晚期糖基化终产物对人内皮细胞表达MCP-1和VCAM-1的影响及阿托伐他汀的干预

目的观察晚期糖基化终产物对体外培养人脐静脉内皮细胞表达单核细胞趋化蛋白1和血管细胞黏附分子1的影响及阿托伐他汀的干预作用,探讨晚期糖基化终产物诱发动脉粥样硬化形成的机制和阿托伐他汀治疗的机制。方法胶原酶消化法分离获取人脐静脉内皮细胞;倒置相差显微镜形态观察法及免疫细胞化学染色法鉴定人脐静脉内皮细胞;逆转录聚合酶链反应法对单核细胞趋化蛋白1、血管细胞黏附分子1及晚期糖基化终产物受体基因表达进行分析;活性氧检测试剂盒检测细胞内活性氧产生量,倒置荧光显微镜下观察细胞内活性氧荧光强度。结果倒置相差显微镜下可见培养的细胞呈卵圆形或多角形,典型的铺路石样排列,经CD31、CD34染色,细胞浆内有棕黄色颗粒沉着(CD31、CD34阳性)。与空白对照组相比,晚期糖基化终产物(10-4~10-1g/L)呈浓度依赖性增强人内皮细胞单核细胞趋化蛋白1和血管细胞黏附分子1基因表达,10-4g/L晚期糖基化终产物组人内皮细胞单核细胞趋化蛋1和血管细胞黏附分子1基因表达水平开始显著增高(0.26±0.02比0.17±0.04;0.22±0.02比0.08±0.01,P<0.01);与晚期糖基化终产物组相比,阿托伐他汀(0.1、1、10μ...     

体外制备的晚期糖基化终产物对内皮祖细胞数量的影响

目的观察体外制备的晚期糖基化终产物对内皮祖细胞数量的影响。方法人血清白蛋白与葡萄糖共同孵育90d后,行Bradford检测法蛋白定量和荧光值测定。从正常成人外周血中分离提取单个核细胞,培养7d后,流式细胞仪鉴定细胞表型,分别加入浓度为2mg/L、20mg/L和200mg/L的晚期糖基化终产物并设置对照组,干预不同的时间(0h、24h、48h和72h),200倍光学显微镜下随机取10个视野计数。结果该方法制备的晚期糖基化终产物具有荧光性。细胞培养7d,CD34/CD133/KDR单克隆抗体流式细胞仪鉴定细胞,结果发现表达KDR达78.60%±2.20%、CD34为8.60%±2.00%和CD1332.80%±0.60%,提示大部分细胞为内皮祖细胞。以不同时间(0h、24h、48h和72h)和浓度(2mg/L、20mg/L和200mg/L)晚期糖基化终产物干预内皮祖细胞生长,对比0h组每个视野下细胞数量(186.0±6.7),干预24h细胞数量减少(146.67±4.98),72h降至最低(73.67±3.76)(P<0.001),呈现明显的时间效应(r=0.9658,P<0.01);终浓度为2mg/L或20mg/L晚期糖基化终产物干预内皮祖细胞72h后,与同时培养72h的对照组无显著差异(P>0.05),但随着浓度加大,浓度效明显(r=0.9988,P<0.01)。结论此方法制备的晚期糖基化终产物符合文献所述的特性,晚期糖基化终产物能抑制内皮祖细胞生长,具有时间效应和浓度效应。     

糖基化终产物对人血管内皮细胞过氧化体增殖物激活型受体γ基因表达的影响

为探讨糖基化终产物对人血管内皮细胞表达过氧化体增殖物激活型受体γ基因的影响 ,体外培养人血管内皮细胞株 (ECV30 4 ) ,分别用不同浓度葡萄糖 (0、2 0、5 0和 80mmol L)孵育的糖基化终产物修饰牛血清白蛋白(2 0 0mg L)、不同浓度的糖基化终产物修饰牛血清白蛋白 (5 0、10 0、2 0 0和 4 0 0mg L)干预 2 4h和葡萄糖浓度为 5 0mmol L孵育的糖基化终产物修饰牛血清白蛋白干预细胞 0、12、2 4、36、4 8和 72h ,逆转录聚合酶链反应检测细胞中过氧化体增殖物激活型受体γmRNA的表达水平。结果发现 ,葡萄糖浓度为 2 0、5 0和 80mmol L孵育的糖基化终产物修饰牛血清白蛋白及浓度为 5 0、10 0、2 0 0和 4 0 0mg L的糖基化终产物修饰牛血清白蛋白都减少过氧化体增殖物激活型受体γmRNA的表达 (P <0 .0 0 1) ,干预 12、2 4、36、4 8和 72h后过氧化体增殖物激活型受体γmRNA表达均较未干预组明显减少 (P <0 .0 0 1)。此结果提示 ,糖基化终产物可抑制人血管内皮细胞过氧化体增殖物激活型受体γ基因的表达。     

