端粒酶逆转录酶基因修饰人骨髓间质干细胞的实验

背景:人骨髓间充质干细胞经过有限次的细胞传代后,就会停止增殖,发生衰老和死亡。有研究表明,端粒与细胞寿命的控制密切相关,是否可通过外源性人端粒酶逆转录酶基因的异位表达,诱导人骨髓间充质干细胞的端粒酶活性,维持端粒长度的稳定,从而延长人骨髓间充质干细胞的生命周期并保持其多潜能分化特性?目的:观察外源性人端粒酶逆转录酶基因的异位表达对人骨髓间质干细胞端粒酶活性及细胞生命周期的影响。设计:重复测量实验。单位:郑州大学医学院干细胞研究中心。材料:实验于2003-10/2005-12在郑州大学医学院干细胞研究中心完成。人骨髓间质干细胞采自郑州大学第一附属医院及第三附属医院小儿外科和门诊20名健康志愿者。增强型绿色荧光蛋白-C1质粒和增强型绿色荧光蛋白-人端粒酶逆转录酶质粒由加拿大Dr.ChantalAutexier馈赠。DH5α菌株由郑州大学医学院重点分子医学实验室侯卫红博士馈赠。方法:无菌条件下,抽取健康志愿者胸骨骨髓2mL,经离心、洗涤及传代培养后备用。①阳离子脂质体转染及阳性克隆的筛选和扩增结果:将第5代人骨髓间充质干细胞接种至24孔培养板中,将携带有增强型绿色荧光蛋白报告基因和人端粒酶逆转录酶目的基因的质粒pEGFP-人端粒酶逆转录酶通过脂质体转染法转入人骨髓间充质干细胞中,转染共分4组:正常对照组、脂质体组、增强型绿色荧光蛋白-C1质粒组、增强型绿色荧光蛋白-人端粒酶逆转录酶质粒组,并用G418筛选法进行抗性克隆的筛选与扩增。②人骨髓间充质干细胞转染前后人端粒酶逆转录酶mRNA的表达及端粒酶活性的检测:通过RT-PCR和PCR-ELISA对选用转染增强型绿色荧光蛋白-人端粒酶逆转录酶质粒的第5代人骨髓间充质干细胞(以下简称为转H人骨髓间充质干细胞第5代)、转染增强型绿色荧光蛋白-C1质粒的第5代人骨髓间充质干细胞(以下简称为转C人骨髓间充质干细胞第5代)、未转染的第10代人骨髓间充质干细胞、K562细胞(阳性对照)转染前后人端粒酶逆转录酶mRNA的表达情况,对转H第5及30代人骨髓间充质干细胞、转C第5代人骨髓间充质干细胞及未转染的第10代人骨髓间充质干细胞端粒酶活性的影响进行检测。③转H人骨髓间充质干细胞染色体核型分析:采用胰蛋白酶-Giemsa染色法转H人骨髓间充质干细胞染色体核型分析。④转H人骨髓间充质干细胞定向诱导分化为神经元样细胞及RT-PCR鉴定:将转染细胞在重组人表皮生长因子和碱性成纤维生长因子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(蛋白微管相关蛋白和神经丝亚单位M表达)。主要观察指标:①不同转染组阳离子脂质体转染及阳性克隆的筛选和扩增结果。②不同转染组人端粒酶逆转录酶mRNA的表达及端粒酶的活性。③转H人骨髓间充质干细胞染色体核型分析结果。④转H人骨髓间充质干细胞定向诱导分化为神经元样细胞及RT-PCR鉴定结果。结果:①随G418浓度的下降,正常对照组、脂质体组细胞全部死亡,从而得到稳定表达增强型绿色荧光蛋白的骨髓间充质干细胞;经G418加压筛选后得到1个连续传到第35代且生长旺盛的抗性细胞克隆,倒置显微镜下观察与未转染人骨髓间充质干细胞相比无明显差异。②转C第5代人骨髓间充质干细胞和未转染第10代人骨髓间充质干细胞的人端粒酶逆转录酶mRNA表达阴性,而K562和转H第5代人骨髓间充质干细胞的人端粒酶逆转录酶mRNA表达阳性。③转H第5代人骨髓骨髓间充质干细胞组和转H第30代人骨髓间充质干细胞端粒酶为阳性。④转H人骨髓间充质干细胞第10,20,30代的染色体总数均为23对,且含2条X性染色体,仍为正常2倍体,染色体形态和数目均正常。⑤较多转H人骨髓间充质干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和神经丝亚单位M表达增强。结论:外源性人端粒酶逆转录酶基因可以在人骨髓间充质干细胞中获得异位表达,并能诱导人骨髓间充质干细胞的端粒酶活性。外源性人端粒酶逆转录酶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。     

