Hyperbaric Oxygen Stimulates the Proliferation and Differentiation of Raw264.7 Cells

Background: Hyperbaric Oxygen (HBO) Therapy improves the outcome of various types of sugery, such as postoperative bone grafts, fixation of jaw fractures, and osteoplasty of jaw deformities. Therefore, it is important to determine the effects of HBO on bone regeneration. The purpose of this study was to clarify the influence of a hyperbaric oxygen environment on bone regeneration at the osteoclastogenic cytokines level. Sample & Methods: RAW264.7 cells were stimulated under the various conditions by using a hyperbaric oxygen chamber. We evaluated the ability of the RAW264.7 macrophages to proliferate, differentiate and produce various osteoclastogenic cyto-kines. Results: A hyperbaric oxygen (HBO) environment and high concentration oxygen (HCO) environment increase cellular proliferation in a time-dependent manner. On the other hand, a HCO environment and a hyperbaric with room air (HBA) environment enhanced the differentiation of RAW264.7 cells. In addition, NFATc1 and c-Fos were increased by both the HBA environment and HCO environment. However, the effects of HBA and HCO environments were in contrast with each other with regard to RANK, TNF-α, C-FMS and TRAP. Conclusions: It was suggested that a HBO environment influenced the bone regeneration by altering osteoclastogenic cytokines level, and that a HCO environment and HBA environment acted independently on the proliferation and differentiation of macrophages and the secretion of osteoclastogenic cytokines, and that they acted in concert in a hyperbaric oxygen environment to induce conditions favoring regeneration.