Vascular cell behavior on glycocalyx–mimetic surfaces: Simultaneous mimicking of the chemical composition and topographical structure of the vascular endothelial glycocalyx

Abstract

The endothelial glycocalyx is a carbohydrate–rich layer overlying the outermost surface of endothelial cells. It mediates intercellular interactions by specific chemical compositions (e.g., proteoglycans containing glycosaminoglycan (GAG) side chains) and micro/nanotopography. Inspired by the endothelial glycocalyx, we fabricated a series of glycocalyx–mimetic surfaces with tunable chemical compositions (GAG–like polymers with different functional units) and topographical structures (micro/nanopatterns with pillars different in size). The combination of micro/nanopatterns and GAG–like polymers was flexibly and precisely controlled by replica molding using silicon templates (Si templates) and visible light–initiated polymerization. Human umbilical vein endothelial cells (HUVECs) and human umbilical vein smooth muscle cells (HUVSMCs) were suppressed on surfaces modified with polymers of 2–methacrylamido glucopyranose (MAG) but promoted on surfaces modified with polymers of sodium 4–vinyl–benzenesulfonate (SS) and copolymers of SS and MAG. Surface micro/nanopatterns showed highly complicated effects on surfaces grafted with different GAG–like polymers. Moreover, the spread of HUVSMCs was highly promoted on all flat/patterned surfaces containing sulfonate units, and the elongation effect was stronger on surfaces with smaller pillars. On all the flat/patterned surfaces modified with GAG–like polymers, the adsorption of human vascular endothelial growth factor (VEGF) and human basic fibroblast growth factor (bFGF) was improved, and the amount of VEGF and bFGF absorbed on patterned surfaces containing sulfonate units decreased with pattern dimensions. The decreasing trend of VEGF and bFGF adsorption was in accordance with HUVEC density, suggesting that glycocalyx–mimetic surfaces influence the adsorption of VEGF and bFGF and further influence the growth behavior of vascular cells.