狗骨髓基质细胞的体外诱导成骨潜能研究

目的：观察狗骨髓基质细胞的生长特点及诱导条件下的成骨能力。方法：采用成年狗双侧髂骨取材进行骨髓基质细胞培养，应用四甲基偶氮唑蓝微量酶反应比色法观察细胞增殖；以对硝基苯磷酸盐法及骨钙素含量放免测定法测定碱性磷酸酶活性及骨钙素含量；用Von Kossa染色法观察矿化结节；用间接免疫荧光染色法测定Ⅰ型胶原。观察在培养液中添加地塞米松、维生素C、β-甘油磷酸钠条件下骨髓基质细胞生长及成骨分化情况。结果：骨髓基质细胞呈成纤维样表现，增殖力强。诱导条件下的细胞碱性磷酸酶活性及骨钙素含量明显增高，Ⅰ型胶原表达增多，10～12d达到高峰，并出现矿化结节。结论：狗骨髓基质细胞在本实验条件下，成骨能力肯定，增殖能力强，可作为骨组织工程的种子细胞。     

骨髓基质细胞成脂肪分化的研究进展

实验与临床研究证明，骨髓基质细胞成脂肪分化与骨质疏松存在着不可忽视的关系。在去卵巢或类固醇诱发的骨质疏松的动物模型均发现，骨量的丢失伴有骨髓腔内的脂肪细胞的数目大大增加。各种原因导致的骨质疏松患者中，骨髓腔内的脂肪细胞与松质骨的骨量成反比。对成纤维细胞克隆形成单位（CFU-Fs）的分析表明，9月龄大鼠骨髓中的基质干细胞数量明显少于6月龄大鼠，提示了骨髓基质细胞数量的减少和髓内脂肪细胞的增多存在某种关系。     

酒精性骨坏死发病机制和葛根素对其的预防作用

目的 探讨酒精性骨坏死发病机制和葛根素的预防作用。方法分离培养小鼠骨髓基质细胞（MSCs），随机分为3组：A组（酒精组），给予酒精0、0．03、0．09、0．15mol／L；B组（葛根素组），酒精0．09mol／L和葛根素终浓度为0．01mr,／ml；C组（对照组），无酒精与葛根素。苏丹Ⅲ染色，光镜下脂肪细胞计数；测定细胞内甘油三酯含量、碱性磷酸酶活性和细胞培养液中骨钙素含量。采用完整细胞斑点印迹分子杂交方法检测A组和C组细胞中422（aP2）mRNA和Ⅰ型胶原mRNA的表达。采用RT-PCR技术检测3组细胞中PPARγmRNA和osteocalcin mRNA的表达。结果酒精处理细胞后21d，MSCs分化为脂肪细胞的数量随酒精作用时间延长及浓度增大而增多；细胞内甘油三酯含量明显增高，ALP活性降低，骨钙素含量显著减少。0．09mol／L酒精作用细胞6d，A组中422（aP2）mRNA表达含量显著增高，Ⅰ型胶原mRNA表达含量明显降低。B组和C组细胞中PPARγmRNA表达明显低于A组，osteocalcin mRNA表达明显高于A组，而B组与C组间差异无统计学意义（P〉0．05）。结论酒精能诱导MSCs大量成脂分化，减少其成骨分化，这可能与酒精性骨坏死的发生机制有关。葛根素能够对抗酒精诱导MSCs成脂分化，可能预防骨坏死。     

