Comparison of in vitro human endothelial cell response to self-expanding stent deployment in a straight and curved peripheral artery simulator

Abstract

Haemodynamic forces have a synergistic effect on endothelial cell (EC) morphology, proliferation, differentiation and biochemical expression profiles. Alterations to haemodynamic force levels have been observed at curved regions and bifurcations of arteries but also around struts of stented arteries, and are also known to be associated with various vascular pathologies. Therefore, curvature in combination with stenting might create a proatherosclerotic environment compared with stenting in a straight vessel, but this has never been investigated. The goal of this study was to compare EC morphology, proliferation and differentiation within in vitro models of curved stented peripheral vessel models with those of straight and unstented vessels. These models were generated using both static conditions and also subjected to 24 h of stimulation in a peripheral artery bioreactor. Medicalgrade silicone tubes were seeded with human umbilical vein endothelial cells to produce pseudovessels that were then stented and subjected to 24 h of physiological levels of pulsatile pressure, radial distention and shear stress. Changes in cell number, orientation and nitric oxide (NO) production were assessed in straight, curved, non-stented and stented pseudovessels. We report that curved pseudovessels lead to higher EC numbers with random orientation and lower NO production per cell compared with straight pseudovessels after 24 h of biomechanical stimulation. Both stented curved and stented straight pseudovessels had lower NO production per cell than corresponding unstented pseudovessels. However, in contrast to straight stented pseudovessels, curved stented pseudovessels had fewer viable cells. The results of this study show, for the first time, that the response of the vascular endothelium is dependent on both curvature and stenting combined, and highlight the necessity for future investigations of the effects of curvature in combination with stenting to fully understand effects on the endothelial layer.

Device-Based In Vitro Techniques for Mechanical Stimulation of Vascular Cells: A Review

“…One group has described a method for including a lipid pool in the mock artery wall; this simulates a diseased vessel with a plaque [170]. Another group adapted their flow system to test curved mock arteries and compare them to those in a straight configuration [166]. This may better represent the in vivo situation, because although some arteries are fairly straight, much of the vascular system consists of curved or tortuous arteries, and atherosclerosis tends to develop in such vessels more often than straight ones [40].…”

“…The morphological characteristics of interest include cell alignment [153,154,157,159,161,164,166], cell elongation [154,159,161], and alignment of cytoskeletal actin filaments [130,149]. Cell density, viability, and adhesion have also been considered variables of interest [136,151,170].…”

“…The vessel mechanical properties are also more uniform and easier to characterize [170]. As with explanted vessels, ultrasonic sensors can be used to measure the flow rate and flow profile [166].…”

“…Materials used to construct the mock artery include PVA cryogel [170], silicone elastomers [136,153,161,166], and 3D PLCL scaffolds [157]. Sylgard V R 184 (Dow Corning, Midland, MI), a commercially available silicone elastomer, has been used several times in mock artery applications [131,149,152,154,170].…”

“…Generally, researchers expose the cells to mechanical stimuli and then analyze the change in physical or biochemical cell response. To quantify morphology, cells are fixed and stained, then a segment of the mock artery is cut out and examined with bright field, phase contrast, or fluorescence microscopy [153,154,161,166]. Alternatively, live cells 040801-14 / Vol.…”