ANGPT1 and acute respiratory distress syndrome: After injection, MSCs can differentiate into lung tissue or secrete factors (e.g., angiopoietin-1 (ANGPT1), EGF, VEGF, PGE2, HGF, VEGFA, KGF, and IL-10) that can induce host repair/regenerative mechanisms [53], promote epithelial and endothelial repair, increase alveolar fluid clearance, regulate lung epithelial and endothelial permeability, and reduce inflammation in patients with ARDS lung injury [52, 54, 55].