淫羊藿苷调控BMP-2与OSX促进成骨细胞增殖的研究

目的:探讨淫羊藿苷(ICA)调控BMP-2与OSX对成骨细胞MC3T3-E1增殖的影响。方法:不同浓度淫羊藿苷处理成骨细胞后,细胞增殖实验(CCK-8)和碱性磷酸酶(ALP)检测评价成骨增殖分化能力,激光共聚焦显微镜观察成骨细胞的骨架形态,免疫印迹法(WesternBlot)检测骨形态发生蛋白-2(BMP-2)和成骨相关转录因子(OSX)表达。结果:与对照组相比,淫羊藿苷促进成骨细胞增殖分化,4μg/L淫羊藿苷对成骨细胞增殖作用最佳。细胞活性升高,镜下可见细胞伸展更多伪足,Western Blot显示BMP-2和OSX表达增高(p0.05)。结论:淫羊藿苷有促进成骨细胞增殖分化,可能是通过调节BMP-2和OSX蛋白表达。     

仿生控释BMP-2和VEGF的PELA微球支架对骨髓间充质干细胞向成骨细胞分化的Wnt/β-catenin通路的影响

目的制备外黏附复合重组人骨形态发生蛋白(recombinant human bone morphogenetic protein 2,rh BMP-2)内包封血管内皮细胞生长因子(vascular endothelial growth factor,VEGF)的微囊,并研究其对骨髓间充质干细胞(bone mesenchymal stem cells,BMSCs)向成骨细胞分化的Wnt/β-catenin通路的影响。方法以聚乳酸-聚乙二醇-聚乳酸三嵌段共聚物(polylactide-poly-ethylene glycol-polylactide,PELA)作为微囊的囊材,制备其外黏附rh BMP-2、内包封VEGF的微囊,制备微囊支架,实验分为对照组、BMP-2/PELA组、PELA/VEGF组和BMP-2/PELA/VEGF组。ELISA法检测微囊支架在1、2、4、8、12、16、22、28、35、42 d于PBS中缓释的rh BMP-2和VEGF的浓度;MTT法检测微囊支架对BMSCs作用3、7、14 d细胞活性的影响;Western blot法检测微囊支架对BMSCs作用3、7、14 d,BMSCs向成骨细胞分化中Wnt/β-catenin通路及碱性磷酸酶(alkaline phosphatase,ALP)蛋白表达的影响。结果微囊支架在PBS中第2天,BMP-2释放了约60%,而VEGF则释放了约32%;4组微囊支架对BMSCs作用3、7、14 d,细胞活性差异无统计学意义(P0.05)。在第14天,BMP-2/PELA/VEGF组Wnt、β-catenin及ALP的表达量均显著高于第3和7天(P0.05),而第7天的表达量均显著高于第3天(P0.05)。结论成功制备了BMP-2/PELA/VEGF微囊支架,对BMSCs无细胞毒性作用,可使BMSCs向成骨细胞进一步分化。     

珠子参总皂苷对大鼠成骨细胞的保护作用及其机制初探

离体培养大鼠原代成骨细胞,分别采用MTT法、EdU成像法、测定碱性磷酸酶法、茜素红染色法考察了不同浓度珠子参总皂苷对成骨细胞活力、增殖、分化、矿化等的影响;并采用Western bloting法研究了不同浓度珠子参总皂苷对成骨细胞OPG和RANKL蛋白表达的影响。结果表明,珠子参总皂苷浓度为100μg·mL~(-1)时可提高成骨细胞活力;浓度为50μg·mL~(-1)、100μg·mL~(-1)、200μg·mL~(-1)时可显著促进成骨细胞增殖、分化和矿化;珠子参总皂苷呈浓度依赖性地提高OPG/RANKL相对表达比值。     

