受照脑胶质瘤细胞诱导神经干细胞旁效应

目的 探讨受照脑胶质瘤细胞U251是否可通过在未受照神经干细胞（NSCs）中产生旁效应从而影响神经干细胞的增殖、干性及分化等特性。方法 将细胞分为NSCs组、NSCs+U251组（与U251共培养的NSCs）和NSCs+受照U251组（与10 Gy X射线照射后的U251共培养的NSCs）。采用插入式小室共培养U251和NSCs。通过细胞计数、测量神经球直径等方法评估NSCs增殖、成球能力的变化；采用免疫荧光实验检测Nestin蛋白的表达评估NSCs干性维持能力的变化；检测Tuj1、GFAP蛋白的表达、测量分化后神经元细胞的树突数目、轴突长度以及胶质细胞突起终端数、突起长度等评估神经干细胞分化能力的变化情况。结果 NSCs+受照U251组的细胞数量明显低于NSCs+U251组（t=2.52，P<0.05）；NSCs+受照U251组的Nestin阳性率和成球能力明显低于NSCs+U251组（t=-3.50，P<0.05）；NSCs+受照U251组向神经元和胶质细胞（t=6.09，P<0.05）分化的比例和程度也明显低于NSCs+U251组。结论 受照胶质瘤细胞可通过电离辐射旁效应显著抑制未受照神经干细胞的增殖、干性和分化能力。

Irradiated glioma cells induce bystander effects in neural stem cells

Objective To investigate whether irradiated U251 glioma cells can induce bystander effects in unexposed neural stem cells (NSCs) thus affecting its proliferation, stemness and differentiation. Methods The cells were divided into NSCs group, NSCs+U251 group (co-cultured with U251) and NSCs+ IR U251 group (co-cultured with 10 Gy irradiated U251). Glioma cells and NSCs were co-cultured in a transwell insert set. Cell counting and neurosphere diameter measuring were carried out to evaluate the proliferation and neurosphere formation ability of NSCs. Immunofluorescence assay was performed to detect the expression of Nestin protein to evaluate the stemness maintenance of NSCs, and to measure the expression levels of Tuj1 and GFAP proteins, the number of neuronal dendrites, synaptic length, the number of glial protrusions, as well as the length of glial protrusions. Results The number of NSCs cultured with irradiated U251 cells was obviously smaller than that of NSCs cultured with sham-irradiated U251 cells (t=2.52, P<0.05). The neurosphere formation ability of NSCs and the percentage of Nestin positive NSCs after co-culture with irradiated U251 cells significantly reduced in comparison with those after co-culture with sham-irradiated U251 cells (t=-3.50, P<0.05). The percentages and the extent of NSCs differentiating into neuronal cells and glial cells(t=6.09, P<0.05)decreased obviously after co-culture with irradiated U251 cells in comparison with those after co-culture with sham-irradiated U251 cells. Conclusions Irradiated glioma cells can significantly inhibit the proliferation, stemness and differentiation of unexposed NSCs due to bystander effect.