骨髓脂肪细胞与成骨细胞分化的信号转导调控机制

骨髓基质干细胞具有多向分化潜能和自我增殖能力.在不同调节因子的作用下分化为多种细胞,如成骨细胞、软骨细胞、脂肪细胞、成肌细胞、神经细胞和血管内皮细胞等.近年研究发现,骨质疏松的发生可能与骨髓内环境中骨髓基质干细胞向成骨细胞分化能力的减弱,使得骨髓脂肪细胞的数量增多,脂肪细胞与成骨细胞的比例失调有关.骨髓基质干细胞纵向分化为成熟骨髓脂肪细胞及成骨细胞的过程受到多种通路的调控和影响,而分化成熟的成骨细胞和脂肪细胞在一定条件下也可以相互转化,这提示我们以后是否可以通过药物或其他手段来抑制BMS向脂肪细胞的分化、增殖能力进而使更多成骨细胞生成,甚至通过脂肪细胞去分化再分化为成骨细胞,从而有效地刺激骨形成,以达到治疗骨丢失和骨代谢异常的目的.基于此,本文结合最新研究进展,重点叙述骨髓基质干细胞向成熟脂肪细胞与成骨细胞分化过程中的信号转导调节机制以及两条信号转导间信号转导因子的相互影响.同时叙述了成熟骨髓脂肪细胞和成骨细胞在一定条件下相互转化可能的机制,希望可以为以后研究开发骨组织合成代谢药物提供新思路.     

成骨生长肽对大鼠骨髓基质细胞增殖和成骨分化的作用

目的：观察成骨生长肽诱导体外培养的大鼠骨髓基质细胞增殖及向成骨分化的作用。方法：取6周龄SD大鼠，贴壁法分离培养骨髓基质细胞，在不同浓度成骨生长肽的诱导下，观察细胞形态变化，绘制骨髓基质细胞生长曲线，碱性磷酸酶和钙结节组织化学染色。结果：成骨生长肽对骨髓基质细胞增殖和成骨分化的作用呈剂量依赖性：成骨生长肽浓度在10^-10及10^-11mol／L时促进骨髓基质细胞增殖，而在10^-8及10^-9mol／L时对骨髓基质细胞的增殖略有抑制作用；成骨生长肽浓度在10^-10及10^-11mol／L时骨髓基质细胞碱性磷酸酶染色基本呈阴性，与对照组相比差异无统计学意义，而在10^-8及10^-9mol／L浓度下可以显著提高骨髓基质细胞碱性磷酸酶染色的阳性率。结论：成骨生长肽可以明显促进大鼠骨髓基质细胞增殖及向成骨细胞分化，其促成骨活性具有显著的浓度依赖性。     

柚皮苷促进成骨细胞分化并有效改善卵巢切除所致的骨质疏松

目的 评价柚皮苷对成骨细胞增殖与分化的作用,并采用大鼠骨质疏松模型评价柚皮苷的治疗效果.方法 采用不同浓度的柚皮苷处理大鼠骨髓基质细胞,观察其增殖、分化与功能的改变.采用低、中、高三种不同剂量的柚皮苷作为治疗组,磷酸缓冲液(PBS)作为对照组,对卵巢摘除诱发骨质疏松的大鼠灌胃2个月.应用骨质疏松大鼠右侧股骨的X线照片和显微CT扫描测量骨矿密度以及骨体积分数,使用骨质疏松大鼠左侧胫骨的病理切片检测组间骨小梁厚度和骨小梁间隙的变化.结果 体外研究表明柚皮苷可有效增加骨髓基质细胞的增殖和成骨分化,浓度为10 μg/ml时对骨钙素的表达具有最显著的作用.骨髓基质细胞对柚皮苷的治疗呈现一种延迟反应模式.柚皮苷并有效逆转了卵巢切除导致的骨质疏松,增加了骨密度、骨容量和骨小梁厚度.300 mg/kg(中剂量)是具有满意治疗效果的最优剂量.结论 柚皮苷促进骨髓基质细胞的分化与增殖,增加骨钙素的表达,它能有效逆转卵巢切除大鼠的骨质疏松过程.本研究表明柚皮苷是治疗骨质疏松的潜在有效药物.     

人骨髓基质细胞培养及向成骨细胞的诱导分化

目的研究人骨髓基质细胞体外培养及向成骨细胞诱导分化的实验方法。方法采用梯度离心法获得人骨髓基质细胞，细胞纯化后使用分化培养液将骨髓基质细胞向成骨细胞方向诱导分化。通过形态学观察、生化指标检测、细胞染色和矿化结节测定等方法，确定细胞的功能状态和分化程度。结果显微镜观察显示获得的人骨髓基质细胞生长状况良好，生化指标稳定；经分化培养液培养的细胞增殖速度明显减慢，生长状态平稳。细胞在分化培养过程中，上清液中碱性磷酸酶分泌量明显增加，细胞碱性磷酸酶染色明显浓染，随时间呈显著增强趋势；采用常规培养液培养的骨髓基质细胞，在汇合后不能形成明显的矿化结节。用分化培养液培养的人骨髓基质细胞，在14d时开始出现矿化结节，在21d时呈现密集的茜素红染色矿化结节。结论梯度离心法获得的人骨髓基质细胞生长情况良好，功能状态稳定；体外培养的人骨髓基质细胞在一定条件下可以向成骨细胞方向诱导分化，并具有良好的成骨细胞功能特征，可以满足进一步研究的需要。     