Notch信号通路相关分子在脊椎生长过程中的差异表达及其对软骨细胞分化的调控作用

目的探讨Notch信号通路相关分子在脊椎生长过程中的差异表达及其对软骨细胞分化的调控作用。方法采用RT-PCR检测各不同发育年龄段小鼠椎间盘Notch信号分子mRNA的表达情况,筛选调控脊椎正常生长发育的重要信号分子,并采用免疫组化法进行验证。用重组腺病毒介导Dll-1、Jag-1、骨形态发生蛋白-2(bone morphogeneticprotein-2,BMP-2)在髓核(nucleus pulposus,NP)细胞中过表达,RT-PCR检测软骨细胞特征性标志物蛋白聚糖(aggrecan,ACAN)和Ⅱ型胶原(collagen typeⅡ,COL2A1)的表达,甲苯胺蓝染色检测软骨细胞基质分泌情况。结果小鼠脊椎生长发育过程中,Notch信号分子mRNA的表达总体呈下降趋势,其中Dll-1、Dll-3、Jag-1下降趋势尤其显著;Dll-1和Jag-1广泛表达于软骨细胞胞膜,随着小鼠年龄的增大,二者在椎间盘中的表达显著下降;BMP-2过表达可促进NP细胞成软骨分化,ACAN和COL2A1表达升高,甲苯胺蓝染色增强;Dll-1、Jag-1过表达可显著抑制BMP-2诱导的成软骨分化效应。结论 Notch信号分子,尤其是Dll-1、Jag-1对正常脊椎生长及椎间盘软骨细胞的成熟分化具有明显的负性调节作用。     

重组腺相关病毒介导克老素基因表达对2型糖尿病大鼠肾脏纤维化的作用及其机制

目的观察重组腺相关病毒(recombinant adeno-associated virus,rAAV)介导的克老素(klotho,KL)基因表达对2型糖尿病(type 2 diabetes mellitus,T2DM)大鼠肾脏纤维化的影响及其机制。方法将SD大鼠随机分为4组,随机选3组建立T2DM大鼠模型,分别经尾静脉注射rAAV.mKL(T2DM-mKL组)、rAAV.GFP(T2DM-GFP组)和PBS(T2DM-PBS组),正常对照(SD-PBS组)大鼠经尾静脉注射PBS,12周后,处死动物,收集肾脏组织标本,冰冻切片观察GFP,Masson染色观察肾脏组织病理变化及胶原纤维表达;免疫组化法检测各组大鼠肾脏组织中KL和波形蛋白(vimentin,VIM)的表达;RT-PCR法检测各组大鼠肾脏组织中Rho激酶(Rho associated coiled-coilforming protein kinase,ROCK)基因mRNA转录水平;Western blot法检测各组大鼠肾脏组织中ROCKⅠ蛋白活性。结果 T2DM-GFP组、T2DM-mKL组大鼠肾脏组织中GFP表达较强;T2DM-mKL组大鼠肾小球基底膜结构较清晰完整,肾小球系膜区及肾小管间质区胶原纤维明显较T2DM-PBS组和T2DM-GFP组减少;T2DM-mKL组KL蛋白的表达明显高于其他各组(P<0.01),VIM蛋白的表达明显低于其他各组,与T2DM-PBS组和T2DM-GFP组VIM蛋白的表达相比,差异有统计学意义(P<0.01);T2DM-mKL组ROCKⅠmRNA转录水平及其蛋白活性均明显低于T2DM-PBS组(P均<0.05)。结论 rAAV.mKL转染可明显增加T2DM大鼠肾脏中KL基因的表达,延缓糖尿病肾纤维化进程,其机制可能与KL抑制ROCK信号通路活性相关。     

控释重组人骨形态发生蛋白-2和血管内皮生长因子的微囊支架对骨髓间充质干细胞向成骨细胞分化的影响

目的探讨控释重组人骨形态发生蛋白-2(recombinant huaman bone morphogenetic protein-2,rhBMP-2)及血管内皮生长因子(vascular endothelial growth factor,VEGF)微囊支架对骨髓间充质干细胞(bone marrow mesenchymal stem cells,b MSCs)向成骨细胞分化的影响。方法以聚乳酸-聚乙二醇-聚乳酸三嵌段共聚物[polylactide-poly(ethylene glycol)-polylactide,PELA]为囊材,采用复乳溶剂挥发法制备外黏附rhBMP-2内包封VEGF的微囊支架。经ELSIA法检测微囊支架在PBS中释放rhBMP-2和VEGF的浓度。将微囊支架加入bMSCs,于培养后第3、7、14天,MTT法检测微囊支架对bMSCs活性的影响,Western blot法检测微囊支架对bMSCs向成骨细胞分化过程中MAPK通路相关蛋白及碱性磷酸酶(alkaline phosphatase,ALP)表达水平的影响。结果微囊支架于PBS中培养第2天rhBMP-2释放约60%,VEGF释放约32%。随着培养时间的延长,微囊支架对bMSCs的细胞活性无明显影响(P0. 05);培养后第14天磷酸化ERK1/2及ALP表达水平均显著高于第3和7天(P 0. 05),培养后第7天显著高于第3天(P 0. 05);培养后第3、7、14天磷酸化JNK及磷酸化p38表达水平变化差异无统计学意义(P 0. 05)。结论控释rhBMP-2及VEGF的微囊支架可诱导bMSCs向成骨细胞分化,可能是通过激活MAPK通路发挥作用。     

