Local elastic modulus of atherosclerotic lesions of rabbit thoracic aortas and its relation to histology

Local elastic modulus of atherosclerotic lesions was measured by a pipette aspiration method in thoracic aortas of male Japanese White rabbits fed cholesterol diet for 8, 16, and 24 weeks. Local elastic modulus of the atherosclerotic lesion in the aortic arch was 26.9±2.4 kPa (mean±SEM), 33.1±1.9, and 47.5±3.9 for the 8-, 16-, and 24-week groups, respectively, while that of normal tissue was 38.2±1.7 kPa, indicating that the atherosclerotic lesion is softer than the normal tissue at its initial stage, and then gets stiffer with the progression of the disease. Histological observation showed that the initial lesion was mainly composed of foam cells and the stiffening accompanied the appearance of smooth muscle cells in the sub-intimal region. These results suggest that change in mechanical properties of atherosclerotic lesion is not simple and has a close correlation with its histology