Aged aortic perivascular adipose tissue exacerbates aortic stiffness in mice.

Aging is characterized by progressive large artery stiffening, a major risk factor for cardiovascular disease. The aorta is surrounded by aortic perivascular adipose tissue (APVAT), which has been shown to contribute to greater compliance in young healthy rodents in ex vivo assessments of aortic stiffness. However, whether APVAT maintains this positive influence on compliance with advancing age is unknown. Therefore, we assessed ex vivo aortic stiffness with APVAT either intact or removed in young (4-6 mo) and old (22-25 mo) mice. In young mice, aortic stiffness did not differ between vessels with intact APVAT and those with APVAT removed. In contrast, in old mice, aortic stiffness was significantly greater when APVAT was left intact compared with cleaned aortas, indicating that aged APVAT exerts a detrimental influence on aortic stiffness. To explore potential mechanisms, we assessed collagen deposition within APVAT and found that aged mice exhibited significantly greater APVAT-specific collagen accumulation compared with young animals. These findings suggest that with aging, APVAT undergoes fibrotic remodeling that contributes to increased aortic stiffness.<b>NEW & NOTEWORTHY</b> We show that the mechanical influence of APVAT on the aorta is strongly age-dependent. In contrast to young animals, aged APVAT increases passive aortic stiffness and displays increased collagen deposition, implicating fibrotic remodeling of APVAT as a novel contributor to age-related arterial stiffening.