STIMULATION OF OSTEOBLAST PROLIFERATION BY THE CARTILAGE-DERIVED GROWTH-PROMOTING FACTORS CHONDROMODULIN-I AND CHONDROMODULIN-II

We previously reported the isolation of the cartilage-derived growth p romoting factors chondromodulin-I (ChM-I) and chondromodulin-II (ChM-I I) from fetal bovine epiphyseal cartilage, Both of these factors stimu late the growth and matrix formation of chondrocytes in vitro. In the present study, we found that ChM-I and ChM-II stimulated the prolifera tion of clonal mouse osteoblastic MC3T3-E1 cells as well as primary mo use osteoblasts in culture, Unlike other known growth factors, these f actors did not support the proliferation of fibroblasts. Concomitantly with growth stimulation of osteoblasts, there was a reduction of alka line phosphatase (ALP) activity in the cells, the expression of the di fferentiated phenotype. These results suggest that epiphyseal cartilag e mag play a functional role in longitudinal bone growth by production of these unique growth-promoting factors. (C) 1997 Federation of Euro pean Biochemical Societies.