骨髓脂肪细胞生成及其在骨质减少性疾病中的意义

骨髓基质系统由基质细胞谱系构成 ,包括未分化的基质干细胞及定型分化的脂肪细胞、成骨细胞、造血支持细胞等多种细胞类型。在定型分化的细胞中 ,以脂肪细胞最为丰富。骨髓脂肪细胞生成在机体的能量储存、骨代谢、脂肪代谢、造血支持中发挥重要的病理生理学作用。尤其因增龄、绝经、代谢性异常等导致的多种骨质减少性疾病中 ,骨体积的减少则伴随骨髓脂肪成分的增加 ,脂肪细胞生成是骨质减少性疾病中的重要并发症。笔者旨就骨髓脂肪细胞功能、分化机制及其在骨质减少性疾病发生机理及临床治疗中的意义作一综述。一、骨髓脂肪细胞的病理生理学…     

髓内脂肪细胞促骨髓基质细胞凋亡的实验研究

目的观察髓内脂肪细胞对骨髓基质细胞凋亡的影响,拟阐明骨质疏松的可能发病机制.方法建立脂肪细胞与骨髓基质细胞的共培养体系,用TUNEL法与流式细胞仪检测凋亡.结果在各实验组中均可见到凋亡细胞,且随着脂肪细胞浓度增加,凋亡细胞数目增多.流式细胞仪上表现为Annexin V^＋和PI^-.结论髓内脂肪细胞能够诱导骨髓基质细胞凋亡.     

骨髓基质干细胞成脂分化的调控及其对骨质疏松的影响

研究发现随着年龄的增长和绝经期后骨质疏松,骨髓腔内的脂肪细胞逐渐增多,取代了成骨细胞,因此抑制骨髓基质干细胞成脂分化是目前治疗骨质疏松的新途径。应用各种成脂诱导剂建立体外定向诱导骨髓基质干细胞成脂分化模型是研究新途径的基础。除了通过光学显微镜观察成脂分化的能力,还可运用分子生物学的方法定性、定量检测成脂分化的程度。过氧化物酶增殖子激活受体(PPARγ)是脂肪细胞的分化过程中起关键性作用的调节因子,组蛋白去乙酰化酶(SIRT1)被激活后能抑制PPARγ的表达,减少脂肪细胞的生成,起到预防和治疗骨质疏松的作用。笔者就以上方面和对减少骨髓脂肪分化的策略作了综述。     

Interconversion potential of cloned human marrow adipocytes in vitro

Information on the interconversion potential of adipocytes and other end cells characteristic of the stromal fibroblastic cell lineages, key in the understanding of bone turnover in metabolic diseases such as osteoporosis, is limited. The object of the present study was: i) to isolate relatively pure populations of adipocytes from human bone marrow; ii) to clone single adipocytes from these populations; and iii) to examine in vitro the interconversion potential of the progeny of these single-cloned adipocytes between the osteogenic and adipogenic phenotypes. Adipogenic colonies were isolated from the low-density floating fraction of normal bone marrow cells cultured in adipogenic media for 4 days. Single adipocytes were isolated and cloned by limiting dilution. Cloned adipocytes were found to dedifferentiate into fibroblast-like cells, and subsequently to differentiate into two morphologically distinct cell types: osteoblasts and adipocytes in appropriate culture systems. The adipocytic phenotype was confirmed by morphology, oil red O staining, and immunocytochemistry using antiserum to aP2. The osteogenic phenotype was confirmed by alkaline phosphatase, osteocalcin immunostaining using specific osteocalcin antiserum, and formation of mineralized cell aggregates. These findings demonstrate the extent of plasticity between the differentiation of adipocytic and osteogenic cells in human bone marrow stromal cell cultures. We have shown the ability of isolated clonal adipogenic cells to redifferentiate into cells of the osteogenic and adipogenic lineage and the interconversion potential of human marrow stromal cells in vitro. These results provide further evidence that the osteogenic and adipogenic cells share a common multipotential precursor.     

