Inhibition effect of osteoprotegerin on the differentiation and the activity of bone absorption of osteoclast

doi:10.3321/j.issn:1673-8225.2004.14.008

Abstract：BACKGROUND: Osteoprotegerin(OPG) can inhibit the differentiation of osteoclast, inhibit the activity of bone absorption of mature osteoclast and induce its apoptosis, whicb has potential merit in the fields of osteoporosis,rheumatoid arthritis, and cancerous bone metastasis.OBJECTIVE: To identify the biological activity of human OPG expressed in CHO cells.DESIGN: A randomized controlled experimental study was conducted.SETTING and PARTICIPANTS: The experiment was completed in the Institute of Orthopaedic Surgery, Xijing Hospital, Fourth Military Medical University. The subjects were human osteosarcoma cell strain MG63, Chinese hamster CHO cell strain, clonal plasmid pUC19 and eukaryon-expressed plasmid pcDNA3 were stored by our department. Twelve male BABL/c mice aged 6-8 weeks old were obtained from Center for Experimental Animals of our university.INTERVENTIONS: cDNA in human OPG code area was acquired through RT-PCR method and the eukaryon-expressed carrier was establishezd as well,and then CHO cells were transfected under the mediation of liposome. Cell line that could stably express OPC was scanned by Western blot. Enriched liquid of conditional culture medium containing OPG protein was obtained. Experiment group: enriched liquid of conditional culture medium containing OPG protein was added into mice osteoclast culture medium in vitro. Control group: emiched liquid of CHO culture medium containing transfected pcDNA3 empty carrier was added into control group 1 and complete culture nedium was added into control group 2.MAIN OUTCOME MEASURES: The effects of human OPG on the differentiation and bone absorption of osteoclast.RESULTS: CHO cells that transfected by human OPG code area genes could secrete and express OPG. Myelocyte in mice could stably differentiate osteoclast-like cell that has the function of bone absorption under the existence of lα, 25(OH) 2D3(1 × 10-8 mol/L) . TRAP stained positive cells significantly decreased in the culture system, which was added by enriched supernatant of CHO culture solution containing OPG( t = 5. 547, P ＜ 0.01 ), and the numbers of bone absorption lacuna significantly decreased as well( t =3.409, P ＜0.01).CONCLUSION: Human OPG could be secreted and expressed in CHOcells, which has inhibitive reactions on the differentiation and bone absorption of osteoclast under the condition of culture in vitro.