高壓氧刺激的骨母細胞藉由FGF-2/MEK/ ERK 1/2/NF-κB及PKC/JNK路徑的啟動而增生

Abstract

二、英文摘要 Nonunion and delayed union can occur in the process of fracture healing and the likehood of such delay occurring is up to 10%. They present great challenge in the clinic treatments for fracture. In the past ,orthopaedic surgen treated the nonunion and delayed union by surgical decortication and autogenous bone graft.These methods are not always successful and can cause patients suffer more pain and risk of wound infection. The search for better alternatives have been ongoing for a long time. When an injury occurs,hypoxia is a commonly seen microenvironment in the bone or soft tissue at the injury site. This detrimental situation will impede the subsequent steps of the damage repair,such as inflammatory cell recruitment,matrix processing,angiogenesis and activation of mesenchymal osteoblast(OB) precursors. It has been well demonstrated that hyperbaric oxygen (HBO) therapy to promote osteogenesis on osteoradionecrosis by increasing the OB activity and neoagiogenesis However,the actual mechanism that promotes osteoblastic & angiogenic growth remains incompletely understood. To investigate whether the hyperbaric oxygen(HBO) can promote the growth-arrest osteoblast(OB) cells to proliferate and differentiate,and to determine the probable mechanism which are involved in proliferation of OB cells. OB cells were exposured to O2 with different levels of saturation and pressure for 3 days and 7 days. The OB cells were divided into four groups: 1. The Control Group(Group C ):cells were cultured under ambient oxygen (21% O2) and normal pressure(1ata). 2. The Pressure Group(Group P) :cells were treated with high pressure(2.5ata) only twice daily. 3.High Oxygen Group(Group O): Cells were treated with high concentration oxygen(50%) only twice daily. 4.Pressure and High Oxygen group(Group P+O): Cells were treated with high pressure(2.5ata) and high concentration oxygen(50%) twice daily. XTT was used to detect the cells proliferation and cell cycle progression was determined by Flow analysis.Expression of growth factors was assayed by RT-PCR. In addition, we determined HBO activated signaling pathway in OB cells by Western Blot analysis. It was demonstrated that HBO significantly promote OB cell proliferation and stimulated cell cycle progression after the cells had been treatmented for three days.Afterward, the effect attenuated day by day.It was also found that HBO stimulated the OB cells to produce the FGF-2 growth factors.Multiple signaling pathways,including FGF-2/MEK/ERK 1/2/Akt/ p70s6k /NF-κB and PKC/JNK,are involved in the proliferation of OB cells by HBO stimulation . Our data showed that HBO has a positive effect on stimulating grow-arrested OB cells to proliferate and differentiate through activation of FGF-2/MEK/ERK 1/2/Akt/ p70s6k /NF-κB and PKC/JNK signaling pathway.Under optimal oxygen tension and pressure,HBO may be useful for fracture healing in clinical application.