Paper-supported Co-culture System for Investigation of Exosomes Mediated Interactions between Breast Cancer Cells and Lung Fibroblasts

Abstract A multi-layer paper supported co-culture system was developed for investigation of the interactions between breast cancer cells and lung fibroblasts mediated by exosomes. Within the multi-layer structure, the tumor layer and the recruitment layer were impregnated with breast cancer cells and lung fibroblasts respectively, and these two layers were separated by the invasion layers. The co-culture device was constructed by assembling multiple layers of paper. Disassembling such a device enabled cells on each layer to be analyzed individually, which was used to study cell interactions from both time and space aspects. The impregnation of either breast cancer cells or the breast cancer cells derived exosomes on the tumor layer resulted in the conversion of lung fibroblasts on the recruitment layer into cancer-associated fibroblasts. The cancer-associated fibroblasts induced by exosomes were thereafter seeded on the recruitment layer, which showed stronger breast cancer cell recruitment than primary cells. These results suggest that the conversion of host-organ fibroblasts mediated by tumor exosomes is essential for the formation of pre-metastasis niche, and the pre-metastasis niche, in turn, recruits tumor cells to achieve organotropic metastasis.