晚期糖基化终产物诱导血管内皮细胞骨架形态改变的机制

目的研究晚期糖基化终产物修饰蛋白对内皮细胞细胞骨架肌动蛋白的形态学影响及特异的糖基化终产物受体和氧化应激在此病理过程中的作用。方法用不同浓度的糖基化终产物修饰人血清白蛋白与人脐静脉内皮细胞株ECV304在体外共同培养不同时间，并设立对照组进行比较，采用免疫荧光染色法显示细胞骨架的形态学改变。结果与对照组相比，糖基化终产物修饰人血清白蛋白以时间和剂量依赖的方式影响内皮细胞骨架肌动蛋白聚合丝状和可溶性单体（或球状）形态的改变。随着糖基化终产物修饰人血清白蛋白作用浓度和时间的增加，丝状肌动蛋白所形成的外周致密带边缘出现锯齿样断裂，趋于变细崩解消散，最终形成由非极性单行排列的肌动蛋白丝组成的应力纤维。可溶性单体表现为向细胞浆和胞膜移位，胞浆区出现点状和丝状染色，细胞间距离明显增大。可溶性糖基化终产物受体的抗体和烟酰胺腺嘌呤二核苷酸磷酸盐氧化酶抑制剂均可阻断糖基化终产物对细胞骨架的影响。结论糖基化终产物修饰蛋白对细胞骨架的影响是通过与内皮细胞上的糖基化终产物受体结合并引起细胞内的氧化应激所介导的，这一作用可能与糖基化终产物所致血管通透性升高有关。     

晚期糖基化终产物诱导血管内皮细胞环氧合酶2表达

目的探讨晚期糖基化终产物对人血管内皮细胞环氧合酶2表达的影响。方法取人脐静脉内皮细胞ECV304与人血清白蛋白修饰的晚期糖基化终产物体外共同培养,然后用Western blot检测环氧合酶2的表达水平。结果内皮细胞环氧合酶2基础表达水平极低,人血清白蛋白修饰的晚期糖基化终产物可诱导环氧合酶2的表达,呈时间与剂量依赖关系;抑制核因子κB的活性可抑制环氧合酶2的表达。结论人血清白蛋白修饰的晚期糖基化终产物可通过激活核因子κB,而引起环氧合酶2的表达。这一作用机制可能参与血管损伤反应。     

糖基化终产物对大鼠主动脉平滑肌细胞单核细胞趋化蛋白1基因表达的影响

为探讨糖基化终产物对大鼠主动脉平滑肌细胞表达单核细胞趋化蛋白 1基因的影响 ,体外分离培养大鼠主动脉平滑肌细胞 ,然后用不同浓度葡萄糖 (0、5、2 0、5 0和 80mmol L)制备的糖基化终产物 BSA(2 0 0mg L)干预 2 4h和用葡萄糖浓度为 5 0mmol L孵育的糖基化终产物 BSA干预 0、12、2 4和 36h ,逆转录聚合酶链反应检测细胞中单核细胞趋化蛋白 1mRNA表达水平。结果发现 ,葡萄糖浓度 2 0mmol L、5 0mmol L和 80mmol L孵育的糖基化终产物都增加单核细胞趋化蛋白 1mRNA的表达 ,其中 5 0mmol L组作用最明显 (P <0 .0 0 5 ) ,干预 12h、2 4h、36h后单核细胞趋化蛋白 1mRNA表达均较未干预组明显增加 (P <0 .0 0 1)。结果提示 ,糖基化终产物促进大鼠主动脉平滑肌细胞单核细胞趋化蛋白 1基因的表达     

