MSCs ameliorated the collagen deposition in the CHPH and SuHx-PH rat models. (A and F) Light-field microscopic analysis of Masson’s trichrome staining and immunohistochemical staining for MMP2 and MMP9 expression of lung sections from normal rats and the CHPH/SuHx-PH models with or without MSC treatment. (B and G) mRNA expression of lung collagen I and collagen III from normal rats and CHPH/SuHx-PH models with or without MSC treatment (normalized to 18 s). (C and H) Protein level of hydroxyproline from normal rats and CHPH and SuHx-PH models with or without MSC treatment. (D, E, I, and J) Protein expression of lung MMP2 and MMP9 from normal rats and CHPH/SuHx-PH models with or without MSC treatment (D, E, I, and J). Error bars represent means ± SEM (n = 5 in each group). *P < 0.05, **P < 0.01, and ***P < 0.001. Scale bars: 50 μm and 200 μm. Col = collagen; MMP = matrix metallopeptidase.