Terminal Differentiation and Calcification in Rabbit Chondrocyte Cultures Grown in Centrifuge Tubes: Regulation by Transforming Growth Factor β and Serum Factors
Abstract
Rabbit chondrocyte cultures on plastic dishes are capable of depositing a cartilaginous matrix, although the matrix does not calcify unless high levels of phosphate are added to the medium. In the present study, we cultivated a pelleted mass of rabbit growth-plate chondrocytes in the presence of Eagle's minimum essential medium supplemented with 10% fetal bovine serum and 50 micrograms of ascorbic acid per ml in a plastic centrifuge tube. These cells proliferated for several generations and then reorganized into a cartilage-like tissue that calcified without additional phosphate. The deposition of minerals was observed only after synthesis of a short-chain collagen and alkaline phosphatase. Serum factors were required for the increases in alkaline phosphatase and calcium contents. 5-Bromo-2'-deoxyuridine abolished the increases in uronic acid, alkaline phosphatase, and calcium contents. Transforming growth factor beta, at very low concentrations, suppressed the expression of the mineralization-related phenotype by chondrocytes. These results suggest that cartilage-matrix calcification can be controlled by growth factor(s) and that chondrocytes induce the mineralization of extracellular matrix when terminal differentiation is permitted in the absence of an artificial substrate.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- December 1988
- DOI:
- 10.1073/pnas.85.24.9552
- Bibcode:
- 1988PNAS...85.9552K