T lymphocyte differentiation in vitro from adult human prethymic CD34+ bone marrow cells

Pluripotent lymphohematopoietic stem cells are probably confined to bone marrow cells expressing CD34 surface molecules. To investigate the capacity of adult human CD34+ bone marrow cells to differentiate along the T lymphoid lineage, we plated purified CD34+ cells from healthy adults in liquid culture on adherent thymic stromal cells prepared from HLA- or blood group-mismatched postnatal thymic tissue. We show that purified CD34+CD3-CD4-CD8- bone marrow cells contained progenitors with the ability to differentiate into CD4+ and CD8+ T lymphocytes expressing surface (s)CD3 and T cell receptor alpha/beta in vitro. These progenitors were found in the CD34+CD2+sCD3-CD4-CD8-, CD34+CD7+sCD3-CD4-CD8-, and CD34+CD2+CD7+sCD3-CD4-CD8-, as well as in the CD34+CD2-sCD3-CD4-CD8-, CD34+CD7-sCD3-CD4-CD8-, and CD34+CD2-CD7- sCD3-CD4-CD8- subsets, indicating that T lymphocyte progenitors sensitive to signals mediated by thymic stroma in vitro are not restricted to CD34+ cells already coexpressing early T lymphocyte- associated markers. Finally, we show that T lymphopoiesis was enhanced by c-kit ligand.     

阵发性睡眠性血红蛋白尿症患者骨髓CD34+CD59+细胞的体外扩增

目的研究阵发性睡眠性血红蛋白尿症(PNH)患者CD34+CD59+细胞的分离、纯化及其体外扩增的条件和性能,为探索PNH新的治疗途径提供实验依据.方法利用免疫磁珠-流式细胞仪二步分选法,从PNH患者骨髓中分选出CD34+CD59+细胞,然后对CD34+CD59+细胞在不同造血生长因子组合条件下,进行体外扩增培养2周.结果体外扩增的最适宜的生长因子组合为SCF+IL-3+IL-6+FL+Tpo+Epo,最适宜的扩增时机为第7天,在此条件下,CD34+CD59+细胞的扩增倍数为22.42±3.73倍.CD34+CD59+细胞在扩增以后,仍保持较好的形成集落形成单位的能力,但是其向多系分化的潜能有所下降.结论 PNH患者CD34+CD59+细胞能够进行体外扩增.按照最佳扩增条件,在对PNH患者进行自体骨髓移植或自体外周血干细胞移植时有一定的应用价值.     

