The effect of adsorbed vitamin D and K to hydroxyapatite on ALP activity of MC3T3-E1 cell

This study describes the adsorptive property of vitamins on HA and the effect of the HA adsorbed vitamin on the alkaline phosphatase (ALP) activity for effective use as a bone graft substitute. The vitamins used were calciferol (D(3)), menaquirone (K(2)) and 25-hydroxycholecalciferol (25(OH)D(3)). These vitamins were adsorbed on HA at 4, 10, 20, 37 and 50 degrees C. The adsorption amount was constant below 20 degrees C, and decreased as the incubation temperature increased over 20 degrees C. The order of the adsorption amount was: 25(OH)D(3) > K(2) > D(3). The HA adsorbed vitamins (HA/D(3), HA/25(OH)D(3) and HA/K(2)) were suspended in physiological saline for 48 h for the release test. The release ratio of all vitamins increased with incubation time. The order of the release ratio was: 25(OH)D(3) > K(2) > D(3), which was proportional to that of the adsorption amount. The ALP activity of MC3T3-E1 osteoblast-like cells on HA, HA/D(3), HA/25(OH)D(3) and HA/K(2) was also investigated. The ALP activity was higher on HA/25(OH)D(3) than on any other samples. However, HA/K(2) and HA/D(3) showed similar ALP activity to HA.