| 1848 Ectopic Bone Induction by RhBMP-2 Released from Biomimetic Coatings on Titanium Implants | ||
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Y.M. LIU1, E.B. HUNZIKER2, and K. DE GROOT1, 1 Leiden University, IsoTis NV, Biothoven, Netherlands, 2 ITI Research Institute for Dental and Skeletal Biology, Bern, Switzerland We have recently shown that recombinant human bone morphogenetic protein 2 (rhBMP-2) can be co-precipitated with calcium phosphate layers onto the surfaces of titanium-alloy (Ti6Al4V) implants and retain its bioactivity as an osteoinductive agent. Objective: To investigate if biomimetically incorporated rhBMP-2 is effective for the acceleration and intensification of bone formation activities by a slow release mode over an extended period of time. Methods: Calcium phosphate coatings were deposited upon the surfaces of Ti6Al4V discs (Ø 1cm). Samples were immersed in 5-times concentrated simulated body fluids for 24 hours of 37oC and then in supersaturated solutions of calcium phosphate (pH 7.4) containing rhBMP-2 (at 10mg/l) for 48 hours at 37oC under sterile conditions. Such Ti6Al4V discs (n=6) were implanted subcutaneously in rats. Samples were retrieved at 7-days intervals over a period of 5 weeks and subjected to histological, histomorphometrical and statistical analysis. Results: Bone formation occurred after two weeks implantation and continued till 5 weeks. Bone deposited directly upon the coated surface of each implant with a long distance effect and it had been formed by an intramembranous mechanism. The total bone volume increased significantly (p<0.005) from 3.0mm3 per disc at week 2 to 5.4mm3 at week 3. The highest net rate of bone formation was 0.43mm3 per disc per day during 5 weeks implantation time. The coating was continually degraded over the implantation time. After 5 weeks, approximately one third of coating volume was removed. Conclusion: Biomimetic calcium phosphate coatings act as suitable carriers for rhBMP-2, the biopotency of which remains unchanged after its release at a sufficiently slow rate and in adequate quantities to induce ecotopic bone formation. This system is of great potential value for implants to be used in orthopedic and dental surgery.
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| Seq #193 - Implant Histology and Bone Regeneration 1:45 PM-3:45 PM, Friday, 27 June 2003 Svenska Massan H1 | ||
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