| Summary: | 碩士 === 國防醫學院 === 生物及解剖學研究所 === 85 === After menopause or ovariectomy, increase in production of interleukin-1 (IL-1) and tumor necrosis factor (TNF) could result in dramatic bone loss and subsequent osteoporosis and mortality. Recent studies showed that IL-1 may play an uncoupling role (by stimulation of bone resorption and inhibition of bone formation) in postmenopausal osteoporosis (PMO) . In addition, IL-1 can induce IL-6 type cytokines [IL-6, IL-11 and oncostatin M (OSM)] secretion. Therefore, IL-6, IL-1 I or OSM could play a role in the pathogenesis of PMO. Current evidences demonstrate that both IL-6 and IL- 11 stimulate osteoclastic bone resorption. However, up to now, effects of IL-6, IL-11 and OSM on osteogenesis and their possible role in PMO are still unclear.
The purposes of this study were to: 1) characterize MC3T3-E1 cells is a suitable model for the study of osteogenesis, 2) investigate the effects of IL-6 and OSM on osteogenesis using MC3T3-E1 cell culture system, and 3) investigate the effects of IL-11 on osteogenesis using both ICR calvarial cells and MC3T3-E1 cell culture system.
During culture of 13-14 day ICR single fetal calvarial cell or MC3T3-E cells, different doses of IL-6, IL-11 and OSM were added into the experimental dishes. The precise effects and possible mechanism of IL-6, IL- 11 and OSM on osteogenesis were investigated using phase contrast microscopy, cytochemical evaluation of alkaline phosphatase, 3H-thymidine incorporation, alkaline phosphatase expression assay, collagen synthesis assay, DAPI (4',6-diamidino-2-phenylindole) staining, PI (propidiurm iodide) staining and TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling).
Time course characterization of MC3T3-E1 cells showed that they could proliferate and differentiate similar to calvarial cell in culture and osteogenic cells in vivo. IL-6, IL-11 and OSM showed dose-related inhibition on osteogenesis. IL-6 and OSM exerted potent inhibition on bone formation by reducing both 3H-thymidine incorporation and alkaline phosphatase expression. IL-11 significantly inhibited bone cell proliferation while stimulated alkaline phosphatase expression at highest dose (1000 U/ml). In addition, IL-6, IL-11 and OSM didn't induce MC3T3-E1 cell apoptosis. The results of this study indicated that : 1) a new in vitro MC3T3-E1 cell culture model for the study of osteogenesis was established and 2) IL-6, IL-11 and OSM exerted dose-related inhibitory effects on osteogenesis.
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