骨形态发生蛋白-2对股骨头坏死大鼠模型的愈合作用

正骨形态发生蛋白(bone morphologenetic protein,BMP)是转化生长因子β超家族的成员,可诱导原始间质细胞向骨与软骨趋化、增殖、分化。正常的BMP含量是维持骨的结构和功能的重要条件之一,BMP在体内诱导成骨的作用,已被REN等[1]证实。骨形态发生蛋白-2(BMP-2)为BMP家族中的重要成员。本文通过检测股骨头坏死模型大鼠阶段性病症,观察BMP-2在骨形成、骨愈合及治疗骨缺损中的作用,为股骨头坏死的治疗提供了新思路。     

重组人骨形态发生蛋白-2的制备及成骨活性表征

骨形态发生蛋白-2(BMP-2)是重要的骨诱导生长因子,是提高骨修复材料活性和临床骨修复效果的有效手段和关键物质。由于BMP-2在体内含量低,依靠从动物体内提取难以满足临床需求。本文研究满足临床需求的BMP-2的制备方法,并评价其生物活性。采用密码子优化方法,并通过进一步更换其中部分核苷酸编码,得到优化的hBMP-2基因的DNA序列,制备大肠杆菌rhBMP-2菌株,通过发酵及工艺优化,获得BMP包涵体,经分离纯化与复性,制备出高纯度的rhBMP-2。测定C2C12细胞的碱性磷酸酶(ALP)活性来表征单倍体和二倍体BMP-2的成骨活性,发现二倍体rhBMP-2的成骨活性明显高于单倍体rhBMP-2,并且随着BMP-2浓度增加,碱性磷酸酶活性上升。体内动物异位成骨实验发现rhBMP-2肌带植入小鼠体内3周后,取出的异位骨颗粒鲜艳饱满,骨结构完整;HE切片和Masson三色切片都显示出良好的异位成骨效果。此方法制备的rhBMP-2具有良好的诱导成骨分化能力,可用于骨组织修复,满足临床需要。     

间充质干细胞及基因转移方法促进新骨生成和大节段骨缺损的修复

目的构建含人骨形态蛋白-2(BMP-2)基因的重组腺病毒,并转染入间充质干细胞,诱导其向骨细胞分化,从而生成新骨并修复骨缺损。方法用重组腺病毒作为载体,将人BMP-2基因转染入小鼠胚胎间充质干细胞,Western blot检测BMP-2蛋白的分泌表达。观察重组腺病毒Adv-BMP-2转染后小鼠间充质干细胞的增殖变化,并进行碱性磷酸酶活性、钙化结节形成和细胞中成骨相关蛋白mRNA转录水平等细胞分化的指征检定。将Adv-BMP-2转染后的小鼠间充质干细胞注入裸鼠右侧大腿四头肌内,观察新骨生成情况。将重组腺病毒Adv-BMP-2转染的大鼠骨髓间充质干细胞用于大鼠大节段骨缺损的修复,并对植入的骨髓间充质干细胞进行跟踪观察。结果Western blot分析表明,重组腺病毒Adv-BMP-2转染的细胞可分泌表达BMP-2蛋白。转染后的小鼠间充质干细胞的增殖速度与重组腺病毒Adv-BMP-2的转染量呈剂量相关。Adv-BMP-2转染的干细胞碱性磷酸酶上升,并在体外形成钙结节,同时,成骨相关蛋白Osteopontin、Osteocalcin、Bone sialoprotein及Collagenα1(I)的mRNA水平也上升。用Adv-BMP-2转染的间充质干细胞能在裸鼠的大腿肌肉内形成发育成熟的新骨,转染的自体性骨髓间充质干细胞能有效修复大鼠大节段股骨缺损。在免疫抑制剂FK506的支持下,Adv-BMP-2转染的同种异体骨髓间充质干细胞也能修复大鼠的大节段骨缺损。没有FK506支持下的Adv-BMP-2转染的同种异体骨髓间充质干细胞及重组腺病毒Adv-β-gal转染的骨髓间充质干细胞则不能在体内形成新骨。植入骨缺损部位的骨髓间充质干细胞能直接参与骨缺损的修复,且有向全身其他组织器官迁移的趋势,但生存期较短。结论用腺病毒介导的BMP-2基因转染入间充质干细胞能有效诱导干细胞向骨细胞分化,生成新骨并修复骨缺损。     

