阿司匹林对体外培养骨髓基质细胞成骨性分化的影响

目的：探讨阿司匹林对骨髓基质细胞成骨性分化的影响。方法：培养SD大鼠骨髓基质细胞（BMSCs）,传代3次后进行成骨诱导分化,诱导培养基中加入不同浓度阿司匹林（0.5、1、2、5、10mmol/L）,同时设立对照组。采用cck-8法分析细胞增殖情况。比较阿司匹林组与对照组在细胞碱性磷酸酶（ALP）活性、骨钙素（OC）分泌量、钙结节染色等方面的成骨性差异。结果：阿司匹林无促进细胞增殖活性,而高浓度阿司匹林能够强烈抑制细胞增殖。0.5、1、2mmol/L浓度阿司匹林可促进BMSCs的成骨性分化,中低浓度组碱性磷酸酶含量、骨钙素分泌量在不同阶段显著高于对照组。14天茜素红染色可见中低浓度组钙结节数量高于对照组。结论：中低浓度阿司匹林作用于骨髓基质细胞可促进其成骨细胞特性表达,这表明阿司匹林有促进骨代谢合成的作用。     

阿司匹林对体外培养骨髓基质细胞成骨性分化的影响

目的:探讨阿司匹林对骨髓基质细胞成骨性分化的影响。方法:培养SD大鼠骨髓基质细胞(BMSCs),传代3次后进行成骨诱导分化,诱导培养基中加入不同浓度阿司匹林(0.5、1、2、5、10mmol/L),同时设立对照组。采用cck-8法分析细胞增殖情况。比较阿司匹林组与对照组在细胞碱性磷酸酶(ALP)活性、骨钙素(OC)分泌量、钙结节染色等方面的成骨性差异。结果:阿司匹林无促进细胞增殖活性,而高浓度阿司匹林能够强烈抑制细胞增殖。0.5、1、2mmol/L浓度阿司匹林可促进BMSCs的成骨性分化,中低浓度组碱性磷酸酶含量、骨钙素分泌量在不同阶段显著高于对照组。14天茜素红染色可见中低浓度组钙结节数量高于对照组。结论:中低浓度阿司匹林作用于骨髓基质细胞可促进其成骨细胞特性表达,这表明阿司匹林有促进骨代谢合成的作用。     

猪脂肪基质细胞成骨与成脂分化潜能的研究

目的:探索猪脂肪基质细胞体外培养和向成骨与脂肪细胞分化的条件。方法:常规方法培养猪脂肪基质细胞,分别向成骨细胞与脂肪细胞进行诱导,应用免疫组化(碱性磷酸酶法、茜素红)及油红O染色对诱导分化的细胞进行鉴定。结果:在体外培养条件下,猪的脂肪基质细胞呈成纤维样,生长旺盛,在一定的条件下,可分别被诱导分化为成骨细胞与脂肪细胞,向成骨分化的细胞表达碱性磷酸酶,在培养皿中可形成钙化斑。而在向脂肪细胞诱导分化过程中,细胞中可见有小脂滴生成,用油红O染色呈橘红色。结论:脂肪基质细胞是一种混合细胞,除了能向脂肪细胞分化外,在一定的诱导条件下,也能向成骨细胞分化。     

成骨细胞中基因表达的调控

在骨骼发生、重塑和再生过程中,成骨细胞产生细胞基质蛋白和基质矿化的调节因子,它们来自于间叶细胞的前体细胞,随着成骨细胞的发生、增殖和分化,这些细胞因子经历了一个基因表达的过程。成熟的成骨细胞产生特征性的细胞外胶原基质,随后被羟灰石晶体矿化。除了一些基本功能外,矿化骨是钙和磷的主要载体,还有造血的功能。人类的一些疾病如骨质疏松症、关节炎、骨肿瘤等会导致骨量减少、骨密度降低。成骨细胞形成和修复是整形外科以及牙科修复治疗的基础。理解成骨细胞形成的细胞和分子机制对于更好的治疗这些疾病是非常重要的。     

