Bound phosphoproteins enhance mineralization of alkaline phosphatase-collagen complexes in vivo

Authors

  • DR. Theo van den Bos,

    Corresponding author
    1. Experimental Oral Biology Group, Department of Periodontology, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands
    2. Department of Cell Biology and Histology, Academic Medical Centre, University of Amsterdam, The Netherlands
    • Exp. Oral Biology Group Laboratory of Cell Biology and Histology Meibergdreef 15 1105 AZ Amsterdam, The Netherlands
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  • Wouter Beertsen

    1. Experimental Oral Biology Group, Department of Periodontology, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands
    2. Department of Cell Biology and Histology, Academic Medical Centre, University of Amsterdam, The Netherlands
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Abstract

Phosphoproteins (PP) covalently bound to a collagenous matrix have been reported to promote its mineralization in vitro. It was the aim of the present study to determine whether PP also enhance the mineralization of collagen in vivo. To this end, collagen slices were prepared from demineralized bovine cortical bone. Following immobilization of rat dentin phosphoprotein (PP) to the slices, bovine intestinal alkaline phosphatase (ALP) was bound according to the SATA-MHS coupling method. Controls were without enzyme. The slices were implanted into skin pockets prepared over the skull of female Wistar rats (6–10 weeks old). After 3–31 days the implants were removed and analyzed for calcium and phosphate content. It was shown that slices of PP-treated bone collagen mineralized more rapidly and to a greater extent than bone collagen slices without PP. Controls remained free of mineral. It is concluded that mineralization of collagenous matrices, induced by alkaline phosphatase, is enhanced by bound phosphoproteins following implantation in subcutaneous connective tissue.

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