Li et al. showed that the treatment with bone marrow mesenchymal stem cell (BMSC)-derived CM in rats with silica-induced pulmonary fibrosis resulted in a reduced overall collagen deposition, along with decreased mRNA levels of collagen I, collagen III, and fibronectin, TGF-β1 and hydroxyproline [77]. The gene discussed is TGFB1; the disease is pulmonary fibrosis.