Preventive Effects of Puerarin on Alcohol-induced Osteonecrosis

Alcohol can induce adipogenesis by bone marrow stromal cells and may cause osteonecrosis of the femoral head. Currently, there are no medications available to prevent alcohol-induced osteonecrosis. We hypothesized puerarin, a Chinese herbal medicine with antioxidative and antithrombotic effects, can prevent alcohol-induced adipogenesis and osteonecrosis. Both bone marrow stromal cells (in vitro) and mice (in vivo) were treated either with ethanol or with ethanol and puerarin, with an untreated group serving as a control. In the in vitro study, the number of adipocytes, contents of triglycerides, and levels of PPARγ mRNA expression were decreased and alkaline phosphatase activity, contents of osteocalcin, and levels of osteocalcin mRNA expression were increased in cells treated with both alcohol and puerarin, compared with cells treated with alcohol only. In the in vivo study, marrow necrosis, fat cell hypertrophy and proliferation, thinner and sparse trabeculae, diminished hematopoiesis, and increased empty osteocyte lacunae in the subchondral region of the femoral head were observed in mice treated with alcohol. However, no such changes were seen in femoral heads of mice treated with alcohol and puerarin. The data suggest puerarin can inhibit adipogenic differentiation by bone marrow stromal cells both in vitro and in vivo and prevents alcohol-induced osteonecrosis in this model. Investigation performed at Orthopaedic Institute of Zhengzhou University, Zhengzhou, Henan, China. Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.     

Alcohol-induced adipogenesis in bone and marrow: a possible mechanism for osteonecrosis

The effect of alcohol on rabbit bone marrow and on the differentiation of mouse bone marrow stromal cells was investigated. Alcohol was administered intragastrically at a dose of 10 mL/kg/day for 1 to 6 months. Alcohol induced a significant increase in serum lipid peroxides, triglyceride, and cholesterol, and a reduction in superoxide dismutase activity. Fatty infiltration in the liver and adipogenesis in bone marrow were found histologically after alcohol administration. Fat cell hypertrophy and proliferation and diminished hematopoiesis in the subchondral area of the femoral head were observed. Triglycerides were deposited in osteocytes, which became pyknotic, and the percentage of empty osteocyte lacunae increased. None of these abnormal changes were detectable in the control group. In the in vitro study, the marrow stromal cells were treated with increasing (0.03, 0.09, and 0.15 mol/L) concentrations of ethanol for 4 to 21 days. Alcohol induced the differentiation of the cells into adipocytes. The number of adipocytes increased with longer durations of exposure to ethanol and with higher concentrations. Cells treated with ethanol also showed diminished alkaline phosphatase activity and expression of osteocalcin. These novel findings indicate that alcohol can directly induce adipogenesis, decrease osteogenesis in bone marrow stroma, and produce intracellular lipid deposits resulting in the death of osteocytes, which may be associated with the development of osteonecrosis, especially in patients with long-term and excessive use of alcohol.     

