could ameliorate bleomycin-induced pulmonary fibrosis by promotion of lung regeneration and inhibition of lung fibrogenesis.