The intima with early atherosclerotic lesions is load-bearing component of human thoracic aorta

The aim of the study was to evaluate the mechanical properties of the adventitia, media, and especially intima of the human thoracic aortic wall in the early stages of atherosclerosis (stage I to III according to the Stary's classification). Histological and immunohistochemical techniques were used to evaluate the severity of atherosclerosis and the correctness of separation of the respective layers. Circumferential specimens of the adventitia, media, and intima (n = 193) were prepared from 27 arteries. The mechanical properties, i.e. the ultimate tensile strength, the maximum strain, and the maximum tangential elastic moduli, were determined in uniaxial tensile test and presented as a median (Me). The tensile strength of the intima (Me = 105 kPa) is comparable to the media (Me = 123 kPa) and lower than for the adventitia (Me = 808.5 kPa). The intima also undergoes the lowest maximum strain (Me = 0.008), and its elastic modulus (Me = 11510 kPa) is significantly higher compared to the media (Me = 5280 kPa). Therefore, presented results indicate that even in the early stages of atherosclerotic development the intima takes part in the process of mechanical loads bearing.