Platelets stimulate proliferation of bone cells: involvement of platelet-derived growth factor, microparticles and membranes

Authors

  • Reinhard Gruber,

    1. Reinhard Gruber, Georg Watzek, School of Dentistry, Department of Oral Surgery, University of Vienna, and Ludwig Boltzmann Institute of Implantology, Vienna, Austria
      Franz Varga, Ludwig Boltzmann Institute of Osteology, Hanusch Hospital, Vienna, Austria
      Michael B. Fischer, Department of Transfusion Medicine University of Vienna, Vienna, Austria
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  • Franz Varga,

    1. Reinhard Gruber, Georg Watzek, School of Dentistry, Department of Oral Surgery, University of Vienna, and Ludwig Boltzmann Institute of Implantology, Vienna, Austria
      Franz Varga, Ludwig Boltzmann Institute of Osteology, Hanusch Hospital, Vienna, Austria
      Michael B. Fischer, Department of Transfusion Medicine University of Vienna, Vienna, Austria
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  • Michael B. Fischer,

    1. Reinhard Gruber, Georg Watzek, School of Dentistry, Department of Oral Surgery, University of Vienna, and Ludwig Boltzmann Institute of Implantology, Vienna, Austria
      Franz Varga, Ludwig Boltzmann Institute of Osteology, Hanusch Hospital, Vienna, Austria
      Michael B. Fischer, Department of Transfusion Medicine University of Vienna, Vienna, Austria
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  • Georg Watzek

    1. Reinhard Gruber, Georg Watzek, School of Dentistry, Department of Oral Surgery, University of Vienna, and Ludwig Boltzmann Institute of Implantology, Vienna, Austria
      Franz Varga, Ludwig Boltzmann Institute of Osteology, Hanusch Hospital, Vienna, Austria
      Michael B. Fischer, Department of Transfusion Medicine University of Vienna, Vienna, Austria
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Reinhard Gruber, Ph.D.,
School of Dentistry
Department of Oral Surgery
University of Vienna
Waehringerstraße 25a
A-1090 Vienna
Austria
Tel: + 43 4277 67152
Fax: + 43-1-4277-67159
e-mail: reinhard.gruber@akh-wien.ac.at

Abstract

Abstract: Platelets have been implicated in accelerated bone regeneration in grafting applications. The beneficial effects of platelets may involve their ability to stimulate the proliferation of osteoblasts. We therefore determined the mitogenic response of human trabecular bone-derived cells to human platelets and supernatants of thrombin-activated platelets. We can show a ∼ 50-fold increase in DNA-synthesis of bone cells (BC) cultured in the presence of platelets as determined by [3H]-thymidine incorporation. Preventing cell-to-cell contact by a membrane filter did not abrogate the stimulatory effect, indicating the release of soluble factor(s) that are mitogenic for BC. The lipid fraction of the platelets had no effect on [3H]-thymidine uptake into the DNA of BC. Platelet-released supernatant (PRS) increased the rate of [3H]-thymidine incorporation to ∼ 20-fold and retained 56% of their activity after incubation at 56 °C, and 27% at 100 °C, respectively. Neutralizing antibodies raised against platelet-derived growth factor (PDGF) partially suppressed the mitogenic potential of PRS. Gel exclusion chromatography analysis showed that molecules ranging from 25 kDa to more than 70 kDa within the PRS can stimulate BC proliferation. The highest amount of PDGF was detected in fractions corresponding to a molecular weight of 28–37 kDa as determined by immunoassay. The mitogenic activity was not restricted to soluble growth factors because microparticles in the PRS and platelet membranes also increased BC proliferation. Our data indicate that native platelets, the respective PRS, microparticles, and platelet membranes can stimulate the mitogenic activity of BC, thereby contributing to the regeneration of mineralized tissue.

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