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-1ฮฑ (SDF-1ฮฑ). Therefore, we investigated the influence of HBO on hypoxia-inducible factor 1 (HIF-1), which is a central regulator of SDF-1ฮฑ and is down-regulated in diabetic wounds. The effects of HBO on HIF-1ฮฑ function were studied in human dermal fibroblasts, SKRC7 cells, and HIF-1ฮฑ 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-1ฮฑ-expressing adenovirus (Adv-HIF) into experimental wounds in db/db mice exposed to HBO. HBO activates HIF-1ฮฑ at several levels by increasing both HIF-1ฮฑ stability (by a non-canonical mechanism) and activity (as shown both by induction of relevant target genes and by a specific reporter assay). HIF-1ฮฑ induction has important biological relevance because the induction of fibroblast proliferation in HBO disappears when HIF-1ฮฑ is knocked down. Moreover, the local transfer of stable HIF-1ฮฑ-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.
Sunkari, Lind, Botusan, Kashif, Liu, Ylรค-Herttuala, Brismar, Velazquez, (). Hyperbaric oxygen therapy activates hypoxia-inducible factor 1 (HIF-1), which contributes to improved wound healing in diabetic mice.ย Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, ;23(1):98-103.ย https://www.ncbi.nlm.nih.gov/pubmed/25532619