Engineering a microfluidic platform for cell extravasation monitoring and downstream characterization of disseminated cells

Metastatic cancer cells and immune cells spread throughout the body via the bloodstream, reaching target sites for immune clearance or establishing secondary tumors in distant organs. As they move from blood circulation to a targeted organ, cells adhere to activated endothelium and then extravasate through it into a tissue-rich environment. The molecular mechanisms that drive the extravasation of immune and cancer cells are not yet fully understood. Most importantly, the phenotypic state identity of the disseminated cancer cells has yet to be characterized. While various sealed microfluidic devices have been developed to study extravasation, few, if any, allow for the efficient collection of extravasated cells. To address this limitation, we designed a biomimetic microfluidic device comprising a network of 3D blood capillaries and a customizable collecting chamber, separated by a porous membrane. Our device enables (i) real-time monitoring of cell extravasation through the endothelium via live imaging and (ii) the collection of disseminated cells for subsequent molecular characterization. We validated the functional properties of the 3D endothelial layer under shear stress and inflammation induction. After injecting promyeloblast cells and metastatic cancer cells into the lumen of the capillary network, we observed cell rolling and extravasation under continuous flow conditions. Finally, we collected extravasated cancer cells for gene expression profiling by real time–quantitative polymerase chain reaction. Overall, our novel microfluidic device reconstitutes a functional 3D blood vessel network, allowing real-time observation of extravasation and the collection of disseminated cells for further characterization.