Endothelial progenitor cells: identity defined?

In the past decade, researchers have gained important insights on the role of bone marrow (BM)-derived cells in adult neovascularization. A subset of BM-derived cells, called endothelial progenitor cells (EPCs), has been of particular interest, as these cells were suggested to home to sites of neovascularization and neoendothelialization and differentiate into endothelial cells (ECs) in situ , a process referred to as postnatal vasculogenesis. Therefore, EPCs were proposed as a potential regenerative tool for treating human vascular disease and a possible target to restrict vessel growth in tumour pathology. However, conflicting results have been reported in the field, and the identification, characterization, and exact role of EPCs in vascular biology is still a subject of much discussion. The focus of this review is on the controversial issues in the field of EPCs which are related to the lack of a unique EPC marker, identification challenges related to the paucity of EPCs in the circulation, and the important phenotypical and functional overlap between EPCs, haematopoietic cells and mature ECs. We also discuss our recent findings on the origin of endothelial outgrowth cells (EOCs), showing that this in vitro defined EC population does not originate from circulating CD133⁺ cells or CD45⁺ haematopoietic cells.     

用差异显示法分析不同生长环境中的造血干细胞/祖细胞基因表达的初步研究

对比分析不同生长环境中的脐血CD34+造血干/祖细胞基因表达变化。方法: 采用静态和动态培养系统培养脐血单个核细胞,1周后收获CD34+造血干/祖细胞, 提取总RNA, 用差异显示法对比分析在不同生长环境中造血干/祖细胞基因表达的差异。 结果: 在所使用的差异显示条件下,得到30个差异表达基因片段,其中一个差异表达片段为RAN基因,该基因属于RAS癌基因家族,可能与造血细胞增殖有关。结论: 不同生长环境影响CD34+造血干/祖细胞的基因表达,这些差异表达的基因可为优化体外培养环境,扩增造血细胞提供分子基础。     

肝素促进脐血巨核祖细胞体外扩增

目的 :探索肝素在脐带血CD34⁺ 细胞定向扩增巨核祖细胞中的作用。方法采用免疫磁珠法 (MACS)分选CD34⁺ 细胞 ,在TPO ,IL 1 1的扩增体系中加入肝素 ,巨核祖细胞集落分析 (CFU MK)测定巨核祖细胞扩增倍数 ,流式细胞仪检测巨核祖细胞分化过程中的特异性标记 (CD34⁺ ,CD41a⁺ ,CD61⁺ ,CD34⁺ CD41a⁺ ,CD41a⁺ CD61 ⁺ ) ,巨核细胞特异性抗体 (CD41a)免疫组化染色和透射电镜观察鉴定巨核细胞形态及超微结构 ,血小板体外活化实验及NOD/SCID小鼠异种体内移植实验评价扩增的巨核祖细胞的功能。结果 :TPO( 5 0ng/ml)与IL-1 1 ( 5 0ng/ml)双因子联合应用 ,7天巨核祖细胞克隆扩增倍数为 83 1 7± 39 41倍 ,1 0天为 2 0 5 0 6± 74 2 6倍 ,流式细胞仪分析显示 7天CD34⁺ CD41a+ 细胞扩增 1 0 5 1± 4 79倍 ,0天加入肝素后 ,7天巨核祖细胞克隆扩增倍数为 1 0 8 2 5± 32 67倍 ,1 0天为 333 0 6± 2 7 5 4倍 ,7天CD34⁺ CD41a⁺ 细胞扩增到 2 9 93± 6 39倍 ,为无肝素组的 2.85倍 ,与双因子组相比有统计学差异 (P <0.0 1 ) ,肝素在第 5天及第 7天加入没有增加巨核祖细胞扩增效果。经全身照射预处理的NOD/SCID小鼠静脉输注扩增第 7天的巨核细胞 (TPO、IL-11、肝素联合 ) ,可明显加速其血小板及白细胞计数的恢复并提高生存率 ;同时 ,体外血小板活化实验证实扩增的巨核细胞在体外可产生血小板 ,有正常巨核细胞功能。结论 :TPO、IL-11组合的扩增体系中加入肝素可进一步改善脐带血巨核祖细胞的扩增效果 ,优化体外扩增体系。     