生存素与CD34在急性髓系白血病患者骨髓细胞中的表达

目的 探讨骨髓细胞中生存素(survivin)和白细胞分化抗原34(CD34)的表达与急性髓系白血病(AML)发生、发展的关系.方法 采用流式细胞术检测62例AML患者和31例非恶性血液病患者骨髓细胞中的survivin及CD34.结果 survivin+/CD34+双表达:AML组骨髓细胞的survivin+/CD34+双表达为(13.74±10.92)%,明显高于对照组(2.53±1.85)%(P<0.01),且治疗缓解组[(4.01±1.41)%]低于治疗未缓解组[(23.83±20.42)%](P<0.01).survivin+/CD34-表达:AML组骨髓细胞的survivin+/CD34-表达为(22.07±16.95)%,明显高于对照组[(12.29±8.80)%](P<0.05),且治疗缓解组[(14.32±7.53)%]低于治疗未缓解组[(29.83±26.37)%](P<0.05).结论 骨髓细胞中survivin表达的检测对血液疾病的转归具有提示的作用,且比CD34和白血病发生、发展的关系更加密切;对AML的治疗效果及预后有一定的评估价值.     

DNA去甲基化对大鼠骨髓间充质干细胞端粒酶反转录酶的调节

背景：DNA去甲基化是一种重要的表观遗传修饰,对肿瘤细胞的端粒酶具有重要调节作用,而对骨髓间充质干细胞端粒酶活性有何影响尚不清楚。目的：观察DNA去甲基化对骨髓间充质干细胞增殖及端粒酶反转录酶蛋白表达的影响。方法：全骨髓贴壁培养法分离培养大鼠骨髓间充质干细胞;按照下列分组加入5-杂氮胞苷,使各组5-杂氮胞苷终浓度分别为0,3,6,12,24μmol/L。加入5-杂氮胞苷后第1,2,3,5,7天进行指标检测。结果与结论：与对照组相比,5-杂氮胞苷干预24h,各浓度组均显著促进细胞增殖活性（P〈0.05）;干预48h,6,12,24μmol/L组显著促进细胞增殖活性（P〈0.05）;干预72h,12,24μmol/L组显著抑制细胞增殖活性（P〈0.05）;干预120,168h,对照组与各浓度组间差异均无显著性意义（P〉0.05）。5-杂氮胞苷干预48h,6,12,24μmol/L组端粒酶反转录酶蛋白IA值较对照组显著增加（P〈0.05）。提示在一定浓度范围及一定作用时间内,5-杂氮胞苷可以促进骨髓间充质干细胞增殖与端粒酶反转录酶蛋白的表达。     

DNA去甲基化对大鼠骨髓间充质干细胞端粒酶反转录酶的调节

背景:DNA去甲基化是一种重要的表观遗传修饰,对肿瘤细胞的端粒酶具有重要调节作用,而对骨髓间充质干细胞端粒酶活性有何影响尚不清楚.目的:观察DNA去甲基化对骨髓间充质干细胞增殖及端粒酶反转录酶蛋白表达的影响.方法:全骨髓贴壁培养法分离培养大鼠骨髓间充质干细胞;按照下列分组加入5-杂氮胞苷,使各组5-杂氮胞苷终浓度分别为0,3,6,12,24 μmol/L.加入5-杂氮胞苷后第1,2,3,5,7天进行指标检测.结果与结论:与对照组相比,5-杂氮胞苷干预24 h,各浓度组均显著促进细胞增殖活性(P < 0.05);干预48 h,6,12,24 μmol/L组显著促进细胞增殖活性(P < 0.05);干预72 h,12,24 μmol/L组显著抑制细胞增殖活性(P < 0.05);干预120,168 h,对照组与各浓度组间差异均无显著性意义(P > 0.05).5-杂氮胞苷干预48 h,6,12,24 μmol/L组端粒酶反转录酶蛋白IA值较对照组显著增加(P < 0.05).提示在一定浓度范围及一定作用时间内,5-杂氮胞苷可以促进骨髓间充质干细胞增殖与端粒酶反转录酶蛋白的表达.     