糖基化终产物促进培养的人脐静脉内皮细胞选择素E的表达

目的 探讨糖基化终产物在糖尿病动脉粥样硬化形成中的作用机理。方法 分离正常人脐静脉内皮细胞，将糖基化终产物修饰的人血清白蛋白及未修饰人血清白蛋白与人脐静脉内皮细胞在体外共同培养，用荧光单克隆抗体染色，流式细胞仪定量检测内皮细胞表面选择素E的表达。结果 正常人脐静脉内皮细胞未表达选择素Eo糖基化终产物修饰的人血清白蛋白能以时间和剂量依赖的方式上调血管内皮细胞粘附分子选择素E的表达（P〈0．015），而人血清白蛋白对人脐静脉内皮细胞粘附分子选择素E的表达无影响。结论 糖基化终产物能上调人脐静脉内皮细胞粘附分子的表达，从而促进动脉粥样硬化时单核，巨噬细胞的浸润。     

不同蛋白糖基化终产物对大鼠动脉平滑肌细胞增殖的影响

探讨大鼠Ⅰ型胶原及牛血清白蛋白的糖基化终产物对大鼠血管平滑肌细胞增殖的影响。用贴块法培养SD大鼠主动脉平滑肌细胞至3-4代，分别用体外合成的大鼠Ⅰ型胶原糖基化终产物和牛血清白蛋白糖基化终产物刺激，并以大鼠Ⅰ型胶原和牛血清白蛋白处理的细胞作为对照，与此同时加入大鼠抗血管内皮生长因子抗体，采用氚标胸腺嘧啶脱氧核苷掺入法测定细胞增殖情况。结果发现，大鼠Ⅰ型胶原糖基化终产物能够显著地促进主动脉平滑肌细胞增殖，抗血管内皮生长因子抗体则能有效地抑制上述作用；牛血清白蛋白糖基化终产物对血管平滑肌细胞的增殖有明显的抑制作用，加入抗血管内皮生长因子抗体后未见明显影响。结果提示，不同蛋白的糖基化终产物对血管平滑肌细胞增殖的影响不同，对细胞因子分泌作用的影响也不相同。     

高迁移率族蛋白1及其受体促进人主动脉血管平滑肌细胞增殖及迁移的作用研究

目的研究高迁移率族蛋白1(HMGB1)及其受体对体外人主动脉血管平滑肌细胞(VSMC)增殖及迁移的影响。方法体外培养人VSMC株,50、100、200μg/L HMGB1作用细胞24 h后,CCK法检测VSMC的增殖情况;细胞划痕修复及Transwell小室实验检测VSMC迁移情况;Real-time PCR及Western blot检测细胞晚期糖基化终产物受体(RAGE)干扰效率;CCK法及Transwell小室实验检测沉默RAGE后HMGB1对细胞增殖及迁移的影响;Western blot检测核因子(NF-κB)蛋白表达水平。结果 HMGB1作用VSMC后可明显促进细胞增殖及迁移(P0.05);转染si RNA-RAGE后,RAGE的m RNA及蛋白表达水平明显下降(P0.05);与HMGB1组相比,si RNA-RAGE可抑制HMGB1诱导的细胞增殖、迁移及NF-κB蛋白表达(P0.05)。结论 HMGB1可促进VSMC增殖及迁移,机制可能与HMGB1和RAGE结合后激活NF-κB表达有关。     

人脐血内皮祖细胞的体外分离和培养

目的建立一种稳定的体外分离和培养人脐血来源内皮祖细胞的方法。方法采用密度梯度离心法从人脐带血中分离单个核细胞,将其接种至人纤维连接蛋白包被的六孔板中,用EGM-2培养基诱导培养。通过形态学观察、细胞表面特异性抗原、摄取功能和体外血管形成能力对内皮祖细胞进行鉴定。结果细胞形态学观察发现,刚分离的单个核细胞较小,呈圆形,4 d后可见少量的圆形和梭形贴壁细胞,8 d后有明显集落形成,14 d后相邻集落相互融合,呈现出典型铺路石样改变。内皮祖细胞能摄取乙酰化低密度脂蛋白,结合荆豆凝集素1,表达CD34、CD133和血管内皮细胞生长因子受体2,并且具有体外血管生成能力。结论采用密度梯度离心法可从人脐带血中成功分离和培养出内皮祖细胞,以用于相关实验研究。     

Induction of Umbilical Cord Blood Mesenchymal Stem Cells into Neuron-Like Cells In Vitro

