Specific gene expression of osteoclasts under different oxygen tension / 中国组织工程研究

ABSTRACT

BACKGROUND:Preliminary studies of our research group have confirmed that the proliferation of preosteoclasts and the differentiation and function of osteoclasts could be inhibited when they were cultured in lower oxygen tension even hypoxia (2%O 2 ), but the gene expression of osteoclasts cultured in vitro have not been reported. OBJECTIVE:To examine the effect of oxygen tension on specific gene expression of osteoclasts in vitro and explore the mechanism of osteoclast differentiation influenced by oxygen tension. METHODS:The preosteoclasts were induced with 10μg/L macrophage colony stimulating facto and 10μg/L soluble receptor activator of nuclear factor-κB ligand into mature osteoclasts. Then the osteoclasts were cultured in normoxia, tissue oxygen and hypoxia (20%, 7%, 2%O 2 ) respectively. cells were then stained for tartarate-resistant acid phosphatase to assess osteoclastic formation. cells were col ected at 1, 2, 3, 4, 5, 6, 7 days after culture respectively. The soluble receptor activator of nuclear factor-κB ligand, tumor necrosis factor receptor-associated factor 6, tartarate-resistant acid phosphatase, and cathepsin K mRNA expression levels were determined using real-time quantitative PCR. RESULTS AND CONCLUSION:The number of osteoclasts positive for tartarate-resistant acid phosphatase in the hypoxia was significantly lower than that in the tissue oxygen and normoxia (P<0.05). Under different oxygen tension, the mRNA expression levels of soluble receptor activator of nuclear factor-κB ligand in osteoclasts maintained unchanged. The mRNA expression levels of tumor necrosis factor receptor-associated factor 6 reached the peak at 5 days after culture in tissue oxygen and normoxia (P<0.05). The mRNA expression time of tartarate-resistant acid phosphatase and Cathepsin K were delayed accompanied by decreased oxygen tension, but the maximum were maintained in tissue oxygen. Compared with normoxia and hypoxia, osteoclasts cultured in tissue oxygen are more prone to differentiate and maintain the activity and functions.