人正常骨髓CD34＋造因细胞的形态学与细胞化学特征

OBJECTIVE: To explore the cytomorphological and cytochemitry features of CD34+ hematopoietic cells. METHODS: Highly purified CD34+ hematopoietic cells isolated from human bone marrow by a two-step method of immunomagnetic beads-FACS sorting were comprehensively examined. RESULTS AND CONCLUSION: CD34+ hematopoietic cells could be sorted into three types in light of morphology and cytochemical staining. Type I was considered as candidates for stem cells,which were most blastlike in morphology and slightly larger than lymphocytes in size with negative reactions to all cytochemical stainings. Type II was considered as multipotent progenitor cells, with sizes similar to small lymphocytes and negative reactions to all cytochemical stainings. Type III was identified as committed progenitor cells whose sizes were heterogeneous and whose reactions to cytochemical stainings ranged from +/- to + +.     

不同发育阶段人表皮干细胞端粒酶反转录酶表达的比较

目的:目前已知端粒酶活性的丧失及其增殖相关基因表达的改变是造成多种成体干细胞体外复制和扩增受限的主要原因,而端粒酶反转录酶对端粒酶活性起关键作用。体外分离培养人胚胎、少儿、成人3种不同皮肤来源的表皮干细胞,对比观察不同发育阶段端粒酶反转录酶表达的差异。方法:实验于2005-09/2007-04在南昌大学第一附属医院烧伤研究所完成。①对象:因创伤等原因致意外流产的妊娠24～26周龄胎儿皮肤标本,4～12周岁少儿及25～45岁成年人烧伤整形植皮手术剩余皮片标本,分别由南昌大学第一附属医院产科、烧伤科提供,产妇与烧伤患者对治疗及实验均知情同意,实验经医院医学伦理委员会批准。②实验方法:取胎儿、少儿和成年人的全层皮肤,用胰蛋白酶和EDTA联合消化法分离表皮,胶原快速贴附法纯化人表皮干细胞,用未黏附的角质细胞作为对照,以含表皮生长因子、角质细胞无血清培养液组成的表皮干细胞培养基进行体外培养。③实验评估:通过β_1整合素、角蛋白19、p63免疫细胞化学染色对培养细胞进行鉴定,计算克隆形成率。以免疫细胞化学染色法和图像定量分析法检测3种不同皮肤来源的表皮干细胞端粒酶反转录酶的表达差异。结果:①细胞生长特征:分离培养的人表皮干细胞呈明显克隆性生长,克隆形成率高于角质细胞对照组(P<0.05)。②表皮干细胞的鉴定:细胞克隆经免疫细胞化学染色后,β_1整合素、角蛋白19、p63均呈阳性表达。③端粒酶反转录酶免疫细胞化学染色及定量表达:不同皮肤来源的表皮干细胞端粒酶反转录酶均呈阳性,但表达强度不同,人胚胎>少儿>成人。3种皮肤来源的表皮干细胞平均吸光度值和阳性面积值均随年龄增加而逐渐降低,人胚胎>少儿>成人(P<0.05)。结论:人胚胎、少儿、成人皮肤来源的表皮干细胞均有端粒酶反转录酶表达,其表达强度依次减弱。提示诱导和增强端粒酶反转录酶的表达对维持表皮干细胞在体外自我更新和增殖能力可能具有重要意义。     

Selective expression of CD45 isoforms on functional subpopulations of CD34+ hemopoietic cells from human bone marrow

We have found that the small population of cells in human marrow that are characterized by their expression of CD34 can be readily subdivided into two apparently nonoverlapping subpopulations of approximate equal size, one expressing CD45RO and one CD45R. Functional studies of these subpopulations revealed that all of the primitive erythroid colony-forming cells (BFU-E) are CD34+ CD45RO+. Similarly, more primitive cells that give rise to both erythroid and granulopoietic colony-forming cells after being maintained for 5 wk on confluent irradiated long-term marrow culture feeder layers, also show this phenotype. In contrast, most granulopoietic colony-forming cells are CD34+ CD45RO- cells. The differential expression of CD45 isoforms on distinct functional subpopulations of hemopoietic cells is consistent with the concept that these molecules play an important role in the differentiation or activation of primitive, normally quiescent, hemopoietic cells. The presence of CD45RO and the lack of CD45R on human cells capable of initiating hemopoiesis in the long-term marrow culture system correspond to the reported lack of CD45R on transplantable hemopoietic stem cells in rodents and may be a useful addition to strategies for human stem cell purification, or for purging CD45R+ leukemic cells.     