罗非鱼鱼皮酶解液对体外培养大鼠骨髓基质细胞的影响

目的:观察两种罗非鱼鱼皮酶解液对大鼠骨髓基质细胞的影响。方法:用密度梯度离心和贴壁筛选的方法获得骨髓基质细胞,用碱性磷酸酶染色法观察是否成功诱导骨髓基质细胞向成骨细胞分化,并分别采用MTT法和PNPP法测定两种酶解液对骨髓基质细胞增殖和碱性磷酸酶活性的影响。结果:密度梯度离心和贴壁筛选可得到较为均一的骨髓基质细胞。这些骨髓基质细胞诱导后可以向成骨细胞分化。两种酶解液作用于骨髓基质细胞时,在浓度0.1mg·ml~(-1)均可以促进骨髓基质细胞增殖,在浓度0.1mg·ml~(-1)1,0.01mg·ml~(-1)均可以提高骨髓基质细胞碱性磷酸酶活力。实验用两种酶解液的三个浓度与成骨诱导液协同作用于骨髓基质细胞时,均没有促进细胞增殖和提高碱性磷酸酶活性的显著作用。结论:两种酶解液可以促进骨髓基质细胞增殖,提高细胞碱性磷酸酶活力;与成骨诱导液协同作用于骨髓基质细胞时,对细胞增殖和碱性磷酸酶活性没有显著促进及提高作用。     

生长分化因子-5及碱性成纤维细胞生长因子诱导家兔椎间盘髓核细胞成骨作用的研究

目的建立家兔椎间盘髓核细胞的体外培养模型,研究重组人生长分化因子-5(recombinant human growth differentiation factor-5,rhGDF-5)和碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)对髓核细胞成骨潜能的激发作用。方法将诱导剂rhGDF-5和bFGF分别及联合加入体外培养的髓核细胞中,观察髓核细胞的成骨表型表达和细胞学特性的变化。结果 rhGDF-5和bFGF均能促进钙盐沉积形成钙结节。rhGDF-5抑制髓核细胞增殖同时增加骨钙素表达;bFGF促进髓核细胞增殖及Ⅰ型胶原表达,但对骨钙素表达无显著影响。联合使用rhGDF-5和bFGF对髓核细胞成骨潜能(促进髓核细胞增殖、Ⅰ型胶原及骨钙素表达和钙盐沉积)的激发作用均优于单独使用其中任一细胞因子。结论 rhGDF-5诱导髓核细胞向成骨细胞分化,bFGF加强该诱导作用,联合使用rhGDF-5和bFGF能充分激发髓核细胞的成骨潜能。     

成骨细胞的骨形成调控机制

成骨细胞在骨的形成、发育、改建、修复过程中发挥重要作用,多种生长因子可影响成骨细胞的增殖、分化及其合成细胞外基质的作用。多种生长因子对成骨细胞的作用既有相同之处,也有不同点。寻找一种或联合应用几种不同的生长因子达到既能促进成骨细胞增殖又保持其成骨活性将是今后研究的热点。     

骨形态发生蛋白与细胞外基质磷酸化糖蛋白相关性研究进展

骨形态发生蛋白(BMP)是转化生长因子β超家族成员,细胞外基质磷酸化糖蛋白(MEPE)是一种细胞外基质的非胶原磷酸化糖蛋白,两者都是成骨信号通路中的重要蛋白。近年来发现MEPE表达水平受BMP的调节,并在磷酸盐代谢调节、成骨细胞增殖分化中发挥重要作用,同时与肿瘤细胞的骨转移有着密切的关联。在此,我们简要综述近年来BMP与MEPE的关系以及它们在肿瘤细胞骨转移方面的作用。     

当归多糖减轻5-氟尿嘧啶对骨髓基质细胞成骨分化的抑制

该实验探讨当归多糖(ASP)对改善5-氟尿嘧啶(5-FU)所致人骨髓基质细胞成骨与成脂分化失衡的作用。人骨髓基质细胞株HS-5体外培养分为:对照组、ASP组、5-FU组、5-FU+ASP组和5-FU+LiCl组。CCK-8检测细胞抑制率,流式细胞术检测细胞凋亡;成骨与成脂诱导分化实验检测细胞成骨与成脂分化能力,Western blot检测Runx2、PPARγ和β-catenin蛋白表达,RT-PCR检测Runx2、OCN、BMP-2、Osterix、PPARγ和β-catenin mRNA表达。结果表明,与对照组相比5-FU作用HS-5细胞后细胞增殖抑制、凋亡率增加,成骨分化能力减弱、成脂分化能力增强,分化相关信号β-catenin蛋白和mRNA表达降低;相比5-FU组,ASP预处理可减少细胞凋亡;恢复细胞成骨分化能力,成骨相关因子Runx2、OCN、BMP-2和Osterix表达升高;降低细胞成脂分化能力,成脂相关因子PPARγ表达减少;β-catenin信号分子表达增加。结果提示,当归多糖可维持5-FU作用后骨髓基质细胞朝成骨方向分化的能力,其机制可能与激活Wnt/β-catenin信号通路有关。     

