Terminal differentiation and calcification in rabbit chondrocyte cultures grown in centrifuge tubes: regulation by transforming growth factor beta and serum factors.
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.
Kato
Y
Y
Department of Biochemistry, Faculty of Dentistry, Osaka University, Japan.
Iwamoto
M
M
Koike
T
T
Suzuki
F
F
Takano
Y
Y
D000469:Alkaline Phosphatase / Q000096:biosynthesis; D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002113:Calcification, Physiologic; D002356:Cartilage / Q000166:cytology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D005470:Fluorometry; D008854:Microscopy, Electron; D008903:Minerals / Q000378:metabolism; D011817:Rabbits; D015291:Transforming Growth Factors / Q000494:pharmacology*
D008903:Minerals; D015291:Transforming Growth Factors; D000469:Alkaline Phosphatase; D001973:Bromodeoxyuridine