Effect of bone-derived growth factor on DNA, RNA, and proteoglycan synthesis in cultures of rabbit costal chondrocytes.

Calvariae and chondrocytes in culture have been reported to release growth factors which stimulate bone and cartilage growth respectively. In the present studies, we examined the effects of bone-derived growth factor (BDGF) on DNA, RNA and proteoglycan synthesis in cultured rabbit chondrocytes. Two partially purified fractions of BDGF were tested, one with an approximate molecular weight (MW) of 20-30,000 and with greater activity on calvarial DNA labeling (BDGF I) and another with an approximate MW 6-13,000 and greater activity on bone collagen labeling (BDGF II). Both fractions had a similar effect and increased the incorporation of -3H-uridine into acid insoluble residues in chondrocytes and the incorporation of 35SO4(2-), 3H-glucosamine and 3H-serine into proteoglycans. However, BDGF II had a greater stimulatory effect on the incorporation of 3H-thymidine than BDGF I. These findings suggest that factor(s) released by bone cells are capable of stimulating cartilage metabolism and growth.