Bleomycin-induced pulmonary fibrosis mouse model

Experiments using animals were approved by the Institutional Animal Care and Use Committee of Fudan University, and the methods were carried out in accordance with the approved guidelines¹⁵. C57BL/6 mice were purchased from the Fudan University Animal Center. C57BL/6 mice aged 6–7 weeks were used for study of pulmonary fibrosis. Mice were randomly divided into two groups: a Prevention group and a Therapy group. There were three subgroups in each group as follows: a Control group, a Bleomycin (BLM) group, and a SAB group. Bleomycin (50 μl, 3.5 units/kg, diluted in sterile saline) was instilled intratracheally (IT) into mice in the BLM and SAB groups, while mice in the Control group received equal volumes of saline. Mice in the SAB subgroups were given daily intraperitoneal (IP) injections of SAB (10 mg/kg body weight). For the SAB subgroup mice within the Prevention group, injections began the third day before bleomycin instillation, whereas for those within the Therapy group, injections began on the tenth day after bleomycin instillation. All mice were killed 3 weeks after bleomycin administration. Lung tissues were either flash frozen and then stored in liquid nitrogen for further analysis or perfused and fixed in 10% formalin for at least 24 h at room temperature for immunohistochemical analysis.