Calcium and phosphate supplementation promotes bone cell mineralization: implications for hydroxyapatite (HA)-enhanced bone formation.

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Chang YL, Stanford CM, Keller JC

Calcium and phosphate supplementation promotes bone cell mineralization: implications for hydroxyapatite (HA)-enhanced bone formation.

J Biomed Mater Res. 2000 Nov;52(2):270-8.

PubMed ID

10951365 [ View in PubMed

]

Abstract

Organic phosphate, in particular beta-glycerophosphate (beta-GP), has been used to induce mineralization in cell culture systems. It serves as a source of inorganic phosphate when hydrolyzed by alkaline phosphatase. This study examined the effect of supplemental calcium and phosphate as well as the influence of various metabolic inhibitors on mineralization in a rat osteoblast-like cell-culture system. Mineralization was induced by supplementation of 1.8 mM of Ca(+2) and 5 mM of beta-GP or Pi. Mineral deposits associated with in vitro mineralization were revealed under SEM and TEM. Levamisole (10-100 microM) inhibited alkaline phosphatase activity and effectively reduced mineral formation. Actinomycin (500 ng/mL) and cycloheximide (50 microg/mL) also reduced mineral depositions by blocking RNA synthesis and protein synthesis, respectively. Levamisole and beta-GP did not appear to influence DNA synthesis. Spontaneous precipitation of calcium phosphate mineral was not detected in the culture medium with calcium and phosphate supplements in the absence of cell culture. The findings suggest that an elevated concentration of calcium and phosphate is crucial for in vitro mineralization. Furthermore, the mineralization process is associated with biologic events rather than with a spontaneous precipitation of calcium phosphate mineral. In view of the degradation potential of hydroxyapatite (HA)-coated implants, these results may be a viable indication that HA enhances bone formation through a similar mechanism.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Levamisole	Alkaline phosphatase, germ cell type	Protein	Humans	Unknown	Inhibitor	Details