端粒酶逆转录酶基因修饰人骨髓间质干细胞的实验研究

目的： 观察外源性hTERT基因的异位表达对人骨髓间质干细胞（MSCs）端粒酶活性及细胞生命周期的影响。方法： 将携带有增强型绿色荧光蛋白（EGFP）报告基因和人端粒酶逆转录酶（hTERT）目的基因的质粒pEGFP-hTERT通过脂质体转染法转入人骨髓MSCs中，并用G418筛选法进行抗性克隆的筛选与扩增。通过RT-PCR和PCR-ELISA对转染前后hTERT mRNA的表达情况及其对端粒酶活性的影响进行检测。将转染细胞在EGF和bFGF的联合诱导下向神经元样细胞定向诱导分化，并用RT-PCR进行鉴定。结果： 未转染的人骨髓MSCs hTERT mRNA表达阴性，且端粒酶呈阴性而转染hTERT基因的人骨髓MSCs hTERTmRNA表达阳性，且端粒酶呈阳性。转染hTERT基因的人骨髓MSCs在体外已连续传到第35代，而未转染的人骨髓MSCs传到第20-25代左右已衰老死亡。 转染hTERT基因的人骨髓MSCs经EGF和bFGF的联合诱导后，较多细胞出现了典型的神经元样形态，且经RT-PCR检测表明，神经元特征性蛋白微管相关蛋白（MAP₂）和神经丝亚单位M（NF-M）表达增强。结论： 外源性hTERT基因可以在人骨髓MSCs中获得异位表达，并能诱导人骨髓MSCs的端粒酶活性。外源性hTERT基因的异位表达不仅可以使人骨髓间质干细胞的寿命明显延长而且不影响其维持干细胞的多向分化潜能特性。     

Isolation and characterization of chorionic mesenchymal stromal cells from human full term placenta

This study focused on the characterization of mesenchymal stromal cells (MSCs) from the chorion of human full term placenta from 15 donors. Chorionic MSCs revealed homologous fibroblast-like morphology and expressed CD73, CD29, CD105, and CD90. The hematopoietic stem cell markers including HLA DR, CD11b, CD34, CD79a, and CD45 were not expressed. The growth kinetics of their serial passage was steady at the later passages (passage 10). The multilineage capability of chorionic MSCs was demonstrated by successful adipogenic, osteogenic and chondrogenic differentiation and associated gene expression. Chorionic MSCs expressed genes associated with undifferentiated cells (NANOG, OCT4, REX1) and cardiogenic or neurogenic markers such as SOX2, FGF4, NES, MAP2, and NF. TERT was negative in all the samples. These findings suggest that chorionic MSCs undifferentiated stem cells and less likely to be transformed into cancer cells. A low HLA DR expression suggests that chorionic MSCs may serve as a great source of stem cells for transplantation because of their immune-privileged status and their immunosuppressive effect. Based on these unique properties, it is concluded that chorionic MSCs are pluripotent stem cells that are probably less differentiated than BM-MSCs, and they have considerable potential for use in cell-based therapies.     

天然脑活素定向诱导大鼠骨髓间充质干细胞向神经元样细胞分化的实验研究

目的： 探讨天然脑活素（NC）诱导骨髓间充质干细胞(MSCs)向神经元样细胞分化的作用。方法: 取6-8周龄SD大鼠,无菌获取胫骨和股骨骨髓,全骨髓贴壁筛选法分离培养并纯化大鼠MSCs,应用天然脑活素诱导MSCs向神经元分化。倒置相差显微镜追踪比较观察分化过程中细胞形态的变化,免疫细胞化学和逆转录-聚合酶链反应 (RT-PCR)方法检测神经元特异性标志物：巢蛋白（nestin）、神经元特异性烯醇化酶(NSE) 、胶质纤维酸性蛋白(GFAP)的表达情况。免疫细胞化学检测细胞微管相关蛋白-2(MAP-2)的表达。结果：经全骨髓贴壁筛选法获得了纯度较高（90%以上）的大鼠MSCs,天然脑活素含药血清诱导分化后的细胞呈现双极、多极和锥形的典型神经元细胞的形态,分别从mRNA和蛋白水平上证实诱导分化后的细胞表达神经元标记物NSE和nestin,不表达神经胶质细胞标记物GFAP。诱导分化后细胞MAP-2的表达明显。结论：天然脑活素可诱导MSCs向神经元样细胞的定向分化。     

