[Cartilage-derived growth factor and antitumor factor: past, present, and future studies]

We isolated growth-cartilage cells from rat and rabbit ribs and cultured them in vitro . Then we found that growth-cartilage cells in culture have a marked osteogenic potential, forming differentiated colonies abundant macromolecules such as proteoglycans and type II collagen in vitro . We also found that calcitonin and parathyroid hormone markedly enhanced proteoglycan synthesis in these cells. In addition to these systemic factors, extracellular matrix components have long been thought to play important roles in the control of cartilage development. Thus, we have searched for regulatory factors in cartilage and found that fetal bovine cartilage contains cartilage-specific growth modulating matrices that stimulate DNA synthesis of cartilage cells in the presence of bFGF. We named this unique principle chondromodulin- I (ChM- I ). The aim of this chapter is to survey various approaches to the study of recent advances in the regulation of cartilage development by locally generated factors.