Mesenchymal stem cells (MSCs) in human umbilical cord blood are multipotent stem cells that differ from hematopoietic stem cells. They can differentiate in vitro into mesenchymal cells such as osteoblasts and adipocytes. However, differentiation into nonmesenchymal cells has not been demonstrated. Here, we report the isolation, purification, expansion, and differentiation of human umbilical cord blood MSCs into neurocytes in vitro. Cord blood samples were allowed to drain from the end of the cord into glass bottles with 20 U/mL preservative-free heparin. MSCs were isolated from human umbilical cord blood, purified, and expanded in Mesencult medium. Surface antigens of MSCs were analyzed by fluorescence-activated cell sorting (FACS). MSC passages 2,5, and 8 were induced to differentiate into neuron-like cells. Neurofilament (NF) and neuron-specific enolase (NSE) were detected by immunohistochemistry staining. Special Nissl bodies were observed by histochemical analysis. The results showed that 6.6 x 10(5) primary MSCs were expanded for 10 passages to obtain 9.9 x 10(8) MSCs, an increase of approximately 1.5 x 10(3)-fold. FACS results showed that the MSCs did not express antigens CD34, CD11a, and CD11b and expressed CD29 and CD71, an expression pattern identical to that of human bone marrow-derived MSCs. Induction results indicated that approximately 70% of the cells exhibited a typical neuron-like phenotype. Immunohistochemistry staining suggested that induced MSCs of different passages expressed NF and NSE. Special Nissl bodies were obvious in the neuron-like cells. These results suggest that MSCs in human umbilical cord blood are capable of differentiating into neuron-like cells in vitro.     

糖基化终末产物对体外诱导大鼠视网膜微血管内皮细胞血管形成的影响

目的 应用Matrigel建立大鼠视网膜微血管内皮细胞血管形成的体外培养体系,研究糖基化终末产物对诱导视网膜微血管内皮细胞血管形成的影响,从而探讨糖基化终末产物在糖尿病微血管病血管新生中的作用.方法 体外培养视网膜微血管内皮细胞,制备糖基化白蛋白.在Matrigel上建立血管形成的体外培养体系,实验分浓度效应组和时间效应组,并进行CD34免疫细胞化学染色.采用光镜下计数管腔数及计算机图像分析对结果进行测定和分析.结果 经分离培养的视网膜微血管内皮细胞在Matrigel上培养形成管腔样结构.糖基化白蛋白(糖基化终末产物)作用于培养的视网膜微血管内皮细胞后,可见管腔形成数目增加,且在一定范围内呈时间和剂量依赖效应(P<0.01).结论 糖基化终末产物可以促进Matrigel体外诱导视网膜微血管内皮细胞的血管形成.     

联合运用晚期糖基化终产物和同型半胱氨酸诱导人脐静脉内皮细胞血管细胞黏附因子1 mRNA表达及机制

目的探讨联合运用晚期糖基化终产物和同型半胱氨酸对人脐静脉内皮细胞血管细胞黏附分子1表达的影响和氧化应激的机制。方法酶消化法获取人脐静脉内皮细胞。逆转录聚合酶链反应检测血管细胞黏附分子1基因的表达。活性氧检测试剂盒检测细胞内氧自由基的荧光信号强度。结果晚期糖基化终产物(10-4～10-1g/L)和同型半胱氨酸(1.35×10-3～1.35g/L)组呈浓度依赖性诱导人脐静脉内皮细胞血管细胞黏附分子1的表达,晚期糖基化终产物(10-4g/L)和同型半胱氨酸(1.35×10-3g/L)联合作用能进一步增加人脐静脉内皮细胞血管细胞黏附分子1基因的表达(1.09±0.18),与单独晚期糖基化终产物(0.14±0.07)和同型半胱氨酸组(0.18±0.06)相比其表达分别增加了7.78倍和6.05倍(P0.01);还原型烟酰胺腺嘌呤二核苷酸磷酸氧化酶特异性抑制剂二亚苯基碘能显著抑制晚期糖基化终产物和同型半胱氨酸联合诱导的血管细胞黏附分子1基因的表达(0.20±0.09比1.19±0.23,P0.01);晚期糖基化终产物组和同型半胱氨酸组均能增加人脐静脉内皮细胞内氧自由基的荧光信号强度,晚期糖基化终产物和同型半胱氨酸联合作用时,细胞内氧自由基的荧光信号强度水平进一步升高,且二亚苯基碘能明显抑制上述效应。结论晚期糖基化终产物和同型半胱氨酸能增加细胞内氧自由基的荧光信号水平,使血管细胞黏附分子1基因的表达上调,且两者存在协同效应;氧自由基水平的增加是导致血管细胞黏附分子1基因表达升高的重要因素;血管细胞黏附分子1可能是通过还原型烟酰胺腺嘌呤二核苷酸磷酸氧化酶途径实现的。     

