Comparison of in situ thoracic implantation and left ventricular injection to establish an animal model of lung cancer brain metastasis

  Objective: To provide a reliable modeling method for studying the mechanism of lung cancer brain metastasis. Methods: Eighteen BALB/c nude nude mice were randomly divided into 2 groups. They were implanted in situ through the thoracic cavity and injected through the left ventricle. They were inoculated with human lung adenocarcinoma PC-9 cells (1×106/ 0.1 mL), the state of the nude mice was observed after inoculation, and the nude mice were killed when they developed severe cachexia. Nude mice were dissected to observe the metastasis of lung, brain, liver and kidney; pathological materials were taken and HE staining was observed. Results: In-situ thoracic implantation group: After 3 weeks, nodules of chest aneurysm formed and gradually enlarged in nude mice No. 4, 6, and 9; nude mice began to lose weight at 4 to 6 weeks and gradually appeared evil The liquid quality was executed at 5-7 weeks. After thoracotomy, there are extensive gray-white tumor nodules and mass formation in the chest cavity, multiple implants on the ribs, pleura, and spine on both sides, the lungs are eroded and compressed, the color is pale, and the shape changes. HE staining showed that extensive implanted tumors formed on the surface of the lung, which were clearly separated from the normal lung tissue; only the 6th nude mice had brain metastases. In the left ventricular injection group: the nude mice began to lose weight at the 3rd week and gradually developed cachexia. All the nude mice were sacrificed at the 4th week. After thoracotomy: Except for No. 11 and No. 18 nude mice, there are 2 to 3 scattered tumors (about 1 to 3 mm in diameter) on the chest wall, the rest of the thoracic cavity visual field is normal; the outline of the lung tissue is clear, and no tumors are formed. HE staining: multiple brain metastases of different sizes appeared in 9 nude mice. In-situ thoracic implantation group: brain metastasis rate was 11.1%; intra-left ventricular injection group: brain metastasis rate was 100%.

   Conclusion: The method of establishing a lung cancer brain metastasis animal model by left ventricular injection guarantees a higher brain metastasis rate than the method of in-situ thoracic implantation.