Abstract 269: Collagen Topographical Patterning Modulates Endothelial Cell Morphology, Gene Expression and Function

Abstract

Endothelial cells (ECs) exposed to laminar shear stress align in the direction of blood flow and express low levels of adhesion molecules. However, it is unknown whether these biological responses result from shear stress per se, or if they can be recapitulated using topography cues from the underlying extracellular matrix (ECM). We hypothesized that collagen topographical patterning can regulate EC assembly and function in the absence of shear stress. We fabricated collagen-coated polydimethylsiloxane microchannels (30μm wide) to induce EC alignment. When grown on microchannels, the ECs underwent striking re-organization of their actin cytoskeleton (aligned within 10 degrees of the microchannel direction) and their focal adhesions (Fig A). Mimicking the reported EC responses to laminar shear stress, aligned ECs were more quiescent (reduced Ki67 expression), and less adhesive for monocytes (with 50% reductions in the expression of intercellular adhesion molecule 1, and in monocyte adhesion in a functional binding assay). DNA microarrays revealed a transcriptional signature of 600 genes that were differentially expressed by ECs cultured on the patterned substrates (Fig B), including genes previously not associated with EC function such as histones (HIST1H2AH, HIST2H2BF) and heat shock proteins (HSPB7, HSPB9). These results demonstrate that topographical cues from the underlying ECM are potent regulators of EC morphology and function and mimic the effects of laminar shear-stress. This work highlights the importance of cell-ECM interactions in maintenance of EC phenotype and has implications in the design of vascular conduits to minimize atherogenesis.