Effects of Strontium on the Physicochemical Characteristics of Hydroxyapatite

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• 作者：S. C. Verberckmoes ; G. J. Behets ; L. Oste ; A. R. Bervoets ; L. V. Lamberts ; M. Drakopoulos ; A. Somogyi ; P. Cool ; W. Dorriné and M. E. De Broe ; et al.
• 关键词：Strontium ; Hydroxyapatite ; X ; ray diffraction ; Mineralization ; Cell culture
• 刊名：Calcified Tissue International
• 出版年：2004
• 出版时间：November 2004
• 年：2004
• 卷：75
• 期：5
• 页码：405-415
• 全文大小：456 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Biochemistry
  Endocrinology
  Orthopedics
  Cell Biology
  
• 出版者：Springer New York
• ISSN：1432-0827

文摘

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 g/ml) and an interference of the element with the hydroxyapatite (HA) formation at high doses (20–100 g/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 g/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 g/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.