The kinetic and biological activity of different loaded rhBMP-2 calcium phosphate cement implants in rats

  1. Esther W. H. Bodde1,
  2. Otto C. Boerman2,
  3. Frans G. M. Russel3,
  4. Antonios G. Mikos4,
  5. Paul H. M. Spauwen5,
  6. John A. Jansen1,*

Article first published online: 15 JAN 2008

DOI: 10.1002/jbm.a.31830

Issue

Journal of Biomedical Materials Research Part A

Journal of Biomedical Materials Research Part A

Volume 87A, Issue 3, pages 780–791, 1 December 2008

Additional Information

How to Cite

Bodde, E. W. H., Boerman, O. C., Russel, F. G. M., Mikos, A. G., Spauwen, P. H. M. and Jansen, J. A. (2008), The kinetic and biological activity of different loaded rhBMP-2 calcium phosphate cement implants in rats. Journal of Biomedical Materials Research Part A, 87A: 780–791. doi: 10.1002/jbm.a.31830

Author Information

  1. 1

    Department of Periodontology and Biomaterials, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands

  2. 2

    Department of Nuclear Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands

  3. 3

    Department of Pharmacology and Toxicology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands

  4. 4

    Department of Bioengineering, Rice University, Houston, Texas

  5. 5

    Department of Plastic and Reconstructive Surgery, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands

*Department of Periodontology and Biomaterials, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands

Publication History

  1. Issue published online: 24 OCT 2008
  2. Article first published online: 15 JAN 2008
  3. Manuscript Accepted: 18 OCT 2007
  4. Manuscript Revised: 17 SEP 2007
  5. Manuscript Received: 2 JUN 2007

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Keywords:

  • BMP;
  • drug release;
  • calcium phosphate cement;
  • PLGA;
  • bone regeneration

Abstract

The healing of large bone defects can be improved by osteogenic bone graft substitutes, due to growth factor inclusion. A sustained release of these growth factors provides more efficient bioactivity when compared with burst release and might reduce the dose required for bone regeneration, which is desirable for socioeconomical and safety reasons. In this study, we compared different rhBMP-2 loadings in a sustained release system of CaP cement and PLGA-microparticles and were able to couple kinetic to biological activity data. Fifty-two rats received a critical-size cranial defect, which was left open or filled with the cement composites. The implants consisted of plain, high, and five-fold lower dose rhBMP-2 groups. Implantation time was 4 and 12 weeks. Longitudinal in vivo release was monitored by scintigraphic imaging of 131I-labeled rhBMP-2. Quantitative analysis of the scintigraphic images revealed a sustained release of 131I-rhBMP-2 for both doses, with different release profiles between the two loadings. However, around 70% of the initial dose was retained in both implant formulations. Although low amounts of rhBMP-2 were released (2.4 ± 0.8 μg in 5 weeks), histology showed defect bridging in the high-dose implants. Release out of the low-dose implants was not sufficient to enhance bone formation. Implant degradation was limited in all formulations, but was mainly seen in the high-dose group. Low amounts of sustained released rhBMP-2 were sufficient to bridge critically sized defects. A substantial amount of rhBMP-2 was retained in the implants because of the slow release rate and the limited degradation. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008

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