Comparison of Mouse Lung Fibrosis Induced by Intravenous Injection and Intratracheal Instillation of Bleomycin

Objective To study the differences of bleomycin-induced pulmonary fibrosis in mice induced by intravenous injection and intratracheal instillation of bleomycin.Methods Forty C57BL/6 mice(female,8 wk of age,17 to 20 g body weight) were randomly divided into two groups(20 mice in each group):in the group V,bleomycin was injected intravenously once in a dose of 150 mg/kg,and in the group I,bleomycin was instilled intratracheally in a dose of 5 mg/kg,respectively.The survival rate,pathological changes and hydroxyproline content in the lung tissue were observed.Results(1) The survival rate of the groups V and I were 50% and 75%,respectively,statiscally with a non-significant difference(P0.05).(2) At 28 days after injection,fibrosis was widely and stably formed mainly in around the bronchia and bronchioles,especially,near the pulmonary hilar area,in the group I mice,however,the same changes were mainly seen under the pleura or perivascular pulmonary tissues in the mice of group V.The pathological score of pulmonary fibrosis was not significantly different between those two groups(P0.05).(3) At 28 days after bleomycin administration,the hydroxyproline content in mice of groups V and I were 634.4±67.1 μg/g and 696.6±41.2 μg/g,respectively,statistically with a non-significant difference between the two groups(P0.05).Conclusions The sites of pulmonary fibrosis in the mice are different between the mice induced by intravenous injection or intratracheal instillation of bleomycin.However,the pathological appearance of pulmonary fibrosis was similar in mice of those two groups.