EFFECTS OF HYPERBARIC OXYGEN EXPOSURE ON MOBILIZATION OF ENDOTHELIAL PROGENITOR CELLS IN HEALTHY VOLUNTEERS

Background: Hyperbaric oxygen therapy (HBO) has been successfully utilized for the treatment of a wide variety of diseases, including diabetes mellitus, osteomyelitis and radiation induced necrotic lesions. These diseases are characterized by significant vascular damage and prolonged wound healing process. HBO has been recently shown to mobilize stem/progenitor cells from the bone marrow. Because of its potential to promote neovascularization it is believed that HBO contributes to vascular damage recovery. In this study we questioned whether hyperbaric oxygen therapy might exert pro-angiogenic effects via the modulation of endothelial progenitor cells. Methods: Peripheral blood samples were collected from 15 healthy human volunteers (5 women and 10 men; mean age: 49.4 +/- 2.56 years; body weight: 70.3 +/- 4.58 kg; height: 1.67 +/- 4.19 m) before and after exposure to hyperbaric oxygen (n= 8) for 20 days (90 min at 2.4 ATA once a day) and exposure to hyperbaric compressed air (n= 7), for 90 minutes at 2.4 ATA twice per day for 20 days. Flow cytometry immunophenotypic analysis was performed on these samples to identify and enumerate endothelial progenitor cells. Results: Our results show a significant effect of hyperbaric oxygen therapy on surface markers of endothelial progenitor cells in healthy volunteers. The number of CD34/CD133-expressing cells increased in volunteers after both the 1st (p < 0.02) and the 10th HBO exposures (p < 0.05). HBO group shows also significant increase of CD34/CD133/VEGFR-2 -expressing cells only at 1st treatment (p < 0.05), compared to basal values, returning to normal values at wash out. Conclusion: HBO might induce modulation of endothelial progenitor cells biology and this mechanism could initiate clinical benefits exerted by neoangiogenesis and neovascularization.