siRNA腺病毒载体对兔骨髓基质细胞成脂分化的干扰效应

目的 观察靶向过氧化物酶体增殖子活化受体-γ(PPARγ)基因siRNA腺病毒载体阻断乙醇诱导兔骨髓基质细胞(MSCs)的成脂分化.方法 培养兔MSCs随机分为7组:N:对照组,M:模型组,CO:感染空载体组,C1:感染无关siRNA组,S1、S2、S3:干扰1、2、3组.将重组腺病毒载体转染细胞,检测MSCs内PPARγ mRNA、osteocalcin mRNA、PPARγ蛋白表达、甘油三酯、ALP活性和培养液骨钙素含量,并计数脂肪细胞.结果 N、M、CO、C1组PPARγ mRNA和osteocalcinmR-NA表达值分别为(0.39±0.02)、(0.75±0.03)、(0.74±0.03)、(0.73±0.02)和(1.09±0.19)、(0.50±0.10)、(0.46±0.12)、(0.49±0.13),M、CO、C1组脂肪细胞多,甘油三酯高,ALP活性与骨钙素量均低.S1、S2、S3组PPARγ mRNA和osteocalcin mRNA表达值分别为(0.28±0.03)、(0.30±0.03)、(0.31±0.01)和(0.92±0.09)、(0.87±0.32)、(0.93±0.25),脂肪细胞数、甘油三酯量、ALP活性值与骨钙素含量均接近正常,与M、CO、C1组间差异有统计学意义(P<0.05),与N组间差异无统计学意义(P>0.05).结论 该腺病毒载体能阻断乙醇诱导的MSCs成脂分化.     

恒定磁场对骨组织中细胞影响的研究

目的阐明恒定磁场对成骨细胞和破骨细胞的生长和功能的影响和对骨髓基质细胞向成骨细胞方向分化的作用，从而在细胞水平较全面的解释磁场治疗骨质疏松的机理。方法利用体外原代培养的成骨细胞、破骨细胞和骨髓基质细胞，分别外加0．38T、0．48T恒定磁场处理后，观察恒定磁场对这三种细胞生长、分化和功能的影响。结果恒定磁场处理可促进骨髓基质细胞向成骨细胞方向分化，促进成骨细胞的增殖、分化及功能的表达，并且抑制破骨细胞的生长、分化和功能。结论恒定磁场促进骨组织的成骨作用，抑制骨分解，是其治疗骨质疏松良好效果的部分机制。     

激素诱导骨髓基质细胞成脂的初步研究

为了探讨激素对骨髓基质细胞分化成脂肪细胞的诱导促进作用,研究激素性股骨头缺血性坏死的病理学机制及其防治方法,用6～8周小鼠股骨骨髓细胞进行原代培养21 d。实验组从细胞种植当天即加入10~(-7)M地塞米松作为诱导剂。通过倒置显微镜及苏丹Ⅲ脂肪染色技术观察骨髓基质细胞及脂肪细胞的形态及生长情况。结果发现,骨髓基质细胞生长成层前为梭形的成纤维细胞样细胞,7～8 d成层后,变为多边形或圆形。10～12 d,实验组中细胞内出现脂肪滴,随培养时间延长,小脂滴融合为大脂滴,脂肪细胞数逐渐增多,苏丹Ⅲ染色显示细胞质中充满大小不等的圆形橘红色脂肪滴,胞核位于细胞中央或一侧。对照组中仅出现极少数脂肪细胞。提示糖皮质激素能够直接促进骨髓基质细胞分化成脂肪细胞,激素性股骨头缺血坏死时骨髓内脂肪细胞增殖肥大可能与此机制有关。     

Differentiation of human marrow stromal precursor cells: bone morphogenetic protein-2 increases OSF2/CBFA1, enhances osteoblast commitment, and inhibits late adipocyte maturation.

Because regulation of the differentiation to osteoblasts and adipocytes from a common progenitor in bone marrow stroma is poorly understood, we assessed effects of bone morphogenetic protein-2 (BMP-2) on a conditionally immortalized human marrow stromal cell line, hMS(2-6), which is capable of differentiation to either lineage. BMP-2 did not affect hMS(2-6) cell proliferation but enhanced osteoblast differentiation as assessed by a 1.8-fold increase in expression of OSF2/CBFA1 (a gene involved in commitment to the osteoblast pathway), by increased mRNA expression and protein secretion for alkaline phosphatase (ALP), type I procollagen and osteocalcin (OC) (except for OC protein), and by increased mineralized nodule formation. Transient transfection with Osf2/Cbfa1 antisense oligonucleotide substantially reduced BMP-2-stimulated expression of ALP mRNA and protein. The effects of BMP-2 on adipocyte differentiation varied: expression of peroxisome proliferator-activated receptor gamma2 (a gene involved in commitment to the adipocyte pathway) was unchanged, mRNA expression of the early differentiation marker, lipoprotein lipase, was increased, and mRNA and protein levels of the late differentiation marker, leptin, and the formation of cytoplasmic lipid droplets were decreased. Thus, by enhancing osteoblast commitment and by inhibiting late adipocyte maturation, BMP-2 acts to shunt uncommitted marrow stromal precursor cells from the adipocyte to the osteoblast differentiation pathway.     

