Patterning microscale extracellular matrices to study endothelial and cancer cell interactions in vitro.

The extracellular matrix (ECM) of the tumor niche provides support to residing and migrating cells and presents instructive cues that influence cellular behaviours. The ECM protein fibronectin (Fn) enables vascular network formation， while hyaluronic acid (HA) is known to facilitate breast tumor development. To recapitulate aspects of the tumor microenvironment， we developed systems of spatially defined Fn and HA for the co-culture of endothelial colony forming cells (ECFCs) and breast cancer cells (BCCs). A micropatterned system was developed using sequential microcontact printing of HA and Fn. This approach supported the preferential adhesion of ECFCs to Fn， but did not support the preferential adhesion of BCCs to HA. Thus， we developed a microstructured analog to spatially organize BCC-laden HA micromolded hydrogels adjacent to ECFCs in fibrin hydrogels. These novel， miniaturized systems allow the analysis of the spatial and temporal mechanisms regulating tumor angiogenesis， and can be applied to mimic other microenvironments of healthy and diseased tissues.