Influence of ~(137)Cs γ-irradiation on morphology and several cytokine mRNA expression of osteoblasts cultured in vitro

Objective To observe the influence of 137 Cs γ-irradiation on morphology and gene expression of osteoblasts cutured in vitro . Methods Osteoblasts were isolated from new-born SD rat crania and cultured in EMEM containing 10% NCS.The osteoblasts of the first passage were irradiated once with 137 Cs γ-rays after cultured for 24 hours.The irradiation doses were 10,25,50 cGy and 1,3,6,9,12 Gy,respectively.Their morphology and ultrastructure were observed under phase-contrast microscope and electronmicroscope.Karyoplasm ratio was determined after Giemsa staining.Total RNA was extracted with TRIzol reagent when the osteoblasts of the first passage were cultured for 14 days.mRNA expressions of insulin-like growth factor-1(IGF-1),osteoprotegerin(OPG) and osteoclast differentiation factor(ODF) were determined with RT-PCR semi-quantitatively and compared among different groups. Results The osteoblasts irradiated with 137 Cs γ-rays over 3 Gy were larger,thinner,containing more nuclei,proliferating slowly, having fewer cell organelles and more lysosomes in the plasma,with decreased ratio of nucleus to plasma.All of the above changes were more obvious with increasing dosage of irradiation.Quantity of IGF-1,OPG,ODF and OPG/ODF mRNA expressions were decreased with increasing dosage of irradiation above 1 Gy.It was obviously correlated with the quantity of irradiation ( P 0.05 or 0.01,respectively). Conclusion By 137 Cs γ-irradiation osteoblasts can be induced to have morphological changes,decreased ability of proliferation,decreased karyoplasms ratio and decreased quantity of IGF-1,OPG,ODF and OPG/ODF mRNA expressions. ;