Figure 1.

Schematic diagram of potential OCL differentiation in the plaque. Soluble RANKL (sRANKL) and OPG are secreted in the atherosclerotic plaque and in the blood stream mainly by smooth muscle cells (SMCs) and endothelial cells (ECs). sRANKL promotes OCL precursor (mainly monocytes/macrophages (M), dendritic cells, and SMCs) differentiation into OCL cells (as indicated by dotted arrows). OPG neutralizes the action of RANKL. The balance between these two soluble molecules regulates the bone resorption in calcified plaques, which is correlated to plaque rupture.