High glucose and glycated substrates alter endothelial cell shape change response to shear stress

Abstract

Endothelial cells line the walls of all blood vessels, where they maintain homeostasis through control of vascular tone, permeability, inflammation, and growth and regression of blood vessels. Endothelial cells are mechanosensitive to fluid shear stress, and hyperglycemia, a hallmark of diabetes, affects endothelial cell function. Clinical evidence suggests interaction between mechanics and high glucose, since diabetic patients have accelerated atherosclerosis at locations of disturbed blood flow. The central hypothesis of this thesis is that high glucose conditions alter endothelial cell adhesion strength and response to fluid shear stress. Two systems were developed to study endothelial cells under shear stress: microfluidic channels and parallel plate system. These systems were successfully designed to apply constant laminar stress onto endothelial cells. However due to inconsistencies and challenges with access to cells inside microchannels, the parallel plate system was used for experimentation. Endothelial cell adhesion strength was tested and cells cultured in high glucose were found to have a response dependent with attachment time. The initial adhesion strength after 6 hours of attachment was higher than low glucose but after 48 hours high glucose adhesion strength was less than low glucose. Separately it was found that substrate glycation had no effect on endothelial cell adhesion strength after 48 hours of attachment. Endothelial cell elongation and alignment was reduced in high glucose and prevented when the cells were grown on glycated collagen substrates. The native collagen and low glucose condition showed the most actin fiber alignment. High glucose reduced alignment only slightly, whereas glycated collagen prevented alignment. This research furthers our understanding of the combine effects of hyperglycemia and shear stress on endothelial cells. Futures studies into the mechanisms of endothelial cell shape change will help elucidate the causes. By understanding the affected pathways, atherosclerosis treatments for people with diabetes can be directly tailored, which would increase efficacy and reduce side effects.%%%%M.S., Biomedical Engineering – Drexel University, 2009