Calcified Tissue International

, Volume 75, Issue 5, pp 405–415

Effects of Strontium on the Physicochemical Characteristics of Hydroxyapatite

  • S. C. Verberckmoes
  • G. J. Behets
  • L. Oste
  • A. R. Bervoets
  • L. V. Lamberts
  • M. Drakopoulos
  • A. Somogyi
  • P. Cool
  • W. Dorriné
  • M. E. De Broe
  • P. C. D’Haese


In a previous experimental study using a chronic renal failure rat model, a dose-related multiphasic effect of strontium (Sr) on bone formation was found that could be reproduced in an in vitro set-up using primary rat osteoblasts. The results from the latter study allowed us to distinguish between a reduced nodule formation in the presence of an intact mineralization at low Sr-doses (1  Μg/ml) and an interference of the element with the hydroxyapatite (HA) formation at high doses (20–100  Μg/ml). To further investigate the latter effect of Sr on physicochemical bone mineral properties, an in vitro study was set up in which the UMR-106 rat osteosarcoma cell line was exposed to Sr, added to the cell culture medium in a concentration range varying between 0–100  Μg/ml. Temporal growth and functionality of the culture was investigated by measurement of the alkaline phosphatase activity and calcium (Ca) concentration in the culture medium (used as an index of Ca-incorporation, i.e., HA formation) at various time points. At the end of the culture period (14 days post-confluence), samples of the mineralized cultures were taken for further analysis using X-ray diffraction (XRD) and Fourier Transform Infra-Red Spectroscopy (FTIR). Synthetic HA doped with various Sr concentrations (based on the cell culture and previous experimental studies and yielding Sr/(Sr+Ca) ratios ranging from 0–60%), was prepared and examined for crystal growth and solubility. Crystal size was assessed using scanning electron microscopy (SEM). Ca incorporation indicated a reduced mineralization in the 20 and 100  Μg/ml Sr groups vs. controls. Sr-doped synthetic HA showed a significant dose-dependent reduction in crystal growth, as assessed by SEM, and an increase in solubility, apparent from 12.7% Sr/(Sr+Ca) on. Moreover, in both mineralized cultures and synthetic HA, XRD and FTIR analysis showed a reduced crystallinity and altered crystal lattice at similar concentrations. These new data support our previous in vivo and in vitro findings and point to a potential physicochemical interference of Sr with HA formation and crystal properties in vivo.


Strontium Hydroxyapatite X-ray diffraction Mineralization Cell culture 


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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • S. C. Verberckmoes
    • 1
  • G. J. Behets
    • 1
  • L. Oste
    • 1
  • A. R. Bervoets
    • 1
  • L. V. Lamberts
    • 1
  • M. Drakopoulos
    • 2
  • A. Somogyi
    • 2
  • P. Cool
    • 3
  • W. Dorriné
    • 3
  • M. E. De Broe
    • 1
  • P. C. D’Haese
    • 1
  1. 1.Department of Nephrology-HypertensionUniversity of AntwerpAntwerpBelgium
  2. 2.European Synchrotron Radiation FacilityGrenobleFrance
  3. 3.Department of ChemistryUniversity of AntwerpAntwerpBelgium

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