Abstract 1455: In vitro blood brain barrier model for evaluation of brain metastasis

Abstract Introduction: Brain metastasis significantly reduces the patient's quality of life and survival, but there are only a few choices of treatment for brain metastasis. The research for brain metastasis is difficult because of its complex and unique microenvironment, including blood-brain barrier (BBB). The BBB maintains strong cell adhesion of the vascular endothelial cells (ECs) to protect the brain parenchyma. The BBB is composed of three cell types: vascular endothelial cells, pericytes, and astrocytes. As the role of pericytes in maintaining the BBB function has become more evident, the reconstituted models of the BBB in which ECs, pericytes, and astrocytes are seeded on the front and back of the insert membrane have gotten our attention. In the field of cancer, the role of not only ECs but also wall cells, corresponding to pericytes in the brain, has been focused on. In this study, we aimed to create the in vitro BBB models and elucidate the interaction of the BBB and the metastasizing cancer cells. Methods: We applied a reconstituted model of the BBB consisting of ECs, pericytes, and astrocytes of human immortalized cells (Ito R, et al. Mol Pharm 2019) and created the co-culture system for evaluating brain metastasis. We constructed four co-culture systems and compared the migration ability of MDA231 in those models: EPA model (ECs, pericytes, and astrocytes), E0A model (ECs and astrocytes), EP0 model (ECs and pericytes), and E00 model (ECs only). We also analyzed the migration ability of the pairs of parental and brain metastatic (BrM) cell lines. Results: The BBB reconstituted model (EPA model), in which ECs were co-cultured with pericytes and astrocytes, showed higher trans-epithelial electrical resistance and lower permeability than the other co-culture models. When cancer cells were seeded, the EPA model strongly inhibited metastatic invasion of cancer cells compared to the other models. It suggests that both pericytes and astrocytes are essential for regulating cancer cell invasion. In addition, when the BrM cells of MDA231 and Ex3LL were seeded, the BrM cells invaded the EPA model more easily than the parental cells. It indicates that this model can reproduce in vivo brain vascular functions. Conclusion: We created the BBB reconstituted model which mimics the brain vascular microenvironment. This model reproduced the in vivo BBB function to protect brain from cancer cells and evaluated the brain metastatic ability of the cancer cells. Using this model, we showed that pericytes and astrocytes were essential for the BBB barrier function against the cancer cells. We need further investigation to elucidate the mechanism of brain metastasis using this BBB model. Citation Format: Shoko Noda-Narita, Atsu Aiba. In vitro blood brain barrier model for evaluation of brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1455.