Rat epiphyseal cells in culture: responsiveness to bone-seeking hormones

Cell cultures derived from young rat epiphyseal cartilage were grown for approximately 2 wk in BGJb medium supplemented with 10% fetal bovine serum to reach confluence. These cells were identified as chondrocytes as checked by morphology, the presence of alkaline phosphatase, and a positive type II collagen antibody reaction. The cells also responded to different hormonal treatment. Parathyroid hormone (PTH) increased cyclic AMP production by 50% within 15 min of treatment, whereas prostaglandin E2 (PGE2) caused an increase of 160%. Calcitonin (CT) did not affect cAMP production in these cells. DNA synthesis 24 h after hormonal treatment was increased by PTH (2.5-fold) and PGE2 (2-fold), but not by CT. Among the vitamin D metabolites, 24,25(OH)2D3 increased significantly the [3H]thymidine incorporation into DNA, whereas 1,25(OH)2D3 effect was minimal. These results provide evidence for the use of these cell cultures as a model for cartilage in vitro when studying biological and hormonal responsiveness.