DISEASE FOCUS: Atherosclerosis and vascular calcification

Vascular calcification

Vascular calcification is a prominent feature of advanced atherosclerotic lesions. Vascular calcification refers to the deposition of calcium phosphate mineral in the intima or media of arterial walls, leading to reduced elasticity and compliance. The mechanism underlying vascular calcification is currently unknown. However, a number of studies have suggested that the process of vascular calcification is similar to the mineralisation process observed in bone (Abedin et al, 2004). This is based on the observation that bone-associated proteins such as osteocalcin, osteonectin, bone morphogenic proteins (BMP) and matrix Gla proteins (MGP) have been detected in vascular calcifications (Trion et al, 2004). VSMC appear to be an important factor in vascular calcification, since VSMC within calcified plaques have been shown to express osteoblast and chondrocyte-like gene expression profiles (Tyson et al, 2003). MGP, osteonectin, osteprotergerin and aggrecan were constitutively expressed by VSMC in normal arteries but were found to be down-regulated in calcified arteries. Since MPG has been shown to inhibit calcification, its down-regulation observed in these plaques may be the key factor in initiating vascular calcification. Little is known about the mechanisms governing vascular calcification.