端粒酶逆转录酶在涎腺恶性肿瘤中的表达

目的研究端粒酶逆转录酶（hTERTmRNA）在涎腺良、恶性肿瘤中的表达及意义。方法采用原位杂交法分别检测hTERTmRNA在涎腺良、恶性肿瘤中的表达。结果在涎腺良、恶性肿瘤中均有hTERTmRNA表达，与正常腺体组织相比差异均有显著性（P〈0．01）。hTERTmRNA活性与涎腺癌的病理分级有关，其恶性程度越高，hTERTmRNA表达信号越强（P〈0．05）。结论hTERTmRNA在涎腺恶性肿瘤中均有阳性表达，可作为涎腺恶性肿瘤诊断的有效指标，并可作为评价预后的有效指标。     

胃癌患者外周血hTERT mRNA转录水平及临床意义

目的研究胃癌患者外周血中hTERT mRNA的表达，探讨其作为胃癌肿瘤细胞标志物的可行性。方法应用实时荧光定量RT—PCR技术检测96例原发性胃癌、50例胃溃疡和60例健康献血员血清中hTERT mRNA表达水平，并对阳性PCR产物进行克隆、测序。结果胃癌组hTERT mRNA表达水平（12．78±0．97）copies／ml，显著高于良性胃溃疡组（0．93±0．23）copies／ml和健康对照组（0．29±0．17）copies／ml。多变量分析表明，hTERT表达水平与患者性别、年龄、肿瘤大小、肿瘤生长方式、肿瘤分化程度、淋巴管侵犯、静脉侵犯均无显著相关性（P〉0．05），而与浸润深度、淋巴结转移、远处转移、pTNM分期及CEA有显著相关性（P〈0．05）。结论qRT—PCR具有快速、敏感和特异的特点。定量分析外周血hTERT mRNA转录水平可作为胃癌的肿瘤细胞标志物之一，用于早期诊断。     

阵发性睡眠性血红蛋白尿症患者骨髓CD34+CD59+细胞与CD34+CD59-细胞生物学性能的研究

目的 探讨阵发性睡眠性血红蛋白尿症(PNH)患CD34^ CD59^ 细胞的特性及PNH克隆呈优势造血的可能原因，以探索PNH发病的内在机制。方法 用免疫磁珠吸附法富集纯化CD34^ 细胞，再用流式细胞仪分选出PNH患的CD34^ CD59^ 细胞、CD34^ CD59^ 细胞及正常对照CD34^ 细胞。分别进行体外扩增液体培养2周，并对扩增前、后的细胞进行半固体培养。结果 ①PNH患CD34^ CD59^ 细胞与正常对照CD34^ 细胞形成集落形成单位(CFU)均在第7天达到扩增高峰，并且扩增后的细胞仍能保持CD59抗原，无GPI锚连蛋白的丢失。②正常对照的CD34^ 细胞在生存、增殖、形成CFU及扩增能力上均明显强于FHN患的CD34^ CD59^ 细胞及CD34^ CD59^-细胞.③PNH患CD34^ CD59^ 细胞及CD34^ CD59^ 细胞体外半固体培养，其形成CFU的能力无明显差异。④PNH患CD34^ CD59^ 细胞及CD34^ CD59^ 细胞在SCF IL3 IL6 FL Tpo及SCF IL3 IL6 FL Tpo Epo组合下液体培养，其生存、增殖、扩增等能力上均无明显差异。但在SCF IL3 IL6 FL Tpo Epo GM-CSF组合下液体培养，CD34^ CD59^ 细胞的生存、增殖、扩增能力均明显强于CD34^ CD59^ 细胞。结论 ①正常对照的CD34^ 细胞在生存、增殖、形成CFU及扩增能力上均明显强于PNH患的CD34^ CD59^ 细胞。②PNH患CD34^ CD59^ 细胞及CD34^ CD59^ 细胞体外半固体培养，以及在SCF IL3 IL6 LF Tpo及SCF IL3 IL6 FL Tpo Ep组合下液体培养，其生存、增殖、扩增等能力上均无明显差异，说明CD34^ CD59^ 细胞在造血能力上并无内在的优势。GM—CSF或许是使PNH克隆呈造血优势的原因之一。     