8-异戊烯基柑橘素促进体外培养成骨细胞成熟矿化的研究

研究8-异戊烯基柑橘素对体外培养大鼠颅骨成骨细胞(rat skull osteoblasts,ROB)的分化成熟及生物矿化的影响.取新生大鼠颅骨多次酶消化法得到成骨细胞,培养于含10%FBS的MEM培养液中,3天后首次换液,待细胞铺满皿底传代培养.以碱性磷酸酶(alkaline phosphatase,ALP)为检测指标,96孔板梯度筛选作用最佳浓度,在最佳浓度作用并成骨性诱导培养的第3、6、9、12天测ALP活性、钙盐沉积量;第12天进行ALP和钙化结节组织化学染色及计数;成骨性诱导后不同时间点提取Total RNA,RT real-time PCR法检测成纤维细胞生长因子(bFGF)、胰岛素样生长因子-1(IGF-1)、成骨相关转录因子Osterix、Runx-2和骨形态发生蛋白-2(BMP-2)的基因表达情况;成骨性诱导的第4、8、12天裂解获得细胞总蛋白,蛋白质印迹法检测人Ⅰ型胶原蛋白(COL-Ⅰ)的蛋白质表达量.研究结果表明:1×10-6 mol/L能显著促进成骨细胞的成熟分化,表现为提高ROB的ALP活性、促进钙盐沉积、增加钙化结节数量;提高bFGF、IGF-1、Osterix、Runx-2和BMP-2 mRNA表达水平;促进COL-Ⅰ的合成.由此可知终浓度为1×10-6 mol/L 8-异戊烯基柑橘素能显著促进ROB的分化成熟及生物矿化,证明8-异戊烯基柑橘素能促进成骨细胞的分化成熟及生物矿化,作为促进骨修复和抗骨质疏松的有效成分具有较大的药用价值.     

Involvement of ligand occupancy in Insulin-like growth factor-I (IGF-I) induced cell growth in osteoblast like MC3T3-E1 cells

Growth factors and matrix proteins regulate the proliferation and differentiation of osteoblasts. The insulin-like growth factor (IGF) system comprises IGF-I, IGF-II, and six high-affinity IGF-binding proteins (IGFBPs). IGFs stimulate cell growth in many types of tissue; IGF-binding proteins regulate cellular actions and can affect cell growth. IGF-I is involved in differentiation, proliferation, and matrix formation in osteoblasts; IGFBP-5 is associated with the extracellular matrix (ECM) and can potentiate the actions of IGF-I. We investigated the effect of ECM proteins on the responses of MC3T3-E1 osteoblast cells to IGF-I and IGFBP-5. In addition, because extracellular signal-regulated kinases 1 and 2 (Erk 1/2) affect cell growth, we evaluated the effects of IGFBP-5 on Erk 1/2 phosphorylation in MC3T3-E1 cells. IGF-I caused an increase in IGFBP-5 expression in cultured MC3T3-E1 cells, and IGF-I plus IGFBP-5 significantly increased cell growth. Likewise, the addition of IGF-I and IGFBP-5 to cultured MC3T3-E1 cells increased the synthesis of the ECM proteins osteopontin (OPN) and thrombospondin-1 (TSP-1), which can bind to alphaVbeta3 integrin receptors on the cell surface. By contrast, the addition of an antibody against ECM proteins inhibited the effects of OPN and TSP-1 on IGFBP-5 expression. The stimulatory effect of IGFBP-5 was mediated via Erk 1/2 activation. These data suggest that IGFBP-5 regulates Erk 1/2 phosphorylation in cultured MC3T3-E1 cells via ECM proteins that may ultimately stimulate the growth of osteoblasts. We determined whether occupation of the alphaVbeta3 integrin receptor affects IGF-I receptor (IGF-IR)-mediated signaling and function in MC3T3-E1 osteoblast cells. Occupation of the alphaVbeta3 integrin receptor with ECM proteins induced IGF-I-stimulated IGF-IR phosphorylation. Conversely, in the presence of the alphaVbeta3-specific disintegrin echistatin, IGF-I-stimulated IGF-IR activation was inhibited. IGF-I-stimulated IGF-IR phosphorylation was accompanied by IRS-1 phosphorylation and MAPK activation. However, these effects were attenuated by echistatin. Thus, occupancy of the alphaVbeta3 disintegrin receptor modulates IGF-I-induced IGF-IR activation and IGF-IR-mediated function in MC 3T3-E1 osteoblasts.     

