Effects of alpha-TCP and TetCP on MC3T3-E1 proliferation, differentiation and mineralization.

Calcium phosphates with high solubility in water such as alpha-tricalcium phosphate (alpha-TCP) and tetracalcium phosphate (TetCP) have received considerable attention as components of bone-substitution materials. However, the osteoblast response to these materials has not yet been clearly understood. This study examined the effects of alpha-TCP and TetCP on osteoblast proliferation, differentiation and mineralization in the culture system of MC3T3-E1 cells. Cells were cultured in a differentiation medium with or without alpha-TCP or TetCP at 1 or 10 microM, and the number of cells attached to the culture plates was determined. To examine osteoblast differentiation, the alkaline phosphatase (ALP) activity was measured and the expression of osteoblastic markers analyzed by RT-PCR. In addition, mineralization was evaluated by staining the calcium deposit with Alizalin red. Culture in the presence of alpha-TCP or TetCP showed no significant influence on cell proliferation. ALP activities of the cells were enhanced by both calcium phosphates for 3d and the expression of type I collagen was promoted at 12h and 1d after incubation. Enhancement of bone-like tissue formation by the addition of alpha-TCP or TetCP at 10 microM was observed after 7d incubation and thereafter. The results of the present study indicate that alpha-TCP and TetCP promote osteogenesis by increasing collagen synthesis and calcification of the extra-cellular matrix.