Characterization of CD133+ hepatocellular carcinoma cells as cancer stem/progenitor cells

The CD133 antigen, identified as a hematopoietic stem cell marker, appears in various human embryonic epithelia including the neural tube, gut, and kidney. We herein investigated whether CD133(+) cells isolated from human hepatocellular carcinoma cell lines possess cancer stem/progenitor cell-like properties. Among the three cell lines studied, the CD133 antigen was found to be expressed only on the surface of Huh-7 cells. CD133(+) cells from Huh-7 performed a higher in vitro proliferative potential and lower mRNA expressions of mature hepatocyte markers, glutamine synthetase and cytochrome P450 3A4, than CD133(-) population of Huh-7 cells. When either CD133(+) or CD133(-) cells were subcutaneously injected into SCID mice, CD133(+) cells formed tumors, whereas CD133(-) cells induced either a very small number of tumors or none at all. Taken together, the identification of CD133(+) cells could thus be a potentially powerful tool to investigate the tumorigenic process in the hepatoma system and to also develop effective therapies targeted against hepatocellular carcinoma.     

The characteristics of endothelial progenitor cells derived from mononuclear cells of rat bone marrow in different culture conditions

Endothelial progenitor cells (EPCs) derived from bone marrow are known to be heterogeneous. In this study, we tried to find favorable conditions that induce the differentiation of mononuclear cells (MNCs) from bone marrow into EPCs. The differentiation capacity of MNCs from rat bone marrow was investigated in different conditions, such as different media, different induction times and different culture surfaces. The cell morphology and endothelial biomarkers associated with differentiated MNCs were studied. Our results indicated that MNCs cultured in EGM-2MV (Endothelial cell basal medium-2, plus SingleQuots of growth supplements) developed a bursiform shape, a late EPC-like morphology, while MNCs cultured in complete medium (CM, M199 with 10% FBS, 20 ng/mL VEGF and 10 ng/mL bFGF) showed a spindle shape, an early EPC-like morphology. Cells of both morphologies were able to incorporate DiI-ac-LDL and bind lectin in vitro. MNCs cultured in EGM-2MV exhibited a higher proliferation rate and higher eNOS expression than MNCs cultured in CM. MNCs cultured in EGM-2MV had the ability to form tubes on Matrigel. Flow cytometry results indicated that CD133 expression was highest at day 12 and that the greatest number of cells positive for both FLK-1 and CD133 appeared at day 20 from cells cultured in dishes without fibronectin coating. In addition, the expression levels of CD133, CD31 and FLK-1/CD133 were not significantly different between cells of different shapes. Our experiments suggest that MNCs from bone marrow can be differentiated into late EP-like cells in EGM-2MV, which have the ability to rapidly proliferate. These MNCs can also be differentiated into early EP-like cells in CM. Additionally, fibronectin may not be necessary for the differentiation of EPCs to mature ECs after three generations. Differentiated MNCs from bone marrow in EGM-2MV have the characteristics of EPCs, although the expression levels of EPC markers were lower than previously reported.     

Novel monoclonal antibodies broadly reactive to human recombinant sapovirus‐like particles