Human mesenchymal stem cells tissue development in 3D PET matrices

Human mesenchymal stem cells (hMSCs) are attractive cell sources for engineered tissue constructs with broad therapeutic potential. Three-dimensional (3D) hMSC tissue development in nonwoven poly(ethylene terephthalate) (PET) fibrous matrices was investigated. HMSCs were seeded onto 3D PET scaffolds and were cultured for over 1 month. Their proliferation rates were affected by seeding density but remained much lower than those of 2D controls. Compared to 2D surfaces, hMSCs grown in 3D scaffolds secreted and embedded themselves in an extensive ECM network composed of collagen I, collagen IV, fibronectin, and laminin. HMSCs were influenced by the orientation of adjacent PET fibers to organize the ECM proteins into highly aligned fibrils. We observed the increased expressions of alpha(2)beta(1) integrin but a slight decrease in the expression of alpha(5)beta(1) integrin in 3D compared to 2D culture and found that alpha(V)beta(3) was expressed only in 2D. Paxillin expression was down-regulated in 3D culture with a concomitant change in its localization patterns. We demonstrated the multi-lineage potentials of the 3D tissue constructs by differentiating the cells grown in the scaffolds into osteoblasts and adipocytes. Taken together, these results showed that hMSCs grown in 3D scaffolds display tissue development patterns distinct from their 2D counterparts and provide important clues for designing 3D scaffolds for developing tissue engineered constructs.     

Extracellular matrix alters the relationship between tritiated thymidine incorporation and proliferation of MC3T3-E1 cells during osteogenesis in vitro

Bone cells in vivo exist in direct contact with extracellular matrix, which regulates their basic biological processes including metabolism, development, growth and differentiation. Thus, the in vitro activity of cells cultured on tissue culture treated plastic could be different from the activity of cells cultured on their natural substrate. We selected MC3T3-E1 pre-osteoblastic cells to study the effect of extracellular matrix on cell proliferation because these cells undergo a progressive developmental sequence of proliferation and differentiation. MC3T3-E1 cells were cultured on plastic or plastic coated with ECM, fibronectin, collagen type I, BSA or poly l-lysine and their ability to proliferate was assessed by incorporation of [3H]dT or by enumeration of cells. Our results show that (1) ECM inhibits incorporation of [3H]dT by MC3T3-E1 cells; (2) collagen type I, but not BSA, poly l-lysine or fibronectin also inhibits incorporation of [3H]dT; (3) the level of ECM inhibition of [3H]dT incorporation is directly related to the number of cells cultured, but unrelated to the cell cycle distribution or endogenous thymidine content; (4) the kinetic profile of [3H]dT uptake suggest that ECM inhibits transport of [3H]dT from the extracellular medium, and (5) cell counts are similar in cultures whether cells are grown on plastic or ECM. These results suggest that decreased incorporation of [3H]dT by cells cultured on ECM is not reflective of bone cell proliferation.     

