[Growth factor activity on cultured chondrocytes (author's transl)]

Somatomedins and vitamin D metabolites have been shown to interact with cartilage metabolism. In the present work their stimulating effect on the growth of rabbit cultured chondrocytes is studied. These cells possess specific binding sites for an insulin like preparation (ILA) distinct from insulin binding sites. They also possess specific nuclear binding sites for one vitamin D metabolite : 24,25- (OH)2D3. In the absence of seric factors, these two types of hormone stimulate the proteoglycan synthesis but do not increase DNA polymerase activities in chondrocytes. Another type of growth factor enhances the cellular multiplication but inhibits the specific protein synthesis (Fibroblast growth factor or Retinal factor). When DNA polymerase activities are induced by fetal calf serum, ILA or vitamin D metabolites may increase the rate of DNA synthesis.