A cell surface marker gene transferred with a retroviral vector into CD34+ cord blood cells is expressed by their T-cell progeny in the SCID- hu thymus

Gene transduction into immature hematopoietic cells collected at birth from the umbilical cord could be useful for the treatment of genetic or acquired disorders of the hematopoietic system diagnosed during pregnancy. The SCID-hu mouse is a convenient model to investigate T- cell lineage gene therapy, since it allows replication of human intrathymic T-cell development. CD34+ cells isolated from cord blood were cocultured with CRIP MFG-murine CD2 (mCD2) cells that produce recombinant retroviruses encoding the mCD2 antigen, a cell surface marker easily detectable by flow cytometry. After 3 and 4 days in coculture, a mean of 19% and 39% human hematopoietic cells, respectively, expressed the mCD2 antigen. CD34+ cells cocultured for 4 days were used to reconstitute human fetal thymus implanted in SCID mice. Five to 10 weeks later, the mCD2 antigen was detected on approximately 10% of human thymocytes repopulating the thymic grafts in four of nine SCID mouse chimeras. Vector genomes were detected in graft cell DNA by Southern blot. Analysis of vector integration indicated that positive cells were of polyclonal origin in three animals and predominantly monoclonal in the other one. Our data show that foreign genes can be transduced into CD34+ cord blood cells endowed with T-cell differentiation potential, and suggest strategies for T-cell lineage gene therapy in the neonate.     

Release from quiescence of CD34+ CD38- human umbilical cord blood cells reveals their potentiality to engraft adults.

Using optimal culture conditions in which the transforming growth factor beta 1 (TGF-beta 1) inhibitory loop has been interrupted by antisense TGF-beta 1 oligonucleotides or anti-TGF-beta serum, we have compared the proliferative capacities and the abilities of the CD34+ CD38- cell populations from bone marrow and umbilical cord blood to generate early progenitors in long-term cultures. The CD34+ CD38- fraction of umbilical cord blood accounts for 4% of the CD34+ fraction compared to only 1% in bone marrow, indicating that umbilical cord blood may be relatively enriched in stem cells. We estimate that the CD34+ CD38- cells from a typical umbilical cord blood sample produce equivalent numbers of colony-forming units (CFU)-granulocyte/erythrocyte/macrophage/megakaryocyte, twice as many CFU-granulocyte/macrophage (GM) and 3 times as many burst-forming units-erythroid as the same population from an average bone marrow sample used in adult transplantation. In addition, the colonies resulting from the umbilical cord blood samples were significantly larger than those from bone marrow, indicating a greater growth potential. However, the content of later progenitors, which may be important for short-term reconstitution, was less in umbilical cord blood-derived than in bone marrow-derived cell preparations, as estimated by a 4-fold lower production of CFU-GM in long-term cultures of CD34+ CD38+ cells. This deficit is partially compensated by the higher growth capacity of the resulting CFU-GM. These studies suggest that umbilical cord blood is a suitable source of cells for adult transplantation.     

Phenotypic Characterization of Immunomagnetically Purified Umbilical Cord Blood CD34+ Cells

ABSTRACT: This study describes the multilineage differentiation pattern of purified CD34+ stem cells obtained from human umbilical cord blood. CD34+ cells were collected from 49 umbilical cord blood samples. Following immunomagnetic purification, cells were double stained with anti CD34 and CD71, CD61, CD7, CD19, CD33, CD36 and triple stained with anti CD34, CD38 and HLA-DR. Analyses were performed using a FACScan flow cytometer. After purification, the mean CD34+ cells' purity was 85.49 ± 7.08%. Several subpopulations of umbilical cord blood CD34+ cells were identified indicating different lineage commitment. The majority of CD34+ cells expressed both CD38 and HLA-DR (91.74 ± 3.76%), while those lacking CD38 were 3.43 ± 2.12% (CD38-DR+) and 1.81 ± 1.54% (CD38-DR-). These data were compared to the expression of lineage commitment markers on purified CD34+ cells from 5 mobilized peripheral blood samples. The percentage of peripheral blood CD34+CD38-DR+ and CD34+CD38-DR- cells was significantly lower than umbilical cord blood, 0.24 ± 0.18% and 0.04 ± 0.03% respectively. The knowledge and standardization of umbilical cord blood CD34+ cells phenotype is critical since umbilical cord blood volume is limited. The homogeneity of CD34+ subpopulation phenotype suggests that monitoring of lineage differentiation antigens may not be relevant for clinical use of umbilical cord blood samples. However, the observed higher percentage of pluripotent CD34+38- stem cells in umbilical cord blood compared to peripheral blood, that might explain the successful clinical use of umbilical cord blood even when low number of cells are used, candidates these antigens as the predictive parameter for clinical use of umbilical cord blood samples.     

