F. Byfield, H. Aranda-Espinoza, V. Romanenko, G. Rothblat, and I. Levitan (USA)
cholesterol, endothelial cells, membrane stiffness, microaspiration
This study investigates the effect of cellular cholesterol on mechanical properties of aortic endothelial cells. Cellular cholesterol content was adjusted to different levels by exposing the cells to methyl--cyclodextrin (MCD):cholesterol solutions at increasing molar ratios of MCD and cholesterol. Mechanical properties of the cells depleted of and enriched with cholesterol were evaluated by measuring the degree of membrane deformation. The experiments were performed on substrate-attached cells using a combination of micropipette aspiration technique and 3-D imaging. Our observations show that while cholesterol enrichment had no effect on the degree of membrane deformation in these cells, cholesterol depletion has a significant stiffening effect on the membrane. Young elastic modulus calculated using a standard linear viscoelastic half-space model was 292 N/m2 and 294 N/m2 for cholesterol enriched and control cells but increased to 365 N/m2 for cholesterol-depleted cells. Since it is known that in model membranes an increase in membrane cholesterol decreases the elasticity the bilayer, our results suggest that cholesterol depletion induces a compensatory process that decreases the elasticity of membrane-cytoskeleton complex of the endothelial cells.
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