Bone-like nodules formed by human bone marrow stromal cells: comparative study and characterization

Autologous bone marrow stromal cells have been proposed as an adjuvant in the treatment of bone nonunion. This cell therapy would require the establishment of culture conditions that permit the rapid expansion of these cells ex vivo while retaining their potential for further differentiation. Our aim was to achieve a full differentiation process using human bone marrow aspirates. We first analyzed the effects of mineralization medium (with ascorbic acid and phosphate) and dexamethasone (dex) during the primary culture of human bone marrow stromal (HBMS) cells on the proliferation/differentiation behavior of first-passage cells. The most appropriate schedule was then selected to further characterize this differentiation model. We showed that primary culture of HBMS cells in proliferation medium (DMEM supplemented with 10% fetal calf serum), with a 48-h treatment by mineralization medium and dex resulted in a better osteoblastic differentiation of first-passage cells than primary culture carried out in mineralization medium with or without dex. We showed that culture of HBMS cells under these conditions (primary culture in proliferation medium, followed by subculture in mineralization medium) led to the formation of specifically mineralized bone-like nodules similar to the ones observed with rat bone marrow stromal cells. Our nodules exhibited three distinct cell types, reproducing in vitro a tissue-like structure. This treatment demonstrated an optimal proliferation and expression of osteoblastic markers such as alkaline phosphatase, osteocalcin, and type I collagen. The primary culture allowed the multiplication of the number of adherent progenitor cells at the initial time of plating by a mean factor of 44,000, which was found to be negatively correlated with age. Thus, this differentiation model could provide a new tool to elaborate an autologous cell therapy designed to enhance osteogenesis.     

Oxysterols regulate differentiation of mesenchymal stem cells: pro-bone and anti-fat.

Pluripotent mesenchymal stem cells can undergo lineage-specific differentiation in adult organisms. However, understanding of the factors and mechanisms that drive this differentiation is limited. We show the novel ability of specific oxysterols to regulate lineage-specific differentiation of mesenchymal stem cells into osteogenic cells while inhibiting their adipogenic differentiation. Such effects may have important implications for intervention with osteoporosis. INTRODUCTION: Oxysterols are products of cholesterol oxidation and are formed in vivo by a variety of cells including osteoblasts. Novel pro-osteogenic and anti-adipogenic effects of specific oxysterols on pluripotent mesenchymal cells are demonstrated in this report. Aging and osteoporosis are associated with a decrease in the number and activity of osteoblastic cells and a parallel increase in the number of adipocytic cells. MATERIALS AND METHODS: The M2-10B4 pluripotent marrow stromal cell line, as well as several other mesenchymal cell lines and primary marrow stromal cells, was used to assess the effects of oxysterols. All results were analyzed for statistical significance using ANOVA. RESULTS AND CONCLUSION: Pro-osteogenic and anti-adipogenic effects of specific oxysterols were assessed by the increase in early and late markers of osteogenic differentiation, including alkaline phosphatase activity, osteocalcin mRNA expression and mineralization, and the decrease in markers of adipogenic differentiation including lipoprotein lipase and adipocyte P2 mRNA expression and adipocyte formation. Complete osteogenic differentiation of M2 cells into cells expressing early and late markers of differentiation was achieved only when using combinations of specific oxysterols, whereas inhibition of adipogenesis could be achieved with individual oxysterols. Oxysterol effects were in part mediated by extracellular signal-regulated kinase and enzymes in the arachidonic acid metabolic pathway, i.e., cyclo-oxygenase and phospholipase A(2). Furthermore, we show that these specific oxysterols act in synergy with bone morphogenetic protein 2 in inducing osteogenic differentiation. These findings suggest that oxysterols may play an important role in the differentiation of mesenchymal stem cells and may have significant, previously unrecognized, importance in stem cell biology and potential therapeutic interventions.