Artikel
Reconstruction of a Critical Sized Segmental Bone Defect in the Ovine Tibia by Tissue Engineering Methods
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Autoren
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J.C. Reichert
- Institue of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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D.R. Epari
- Institue of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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S. Saifzadeh
- Institue of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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G.N. Duda
- Charité - Universitätsmedizin Berlin, Centrum für Muskuloskeletale Chirurgie, Berlin, Germany
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M.A. Schuetz
- Queensland University of Technology, Institute of Health and Biomedical Innovation, Brisbane, Australia
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D.W. Hutmacher
- Institue of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| Veröffentlicht: | 21. Oktober 2010 |
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Gliederung
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Objective: Current approaches for segmental bone defect reconstruction are restricted to autografts and allografts, and metal or ceramic-based implants. Bone grafts possess osteoconductive, osteoinductive, and osteogenic properties, but face significant disadvantages. As a result, research focuses on the development of alternative concepts and the field of tissue engineering has emerged as an important approach to bone regeneration. The objective of the current study was to develop an alternative therapeutic approach to bone grafting by evaluating the regenerative potential of mPCL-TCP scaffolds in combination with and without rhBMP-7 in a large animal model and to compare the outcomes with the application of autologous bone graft (ABG) from the iliac crest.
Methods: A 3 cm mid-diaphyseal defect was created in the right tibia of merino sheep and stabilized. Defects were left untreated (n=8), reconstructed with ABG from the left iliac crest (n=8) or a cylindrical mPCL-TCP scaffold (height: 3 cm, diameter: 2 cm, porosity 70%; Osteopore, Singapore) with (n=8) or without (n=8) rhBMP-7 (3.5 mg, OP-1 implant, Stryker). Animals were held for 12 weeks and allowed unrestricted weight-bearing. Conventional X-rays were taken after surgery and after 6 and 12 weeks. Native CT scans were performed after sacrifice. 3D reconstructions were generated, qualitative and quantitative analysis was performed to assess mineralization and bridging. A torsion test was conducted at an angular velocity of 0.5 deg/s until fracture. The contralateral tibia was used as a paired reference. Defects were then scanned in a µCT and processed for histology (PMMA and paraffin). Statistical analysis was carried out using a one-tailed Mann-Whitney-U-test (SPSS) and p-values <0.05 were considered significant.
Results and conclusions: Conventional X-ray and CT analysis after 12 weeks confirmed the critical nature of the defect. None of the empty control defects showed signs of bridging and were filled with soft tissue only. Only minor bone formation was observed in the scaffold group, however full defect bridging had occurred in all defects reconstructed with ABG or mPCL-TCP with rhBMP-7. Scaffolds showed good osseointegration without any signs of resorption. Biomechanical testing revealed a significant higher torsional moment and stiffness for the ABG and rhBMP-7 groups when compared to the mPCL-TCP group. No significant differences were found between the ABG and rhBMP-7 group. However, the rhBMP-7 treatment tended to result in higher values for both torsional moment and stiffness.
The study results suggest that mPCL-TCP scaffolds combined with a biologically active stimulus such as rhBMP-7 can serve as an equivalent alternative to ABG in the early phase of defect regeneration. These findings however must be confirmed by long-term studies currently underway.
