3D Vasculature Structure in Breast Cancer on a Chip Approaches through Micromilling

The 3D cell culture environment that is found including extracellular matrix (ECM) such as collagen is essential for the behavior and response of cells in tissues such as in breast cancer. This 3D ECM environment also has close interplay vasculature structures allowing for nutrient and oxygen supply. Building cancer on a chip systems with embedded vascular networks allow for more realistic 3D physiological responses and potential testbeds for drug screen. Our approach is to build a 3D vascularized breast cancer on a chip system. Conventional soft lithography methods unfortunately have been mostly limited to 2D and rectangular channel cross-sectional morphology due constraints in fabrication technology. We introduced a novel approach to construct microfluidic channels with curved cross-section in a collagen matrix. Mechanical micromilling was applied to fabricate channel patterns on a polymethylmethacrylate (PMMA) master mold, followed by two-stage micromolding to create a sacrificial gelatin template. We successfully embedded these circular gelatin vascular templates within collagen to create perfusable microfluidic channels. We used thermo-reversible polymers including gelatin to remove the sacrificial template simply by raising temperature slightly while limited effects on the collagen matrix. Breast cancer cells were then pre-seeded into collagen matrix and we then investigated breast cancer cell response to chemical stimuli. The 3D vascular system constructed in our work provides a novel approach for further understanding breast cancer behavior.