Induction of lung lesions by bronchial administration using bronchoscope technique in mice.

This study aimed to establish an exposure method that can induce homogeneous lesions with minimal inter-individual variability. The distribution of lesions induced by bleomycin (BLM) administration was also analyzed. C57BL mice were intrabronchially administered 20 µL of BLM (3 mg/mL) using a bronchoscope in the left or right bronchus. The mice were sacrificed 14 days after administration, and their lungs were evaluated histopathologically. BLM-induced inflammatory lesions were widely observed in the lungs. In the left bronchus-treated group, lesions were uniformly observed throughout the lobe, and no individual differences were noted. Meanwhile, in the right bronchus-treated group, individual differences in the distribution of the pulmonary lesions were observed. The distribution of lesions differed among the four lobes of the right lung owing to their anatomical features. Administration into the left bronchus is recommended for highly homogeneous lung exposure and for establishing models that contribute to highly accurate toxicity and efficacy evaluations.