ATHEROSCLEROTIC CALCIFICATION - RELATION TO DEVELOPMENTAL OSTEOGENESIS

Calcium deposits of atherosclerotic plaque consist of hydroxyapatite a nd may appear identical to fully formed lamellar bone, including trabe culae, lacunae, and areas resembling marrow. Possible mechanisms for b one formation in artery walls are developmental retention of pluripote nt cells or osteoblastic immigration coupled with loss of molecular re gulatory control that unmasks an embryonic osteogenic program. In situ hybridization of calcified human atherosclerotic lesions shows expres sion of bone morphogenetic protein type 2, a potent osteogenic differe ntiation factor. Medial cells of bovine aorta cultured (Dulbecco's mod ified Eagle's medium plus 15% fetal cap serum) for >2 weeks form nodul es similar to those formed by cultured osteoblasts, including the elab oration of hydroxyapatite.