Effect of irradiation on intramembranous ossification

观察x射线照射后成骨细胞的增殖及表型表达的变化。处于活跃增殖、融合和增殖后阶段的成骨细胞样细胞MC3T3-E1接受10gy - x照射。1 ~ 10Gy剂量的辐照使细胞DNA含量降低。另一方面，辐照增强了I型胶原的积累，钙含量与DNA含量归一化。骨钙素mRNA的表达在各阶段均下调，而骨桥蛋白和骨连接素mRNA的表达不变。照射后期每个细胞碱性磷酸酶活性随时间的增加超过对照。碱性磷酸酶阳性细胞的定位与钙化一致。此外，通过能量色散光谱和钙磷比测定，发现钙沉积物的质量与对照相似，即使它们在形态上并不完全相同。综上所述，表型表达的变化与钙化增强密切相关。

Proliferation and changes in the phenotypic expressions of osteoblasts after X-irradiation were investigated. Osteoblast-like cells, MC3T3-E1, at actively proliferating, confluent, and post-proliferation stages were subjected to 10Gy-X-irradiation. One to 10Gy dose of Irradiation decreased the DNA content of cells. On the other hand, irradiation enhanced type I collagen accumulation and Ca content normalized to DNA contents. The expression of osteocalcin mRNA was downregulated by irradiation at all stages, but that of osteopontin and osteonectin mRNAs was unchanged. The time-dependent increase in alkaline phophatase activity per cell exceeded that of the control after irradiation at later stages. The localization of alkaline phophatase positive cells was concordant with that of calcification. In addition, the quality of the calcium deposits was found to be similar to the control by energy dispersive spectrometry and calcium to phosphorus ratio determination, even if they were not exactly the same morphologically. taken together, changes in phenotypic expressions were closely related to calcification enhancement.