OBJECTIVEThe aim of this study is to investigate the effects of irradiation on the proliferation and differentiation of MC3T3-E1 osteoblastic cells.

METHODSMC3T3-E1 cells were irradiated 24 h after initial seeding. Gamma-radiation was administered at 0, 4, and 8 Gy as single doses by using a 60Co source. Cell proliferation was assessed at days 1, 3, 5, and 7 post-irradiation by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylte-trazolium bromide assay. The collagen secretion of the cells was measured through sirius red staining at day 12 post-irradiation. The expressions of osteogenesis-related genes were assessed through real time fluorescence quantitative polymerase chain reaction at day 16 post-irradiation. The matrix mineralization caused by cells was evaluated through alizarin red staining at day 28 post-irradiation.

RESULTSThe cells exposed to 4 Gy or 8 Gy demonstrated significantly lower proliferation rates compared with the non-irradiated group. Doses of 4 Gy or more significantly inhibited the expressions of osteogenesis-related genes (Osterix and osteocalcin). Collagen secretion and cell mineralization were significantly reduced by the 8 Gy dose.

CONCLUSION60Co gamma-rays dose-dependently suppress the proliferation, collagen secretion, and mineralization of MC3T3-E1 cells. Furthermore, radiation seems to dose-dependently inhibit the expressions of osteogenesis-related genes of the cells.

Cell Differentiation ; Cell Line ; Cell Proliferation ; Humans ; In Vitro Techniques ; Osteoblasts ; Osteocalcin ; Osteogenesis

Objective:To investigate the effects of titanium surface modified by micro-arc oxidation (MAO)on the collagen secre-tion and the expression of osteogenesis-related genes of MC3T3-E1 cells.Methods:Pure titanium discs were divided into two groups:Titanium with modified surface by MAO(MAO group)and titanium with polished surface(PT group).Tissue culture polysty-rene plates (TC)were used as controls.Surface morphology of the samples was examined by field-emission scanning electron micros-copy(FESEM).Surface roughness of samples was measured by surface roughness meter.MC3T3-E1 cells were cultured on the sur-face of the samples and the collagen secretion on the samples was measured by sirius red-based colorimetric microassay after 12 days of culture.On day 16 of culture,the expression of osteogenesis-related genes was examined by RT-PCR.Results:A porous oxide layer was observed on the surface of MAO treated samples and the surface roughness was more than that of PT group(P<0.01 ). Cells in MAO group showed higher collagen secretion than in PT or TC groups(P<0.05).MAO treated surface induced higher OSX, COL-Iα1 and OPN expression than PT.Conclusion:MAO treated titanium surface may induce more collagen secretion of MC3T3-E1 cells than PT.