An Engineered Breast Cancer Model on a Chip to Replicate ECM‐Activation In Vitro during Tumor Progression

In this work, a new model of breast cancer is proposed featuring both epithelial and stromal tissues arranged on a microfluidic chip. The main task of the work is the in vitro replication of the stromal activation during tumor epithelial invasion. The activation of tumor stroma and its morphological/compositional changes play a key role in tumor progression. Despite emerging evidences, to date the activation of tumor stroma in vitro has not been achieved yet. The tumor‐on‐chip proposed in this work is built in order to replicate the features of its native counterpart: multicellularity (tumor epithelial cell and stromal cell); 3D engineered stroma compartment composed of cell‐assembled extracellular matrix (ECM); reliable 3D tumor architecture. During tumor epithelial invasion the stroma displayed an activation process at both cellular and ECM level. Similarly of what repeated in vivo, ECM remodeling is found in terms of hyaluronic acid and fibronectin overexpression in the stroma compartment. Furthermore, the cell‐assembled ECM featuring the stromal tissue, allowed on‐line monitoring of collagen remodeling during stroma activation process via real time multiphoton microscopy. Also, trafficking of macromolecules within the stromal compartment has been monitored in real time.