淫羊藿苷促进骨髓间充质干细胞成骨分化缓解小鼠骨质疏松的机制

Icariin alleviates osteoporosis by promoting osteogenic differentiation of bone marrow mesenchymal stem cells in mice

背景:淫羊藿苷是临床用于治疗骨质疏松的常用中草药淫羊藿的主要活性成分,但是其分子机制尚待深入研究。目的:探究淫羊藿苷缓解小鼠骨质疏松的效果和作用机制。方法:通过皮下连续注射地塞米松5周构建C57BL/6小鼠骨质疏松模型,将20只造模成功的小鼠随机分成模型组和治疗组,每组10只,另选择10只未经造模的C57BL/6小鼠作为对照组,治疗组灌胃给淫羊藿苷和生理盐水的混悬液,模型组和对照组灌胃等量生理盐水,每天给药1次,给药期间每天监测小鼠状态,并称量体质量。给药治疗2个月后,采用Micro-CT机对胫骨近端干骺端进行扫描,分析小鼠骨组织微观结构,研究淫羊藿苷对小鼠骨质疏松的治疗效果。同时,分离培养各组小鼠骨髓间充质干细胞,流式细胞术检测其碱性磷酸酶、成骨特异性转录因子、骨钙素、转化生长因子β及RUNX家族转录因子2的表达量,qRT-PCR检测骨桥蛋白、骨涎蛋白、过氧化物酶体增殖物激活受体γmRNA的表达水平,茜素红和油红O染色检测成骨和成脂分化能力。结果与结论:(1)与对照组相比,模型组小鼠胫骨和股骨总湿质量、骨体积分数、骨小梁厚度、骨小梁数目明显下降(P<0.01),骨小梁分离度变大(P<0.001),骨皮质厚度变薄(P<0.001);与模型组相比,治疗组小鼠上述指标均明显改善(P<0.05);(2)与模型组相比,治疗组小鼠骨髓间充质干细胞中成骨相关基因或者相关蛋白的表达明显升高(P<0.05),而成脂相关基因过氧化物酶体增殖物激活受体γmRNA的表达则显著下降;(3)与模型组相比,治疗组小鼠骨髓间充质干细胞茜素红染色吸光度值明显升高(P<0.05),而油红O染色吸光度值明显降低(P<0.05);(4)结果表明,淫羊藿苷可能通过促进小鼠骨髓间充质干细胞的成骨分化,抑制其成脂分化,改善骨髓微环境,促进骨小梁形成,缓解骨质疏松。

BACKGROUND:Icariin is the main active ingredient of epimedium,a commonly used Chinese herbal medicine for the treatment of osteoporosis,but its molecular mechanism needs to be studied in depth.OBJECTIVE:To explore the effect and mechanism of icariin on osteoporosis in mice.METHODS:The osteoporosis models of C57 BL/6 mice were constructed by subcutaneous injection of dexamethasone for 5 weeks.Totally 20 successfully modeled mice were randomly divided into a model group and a treatment group(n=10).An additional 10 non-modeled C57 BL/6 mice were used as a control group.The treatment group was given a suspension of icariin and saline by intragastric administration;the model group and the control group were given the same amount of saline,once a day.The state of the mice was monitored every day during the administration,and the body weight was measured.Two months after the treatment,Micro-CT machine was used to scan the proximal tibia metaphysis to analyze the microstructure of the bone tissue in mice,and to study the therapeutic effect of icariin on osteoporosis in mice.Simultaneously,bone marrow mesenchymal stem cells were isolated and cultured in each group.The expression levels of alkaline phosphatase,osteogenic specific transcription factor,osteocalcin,transforming growth factor β,and RUNX family transcription factor 2 were detected by flow cytometry.The expression levels of osteopontin,bone sialoprotein,and peroxisome proliferator activated receptor γmRNA were determined using qRT-PCR.Alizarin red staining and oil red O staining were applied to detect osteogenic and adipogenic differentiation.RESULTS AND CONCLUSION:(1)Compared with the control group,the bone wet weight,bone volume fraction,trabecular thickness,and trabecular number significantly decreased(P<0.01),trabecular separation became larger(P<0.001),and bone cortical thickness became thinner in the model group(P<0.001).Compared with the model group,above indicators of mice in the treatment group were significantly improved(P<0.05).(2)Compared with the model group,the expression of osteogenic related genes or proteins was significantly increased(P<0.05),and the expression level of lipogenic related gene peroxisome proliferator activated receptor gamma mRNA was significantly decreased in the treatment group.(3)Compared with the model group,the absorbance value of alizarin red staining was significantly increased in mouse bone marrow mesenchymal stem cells of the treatment group(P<0.05),while the absorbance value of oil red O staining was significantly reduced(P<0.05).(4)The results suggest that icariin may relieve osteoporosis by promoting osteogenic differentiation of mouse bone marrow mesenchymal stem cells,inhibiting their adipogenic differentiation,improving bone marrow microenvironment,and finally promoting trabecular bone formation.