Using Hyperbaric Oxygen to Improve the Radiosensitivity of Human U251 Glioma Cells

The aim of this study was to explore the use of hyperbaric oxygen to enhance the radiosensitivity of human glioma cells. Sub-cultured U251 human glioma cells were randomly divided into four groups: an untreated control group, cells treated with hyperbaric oxygen (HBO) only, cells treated with X-ray irradiation (X-ray) only, and cells treated with both HBO and X-ray. Cell morphology, cell proliferation activity, cell cycle distribution, and apoptosis were observed in these groups to evaluate the role of HBO in improving the radiosensitivity of glioma cells. With the increase in X-ray doses (0 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy), the survival fraction (SF) of glioma cells gradually decreased. Significantly lower SF was observed for the cells treated with the HBO and X-ray together than in the X-ray group for each dose (all P < 0.05). The proliferation inhibition was significantly higher in the HBO combined with X-ray group than in the X-ray group for each dose (all P < 0.05) for the U251 cell line. The percentage of G2/M phase cells was significantly higher in the HBO combined with X-ray (2 Gy) group (26.70% ± 2.46%) and the HBO group (22.36% ± 0.91%) than in the control group (11.56% ± 2.01%) and X-ray (2 Gy) group (10.35% ± 2.69%) (all P < 0.05). U251 cell apoptosis was significantly higher in the HBO combined with X-ray (2 Gy) group than in the HBO group, the X-ray (2 Gy) group, and the control group (all P < 0.05). We conclude that HBO can enhance the proliferation inhibition and apoptosis of glioma U251 cells by blocking glioma cells in the G2/M phase and improve the radiosensitivity of U251 glioma cells.