Atomic force microscopy application to study of the biomechanical properties of the aortic intima in the context of early atherosclerosis.

Atherosclerosis is characterized by the infiltration of macrophages, accumulation of lipids, activation of endothelial cells and synthesis of extracellular matrix by vascular smooth muscle cells. However, there have been few atomic force microscopy (AFM) studies of the aortic intima in situ in the context of atherosclerosis. By employing a customized liquid cell for AFM, we investigated the aortic intima obtained from male C57BL/6 ApoE-deficient mice (ApoE-/- ) aged 14 weeks and male C57BL/6 ApoE-sufficient mice (ApoE+/+ ) aged between 18 and 26 weeks that were fed a high-fat and high-cholesterol diet for 4 weeks and performed force spectroscopy mapping of the biomechanical properties of the intima. In the aortas of ApoE-deficient mice, the intima became stiffer than that of ApoE-sufficient mice. In addition, the cytoskeleton of endothelial cells was enlarged, and extracellular matrix accumulated. The biomechanical properties of the aortic intima are altered in early atherogenesis, which may be induced by the enlargement of the endothelial cell cytoskeleton and the increased synthesis of extracellular matrix by activated smooth muscle cells.