Some Factors Controlling Bone Resorption and Formation in Tissue Culture

摘要

Oxygen tension in the gas phase of roller-tube cultures of young mouse calvaria plays a major role in determining the rate and extent of response to various bone resorption stimulating factors, such as parathyroid extract, high concentrations of crystalline vitamin A or crystalline vitamin D. Suboptimal concentrations of these factors may be markedly enhanced by the presence of bone resorption stimulating co-factors such as heparin, although here, too, the system is extremely oxygen-dependent. Bone formation takes place only in the presence of chick embryo extract which presumably contains a bone formation stimulating factor as well as a bone resorption stimulating factor. Very slight new osteoid formation occurs at 10% oxygen, but at 20, 30 and 50% oxygen the amounts may be significant. Calcification of the new osteoid may be observed in the living cultures, but occurs more frequently at the higher oxygen tensions. Although the amount of new osteoid formation is comparable at 30% O2 and 50% O2, bone resorption is markedly stimulated at the higher oxygen tension, resulting in an enormous decrease in bone mass. Biochemical studies confirm these morphological observations. (Author)