The reparative effects of combination treatment with MSC and ATRA on lung tissue in elastase‐induced emphysema. The treatment groups were: (1) vehicle alone, (2) MSCs, (3) ATRA administration for 10 days, or (4) MSC/ATRA initiated 21 days after elastase (PPE) or saline (SAL) installation (IT). Twelve days after the initiation of the treatment, airway function and lung tissue sampling were performed. (A): Representative lung tissue sections (H&E staining) from mice which received: a. intratracheal vehicle instillation, b. elastase instillation followed by vehicle treatment, c. elastase installation followed by ATRA treatment for 10 days, d. elastase installation followed by MSC transfer, and e. elastase installation followed by MSC/ATRA treatment. Values of MLI (B), alveolar surface area (S) (C) and static compliance (Cst) (D) following MSC or/and ATRA treatments. n = 8 in each group. *, p < .05 versus vehicle‐PPE, +, p < .05 versus ATRA/PPE and MSC/PPE. Abbreviations: ATRA, all‐trans retinoic acid; MLI, mean linear intercept; MSC, mesenchymal stem cell; PPE, porcine pancreatic elastase.