Human dental pulp stem cells hook into biocoral scaffold forming an engineered biocomplex

The aim of this study was to evaluate the behavior of human Dental Pulp Stem Cells (DPSCs), as well as human osteoblasts, when challenged on a Biocoral scaffold, which is a porous natural hydroxyapatite. For this purpose, human DPSCs were seeded onto a three-dimensional (3D) Biocoral scaffold or on flask surface (control). Either normal or rotative (3D) cultures were performed. Scanning electron microscopic analyses, at 8, 24 and 48 h of culture showed that cells did not adhere on the external surface, but moved into the cavities inside the Biocoral structure. After 7, 15 and 30 days of culture, morphological and molecular analyses suggested that the Biocoral scaffold leads DPSCs to hook into the cavities where these cells quickly start to secrete the extra cellular matrix (ECM) and differentiate into osteoblasts. Control human osteoblasts also moved into the internal cavities where they secreted the ECM. Histological sections revealed a diffuse bone formation inside the Biocoral samples seeded with DPSCs or human osteoblasts, where the original scaffold and the new secreted biomaterial were completely integrated and cells were found within the remaining cavities. In addition, RT-PCR analyses showed a significant increase of osteoblast-related gene expression and, above all, of those genes highly expressed in mineralized tissues, including osteocalcin, OPN and BSP. Furthermore, the effects on the interaction between osteogenesis and angiogenesis were observed and substantiated by ELISA assays. Taken together, our results provide clear evidence that DPSCs differentiated into osteoblasts, forming a biocomplex made of Biocoral, ECM and differentiated cells.     

Alteration of Cellular Behavior and Response to PI3K Pathway Inhibition by Culture in 3D Collagen Gels

Most investigations into cancer cell drug response are performed with cells cultured on flat (2D) tissue culture plastic. Emerging research has shown that the presence of a three-dimensional (3D) extracellular matrix (ECM) is critical for normal cell behavior including migration, adhesion, signaling, proliferation and apoptosis. In this study we investigate differences between cancer cell signaling in 2D culture and a 3D ECM, employing real-time, live cell tracking to directly observe U2OS human osteosarcoma and MCF7 human breast cancer cells embedded in type 1 collagen gels. The activation of the important PI3K signaling pathway under these different growth conditions is studied, and the response to inhibition of both PI3K and mTOR with PI103 investigated. Cells grown in 3D gels show reduced proliferation and migration as well as reduced PI3K pathway activation when compared to cells grown in 2D. Our results quantitatively demonstrate that a collagen ECM can protect U2OS cells from PI103. Overall, our data suggests that 3D gels may provide a better medium for investigation of anti-cancer drugs than 2D monolayers, therefore allowing better understanding of cellular response and behavior in native like environments.     

Differential growth factor adsorption to calvarial osteoblast-secreted extracellular matrices instructs osteoblastic behavior

Craniosynostosis (CS), the premature ossification of cranial sutures, is attributed to increased osteogenic potential of resident osteoblasts, yet the contribution of the surrounding extracellular matrix (ECM) on osteogenic differentiation is unclear. The osteoblast-secreted ECM provides binding sites for cellular adhesion and regulates the transport and signaling of osteoinductive factors secreted by the underlying dura mater. The binding affinity of each osteoinductive factor for the ECM may amplify or mute its relative effect, thus contributing to the rate of suture fusion. The purpose of this paper was to examine the role of ECM composition derived from calvarial osteoblasts on protein binding and its resultant effect on cell phenotype. We hypothesized that potent osteoinductive proteins present during sutural fusion (e.g., bone morphogenetic protein-2 (BMP-2) and transforming growth factor beta-1 (TGF-β1)) would exhibit distinct differences in binding when exposed to ECMs generated by human calvarial osteoblasts from unaffected control individuals (CI) or CS patients. Decellularized ECMs produced by osteoblasts from CI or CS patients were incubated in the presence of BMP-2 or TGF-β1, and the affinity of each protein was analyzed. The contribution of ECM composition to protein binding was interrogated by enzymatically modulating proteoglycan content within the ECM. BMP-2 had a similar binding affinity for each ECM, while TGF-β1 had a greater affinity for ECMs produced by osteoblasts from CI compared to CS patients. Enzymatic treatment of ECMs reduced protein binding. CS osteoblasts cultured on enzymatically-treated ECMs secreted by osteoblasts from CI patients in the presence of BMP-2 exhibited impaired osteogenic differentiation compared to cells on untreated ECMs. These data demonstrate the importance of protein binding to cell-secreted ECMs and confirm that protein-ECM interactions have an important role in directing osteoblastic differentiation of calvarial osteoblasts.     

