Abstract:Objective To explore the optimal methods of pulmonary fibrosis model induced by nasal instillation of bleomycin in C57BL/6 mice. Methods Thirty 7 to 8-week-old male mice were divided into four groups. Three experimental groups were respectively treated with different doses of 0.10 unit, 0.25 unit, 0.40 unit of bleomycin by nasal instillation after anesthesia (eight mice in each group). The control group were treated with the same volume of PBS (six mice in the group). The body weight and survival rate in each group were examined. At the end of the experiment, all of the mice were sacrificed, and we fixed the lung tissues in formalin, then cut them into slices. The extent of pulmonary inflammation was evaluated by HE staining. And the extent of pulmonary fibrosis was evaluated by Masson staining. Results The body weights of mouse declined gradually but increased on the 8 to 9th day. Until the 14th day, the body weights of drugs were nearly at the same level as the controls. At the 28th day, all of the mice got pulmonary fibrosis in BLM groups, and there was no significant statistical difference between pulmonary fibrosis scores of each group (P > 0.05). But the death rates were higher in groups of 0.25 unit and 0.4 unit, and there was a big difference in each individual. It was not good for the collection of experimental samples and statistical analysis of data. Conclusions Nasal instillation of 0.10 unit bleomycin is a convenient and ideal method in establishing C57BL/6mice model of pulmonary fibrosis.