Reactive oxygen and nitrogen (ROS and RNS) species in irradiated hES cells.

<p>Exponentially growing cultures of hESCs were γ-irradiated and assayed for reactive species using the ROS/RNS-sensitive dye CM-H₂DCF (A), the superoxide-sensitive dye MitoSOX (B), or the nitric oxide-sensitive dye DAF (C). FACS analyses of irradiated hESCs showed increased ROS/RNS, superoxide and nitric oxide over a 72 h post-irradiation interval. Increased levels of these reactive species were in general, found to be dose-responsive at most time points analyzed (A–C). Relative levels of Mn-SOD (as detected by western blotting) correlated inversely with superoxide levels (MitoSox) at a dose of 5 Gy (insert, B). Longer-term analyses conducted 7 days post-irradiation (D) revealed persistent and dose-responsive increases in oxidative stress. Data expressed as the Mean ± S.E.M. of 3–6 independent observations and all values are normalized to controls FACS analyzed on the same day. *, <i>P</i><0.05 and **, <i>P</i><0.01.