Transforming growth factor-beta inhibition of mineralization by neonatal XXXX osteoblasts in monolayer and collagen gel culture.

@entity32 @entity177 @entity880 @entity9356 @entity1810 @entity35
The latent form of transforming growth factor-beta ( @entity1810 ) is a component of the extracellular matrix of bone. The active form, when locally injected in vivo, stimulates both @entity32 and ectopic bone formation. The present study was undertaken to determine if @entity1810 also stimulated mineralization by isolated @entity35 calvarial osteoblasts cultured in collagen gels. Gels were used because they should mimic in vivo conditions better than classical monolayer culture. Compared to cells in monolayers, osteoblasts cultured in collagen gels exhibited slower growth, but higher alkaline phosphatase activity and mineral deposition. Cultured cells also synthesized the osteoblast-specific marker, @entity9356 . The increase in @entity9356 in cell layers was parallel to the increase in mineral deposition. In the presence of @entity1810 , neither cell growth nor alkaline phosphatase activity increased. Instead, a small decrease occurred in both parameters when compared to untreated cultures. Accumulation of collagen, the major component of the extracellular matrix where mineralization occurs, was similar in untreated and @entity1810 -treated cultures. However, 8 pM @entity1810 dramatically suppressed mineral deposition in both types of cultures. Despite @entity1810 stimulating a fourfold increase in @entity880 , the consequent increase in culture medium acidity did not account for the inhibitory effects of @entity1810 on mineralization. These results demonstrate that collagen gel culture is an improved technique over conventional monolayer culture for demonstrating @entity177 and sensitivity to @entity1810 . @entity1810 , at a concentration that has little effect on cell growth, alkaline phosphatase activity, or collagen accumulation, is a potent inhibitor of mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)
