中文摘要：

目的 体外模拟成骨细胞在体内的生存环境,考察活性维生素D3（VD3）、力学拉伸以及两者联合对成骨细胞MC3T3-E1增殖、分化及破骨细胞抑制因子（OPG）和破骨细胞分化因子（RANKL）表达的影响.方法 将10 nmol/LVD3、间断性力学拉伸以及两者联合作用于成骨细胞.流式细胞术检测细胞增殖.荧光探针试剂盒检测碱性磷酸酶（ALP）活性.实时定量PCR检测核心转录因子Runx2、OPG、RANKL mRNA水平,Western blotting检测其蛋白表达.结果 VD3抑制成骨细胞增殖,力学拉伸不能改变这种抑制效应.力学拉伸和VD3单独作用成骨细胞均能增加ALP活性及提高ALP、Runx2 mRNA水平,但当联合刺激后这些指标均降低,且成强度依赖性.力学拉伸增加OPG/RANKL比值,增强成骨作用,联合VD3后,OPG/RANKL比值下降.结论 力学拉伸能有效诱导成骨分化,增加骨形成.VD3与力学拉伸联合抑制成骨细胞增殖和分化,并通过增加RANKL表达而影响骨重建.研究结果为骨质疏松及相关骨疾病的理论和治疗提供有意义的探索.

英文摘要：

Objective To investigate the effect of 1,25-（OH）2-vitamin D3 （VD3） or mechanical strain alone and their combined treatment on proliferation and differentiation of pre-osteoblast MC3T3-E1 cells in vitro, as well as gene and protein expression of osteoprotegerin （OPG） and receptor activator of nuclear factor-KB ligand （RANKL） in those cells. Methods MC3T3-E1 cells were treated with 10 nmol/L VD3, intermitted mechanical strain or with a combination of these two factors. Cell proliferation was assessed with flow cytometry, and alkaline phosphatase （ALP） activity was measured using a fluorometric detection kit. The mRNA expression of ALP, runt-related transcriptional factor 2 （Runx2）, OPG, and RANKL genes was determined by real-time PCR. The proteins expression of Runx2, OPG, and RANKL was determined by Western blotting. Results VD3 inhibited the proliferation of MC3T3-E1 cells, but the mechanical strain had no effect on cell proliferation. Mechanical strain, VD3, and the combined treatment enhanced the ALP activity of MC3T3-E1 cells as well as the protein ex- pression of Runx2. The effect of combined treatment was less pronounced than the effect of VD3 or mechanical strain alone. Mechanical strain promoted the gene and protein expression of osteoprotegerin （OPG） and in- creased the ratio of OPG/RANKL. However, the combination of VD3 and mechanical strain led to a decrease in ratio of OPG/RANKL. Conclusions Mechanical strain might be effective in inducing osteogenic differentiation and increasing bone formation. A joint stimulation with VD3 and strain can decrease proliferation and osteogenic differ- entiation and increase RANKL expression, which might affect bone remodeling. This study supplies some new data, which might be important in theoretical and clinical research of osteoporosis （OP） and other related bone diseases.