依达拉奉体外诱导骨髓间充质干细胞向神经元样细胞分化

目的 采用密度梯度离心和差速贴壁法体外分离、培养、纯化及鉴定成年Wistar大鼠骨髓间充质干细胞（MSCs）,利用碱性成纤维细胞生长因子（bFGF）和依达拉奉联合诱导MSCs定向分化为神经元样细胞。 方法 选用1月龄健康雄性Wistar大鼠,采用Percoll分离液密度梯度离心法获取骨髓中的MSCs,通过差速贴壁法反复传代培养、纯化,取第3代细胞采用流式细胞术、免疫细胞化学等方法检测MSCs的纯度,利用bFGF联合依达拉奉诱导MSCs向神经元样细胞分化,并通过扫描电镜、免疫细胞化学等对诱导后的细胞进行鉴定。结果 第3代MSCs经免疫细胞化学及流式细胞仪等检测,间充质干细胞特异性的标记物CD44表达阳性,不表达造血干细胞及白细胞的特异性标记物CD34、CD45,MSCs纯度高达955%。诱导分化后扫描电镜检测可观察到典型的神经元样细胞结构;免疫细胞化学检测发现,细胞表达神经元特异性烯醇化酶（NSE）,不表达胶质纤维酸性蛋白（GFAP）,Nestin的表达随着细胞成熟而减弱。 结论 密度梯度离心和差速贴壁法可获得高纯度的MSCs;依达拉奉能高效地定向诱导MSCs分化为神经元样细胞。     

端粒酶活性在骨髓间充质干细胞体外分化过程中的表达观察

为了探讨兔骨髓间充质干细胞体外增殖前后及诱导分化内皮细胞过程中端粒酶活性的表达及意义，我们联合应用密度梯度离心和贴壁培养法分离骨髓间充质干细胞，继而诱导其向内皮细胞方向分化，用TRAPeze ELISA法分别检测新鲜分离的骨髓细胞及骨髓间充质干细胞、原代培养的内皮样细胞及传代细胞端粒酶活性，结果发现新鲜分离的骨髓细胞及增殖前的骨髓间充质干细胞端粒酶活性低水平表达，一旦经过VEGF诱导分化，细胞端粒酶活性表达上调，在5代内其端粒酶活性不因细胞传代而下降或消失，说明骨髓间充质干细胞体外有限扩增和诱导分化时保持端粒酶活性，维持组织干细胞特性，为组织干细胞的临床研究奠定理论基础。     

胰腺十二指肠同源框1基因在大鼠骨髓间充质干细胞向胰岛素分泌细胞定向分化过程中的作用

目的:探讨胰腺十二指肠同源框1基因(PDX-1)在大鼠骨髓间充质干细胞(MSCs)向胰岛素分泌细胞定向分化过程中的作用。方法:新型纳米载体Superfect介导含有PDX-1基因的真核表达载体转染骨髓MSCs,G418筛选,分步法进行体外诱导;流式细胞仪检测诱导后胰岛素阳性细胞的比例,SABC免疫细胞化学染色和Western印迹法检测诱导后细胞胰岛素蛋白的表达;ELISA法检测诱导后细胞对葡萄糖刺激的反应能力。结果:Superfect可高效介导重组载体在骨髓MSCs表达,随着转染时间延长,表达逐渐增强PDX-1~ MSCs分化为胰岛素阳性细胞数较转染空白载体和PDX-1~-MSCs组明显增多;诱导后细胞表达胰岛素,转染PDX-1基因后表达明显增加;PDX-1~ MSCs对不同浓度的葡萄糖刺激表现出不同的胰岛素分泌反应。结论:骨髓MSCs体外能分化为胰岛素分泌细胞,PDX-1能显著提高其分化效率。     

