Objective-Isolated systolic hypertension is associated with increased elastase activity, vascular calcification, and vascular stiffness. We sought to determine the importance of elastase activity and matrix degradation in the development of elastocalcinosis. Methods and Results-Elastocalcinosis was induced in vivo and ex vivo using warfarin. Hemodynamic parameters, calcium deposition, elastin degradation, transforming growth factor (TGF)- signaling, and elastase activity were evaluated at different time points in the in vivo model. Metalloproteinases, serine proteases, and cysteine proteases were blocked to measure their relative implication in elastin degradation. Gradual elastocalcinosis was obtained, and paralleled the elastin degradation pattern. Matrix metalloproteinase (MMP)-9 activity was increased at 5 days of warfarin treatment, whereas TGF- signaling was increased at 7 days. Calcification was significantly elevated after 21 days. Blocking metalloproteinases activation with doxycycline and TGF- signaling with SB-431542 were able to prevent calcification. Conclusions-Early MMP-9 activation precedes the increase of TGF- signaling, and overt vascular elastocalcinosis and stiffness. Modulation of matrix degradation could represent a novel therapeutic avenue to prevent the gradual age-related stiffening of large arteries, leading to isolated systolic hypertension. Elastocalcinosis is characterized by a deposition of hydroxyapatite on the elastic lamellae of arteries. It occurs independently of atherosclerosis. 2 Until recently, it was considered as a passive process, taking place with time. However, several studies demonstrated that vascular calcification is an active phenomenon controlled by serum and matrix proteins, such as matrix Gla protein. 3 Moreover, it involves phenotypic changes of vascular smooth muscle cells with the expression of bone-related proteins. 4 Aging is associated with an increased collagen/elastin ratio explained in part by an enhanced degradation of elastin. 5,6 Indeed, elastase activity, mainly endopeptidases, including cysteine proteases, serine proteases, and metalloproteinases, is increased with age in human aortas. 7 In the context of aging and vascular calcification, metalloproteinases, especially matrix metalloproteinases (MMPs), have been thoroughly studied. Investigations on the genetic mutations of MMPs demonstrated its contribution to age-related large artery stiffening. 8,9 Furthermore, enhanced MMP-9 and MMP-2 levels and serum elastase activity were observed in patients with ISH and correlated independently with PWV. 10 In 2000, Vyavahare et al showed for the first time that elastin calcification was blunted by a site specific delivery of MMP inhibitor. 11 Moreover, Qin et al demonstrated, in an animal model, that matrix metalloproteinase inhibition with doxycycline and GM6001 decreased hydroxyapatite accumulation in the aorta. 12 These results suggest that MMPs and elastin degradation are involved in MEC.Elastin degradation induces the release of soluble elastin pep...