Differential effects of 1 alpha, 25-dihydroxycholecalciferol and 24R,25-dihydroxycholecalciferol on the proliferation and the differentiated phenotype of rabbit craniofacial chondrocytes in primary culture.

The response of chondrocytes from the craniofacial complex to vitamin D3 has been investigated in vitro. Chondrocytes were isolated from nasal septal cartilage (NSC), sphenooccipital synchondrosis (SOS) and mandibular condylar cartilage (MCC) of New Zealand rabbits weighing from 250-350 g. Treatment of NSC-chondrocytes with 1,25-(OH)2D3 or 24,25-(OH)2D3 for 6 days from days 4 to 10 in medium containing charcoal-treated FBS increased DNA synthesis dose-dependently at the concentrations of 10(-9) M to 10(-8) M, or 10(-11) M to 10(-9) M, respectively. 1,25-(OH)2D3 inhibited GAG synthesis dose dependently at the concentrations of 10(-11) M to 10(-8) M. 24,25-(OH)2D3 had no effect on GAG synthesis in NSC-chondrocytes. 1,25-(OH)2D3 increased DNA synthesis in SOS-chondrocytes at a concentration of 10(-10) M and inhibited GAG synthesis. 24,25-(OH)2D3 had no significant effect on DNA and GAG syntheses of SOS-chondrocytes. 1,25-(OH)2D3 slightly increased GAG synthesis at a concentration of 10(-10) M in MCC-chondrocytes but had no effect on DNA synthesis. 24,25-(OH)2D3 had no effect on DNA and GAG synthesis in MCC-chondrocytes at concentrations of 10(-11) M to 10(-9) M. These finding suggest that vitamin D3 metabolites, 1,25-(OH)2D3 and 24,25-(OH)2D3 play an important role in the growth of craniofacial cartilage by differently stimulating proliferation and expression of the differentiated phenotype of chondrocytes from NSC, SOS and MCC.