FIG. 7.

Increased antioxidant activity inhibits hUCB-MSCs from undergoing cellular senescence following ionizing radiation. (A) MSC1 hUCB-MSCs, pretreated with 200 U/mL of PEG-catalase for 24 h, were irradiated with γ-rays. One day after irradiation, cells were immunostained using the anti-Ki-67 antibody (upper panel). DAPI staining was used to visualize nuclei. The relative proportion of Ki-67–stained cells is shown in the plot (lower panel). The results of 3 independent experiments were averaged. P value was 0.037. (B) Two or 4 days after irradiation, MSC1 cells were stained using SA-β-Gal and viewed under a phase-contrast microscope (upper panel). The graph represents the percentage of SA-β-Gal–stained cells at 4 days after irradiation (lower panel). IR, γ-irradiation.