黄连素诱导大鼠骨髓间质干细胞分化为神经元样细胞

目的:黄连素体外定向诱导SD大鼠骨髓间质干细胞分化为神经元样细胞。方法:用全骨髓细胞悬液体外扩增和纯化骨髓间质干细胞。选用第5代以后骨髓间质干细胞进行诱导分化,用含10 μg/L碱性细胞生长因子(bFGF)的完全培养液预诱导24 h,后更换含黄连素的无血清DMEM诱导骨髓间质干细胞分化为神经元样细胞。免疫组化鉴定神经元烯醇酶(NSE)、神经丝蛋白(NF)、胶质纤维酸性蛋白(GFAP)的表达。结果:大鼠骨髓间质干细胞体外扩增第5代后细胞形态达到均一,成梭形。加黄连素诱导1h-8 h,间质干细胞胞体逐渐增大并伸出细长突起,形似神经细胞。免疫组化显示诱导的神经元样细胞NSE、NF表达阳性,GFAP阴性。结论:黄连素可诱导骨髓间质干细胞分化为神经元样细胞。     

体外诱导骨髓间充质干细胞向软骨细胞的定向分化及其鉴定

目的: 体外诱导骨髓间充质干细胞(MSC)向软骨细胞定向分化, 并对分化后的细胞进行鉴定。方法: 由健康成人骨髓中分离出MSC, 取第 3代细胞进行实验。鉴定后, 将微小细胞团在TGF -β1、地塞米松(Dex)及维生素C(VitC)等诱导下分化。14d后, 细胞团经石蜡包埋、切片及HE染色后, 进行甲苯胺蓝染色及II型胶原(ColII)的免疫组化染色。采用Westernblot和RT- PCR, 分别检测诱导前后MSC中ColII及前ColIImRNA的表达。结果: HE染色显示, 诱导后细胞呈软骨细胞样形态; 甲苯胺蓝及ColII染色的细胞外基质呈阳性。Westernblot和RT PCR的结果显示, 诱导分化后的MSC可表达ColII和前ColII的mRNA。结论: MSC在TGF- β1、Dex及VitC等诱导后, 可分化为软骨细胞。     

Induction of intervertebral disc-like cells from adult mesenchymal stem cells

The potential of adult mesenchymal stem cells (MSCs) to differentiate towards cartilage, bone, adipose tissue, or muscle is well established. However, the capacity of MSCs to differentiate towards intervertebral disc (IVD)-like cells is unknown. The aim of this study was to compare the molecular phenotype of human IVD cells and articular chondrocytes and to analyze whether mesenchymal stem cells can differentiate towards both cell types after transforming growth factor beta (TGF beta)-mediated induction in vitro. Bone marrow-derived MSCs were differentiated in spheroid culture towards the chondrogenic lineage in the presence of TGF beta(3) dexamethasone, and ascorbate. A customized cDNA-array comprising 45 cartilage-, bone-, and stem cell-relevant genes was used to quantify gene expression profiles. After TGF beta-mediated differentiation, MSC spheroids turned positive for collagen type II protein and expressed a large panel of genes characteristic for chondrocytes, including aggrecan, decorin, fibromodulin, and cartilage oligomeric matrix protein, although at levels closer to IVD tissue than to hyaline articular cartilage. Like IVD tissue, the spheroids were strongly positive for collagen type I and osteopontin. MSC spheroids expressed more differentiation markers at higher levels than culture-expanded IVD cells and chondrocytes, which both dedifferentiated in monolayer culture. In conclusion, mesenchymal stem cells adopted a gene expression profile that resembled native IVD tissue more closely than native joint cartilage. Thus, these cells may represent an attractive source from which to obtain IVD-like cells, whereas modification of culture conditions is required to approach the molecular phenotype of chondrocytes in hyaline cartilage.     

