A synthetic hydroxyapatite(HAP)of bioactive material is widely used because it has an excellent affinity and bone conduction potential, which remain to be elucidated.
HAP granules with different compositions were made and transplantation into the tibia in rabbits was performed to study initial bone conductivity and long-term stability. It was suggested that they are affected by the Ca:P ratio of HAP, fusing temperature, Mg contents and surface structure.
The growth effects for fusing temperature and Mg in osteoblasts(MC 3 T 3-E 1)with caltific activity were studied to determine the HAP affinity for osseous tissues.
Three kinds of synthetic HAP granules of the same composition, which were heated at 1,100, 1,200 and 1,300℃ of the fusing temperature, were employed. In SEM pictures of each granule before dipping and those of cultured MC 3 T 3-E 1, there were no changes on the surface before and after dipping at 1,100℃, but needle-shaped extractives were observed in MC 3 T 3-E1 at 1,200℃ and 1,300℃.
Each granule was dipped at the rate of 1 mg/ml of α-MEM and kept in a CO
2 incubator for 3 days. Ca, P and Mg contents in the culture solution were measured. Ca and P contents decreased and Mg content increased compared with the control group. MC 3 T 3-E 1 cells derived from the neonatal mouse calvaria on a flat bottom microculture plate with 96 wells(1×10
4/well)were distributed. α-MEM was adjusted to be 5, 25, 50 and 75% of solution, each of which were cultured again in the medium after adding to 10% fetus cow serum under the conditions of 37℃ and 5% CO
2 contents.
3H-TdR of 37 kBq was added after 48 hr and the nonirradiated activity of the
3H-TdR uptake of MC 3 T 3-E 1 after 72 hr was measured as synthetic DNA. The
3H-TdR uptake in the group to which conditioned medium was added at 1,100, 1,200 and 1,300℃ further increased as compared with the control with only α-MEM.
MC 3 T 3-E 1 was cultured in the solution after adding to 100~500 mg/
l of Mg and the
3H-TdR uptake was measured. In the experiment, an increase of
3H-TdR uptake in proportion to the Mg was shown.
In MC 3 T 3-E 1, cell proliferation was induced by the dose-dependent medium, with trace elements that affect osteoblasts. Furthermore, the
3H-TdR uptake of MC 3 T 3-E 1 cells was accelerated by Mg in the solution.
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