成骨生长肽对鼠骨髓间充质干细胞增殖及成骨分化的作用

目的探讨成骨生长肽(osteogenic growth peptide,OGP)对鼠骨髓间充质干细胞(mouse bone marrow mesenchymal stem cell,mBMSC)增殖及成骨分化的作用及其分子机制。方法采用乳鼠骨片法分离mBMSC,流式细胞术测定mBMSC表面特征性分子。以10-5 mol/L OGP10-14作用于mBMSC,以不含OGP10-14的成骨诱导培养基作为对照组,MTS法检测OGP10-14对mBMSC增殖的影响;茜素红染色评价OGP10-14对mBMSC成骨分化的作用;qPCR及Western blot法检测OGP10-14干预下mBMSC骨分化相关因子β-catenin、RUNX2、BSP和细胞周期相关因子cyclin B1、CDK2、c-myc mRNA及蛋白表达水平。结果原代分离培养的mBMSC高表达CD29和CD90,低表达CD45和CD11b/c,符合BMSC的表型特征。与对照组相比,OGP10-14组mBMSC培养24、48及72 h时均促进细胞增殖(P 0.05)。茜素红染色显示,对照组部分细胞呈聚集生长,集落状,随诱导时间延长,出现红色层状矿化结节,OGP10-14组mBMSC矿化结节较对照组呈增加趋势。与对照组比较,OGP10-14组β-catenin、RUNX2、BSP mRNA及蛋白水平均升高(P 0.05),cyclin B1、CDK2、c-myc mRNA及蛋白水平均明显升高(P 0.01)。结论 OGP10-14通过促进成骨分化和触发细胞周期cyclin B1/CDK2途径促进mBMSC增殖,进而促进骨形成。     

Effect of Inducible BMP-7 Expression on the Osteogenic Differentiation of Human Dental Pulp Stem Cells

BMP-7 has shown inductive potential for in vitro osteogenic differentiation of mesenchymal stem cells, which are an ideal resource for regenerative medicine. Externally applied, recombinant BMP-7 was able to induce the osteogenic differentiation of DPSCs but based on our previous results with BMP-2, we aimed to study the effect of the tetracyclin-inducible BMP-7 expression on these cells. DPSC, mock, and DPSC-BMP-7 cell lines were cultured in the presence or absence of doxycycline, then alkaline phosphatase (ALP) activity, mineralization, and mRNA levels of different osteogenic marker genes were measured. In the DPSC-BMP-7 cell line, the level of BMP-7 mRNA significantly increased in the media supplemented with doxycycline, however, the expression of Runx2 and noggin genes was upregulated only after 21 days of incubation in the osteogenic medium with doxycycline. Moreover, while the examination of ALP activity showed reduced activity in the control medium containing doxycycline, the accumulation of minerals remained unchanged in the cultures. We have found that the induced BMP-7 expression failed to induce osteogenic differentiation of DPSCs. We propose three different mechanisms that may worth investigating for the engineering of expression systems that can be used for the induction of differentiation of mesenchymal stem cells.     

LIM Mineralization Protein-1 Inhibits the Malignant Phenotypes of Human Osteosarcoma Cells

Osteosarcoma (OS), also known as osteogenic sarcoma, is the most common primary malignancy of bone tumor in children and adolescents. However, its underlying molecular pathogenesis is still only vaguely understood. Recently, LIM mineralization protein-1 (LMP-1) was reported to be an essential positive regulator of osteoblast differentiation. In the present study, we found that the expression of LMP-1 is downregulated in OS tissues compared with adjacent normal tissues. Moreover, we restored the expression of LMP-1 through a recombinant adenovirus. Overexpression of LMP-1 inhibited cell proliferation and invasion, arrested cell cycle progression, and induced apoptosis in vitro. Finally, ectopic LMP-1 expression suppressed the expression of Runx2 and BMP-2 in OS cells. These data demonstrate that LMP-1 is an essential tumor suppressor in the OS pathological process, which will provide a new opportunity for discovering and identifying novel effective treatment strategies.     