Transplantation of microencapsulated umbilical-cord-blood-derived hepatic-like cells for treatment of hepatic failure

AIM: To investigate intraperitoneal transplantation of microencapsulated hepatic-like cells from human umbilical cord blood for treatment of hepatic failure in rats. METHODS: CD34+ cells in umbilical cord blood cells were isolated by magnetic cell sorting. In the in vitro experiment, sorted CD34+ cells were amplified and induced into hepatic-like cells by culturing with a combination of fibroblast growth factor 4 and hepatocyte growth factor. Cultures without growth factor addition served as controls. mRNA ...     

Phenotypic characterization of immunomagnetically purified umbilical cord blood CD34+ cells

This study describes the multilineage differentiation pattern of purified CD34+ stem cells obtained from human umbilical cord blood. CD34+ cells were collected from 49 umbilical cord blood samples. Following immunomagnetic purification, cells were double stained with anti CD34 and CD71, CD61, CD7, CD19, CD33, CD36 and triple stained with anti CD34, CD38 and HLA-DR. Analysis were performed using a FACScan flow cytometer. After purification, the mean CD34+ cells' purity was 85.49 +/- 7.08%. Several subpopulations of umbilical cord blood CD34+ cells were identified indicating different lineage commitment. The majority of CD34+ cells expressed both CD38 and HLA-DR (91.74 +/- 3.76%), while those lacking CD38 were 3.43 +/- 2.12% (CD38-DR+) and 1.81 +/- 1.54% (CD38-DR-). These data were compared to the expression of lineage commitment markers on purified CD34+ cells from 5 mobilized peripheral blood samples. The percentage of peripheral blood CD34+CD38-DR+) and CD34+CD38-DR- cells was significantly lower than umbilical cord blood, 0.24 +/- 0.18% and 0.04 +/- 0.03% respectively. The knowledge and standardized of umbilical cord blood CD34+ cells phenotype is critical since umbilical cord blood volume is limited. The homogeneity of CD34+ subpopulation phenotype suggests that monitoring of lineage differentiation antigens may not be relevant for clinical use of umbilical cord blood samples. However, the observed higher percentage of pluripotent CD34+38- stem cells in umbilical cord blood compared to peripheral blood, that might explain the successful clinical use of umbilical cord blood even when low number of cells are used, candidates these antigens as the predictive parameter for clinical use of umbilical cord blood samples.     

Direct comparison by limiting dilution analysis of long-term culture- initiating cells in human bone marrow, umbilical cord blood, and blood stem cells

Limiting-dilution analysis of long-term culture-initiating cells (LTCIC) is a quantitative method of estimating hematopoietic stem cell activity in clinical samples. We compared the numbers of LTCIC in bone marrow (BM), umbilical cord blood, and blood progenitor cells (obtained from patients with solid tumors at leukapheresis after mobilization with induction chemotherapy and filgrastim administration), using a two- stage long-term culture system and a limiting-dilution technique, scoring cobblestone areas of greater than 15 hematopoietic cells weekly for up to 8 weeks. Samples were obtained from 30 normal BMs, 20 human umbilical cords, and 32 leukapheresis products. Direct comparison of LTCIC in the three sources showed that the median proportions of cells generating hematopoietic foci from unfractionated mononuclear cells at 5 and 8 weeks, respectively, were 1:13,314 and 1:33,949 for BM, 1:12,506 and 1:34,546 for umbilical cord blood, and 1:10,302 and 1:12,891 for leukapheresis product. The estimated proportions of LTCIC from unfractionated mononuclear cells and CD34+ cells were similar in experiments with leukapheresis product. Leukapheresis product was superior to umbilical cord blood and cord blood to BM at 5 and 8 weeks of culture (P = .01). In two-stage long-term cultures, more colonies per flask and CD34+ cells were found in assays of leukapheresis product than in BM or umbilical cord blood cultures (P = .0005). Results obtained by this simplified limiting-dilution analysis correlated well with standard long-term cultures and can be used as a measure of the stem cell population. These data suggest that the incidence of putative stem cells in leukapheresis product and umbilical cord blood are at least comparable with that of BM.