Progressive changes of elastic moduli of arterial wall and atherosclerotic plaque components during plaque development in human coronary arteries

Stiffness of the arterial wall and atherosclerotic plaque components is a determinant of the stress field within plaques, which has been suggested to be an indicator of plaque vulnerability. The diversity and inhomogeneous structure of atherosclerotic lesions complicate the characterization of plaque components. In the present study, stiffness of the arterial wall and atherosclerotic plaque components in human coronary arteries was examined in early and developed atherosclerotic lesions. The force-spectroscopy mode of the atomic force microscope and histological examination were used for determination of elastic moduli at specified locations within samples. Fibrous cap (E = 14.1 ± 3.8 kPa) showed lower stiffness than the fibrous tissue beneath the lipid pool (E = 17.6 ± 3.2 kPa). Calcification zones (E = 96.1 ± 18.8 kPa) and lipid pools (E = 2.7 ± 1.8 kPa) were the stiffest and softest components of atherosclerotic lesions, respectively. The increase of media stiffness (%44.8) and reduction of the elastic modulus of the internal elastic lamina (%28.9) was observed in coronary arteries. Moreover, significant differences were observed between the stiffness of medial layer in diseased parts and free-plaque segments in incomplete plaques of coronary arteries. Our results can be used for better understanding of remodeling mechanisms of the arterial wall with plaque development.