Calcium and phosphate supplementation promotes bone cell mineralization: Implications for hydroxyapatite (HA)-enhanced bone formation
Article first published online: 15 AUG 2000
Copyright © 2000 John Wiley & Sons, Inc.
Journal of Biomedical Materials Research
Volume 52, Issue 2, pages 270–278, November 2000
How to Cite
Chang, Y.-L., Stanford, C. M. and Keller, J. C. (2000), Calcium and phosphate supplementation promotes bone cell mineralization: Implications for hydroxyapatite (HA)-enhanced bone formation. J. Biomed. Mater. Res., 52: 270–278. doi: 10.1002/1097-4636(200011)52:2<270::AID-JBM5>3.0.CO;2-1
- Issue published online: 15 AUG 2000
- Article first published online: 15 AUG 2000
- Manuscript Accepted: 16 FEB 2000
- Manuscript Received: 9 JUN 1999
- NIDR/NIH. Grant Number: DE08540
- Oral and Maxillofacial Surgery Foundation
- alkaline phosphatase;
Organic phosphate, in particular beta-glycerophosphate (β-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 β-GP or Pi. Mineral deposits associated with in vitro mineralization were revealed under SEM and TEM. Levamisole (10–100 μM) inhibited alkaline phosphatase activity and effectively reduced mineral formation. Actinomycin (500 ng/mL) and cycloheximide (50 μg/mL) also reduced mineral depositions by blocking RNA synthesis and protein synthesis, respectively. Levamisole and β-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. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 270–278, 2000.