Abstract 396: Nanoscale Extracellular Matrix Alters Endothelial Function Under Disturbed Flow

Abstract

With 25 million Americans suffering from at least one clinical manifestation of atherosclerosis, there is a pressing need to better understand the biological basis for the development of atherosclerosis. Endothelial cells (EC) that form the inner lining of blood vessels are primarily responsible for resisting atherosclerotic lesion formation. Although hemodynamic shear stress has been thought to be the dominant modulator of EC function, spatial patterning cues from nanoscale extracellular matrices (ECMs) that underlie the endothelium may play an equally important role. Therefore, the goal of this work was to examine how modulation of EC alignment using ECM nanopatterning cues modulates the formation of atherosclerosis. We hypothesized that ECs are more responsive to aligned nanopatterning cues than to disturbed flow, and can resist functional changes associated with atherosclerosis in the presence of disturbed flow. ECs were cultured on fibrillar scaffolds with nanotopography to either induce longitudinal alignment of ECs to mimic the morphology of healthy ECs, or to cause ECs to orient randomly (control) to mimic pathological ECs. ECs were then exposure to disturbed flow for 24 hours. Time-lapse microscopy and F-actin staining were used to quantify migration velocities and cellular orientation. ECs on aligned nanofibrillar scaffolds were induced to align along the direction of the fibrils, even after exposure to disturbed flow, and demonstrated a 2-fold decrease in migrational velocities, compared to randomly oriented ECs. This data suggests that nanoscale cues from aligned nanofibrillar scaffolds direct cell morphology and motility. Functional effects of nanofibrillar organization to resist inflammation, revealed a 2-fold decrease in monocyte adhesion on aligned ECs compared to randomly-oriented ECs, suggesting that ECs on aligned nanofibrillar scaffolds were less prone to atherosclerosis. These results were validated by analysis of inflammatory and shear-mediated markers (NFKB, ICAM, KLF2). This work reveals fundamental insights into the role of nanoscale ECM cues on early events of atherosclerosis, and has important translational potential in the generation of aligned nanofibrillar vascular grafts that resist lesion formation.