High‐Throughput Scaffold System for Studying the Effect of Local Geometry and Topology on the Development and Orientation of Sprouting Blood Vessels

Abstract

Live tissues require vascular networks for cell nourishing. Mimicking the complex structure of native vascular networks in vitro requires understanding the governing factors of early tubulogenesis. Current vascularization protocols allow for spontaneous formation of vascular networks; however, there is still a need to provide control over the defined network structure. Moreover, there is little understanding on sprouting decision and migration, especially within 3D environments. Here, tessellated polymer scaffolds with various compartment geometries and a novel two‐step seeding protocol are used to study vessel sprouting decisions. Endothelial cells first organize into hollow vessels tracing the shape contour with high fidelity. Subsequent sprouts emerge in specific directions, responding to compartment geometry. Time‐lapse imaging is used to track vessel migration, evidencing that sprouts frequently emerge from the side centers, mainly migrating toward opposing corners, where the density of support cells (SCs) is the highest, providing the highest levels of angiogenic factors. SCs distribution is quantified by smooth muscle actin expression, confirming the cells preference for curved compartment surfaces and corners. Displacements within the hydrogel correlate with SCs distribution during the initial tubulogenesis phase. This work provides new insight regarding vessel sprouting decisions that should be considered when designing scaffolds for vascularized engineered tissues.A novel two‐step cell seeding on tesselated scaffolds produces highly organized and oriented vessel networks. Different compartment shapes promote vessel sprouting with specific orientations according to the compartment geometry and encourage distinct support cell distributions. Vessels depart from areas with low support cell concentration (side between corners) and are drawn to areas with higher concentration of support cells (corners).