gms | German Medical Science

Deutscher Kongress für Orthopädie und Unfallchirurgie
72. Jahrestagung der Deutschen Gesellschaft für Unfallchirurgie, 94. Tagung der Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie und 49. Tagung des Berufsverbandes der Fachärzte für Orthopädie und Unfallchirurgie

22. - 25.10.2008, Berlin

Bone sialoprotein coating of materials improves osteogenic cell differentiation in vitro but does not enhance in vivo bone formation

Meeting Abstract

  • S. Schaeren - Orthopädische Klinik, Universitätspital, Basel, Switzerland
  • C. Jaquiéry - Wiederherstellungschirurgie, Universitätspital, Basel, Switzerland
  • E. Schultz-Thater - Institut für chirurgische Forschung, Universitätsspital, Basel, Switzerland
  • F. Wolf - Institut für chirurgische Forschung, Universitätsspital, Basel, Switzerland
  • M. Heberer - Institut für chirurgische Forschung, Universitätspital, Basel, Switzerland
  • I. Martin - Institut für chirurgische Forschung, Universitätsspital, Basel, Switzerland

Deutscher Kongress für Orthopädie und Unfallchirurgie. 72. Jahrestagung der Deutschen Gesellschaft für Unfallchirurgie, 94. Tagung der Deutschen Gesellschaft für Orthopädie und Orthopädische Chirurgie, 49. Tagung des Berufsverbandes der Fachärzte für Orthopädie. Berlin, 22.-25.10.2008. Düsseldorf: German Medical Science GMS Publishing House; 2008. DocPO12-1546

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dkou2008/08dkou642.shtml

Veröffentlicht: 16. Oktober 2008

© 2008 Schaeren et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

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Objective: Engineering cell-based bone graft substitutes requires the use of suitable scaffolds, capable to ‘prime’ osteoprogenitor cells (e.g., bone marrow stromal cells, BMSC) to deposit bone matrix. As opposed to ceramic-based materials, scaffolds made of synthetic polymers without a calcium phosphate component have clear advantages in terms of mechanical properties and handling, but have never been reported to be osteogenic when loaded with osteoprogenitor cells. Bone sialoprotein (BSP) is an extracellular non-collagenous matrix protein playing a key role in the initial phase of deposition of a bone tissue matrix. The goal of this study was to test the hypothesis that coating with BSP of different substrate materials will enhance BMSC differentiation in vitro and bone formation in vivo. In particular, we assessed whether BSP coating of scaffolds made of synthetic polymers would make them osteogenic in an ectopic model, when loaded with BMSC.

Methods: Tissue culture treated polystyrene 24-well plates, ceramic (β-tricalciumphosphate, Osteologic™) and synthetic polymer (Polyactive™) discs of corresponding size were coated with human recombinant BSP in concentrations of 1 and 10ug/ml and analysed for the effective presence of BSP using fluorescence microscopy and ELISA tests. Human bone marrow stromal cells (BMSC) were seeded in the substrates and harvested after 10 and 20 days in culture with osteogenic medium. Real time RT-PCR was used to assess the mRNA expression of osteogenic markers, namely BSP and osteopontin (OP). Porous 3D scaffolds made of the same ceramic and polymer materials as detailed above were also coated with BSP, loaded with BMSC and implanted subcutaneously in nude mice. After 8 weeks, mice were sacrificed and explants were assessed histologically and by computerized histomorphometry.

Results: Coating analyses confirmed the adsorption of BSP on the different substrates, in a dose-dependent fashion. BSP coating of ceramic and of synthetic polymer substrates up-regulated in vitro mRNA expression of BSP (by up to respectively 4.4 and 7.0 fold) and OP (by respectively 3.1 and 6.7 fold). However, BSP coating did not increase the total amount of bone formed in vivo in ceramic-based scaffolds and did not support bone formation using synthetic polymer scaffolds.

Conclusion: Despite the promising in vitro data, our results indicate that BSP coating of ceramic or synthetic polymer materials does not enhance in vivo formation of bone tissue. The study indicates that presentation of BSP to BMSC is not sufficient to prime their functional osteoblastic differentiation on polymeric substrates, and thus reinforces the importance of a ceramic component in a scaffold to be used for BMSC-based bone tissue engineering approaches.