真性红细胞增多症患者骨髓CD34阳性细胞凋亡相关蛋白的表达

目的　了解真性红细胞增多症 (PV)患者骨髓CD34 细胞凋亡受体FAS(CD95 )及凋亡相关蛋白Bcl 2、Bax的表达。方法　应用双色流式细胞仪检测 2 1例PV患者及 8例原发性血小板增多症(ET)患者和 11名正常人骨髓CD34 细胞CD95、Bcl 2、Bax的表达 ;应用RT PCR方法检查PV患者及对照组骨髓造血细胞Bcl 2、BaxmRNA的表达情况并分析其相关性。结果　CD34 细胞CD95表达率PV患者为 (4 2 .6 5± 15 .5 6 ) % ,ET患者为 (4 5 .31± 17.6 2 ) % ,与正常对照组的 (37.5 5± 15 .19) %差异无显著性 (P >0 .0 5 ) ;Bax表达率PV患者为 (35 .83± 9.33) % ,与正常对照组的 (4 1.6 5± 9.0 4 ) %差异无显著性(P >0 .0 5 ) ;Bcl 2表达率PV患者为 (79.35± 14 .4 3) % ,明显高于正常对照组的 (5 5 .84± 13.4 3) % ,(P <0 .0 1) ;Bax/Bcl 2的比值PV患者为 0 .4 7± 0 .14 ,明显低于正常对照组的 0 .76± 0 .2 4 (P <0 .0 1) ;骨髓造血细胞Bcl 2mRNA的表达PV患者明显高于正常对照组 (P <0 .0 1) ,BaxmRNA的表达PV患者与正常对照组差异无显著性 (P >0 .0 5 )。PV患者CD34 细胞Bcl 2高表达与CD34 细胞的凋亡呈负相关 (r=- 0 .4 97,P =0 .0 2 6 )。结论　PV患者骨髓CD34 细胞低凋亡的机制之一是抗凋亡蛋白Bcl 2高表达     

P-Selectin coated microtube for enrichment of CD34+ hematopoietic stem and progenitor cells from human bone marrow

BACKGROUND: Enrichment and purification of hematopoietic stem and progenitor cells (HSPCs) is important in transplantation therapies for hematologic disorders and in basic stem cell research. Primitive CD34+ HSPCs have demonstrated stronger rolling adhesion on selectins than mature CD34- mononuclear cells (MNCs). We have exploited this differential rolling behavior to capture and purify HSPCs from bone marrow by perfusing MNCs through selectin-coated microtubes. METHODS: Bone marrow MNCs were perfused through the cell-capture microtubes coated with adhesion molecules. We washed the device lumen and visualized and estimated captured cells by video microscopy. Adherent cells were eluted by high shear, calcium-free buffer, and air embolism. We used immunofluorescence staining followed by flow cytometry to analyze CD34+ HSPCs. RESULTS: CD34+ HSPC purity of cells captured in adhesion molecule-coated devices was significantly higher than the fraction of CD34+ cells found in bone marrow MNCs [mean (SE) 2.5% (0.8%)]. P-selectin-coated surfaces yielded 16% to 20% CD34+ cell purity, whereas antibody-coated surfaces yielded 12% to 18%. Although CD34+ cell purity was comparable between selectin and antibody surfaces, the total number of CD34+ HSPCs captured was significantly higher in P-selectin devices (approximately 5.7 x 10(4) to 7.1 x 10(4)) than antibody devices (approximately 1.74 x 10(4) to 2.61 x 10(4)). CONCLUSIONS: P-selectin can be used in a compact flow device to capture HSPCs. Selectin-mediated capture of CD34+ HSPCs resulted in enrichment approximately 8-fold higher than the CD34+ cell population from bone marrow MNCs. This study supports the hypothesis that flow-based, adhesion molecule-mediated capture may be a viable alternative approach to the capture and purification of HSPCs.     

