| Budget Amount *help |
¥3,940,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
In order to maintain biocompatibility inside the human body, metallic implants must possess high corrosion resistance. The purpose of this work was to investigate the mechanism behind the release of metal ions from implant materials into the surrounding tissue. In this study, the authors examined the biological effects (based on (a) adhesion of cells and (b) cell metabolic activity) of biofilms formed by L929 fibroblastic cells and U937 macrophages on the corrosion resistance of a pure nickel plate. Pure Ni is not actually used as a biomaterial, but Ni, which corrodes easily, was used to investigate variations in metal ion release under different experimental conditions, and to clarify the corrosion mechanism.
We studied on the affect of adhesive cells on the corrosion resistance of implant metal. L929 fibroblastic cells, which were adhered on the surface of the metals, were cultured for 3 days. Then, the concentration of Ni ion dissolved to the cultured medium was measured with the ICP
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analyzer.
About pure Ni, the amount of Ni ion concentration was increased with the cell density. For NiTi alloy, the amount of dissolution of Ni ion was slighter than that of pure Ni, but the correlation of the concentration between Ni ion and the cell density was significant. On the other hand, when the protein of the cell was fixed with 10% formaldehyde solution, the dissolved Ni ion concentration was slightly compared with that of the living cells. As the results, it was suggested that the corrosion resistance of implant metal was closely depended on the existence of the living adhesive cells. The following conclusions have been reached in this study on the effect of metallic corrosion with cell. (1) The corrosion rate of metallic implant in vitro, the presence of the cell adhesion is controlled. An anchorage-dependent cell (L929) was promoted the release of metallic ions. (2) The metabolic activity of the cell influenced metallic corrosion. The cells that were lost the biological activities did not promote the metal corrosion even if the cells were adhered. Cell adhesion molecules (CAMs) such as fibronectin hardly promoted the release of metallic ions. Less
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