Bone marrow stem cells as a vehicle for delivery of heme oxygenase-1 gene

Bone marrow-derived mesenchymal stem cells (MSCs) are readily accessible adult stem cells that are capable of self-renewal and multilineage differentiation. Human MSCs have been well described and used in xenogenic models for investigation, but rodent MSCs, if available, would eliminate problems associated with transplantation across a species barrier. Here we describe an effective method to generate rat MSCs and use these cells to target gene delivery in vivo. MSCs that were capable of retaining their differentiation potential after several population doublings in culture were generated from rat bone marrow. Marrow-derived MSCs were enriched and infected with an adenoviral vector carrying the heme oxygenase gene (Ad5/HO-1). Transfected rodent MSCs retained their differentiation potential, even after 10 passages, as determined by their ability to differentiate into adipocytes. Western analyses clearly indicated that Ad5/HO-1-transfected rodent MSCs exhibited increased HO-1 expression. Trafficking of fluorescent rat MSCs was evaluated 24 and 48 h after MSC infusion. Most of the infused cells accumulated in the lungs of recipients where they expressed HO-1. Thus, bone marrow-derived MSCs are useful for gene delivery replacement of the products of deficient genes. These cells may be useful for potentiation of wound healing because they retain their pluripotential differentiation ability.     

慢性粒细胞白血病患者骨髓间质干细胞的生物学特征的研究

目的： 研究不同来源（正常人、慢性粒细胞性白血病）骨髓间质干细胞的生物学特征及分化能力。 方法: 分离获取19例慢性粒细胞性白血病（CML）患者的骨髓间质干细胞，同时获取8例正常人的骨髓间质干细胞作为对照。获取的间质干细胞采用低血清培养液培养。瑞士染色观察形态，FACS检测其免疫表型和细胞周期，通过油红O和von Kossa染色来证实向脂肪和骨的分化情况。RT-PCR检测CML特异性表达的BCR/ABL基因；对正常人、CML患者的骨髓间质干细胞进行染色体分析。 结果: 正常人和CML骨髓间质干细胞具有相似的细胞形态、生长特性和免疫表型，而且都可以向骨和脂肪分化。CML来源的MSCs不表达BCR/ABL融合基因，并且具有正常的核型。 结论: 从CML骨髓中可以分离和培养出具有间质干细胞特性的细胞群体，其具有正常的核型且不表达BCR/ABL基因。CML和正常人骨髓间质干细胞具有相似的生物学特性和多向分化能力。     

骨髓间质干细胞定向分化的实验研究

为了探讨体外定向诱导人骨髓间质干细胞(MSC)分化为神经元样细胞的机制,本研究将分离的人MSC进行体外扩增培养,并观察脑心舒定向诱导MSC分化为类神经元样细胞的效应。在光镜下观察细胞形态,用免疫细胞化学法检测神经细胞特异性抗原标志。结果显示人MSC可通过贴壁法成功分离并可在体外大量扩增。脑心舒诱导120min后大部分MSC转变为神经元样细胞,出现胞体和突起,免疫细胞化学染色NSE、nestin呈阳性和GFAP阴性。上述结果提示人骨髓间质干细胞可在体外诱导分化为神经元样细胞。     

PKH26标记大鼠骨髓间质干细胞的实验研究

目的建立PKH26标记大鼠骨髓间质干细胞（MSCs）的方法，并探讨标记MSCs的基本生物学活性。方法大鼠MSCs按PKH26标记程序进行标记后培养，采用激光共聚焦显微镜、流式细胞分析仪等观察细胞生长状态和荧光标记活性变化；应用RT-PCR检测标记后MSCs的GAPDH、nucleostemin及Bmi-1基因的表达；选用碱性磷酸酶染色、Von Kossa染色及骨形成蛋白3（BMP3）基因表达分析等技术，观察标记后MSCs体外分化成骨细胞的特性。结果PKH26标记后细胞呈红色荧光，荧光的强度随着PKH26浓度的增加而递增，并与传代时间和代数相关；标记后细胞生长状态良好，基本生长特性如传代培养和生长曲线无明显改变；细胞GAPDH、nucleostemin及Bmi-1基因表达未见改变；标记MSCs诱导后ALP、Von Kossa染色阳性，呈现典型的成骨细胞形态和生物学特征，并表达BMP3基因。结论PKH26可稳定标记大鼠骨髓MSCs并能传代培养，标记后细胞形态、生长活力及多向分化潜能等无明显影响，该技术可用于追踪MSCs转归、可塑性及干细胞移植方面的实验研究。