Fig. 1

Influence of irradiation on adhesion of tumor cells to an endothelial cell monolayer. a, b, c Adhesion of glioblastoma cells (U-373 MG, U-87 MG) and breast cancer cells (MDA-MB-231). Tumor cells and primary HUVEC were irradiated with 2 Gy, 4 Gy or 8 Gy. The tumor cells were loaded with calcein, placed on an endothelial cell monolayer, incubated for 4 h and then washed out. The number of adherent tumor cells was determined by measuring the remaining calcein fluorescence. The determined adhesion index was normalized to the adhesion index of non-irradiated TC on non-irradiated EC (100%) (n = 8). TC: tumor cells, EC: endothelial cells. d, e Measurement of adhesion of U 373 MG and MDA-MB-231 cells under flow (n ≥ 3). 30,000 tumor cells/ml irradiated with 4 Gy circulated for 2 h at room temperature over a non-irradiated endothelial monolayer. The number of adherent tumor cells was counted microscopically in three visual fields. Mean values ± SEM are shown. Statistical significance was determined with the Student’s t test: *p < 0.05; **p < 0.01. f, g Representative image of adherent tumor cells (U-373 MG) in the flow chamber. Tumor cells were labeled with calcein (g)