Leaf-Vein-Inspired Multi-Organ Microfluidic Chip for Modeling Breast Cancer CTC Organotropism

Liuyin Liu¹Xiaoli Qu²Zhe Wang¹Cheng Ji¹Ling Rui^1*Changjiao Yan^1*

• ¹Department of thyroid, breast and vascular surgery, Xijing Hospital, The Fourth Military Medical University, Xian, China
• ²State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi, China

Objective: Breast cancer is characterized by a high tendency for organ-specific metastasis. This study aims to develop a multi-organ metastasis model for circulating tumor cells (CTCs) of breast cancer to explore their organotropism in common target organs, including the liver, bone, and lung.We fabricated a biomimetic microfluidic organ-on-a-chip inspired by leaf veins. In this system, three-dimensional cultures of human hepatocyte LO2 cells, human bone marrow-derived mesenchymal stem cells, and human fetal lung fibroblast 1 cells were established in separate chambers to mimic liver, bone, and lung microenvironments, respectively. Then, various breast cancer subtypes (MCF-7, SKBR3, MDA-MB-231) were perfused through the system. We quantified their invasive cell numbers and organ-specific localization in each organ. Further, MDA-MB-231 cells overexpressing metastasis-related genes (CXCR4, claudin-2, Linc-ZNF469-3) were tested.Additionally, the integration of tumor organoids with microfluidic chips was employed to evaluate the predictive capacity of this model for patient-specific metastatic patterns.Results: There are significant differences in the number of invasive cells and organ-specific localization among different breast cancer subtypes in each organ. MCF-7 cells show the highest invasion and most prominent localization in bone; SKBR3 cells in liver and lung. MDA-MB-231 cells have no obvious difference in organotropism among the three organs, but their invasive numbers are higher than those of MCF-7 cells. CXCR4-OE, claudin-2-OE, and Linc-ZNF469-3-OE MDA-MB-231 cells demonstrate the highest invasion and most prominent localization in bone, liver, and lung respectively. Organoid cells derived from a breast cancer patient with pulmonary metastasis at initial diagnosis, when perfused into the system, selectively invaded the lung organ, but did not invade the liver, bone, or control pores.This leaf-vein-inspired multi-organ microfluidic chip demonstrates significant application value for studying breast cancer CTC organotropism and serves as a powerful predictive tool for early warning of high-risk organ metastasis.