Gremlin-1 and BMP-4 Overexpressed in Osteoarthritis Drive an Osteochondral-Remodeling Program in Osteoblasts and Hypertrophic Chondrocytes

Osteoarthritis (OA) is a whole joint disease characterized by an important remodeling of the osteochondral junction. It includes cartilage mineralization due to chondrocyte hypertrophic differentiation and bone sclerosis. Here, we investigated whether gremlin-1 (Grem-1) and its BMP partners could be involved in the remodeling events of the osteochondral junction in OA. We found that Grem-1, BMP-2, and BMP-4 immunostaining was detected in chondrocytes from the deep layer of cartilage and in subchondral bone of knee OA patients, and was positively correlated with cartilage damage. ELISA assays showed that bone released more Grem-1 and BMP-4 than cartilage, which released more BMP-2. In vitro experiments evidenced that compression stimulated the expression and the release of Grem-1 and BMP-4 by osteoblasts. Grem-1 was also overexpressed during the prehypertrophic to hypertrophic differentiation of murine articular chondrocytes. Recombinant Grem-1 stimulated Mmp-3 and Mmp-13 expression in murine chondrocytes and osteoblasts, whereas recombinant BMP-4 stimulated the expression of genes associated with angiogenesis (Angptl4 and osteoclastogenesis (Rankl and Ccl2). In conclusion, Grem-1 and BMP-4, whose expression at the osteochondral junction increased with OA progression, may favor the pathological remodeling of the osteochondral junction by inducing a catabolic and tissue remodeling program in hypertrophic chondrocytes and osteoblasts.     

Tranexamic Acid Promotes Murine Bone Marrow-Derived Osteoblast Proliferation and Inhibits Osteoclast Formation In Vitro

Despite modern surgical trauma care, bleeding contributes to one-third of trauma-related death. A significant improvement was obtained through the introduction of tranexamic acid (TXA), which today is widely used in emergency and elective orthopedic surgery to control bleeding. However, concerns remain regarding potential adverse effects on bone turnover and regeneration. Therefore, we employed standardized cell culture systems including primary osteoblasts, osteoclasts, and macrophages to evaluate potential effects of TXA on murine bone cells. While osteoblasts derived from calvarial digestion were not affected, TXA increased cell proliferation and matrix mineralization in bone marrow-derived osteoblasts. Short-term TXA treatment (6 h) failed to alter the expression of osteoblast markers; however, long-term TXA stimulation (10 days) was associated with the increased expression of genes involved in osteoblast differentiation and extracellular matrix synthesis. Similarly, whereas short-term TXA treatment did not affect gene expression in terminally differentiated osteoclasts, long-term TXA stimulation resulted in the potent inhibition of osteoclastogenesis. Finally, in bone marrow-derived macrophages activated with LPS, simultaneous TXA treatment led to a reduced expression of inflammatory cytokines and chemokines. Collectively, our study demonstrates a differential action of TXA on bone cells including osteoanabolic, anti-resorptive, and anti-inflammatory effects in vitro which suggests novel treatment applications.     

The Role of KV7.3 in Regulating Osteoblast Maturation and Mineralization

KCNQ (K_V7) channels are voltage-gated potassium (K_V) channels, and the function of K_V7 channels in muscles, neurons, and sensory cells is well established. We confirmed that overall blockade of K_V channels with tetraethylammonium augmented the mineralization of bone-marrow-derived human mesenchymal stem cells during osteogenic differentiation, and we determined that K_V7.3 was expressed in MG-63 and Saos-2 cells at the mRNA and protein levels. In addition, functional K_V7 currents were detected in MG-63 cells. Inhibition of K_V7.3 by linopirdine or XE991 increased the matrix mineralization during osteoblast differentiation. This was confirmed by alkaline phosphatase, osteocalcin, and osterix in MG-63 cells, whereas the expression of Runx2 showed no significant change. The extracellular glutamate secreted by osteoblasts was also measured to investigate its effect on MG-63 osteoblast differentiation. Blockade of K_V7.3 promoted the release of glutamate via the phosphorylation of extracellular signal-regulated kinase 1/2-mediated upregulation of synapsin, and induced the deposition of type 1 collagen. However, activation of K_V7.3 by flupirtine did not produce notable changes in matrix mineralization during osteoblast differentiation. These results suggest that K_V7.3 could be a novel regulator in osteoblast differentiation.