A novel optimized orthotopic mouse model for brain metastasis with sustained cerebral blood circulation and capability of multiple delivery

Brain metastasis is thought to be related to the high mortality and poor prognosis of lung cancer. Despite significant advances in the treatment of primary lung cancer, the unique microenvironment of the brain renders current therapeutic strategies largely ineffective against brain metastasis. The lack of effective drugs for brain metastasis treatment is primarily due to the incomplete understanding of the mechanisms underlying its initiation and progression. Currently, our understanding of brain metastasis remains limited, primarily due to the absence of appropriate models that can realistically simulate the entire process of tumor cell detachment from the primary site, circulation through the bloodstream, and eventual colonization of the brain. Therefore, there is a pressing need to develop more suitable lung cancer brain metastasis models that can effectively replicate these critical stages of metastasis. Here, based on the traditional carotid artery injection model, we established a novel orthotopic mouse model by using a light-controlled hydrogel to repair the puncture site on the carotid artery, with sustained cerebral blood circulation and the capability of multiple delivery cancer cell to mimic lung cancer brain metastasis. The optimized orthotopic mouse model significantly reduced cerebral ischemia and improved cerebral oxygenation by 60% compared to the traditional orthotopic mouse model, enhancing post-operative survival rates. It also showed a reduction in pro-inflammatory cytokines and featured less inflammatory and more resting states of microglial and astrocyte cells. Furthermore, the optimized orthotopic mouse model markedly increased the success rate and absolute number of the metastatic clones in the brain. Additionally, the multiple delivery model based on the optimized orthotopic mouse model substantially augmented the tumor clone number and formation rates compared to single injection in the optimized orthotopic mouse model. This model overcomes previous limitations by maintaining cerebral circulation, providing a more accurate simulation of the continuous entry of tumor cells into cerebral circulation. It offers a robust platform for studying the interactions of cancer cells with the brain microenvironment and testing new therapeutic approaches.