Extracellular matrix production by mouse 3T3-F442A cells during adipose differentiation in culture

When cultured 3T3-F442A cells undergo adipose differentiation, they produce extracellular matrix (ECM) that is not present in undifferentiated cells. This ECM stains strongly with ruthenium red, tannic acid and with Alcian blue at both pH 1 and 2.5, showing histochemical characteristics similar to sulphated and non-sulphated glycosaminoglycans. Under the electron microscope, ECM was observed bound to the cell surface and in the intercellular space; it was composed of fibrils of several thicknesses with attached granules and fibrous long-spacing forms of collagen. In addition, adipocytes were observed as rounded cells interconnected with the ECM fibrils, thus giving rise to fat cell clusters similar to the adipocyte lobules found in adipose tissue. Since fat cell clusters in culture emerge by clonal expansion of one adipose precursor cell, we suggest that this ECM can keep daughter adipocytes interconnected during differentiation. ECM production by adipocytes might have some significance for the formation of fat cell lobules in vivo.     

The beta3 chain short arm of laminin-332 (laminin-5) induces matrix assembly and cell adhesion activity of laminin-511 (laminin-10)

The basement membrane (BM) protein laminin-332 (Lm332) (laminin-5) has unique activity and structure as compared with other laminins: it strongly promotes cellular adhesion and migration, and its alpha3, beta3, and gamma2 chains are all truncated in their N-terminal regions (short arms). In the present study, we investigated the biological function of the laminin beta3 chain. When the beta3 chain short arm (beta3SA) was overexpressed in HEK293 cells (beta3SA-HEK), they deposited a large amount of beta3SA and a small amount of laminin-511 (Lm511) (laminin-10) on culture plates. Control HEK293 cells secreted Lm511 but failed to deposit it. The extracellular matrix (ECM) deposited by beta3SA-HEK cells strongly promoted cell attachment and spreading. The beta3SA-HEK ECM did not directly bind Lm511, but it stimulated control HEK293 cells to deposit Lm511 on the culture plates. Although purified beta3SA did not support cell adhesion by itself, it enhanced the cell adhesion activity of Lm511. Experiments with anti-integrin antibodies also suggested that the strong cell adhesion activity of the beta3SA-HEK ECM was derived from the synergistic action of beta3SA and Lm511. It has previously been found that beta3SA binds an unknown cell surface receptor. Taken together, the present study suggests that the short arm of the laminin beta3 chain enhances the matrix assembly of Lm511 and its cell adhesion activity by interacting with its receptor.     

Growth and survival signalling in B16F10 melanoma cells in 3D culture

The two‐way communication between the ECM (extracellular matrix) and the cytoplasm via the integrins has many functions in cancer cells, including the suppression of apoptosis. As cells in a 3D (three‐dimensional) architecture resemble the in vivo situation more closely than do cells in more conventional 2D cultures, we have employed a substratum that prevents cell adhesion and induces cell aggregation to determine why highly metastatic B16F10 melanoma cells resist anoikis. We compared the behaviour of B16F10 cells in 2D [on tPS (tissue culture polystyrene)] and 3D culture {on polyHEMA [poly(2‐hydroxyethylmethacrylate)]} configurations. For this, we analysed cell morphology, proliferation, apoptosis and the activation status of several proteins involved in cell proliferation and survival [RhoA, FAK (focal adhesion kinase), Akt, ERK1/2 (extracellular‐signal‐regulated kinase 1/2)]. B16F10 cells in 3D architecture were able to proliferate as cell aggregates for 3 days, after which the number of cells decreased. The normal Swiss 3T3 cells used as an anoikis‐sensitive control did not proliferate on the anti‐adhesive substratum. Rho A was activated in B16F10 aggregates throughout their time in culture, whereas it was not in Swiss 3T3 aggregates. An absence of apoptotic activity was correlated with the proliferation of B16F10 cells in aggregates: caspase 3 was significantly activated only after 3 days in culture on polyHEMA. FAK and Akt were transiently activated, and their inactivation was correlated with the induction of apoptosis. ERK1/2 were activated throughout the 3D culture. No survival protein was activated in Swiss 3T3 aggregates. Data obtained from cells in 3D culture suggest that B16F10 cells are resistant to anoikis through the activation of the FAK and Akt signalling pathways.