Inhibition of DNA synthesis and tube morphogenesis of cultured vascular endothelial cells by chondromodulin-I.

Cartilage is an avascular tissue, and exhibits anti-angiogenic properties. Cartilage extracts have been shown to contain an inhibitor for DNA synthesis in vascular endothelial cells in vitro. Here we purified the inhibitory activity in the 10-50 kDa fraction of guanidine extracts from fetal bovine epiphyseal cartilage, and found that the inhibitor was identical with chondromodulin-I (ChM-I). Purified ChM-I inhibited tube morphogenesis of cultured vascular endothelial cells, as well as DNA synthesis. These results indicate that cartilage-specific glycoprotein ChM-I may participate in the maintenance of avascularity and anti-angiogenic properties of cartilage.