Fabrication of the high osteoconductive bone replacement

由于生长骨骨骺的成分是含有大量碳酸盐离子的碳酸盐磷灰石，本研究的目的是用碳酸盐磷灰石成分制备高导骨替代物。要实现这一目标，必须解决两个条件。一种是类似于羟基磷灰石的高骨导电性，另一种是类似于自体移植物的骨替代物。本年度，利用成骨细胞、破骨细胞和实验动物对含碳酸盐磷灰石成分骨置换的可行性进行了评价。以方解石块为前驱体制备碳酸盐磷灰石块体。以烧结羟基磷灰石为对照，在碳酸盐磷灰石盘上培养骨髓细胞分化制备成骨样细胞。碳酸盐磷灰石的初始细胞附着、增殖和分化基本相同。在用破骨细胞评价的情况下，作为对照的烧结羟基磷灰石表面未观察到吸收凹坑。然而，在碳酸盐磷灰石盘表面观察到反应凹坑，表明碳酸盐磷灰石可能是骨替代物。下一步，用碳酸盐磷灰石颗粒或烧结羟基磷灰石颗粒重建实验动物骨缺损，进行组织学评价。碳酸盐磷灰石颗粒和烧结羟基磷灰石颗粒均表现出良好的骨导电性，被新生骨覆盖。在碳酸盐磷灰石中，也发现了破骨反应。因此，在本研究的基础上，碳酸盐磷灰石可能是一种理想的骨替代物。

The objective of this research is to fabricate high osteoconductive bone replacement with carbonate apatite composition since composition of the epiphysis of growing bone is carbonate apatite containing larger amount of carbonate ions. For the achievement of this objective two requirements should be solved. One is the high osteoconducitivity similar to hydroxyapatite and the other is the replacement to bone similar to the autograft.In this year, feasibility of the bone replacement with carbonate apatite in its composition was evaluated using osteoblasts, osteoclasts and experimental animal. The carbonate apatite block was prepared using calcite block as precursor.Osteoblast-like cell was prepared by differentiating bone marrow cell was cultured on the carbonate apatite disk using sintered hydroxyapaite as control. It was found that carbonate apatite showed almost the same initial cell attachment, proliferation and differentiation. In the case of evaluation using osteoclasts, no resorption pits were observed on the surface of sintered hydroxyapatite which was used as control. However, resporption pits were observed on the surface of carbonate apatite disk indicating that carbonate apatite could be a bone replacement.As the next step, bone defect made at the experimental animal was reconstructed with carbonate apatite granule or sintered hydroxyapatite granular for the histological evaluation. Both carbonate apatite granular and sintered hydroxyapatite granular showed good osteocondutivity and thus covered with the new bone. In the case of carbonate apatite, osteoclastic resporption was also found.It. was concluded, therefore that carbonate apatite could be an ideal bone replacement based on the result obtained in the present study.