Sapovirus (SaV), a member of the family Caliciviridae, is an important cause of acute epidemic gastroenteritis in humans. Human SaV is genetically and antigenically diverse and can be classified into four genogroups (GI, GII, GIV, and GV) and 16 genotypes (7 GI [GI.1–7], 7 GII, [GII.1–7], 1 GIV and 1 GV), based on capsid sequence similarities. Monoclonal antibodies (MAbs) are powerful tools for examining viruses and proteins. PAI myeloma cells were fused with spleen cells from mice immunized with a single type of recombinant human SaV virus‐like particles (VLPs) (GI.1, GI.5, GI.6, GII.3, GIV, or GV). Sixty‐five hybrid clones producing MAbs were obtained. Twenty‐four MAbs were characterized by ELISA, according to their cross‐reactivity to each VLP (GI.1, GI.5, GI.6, GII.2, GII.3, GII.4, GII.7, GIV, and GV). The MAbs were classified by this method into: (i) MAbs broadly cross‐reactive to all GI, GII, GIV and GV strains; (ii) those reactive in a genogroup‐specific; and (iii) those reactive in a genotype‐specific manner. Further analysis of three broadly cross‐reactive MAbs with a competitive ELISA demonstrated that at least two different common epitopes are located on the capsid protein of human SaVs in the four genogroups. The MAbs generated and characterized in this study will be useful tools for further study of the antigenic and structural topography of the human SaV virion and for developing new diagnostic assays for human SaV.     

CD34分子的胞外结构域cDNA分离与表达

CD34分子是一种重要的造血干／祖细胞表面标志,广泛用于造血干／祖细胞的鉴定和分选。由于CD34分子具有受体样结构并能传递细胞同型聚集的信号,故它是一种信号分子,但其在造血系统的天然配体与确切的生理功能至今仍不明确。研究中我们分离了CD34分子的细胞外结构域cDNA,并进行了原核融合表达及纯化。DNA序列分析和竞争结合抑制实验证明我们获得了纯化的CD34分子的细胞外结构域的重组蛋白,可作为CD34可溶性受体,用于进一步研究CD34分子的生理功能。     

一种新型生物反应器在造血干/祖细胞体外扩增中的应用

针对造血干/祖细胞体外扩增对培养环境的需求, 结合静/动态培养的特点, 开发了一种新型的生物反应器用于造血干/祖细胞的体外扩增.在该生物反应器内, 采用SCF TPO Flt-3细胞因子组合, 比较了静态和循环培养两种方式体外扩增脐血CD34 细胞的效果.培养7 d后, 总细胞分别扩增了(13.86 ± 4.26)和(7.23 ± 2.67)倍, 显示静态培养有利于总细胞的扩增; CD34 细胞扩增倍数、培养物中CD34 细胞含量均相近, 无显著性差异; 而CD34 CD38-细胞扩增倍数以及培养物中CD34 CD38-细胞的百分含量分别为(1.82 ± 0.58)和(3.90 ± 0.85)倍以及(9.45 ± 4.85)和(37.47 ± 14.06)%, 循环培养明显高于静态培养.可见, 在该生物反应器内, 采用静态和循环两种培养方式, 均能实现造血干/祖细胞的体外扩增, 但静态培养促使造血干细胞向定向祖细胞分化, 而循环培养则更有利于早期造血干细胞的扩增.     

一种新型生物反应器在造血干/祖细胞体外扩增中的应用

针对造血干/祖细胞体外扩增对培养环境的需求, 结合静/动态培养的特点, 开发了一种新型的生物反应器用于造血干/祖细胞的体外扩增。在该生物反应器内, 采用SCF+TPO+Flt-3细胞因子组合, 比较了静态和循环培养两种方式体外扩增脐血CD34+细胞的效果。培养7 d后, 总细胞分别扩增了(13.86 ± 4.26)和(7.23 ± 2.67)倍, 显示静态培养有利于总细胞的扩增; CD34+细胞扩增倍数、培养物中CD34+细胞含量均相近, 无显著性差异; 而CD34+CD38-细胞扩增倍数以及培养物中CD34+CD38?细胞的百分含量分别为(1.82 ± 0.58)和(3.90 ± 0.85)倍以及(9.45 ± 4.85)和(37.47 ± 14.06)%, 循环培养明显高于静态培养。可见, 在该生物反应器内, 采用静态和循环两种培养方式, 均能实现造血干/祖细胞的体外扩增, 但静态培养促使造血干细胞向定向祖细胞分化, 而循环培养则更有利于早期造血干细胞的扩增。     

