Aortic valve: turning over a new leaf(let) in endothelial phenotypic heterogeneity. Arterioscler Thromb

Aortic valve diseases are debilitating cardiovasculardisorders associated with significant morbidity andmortality. Although there continue to be major ef-forts to improve the longevity of replacement valves and to improve tissue engineered substitutes,1 the underlying mech-anisms that may be responsible for the initiation and devel-opment of valve pathology have received less attention than have other sclerosing cardiovascular diseases such as athero-genesis. The endothelium lining of the cardiovascular system plays an important regulatory role in vascular physiology and pathology. In similar fashion, the surfaces of valve leaflets are presumed to be generally protected (eg, anticoagulant) and regulated (eg, permeability) by the endothelium. The functional properties of endothelium or its presence/absence are associated with a variety of valve pathologies,2 and systemic endothelial dysfunction is linked to aortic valve calcification.3 However, only recently have cell and molecu