No abstract

Hyperbaric oxygen (HBO) therapy has been used as an adjunctive therapy for diabetic foot ulcers, although its mechanism of action is not completely understood. Recently, it has been shown that HBO mobilizes the endothelial progenitor cells (EPCs) from bone marrow that eventually will aggregate in the wound. However, the gathering of the EPCs in diabetic wounds is impaired because of the decreased levels of local stromal-derived factor-1α (SDF-1α). Therefore, we investigated the influence of HBO on hypoxia-inducible factor 1 (HIF-1), which is a central regulator of SDF-1α and is down-regulated in diabetic wounds. The effects of HBO on HIF-1α function were studied in human dermal fibroblasts, SKRC7 cells, and HIF-1α knock-out and wild-type mouse embryonic fibroblasts using appropriate techniques (Western blot, quantitative polymerase chain reaction, and luciferase hypoxia-responsive element reporter assay). Cellular proliferation was assessed using H(3) -thymidine incorporation assay. The effect of HIF in combination with HBOT was tested by inoculating stable HIF-1α-expressing adenovirus (Adv-HIF) into experimental wounds in db/db mice exposed to HBO. HBO activates HIF-1α at several levels by increasing both HIF-1α stability (by a non-canonical mechanism) and activity (as shown both by induction of relevant target genes and by a specific reporter assay). HIF-1α induction has important biological relevance because the induction of fibroblast proliferation in HBO disappears when HIF-1α is knocked down. Moreover, the local transfer of stable HIF-1α-expressing adenovirus (Adv-HIF) into experimental wounds in diabetic (db/db mice) animals has an additive effect on HBO-mediated improvements in wound healing. In conclusion, HBO stabilizes and activates HIF-1, which contributes to increased cellular proliferation. In diabetic animals, the local transfer of active HIF further improves the effects of HBO on wound healing.

Introduction Cancer is affecting a growing number of persons. Still, the treatment and survival of cancer is improving. Radiation therapy is used in the treatment of cancer. Late radiation-induced injuries afflict 5-15% of irradiated patients. The urinary bladder and bowel may be affected after irradiation of cancer in the pelvic region. Symptoms can be severe, with impaired health related quality of life (HRQoL). Hyperbaric oxygen therapy (HBOT) involves breathing oxygen at high ambient pressure. HBOT can reverse radiation-induced injuries, alleviate patient-perceived symptoms, and improve HRQoL. We aimed to clarify the effects of HBOT on late radiation-induced injuries in the urinary bladder and bowel, and to clarify some of the underlying mechanisms through which HBOT exerts its effects. Methods A prospective cohort study assessed effects of HBOT on patient-perceived symptoms (Paper I). A rat study assessed reversal of radiation-induced stress with HBOT (Paper II). A methodological experiment assessed reversal of HBOT on cellular death induced by radiation (Paper III). A multi-center, randomized, controlled trial assessed patient-perceived symptoms, HRQoL, and objective clinical outcomes (Paper IV). Result HBOT can alleviate patient-perceived symptoms, reduce objective findings, and improve HRQoL in patients affected by late radiation-induced injuries (Paper I, IV). Oxidative stress and downstream effects, induced by the irradiation, can be reversed by HBOT (Paper II). Paper III outlines a method for studies on urothelial cells exposed to radiation and HBOT. Conclusion HBOT can reduce radiation-induced oxidative stress and inflammatory response. HBOT can reverse injuries induced by radiation therapy to the pelvic region, alleviate patient-perceived symptoms and lead to improved HRQoL.

HBO treatment is an alternative to standard surgical removal of infected bone flaps and is particularly useful in complex situations. It can improve outcomes, reduce the need for reoperations, and allow infection control without mandatory removal of foreign material. HBO therapy is a safe, powerful treatment for postoperative cranial and spinal wound infections, it seems cost-effective, and it should be included in the neurosurgical armamentarium.

These findings underscore the specific sensitivity of the frontal lobe to acute hypobaric hypoxia and of limbic and central structures to blood gas changes emphasizing the involvement of these brain areas in acute hypoxia.