多药耐药基因在人骨髓CD34+细胞中的表达及对化疗药物的耐受性

目的　探讨人多药耐药 (MDR1)基因过表达能否提高骨髓造血干 /祖细胞对化疗药物的耐受性。方法　应用免疫磁性分选系统 (miniMACS)体外分离、纯化骨髓CD34 细胞并进行扩增 ;采用脂质体介导的基因转移方法 ,将人MDR1基因转染骨髓CD34 细胞 ,并运用流式细胞术检测基因转导前后造血干 /祖细胞中MDR1基因的编码产物 Pl70糖蛋白表达和功能变化。MTT法检测基因转导前后造血干 /祖细胞对化疗药物耐受性的改变。结果　MDR1基因转导后 4 8h骨髓造血干 /祖细胞Pl70抗原表达为 (2 3 6± 2 34) % ,明显高于转导前 (11 2± 2 2 ) % (P <0 0 1)。P170的功能活性被Rh 12 3的摄取和排除试验证实。转基因后细胞表现为典型的多药耐药表型 ,对P170谱的多种化疗药的耐受性提高了约 2～ 8倍 ,对非P170谱的顺铂、氨甲喋呤耐受性没有改变。结论　人多药耐药基因能提高骨髓造血干 /祖细胞对多种化疗药物的耐受性 ,表现为典型的多药耐药表型。     

Long-term erythropoiesis from constant numbers of CD34+ cells in serum- free cultures initiated with highly purified progenitor cells from human bone marrow

To directly study the biological properties of purified hematopoietic colony-forming cell precursors, cells with a CD34+ CD45RAlo CD71lo phenotype were purified from human bone marrow using density separation and fluorescence-activated cell sorting, and were cultured in serum-free culture medium supplemented with various cytokines. In the presence of interleukin 3 (IL-3), IL-6, erythropoietin, and mast cell growth factor (a c-kit ligand), cell numbers increased approximately 10(6)-fold over a period of 4 wk, and the percentage of cells that expressed transferrin receptors (CD71) increased from less than 0.1% at day 0 to greater than 99% at day 14. Interestingly, the absolute number of CD34+ CD71lo cells did not change during culture. When CD34+ CD71lo cells were sorted from expanded cultures and recultured, extensive cell production was repeated, again without significant changes in the absolute number of cells with the CD34+ CD71lo phenotype that were used to initiate the (sub)cultures. These results document that primitive hematopoietic cells can generate progeny without an apparent decrease in the size of a precursor cell pool.     

人正常骨髓 CD_(34)~ 造血细胞的形态学与细胞化学特征

目的：探讨ＣＤ３４＋造血细胞的形态学特征。方法：采用免疫磁珠－流式细胞仪分选二步法获取高纯度的人正常骨髓ＣＤ３４＋造血细胞。结果和结论：ＣＤ３４＋造血细胞从形态上可分为３型，Ⅰ型胞体略大于淋巴细胞，各种细胞化学染色阴性，最原始，拟定候选干细胞群；Ⅱ型为典型的小淋巴细胞状，细胞化学亦为阴性，拟定多向祖细胞阶段；Ⅲ型胞体极不均一，依分化方向不同其细胞化学表现为±～＋＋，拟定定向祖细胞阶段。