人类CD34^＋造血干／祖细胞的分子生物学特性

造血干／祖细胞（ＨＳＣ／ＨＰＣ）以有序的不同年龄等级结构状态存在于体内,它们的增殖、分化、成熟及程序死亡是一个连续的动态过程。ＣＤ３４抗原是目前所能认识表达在ＨＳＣ／ＨＰＣ表面上的最早抗原分子,对其分子结构的研究使人们更加认识到ＣＤ３４＾＋ＨＳＣ／ＨＰＣ的不同功能亚群、表达范围及其它生物学特征,诸如细胞周期状态、光散射性、造血生长因子受体（ＨＧＦｓＲ）Ｐ糖蛋白（Ｐｇｐ）或多药耐药基因（ＭＤＲ）的表     

体外培养脐血单个核细胞与CD34+富集细胞

对比MNC和CD34 +富集细胞在SCF +IL 3+IL 6 +FL +Tpo细胞因子组合下的体外扩增特性 ,发现 :CD34 +富集细胞具有很高的扩增潜力 ,在本实验条件下其总细胞持续扩增了 8周 ,扩增倍数达 312 70 9± 86 40 5倍 ;而MNC在培养至第 4周扩增就已呈现下降趋势 ,最大仅扩增了 5 3 3± 6 2倍。对比集落和CD34 +细胞的扩增发现 ,MNC的集落密度和CD34 +细胞含量由第 0天至第 7天有一个上升的过程 ,而CD34 +富集细胞在培养过程中 ,集落密度和CD34 +细胞含量却始终呈下降趋势。在体外培养过程中 ,CD34 +富集细胞的CFU GM和CD34 +细胞最大分别扩增了 185 7± 14 1和 191 7± 188 8倍 ,明显高于MNC的 12 4± 3 2和 5 0 6± 33 2倍 ;而CD34 +富集细胞和MNC的BFU E则只实现了少量扩增 ,分别为 7 2± 5 2和 10 1± 3 4倍。结果显示 ,从CD34 +富集细胞出发扩增造血干 祖细胞 ,可以得到更多的CD34 +细胞和CFU GM集落形成细胞     

Pinocembrin, a major flavonoid in propolis, improves the biological functions of EPCs derived from rat bone marrow through the PI3K-eNOS-NO signaling pathway

The number and quality of endothelial progenitor cells (EPCs) are damaged to varying degrees in patients at risk for developing atherosclerosis. The improvement of the quantity and functions of EPCs can enhance repair of injured endothelial monolayer resulting in inhibiting atherosclerosis. The purpose of this study was to investigate the effect of pinocembrin (PIN), a major flavonoid in propolis on the differentiation and biological functions of EPCs and the potential mechanisms of these effects. Flow cytometry analysis revealed that PIN treatment increased the number of CD34⁺, CD133⁺, FLK-1⁺, CD133⁺/FLK-1⁺ and CD34⁺/FLK-1⁺ mononuclear cells (MNCs) in the peripheral blood of apoE^−/− mice compared to untreated control mice. In vitro PIN treatment significantly increased the number of CD34⁺, CD133⁺, FLK-1⁺ and CD133⁺/FLK-1⁺ MNCs derived from SD bone marrow compared to untreated controls by 42.1, 84.6, 165.9 and 23.1 %, respectively. Additionally, PIN can improve biological functions of EPCs, such as proliferation, migration, adhesion, and in vitro tube formation and NO release. All of these improvements were inhibited by {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, while L-NAME only inhibited the PIN-induced increase in EPC proliferation and adhesion. We conclude that PIN can both promote the differentiation of EPCs in vitro and ex vivo and improve the biological functions of EPCs. The PI3K-eNOS-NO signaling pathway may be involved in the PIN-induced increase in the proliferation and adhesion of EPCs.