Development of a Single-Cell Migration and Extravasation Platform through Selective Surface Modification.

Cell migration through three-dimensional (3D) tissue spaces is integral to many biological and pathological processes, including metastasis. Circulating tumor cells (CTCs) are phenotypically heterogeneous, and in vitro analysis of their extravasation behavior is often impeded by the inability to establish complex tissue-like extracellular matrix (ECM) environments and chemotactic gradients within microfluidic devices. We have developed a novel microfluidic strategy to manipulate surface properties of enclosed microchannels and create 3D ECM structures for real-time observation of individual migrating cells. The wettability of selective interconnected channels is controlled by a plasma pulse, enabling the incorporation of ECM exclusively within the transmigration regions. We applied this approach to collectively analyze CTC-endothelial adhesion, trans-endothelial migration, and subsequent motility of breast cancer cells (MDA-MB-231) through a 3D ECM under artificial gradients of SDF-1α. We observed migration velocities ranging from 5.12 to 12.8 μm/h, which closely correspond to single-cell migration in collagen blocks, but are significantly faster than the migration of cell aggregates. The compartmentalized microchannels separated by the porous ECM makes this in vitro assay versatile and suitable for a variety of applications such as inflammation studies, drug screening, and coculture interactions.