Bone morphogenetic protein expression in human atherosclerotic lesions.

Artery wall calcification associated with atherosclerosis fre- quently contains fully formed bone tissue including marrow. The cellular origin is not known. In this study, bone morphoge- netic protein-2a, a potent factor for osteoblastic differentiation, was found to be expressed in calcified human atherosclerotic plaque. In addition, cells cultured from the aortic wall formed calcified nodules similar to those found in bone cell cultures and expressed bone morphogenetic protein-2a with prolonged cul- ture. The predominant cells in these nodules had immunocytochemical features characteristic of microvascular pericytes that are capable of osteoblastic differentiation. Pericyte-like cells were also found by immunohistochemistry in the intima of bovine and human aorta. These findings suggest that arterial cal- cification is a regulated process similar to bone formation, possibly mediated by pericyte-like cells. (J. Clin. Invest.