Limited DNA damage in human endothelial cells after hyperbaric oxygen treatment and protection from subsequent hydrogen peroxide exposure

Background: In vitro studies on hyperbaric oxygen (HBO) therapy suggest that HBO may cause DNA damage, but this has not been evaluated using endothelial cells. Methods: Human umbilical cord endothelial cells (HUVECs) were exposed either to H(2)O(2) or to HBO for 90 min, with or without subsequent H(2)O(2) exposure. Measurements included the comet assay for DNA damage, and reduced and oxidised glutathione levels. Results: HUVECs showed sensitivity to H(2)O(2) (EC(50) of 0.2 mM for DNA migration). A single 90 min HBO treatment at 2.2 ATA caused a statistically significant (ANOVA. P < 0.05) increase of DNA migration in HUVECs to 6.8 +/- 0.3% (mean +/- SEM, n = 8), which returned to normal levels (4.9 +/- 0.1%, n = 6) after 24 h. Further exposure to 0.2 mM H(2)O(2) after HBO treatment significantly increased the DNA migration in HBO-treated cells immediately post-treatment; but 24 h later the cells showed 22% less DNA damage and higher glutathione than controls. Conclusion: A single HBO exposure causes limited DNA damage to HUVECs, which repairs quickly. HBO treatment protects against H(2)O(2)-induced DNA damage and involves cellular glutathione. Significance: Endothelial cells are unlikely to be compromised during HBO therapy. (C) 2011 Elsevier B.V. All rights reserved.