Study Could Lead to Drug Therapies for Preventing Atherosclerosis

Finally getting to preventing my cause.
By changing the behavior of certain cells within human blood vessels, Cornell University researchers have discovered important clues as to the underlying causes of atherosclerosis – a discovery researchers hope can lead to more targeted drug therapies for the prevention of the disease.

“One of the things we wanted to do was understand how aging is linked to atherosclerosis, and how the mechanism of vessel stiffening plays into this link,” said Cynthia Reinhart-King, Cornell professor of biomedical engineering and lead author of “Age-Related Intimal Stiffening Enhances Endothelial Permeability and Leukocyte Transmigration,” to be published online Dec. 7 in the journal Science Translational Medicine.

Age-Related Intimal Stiffening Enhances Endothelial Permeability and Leukocyte Transmigration

http://stm.sciencemag.org/content/3/112/112ra122

Abstract

Age is the most significant risk factor for atherosclerosis; however, the link between age and atherosclerosis is poorly understood. During both aging and atherosclerosis progression, the blood vessel wall stiffens owing to alterations in the extracellular matrix. Using in vitro and ex vivo models of vessel wall stiffness and aging, we show that stiffening of extracellular matrix within the intima promotes endothelial cell permeability—a hallmark of atherogenesis. When cultured on hydrogels fabricated to match the elasticity of young and aging intima, endothelial monolayers exhibit increased permeability and disrupted cell-cell junctions on stiffer matrices. In parallel experiments, we showed a corresponding increase in cell-cell junction width with age in ex vivo aortas from young (10 weeks) and old (21 to 25 months) healthy mice. To investigate the mechanism by which matrix stiffening alters monolayer integrity, we found that cell contractility increases with increased matrix stiffness, mechanically destabilizing cell-cell junctions. This increase in endothelial permeability results in increased leukocyte extravasation, which is a critical step in atherosclerotic plaque formation. Mild inhibition of Rho-dependent cell contractility using Y-27632, an inhibitor of Rho-associated kinase, or small interfering RNA restored monolayer integrity in vitro and in vivo. Our results suggest that extracellular matrix stiffening alone, which occurs during aging, can lead to endothelial monolayer disruption and atherosclerosis pathogenesis. Because previous therapeutics designed to decrease vascular stiffness have been met with limited success, our findings could be the basis for the design of therapeutics that target the Rho-dependent cellular contractile response to matrix stiffening, rather than stiffness itself, to more effectively prevent atherosclerosis progression.