| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
1.Effect of diluted HC1 treatment for material induced osteoinduction
Dilute HC1 treatment effectively removed sodium from the sodium titanate layer of alkali-treated porous titanium and contributed to the formation of the titania layer on the surface of porous bioactive titanium. In addition, dilute HC1-treated porous bioactive titanium (HC1-AH implant) possessed a more complex surface than conventional porous bioactive titanium. We have confirmed better osteoinductivity of the HC1-AH implant, which induced ectopic bone growth in the back muscles of beagle dogs within 3 months. Furthermore, the HC1-AH implant exhibited long-lasting bioactivity over one year, which was confirmed using orthotopic implantation in a rabbit model, intramuscular implantation and lumbar interbody fusion in a canine model.
2.Relation of EP4 agonist to material induced osteoinduction
Porous b-TCP, which has osteoinductive ability was implanted in dog dorsal muscle. EP4 agonist of 10μg/kg/3weeks was injected and t
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he implants were extracted 3, 6, and 12 weeks after. The effect of EP4 agonist to osteoinduction and degradation of implants were evaluated histologically. At 6weeks, implants of injected group showed abundant bone formation more than those of control group. At 12 weeks, the implants of injected group degraded rapidly. At 3 and 6 weeks, TRAP positive cells appeared in injected group more than control group. These data indicated that EP4 agonist enhanced bone formation and degradation of porous b-TCP by stimulating not only osteoblast differentiation but also osteoclastgenesis.
3.The elucidation of osteoinduction mechanism by calcium deficient hydroxyapaite.
Porous CDHA blocks (Ca/P, 1.61; porosity, 70-78%; average pore size, 300um ; φ4 × 4mm cylinder) were implanted into the dorsal muscle of five beagle dogs and five SD rats, for periods of 1, 2, 3, 4, 5, 6 or 8 weeks. In the specimens extracted from the dogs, newly bone formation was observed on weeks 4, whereas in the rats, no bone formation was detected within 8 weeks in all implants. In the dogs, some TRAP positive multinucleated cells were observed in the peripheral region of the implant on weeks 1 and 2. After week 3, a large number of TRAP positive cells were detected in all regions of the implant (Fig. 2A). In the rats, a small number of TRAP positive cells were observed in only the peripheral region of implant on all weeks. According to the TEM observation, multinucleated cells in the specimens extracted from the dogs, showed the polar localization of nuclei and ruffled border-like structures, which were characteristic of osteoclasts. However, in the specimens extracted from the rats, they showed no osteoclast-like structure. The data of RT-PCR have not shown the difference between the dogs and rats. Based on these results, it was suggested that osteoclast-like multinucleated cell is one of the key factors to have osteoinductivity. Less
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