Controlled tumor heterogeneity in a co-culture system by 3D bio-printed tumor-on-chip model

Abstract Background: Cancer treatment resistance is a consequence of cell diversity and tumor heterogeneity. Tumor cell-cell and cell-microenvironment interactions significantly influence tumor progression and invasion, which have important implications for diagnosis, therapeutic treatment and chemoresistance. Method: In this study, we develop 3D bioprinted in vitro models of the breast cancer tumor microenvironment (TME) made of co-cultured cells distributed in a hydrogel matrix with controlled architecture to model tumor heterogeneity. We hypothesize that the tumor could be represented by a cancer cell-laden co-culture hydrogel construct, whereas its microenvironment can be modeled in a microfluidic chip capable of producing a chemical gradient. Breast cancer cells (MCF7 and MDA-MB-231) and non-tumorigenic mammary epithelial cells (MCF10) were embedded in the alginate-gelatine hydrogels and printed using a multi-cartridge extrusion bioprinter. Results: Our method gives special control on the cell positions in the co-culture system, whereas different tumor architectures can be designed. Cellularly heterogeneous samples comprised of two different cancer cells with controlled density are developed in specific initial locations, i.e. two cell types randomly mixed or positioned in sequential layers. A migration-inducing chemical microenvironment was created in a chamber with a gradual chemical gradient to study the cell migration in the complex tumor construct toward the chemoattractant. As a proof of concept, the different migration pattern of MC7 cells toward the epithelial growth factor gradient was studied with presence of MCF10 in different ratio in this device. Conclusion: Combining 3D bioprinting with microfluidic device in our method provides a great tool to create different tumor architectures as can be seen in different patients, and study cancer cells behaviour with accurate special and temporal resolution.