Regulation of bone-related genes expression by bone-like apatite in MC3T3-E1 cells

Bone-like apatite on HA/TCP ceramics sintered at 1,100 degrees C (HT1) and 1,200 degrees C (HT2) could be obtained via immersing substrates into simulated body fluid (SBF) for 3 days. When MC3T3-E1 preosteoblastic cells cultured on the surface of the bone-like apatite for 3 days, SEM observations revealed cell membrane features with secreted crystals very similar to in vivo bone formation during intramembranous ossification with a direct bone apposition on the ceramics. According to semi-quantitative RT-PCR method, mRNA expressions of osteocalcin (marker of late-stage differentiation) and type 1 collagen were increased in cultures with HT1S and HT2S when compared to HT1 and HT2 after cultured for 6 days. The results indicated that bone-like apatite had the ability to support the growth of osteoblast-like cells in vitro and to promote osteoblast differentiation by stimulating the expression of major phenotypic markers. Taken together, our findings will be helpful in understanding the mechanism of osteoinductivity of calcium phosphate ceramics and in constructing more appropriate biomimetic substrate.