Effect of elastin on delamination strength in the porcine aortic tunica media

Abstract

Aortic dissection (AD) is a disease in which the tunica media is separated into two layers and blood flows in the newly created lumen. To elucidate the etiology of AD, we investigated the effect of the decrease in elastin, which occurs in actual AD, on the delamination strength of the aorta. Healthy porcine aortas were purchased, and half specimens were immersed in an elastase solution, for elastin digestion. The delamination test was performed on the specimens in both the circumferential θ and longitudinal z directions. The area fractions of elastin and collagen were measured via a histological analysis, such as Elastica–Masson and Azan stains. In healthy specimens, the delamination strength in the z-direction tended (albeit insignificantly) to be higher than that in the θ-direction. Conversely, in elastase-treated specimens, the delamination strengths in both directions were almost the same and were significantly lower than those recorded in the healthy specimens. The area fraction of elastin, but not of collagen, was significantly lower in elastase-treated specimens compared with control specimens. These results indicate that a decrease in elastin causes a reduction in the delamination strength, especially in the z-direction, which may result in dissection propagation in that direction in AD.