Experimental study of pulmonary artery infusion with cisplatin in a solitary pulmonary tumor model using a rat colorectal adenocarcinoma cell line

OBJECTIVES: We assessed a tumor model prepared by open lung injection to study metastatic lung tumors, and evaluated the efficacy of pulmonary artery infusion. METHODS: Subjects were 30 male F344 rats. In experiment 1, we evaluated chemosensitivity of a rat colorectal adenocarcinoma cell line (RCN-9) using a colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In experiment 2, we injected RCN-9 cells into the left lung on day 0; on day 10, we measured tumor tissue blood flow before and after pulmonary arterial occlusion. In experiment 3, we injected RCN-9 cells into the left lung and conducted no further procedures in controls. The pulmonary artery infusion group underwent pulmonary artery infusion with 0.1 mg of cisplatin on day 3 and the sham group injection with saline solution alone. On day 10, rats were sacrificed and maximum tumor cross-section measured. RESULTS: In experiment 1, the drug concentration required to inhibit cell growth 50% was 2.45 x 10(-6) M. In experiment 2, tumor tissue blood flow decreased significantly after arterial occlusion (p = 0.003). In experiment 3, the maximum tumor cross-section in the pulmonary artery infusion group was significantly smaller than in shams (p = 0.0027) and controls (p = 0.0019). CONCLUSIONS: The pulmonary artery supplies tumors with blood, so this model appears useful in studying metastatic lung tumors, whose size was reduced significantly by pulmonary artery infusion with cisplatin. Pulmonary artery infusion is thus a promising modality in metastatic lung tumor treatment.