Isolation and characterization of human CD34(-)Lin(-) and CD34(+)Lin(-) hematopoietic stem cells using cell surface markers AC133 and CD7

Recent evidence indicates that human hematopoietic stem cell properties can be found among cells lacking CD34 and lineage commitment markers (CD34(-)Lin(-)). A major barrier in the further characterization of human CD34(-) stem cells is the inability to detect this population using in vitro assays because these cells only demonstrate hematopoietic activity in vivo. Using cell surface markers AC133 and CD7, subfractions were isolated within CD34(-)CD38(-)Lin(-) and CD34(+)CD38(-)Lin(-) cells derived from human cord blood. Although the majority of CD34(-)CD38(-)Lin(-) cells lack AC133 and express CD7, an extremely rare population of AC133(+)CD7(-) cells was identified at a frequency of 0.2%. Surprisingly, these AC133(+)CD7(-) cells were highly enriched for progenitor activity at a frequency equivalent to purified fractions of CD34(+) stem cells, and they were the only subset among the CD34(-)CD38(-)Lin(-) population capable of giving rise to CD34(+) cells in defined liquid cultures. Human cells were detected in the bone marrow of non-obese/severe combined immunodeficiency (NOD/SCID) mice 8 weeks after transplantation of ex vivo-cultured AC133(+)CD7(-) cells isolated from the CD34(-)CD38(-)Lin(-) population, whereas 400-fold greater numbers of the AC133(-)CD7(-) subset had no engraftment ability. These studies provide novel insights into the hierarchical relationship of the human stem cell compartment by identifying a rare population of primitive human CD34(-) cells that are detectable after transplantation in vivo, enriched for in vitro clonogenic capacity, and capable of differentiation into CD34(+) cells. (Blood. 2000;95:2813-2820)     

VEGFR-3 and CD133 identify a population of CD34+ lymphatic/vascular endothelial precursor cells

Human CD133 (AC133)(+)CD34(+) stem and progenitor cells derived from fetal liver and from bone marrow and blood incorporate a functional population of circulating endothelial precursor cells. Vascular endothelial growth factor receptor 3 (VEGFR-3) regulates cardiovascular development and physiological and pathological lymphangiogenesis and angiogenesis. However, the origin of VEGFR-3(+) endothelial cells (ECs) and the mechanisms by which these cells contribute to postnatal physiological processes are not known, and the possible existence of VEGFR-3(+) lymphatic or vascular EC progenitors has not been studied. Using monoclonal antibodies to the extracellular domain of VEGFR-3, we show that 11% +/- 1% of CD34(+) cells isolated from human fetal liver, 1.9% +/- 0.8% CD34(+) cells from human cord blood, and 0.2% +/- 0.1% of CD34(+) cells from healthy adult blood donors are positive for VEGFR-3. CD34(+)VEGFR-3(+) cells from fetal liver coexpress the stem/precursor cell marker CD133 (AC133). Because mature ECs do not express CD133, coexpression of VEGFR-3 and CD133 on CD34(+) cells identifies a unique population of stem and progenitor cells. Incubation of isolated CD34(+)VEGFR-3(+) cells in EC growth medium resulted in a strong proliferation (40-fold in 2 weeks) of nonadherent VEGFR-3(+) cells. Plating of these cells resulted in the formation of adherent VEGFR-3(+)Ac-LDL(+) (Ac-LDL = acetylated low-density lipoprotein) EC monolayers expressing various vascular and lymphatic endothelial-specific surface markers, including CD34, VE-cadherin, CD51/61, CD105, LYVE-1, and podoplanin. These data demonstrate that human CD34(+)CD133(+) cells expressing VEGFR-3 constitute a phenotypically and functionally distinct population of endothelial stem and precursor cells that may play a role in postnatal lymphangiogenesis and/or angiogenesis.     

CD34-/CD133+/VEGFR-2+ endothelial progenitor cell subpopulation with potent vasoregenerative capacities

Our goal was to identify functionally important subpopulations within the heterogenous group of endothelial progenitor cells (EPC). Fluorescence-activated cell sorter analysis of CD133+ progenitor cells revealed the presence of CD34+ and CD34- subpopulations. CD34-/133+ progenitors differentiate into CD34+/133+ EPC, adhere more potently than these in response to SDF-1, and rapidly home to sites of limb ischemia in human volunteers. In human coronary atherectomy samples, fewer CD34-/133+ than CD34+/133+ EPC are present in stable plaques, whereas cell numbers increase with a reversion of the ratio in unstable lesions. In CD34-/133+ EPC-injected nude mice, more transplanted cells coexpressing endothelial markers home to carotid artery lesion endothelium than in CD34+/133+-injected mice. In the former, lesions were smaller and reendothelialization higher than in the latter. We identified a new CD34-/133+ EPC subpopulation, which is apparently a precursor of "classical" CD34+/133+ EPC, and functionally more potent than these with respect to homing and vascular repair.     

Ex vivo generation of CD34(+) cells from CD34(-) hematopoietic cells

The human Lin(-)CD34(-) cell population contains a newly defined class of hematopoietic stem cells that reconstitute hematopoiesis in xenogeneic transplantation systems. We therefore developed a culture condition in which these cells were maintained and then acquired CD34 expression and the ability to produce colony-forming cells (CFC) and SCID-repopulating cells (SRCs). A murine bone marrow stromal cell line, HESS-5, supports the survival and proliferation of Lin(-)CD34(-) cells in the presence of fetal calf serum and human cytokines thrombopoietin, Flk-2/Flt-3 ligand, stem cell factor, granulocyte colony-stimulating factor, interleukin-3, and interleukin-6. Although Lin(-)CD34(-) cells do not initially form any hematopoietic colonies in methylcellulose, they do acquire the colony-forming ability during 7 days of culture, which coincides with their conversion to a CD34(+) phenotype. From 2.2% to 12.1% of the cells became positive for CD34 after culture. The long-term multilineage repopulating ability of these cultured cells was also confirmed by transplantation into irradiated NOD/SCID mice. These results represent the first in vitro demonstration of the precursor of CD34(+) cells in the human CD34(-) cell population. Furthermore, the in vitro system we reported here is expected to open the way to the precise characterization and ex vivo manipulation of Lin(-)CD34(-) hematopoietic stem cells.     

Effects of atorvastatin on circulating CD34+/CD133+/ CD45− progenitor cells and indices of angiogenesis (vascular endothelial growth factor and the angiopoietins 1 and 2) in atherosclerotic vascular disease and diabetes mellitus

Abstract. Jaumdally RJ, Goon PKY, Varma C, Blann AD, Lip GYH (City Hospital, Birmingham, United Kingdom). Effects of atorvastatin on circulating CD34+/CD133+/CD45? progenitor cells and indices of angiogenesis (vascular endothelial growth factor and the angiopoietins 1 and 2) in atherosclerotic vascular disease and diabetes mellitus. J Intern Med 2010; 267 : 385–393. Background. Cardiovascular disease (CVD) remains a major cause of morbidity and mortality, especially in the presence of diabetes, possibly because of endothelial damage. Increased circulating progenitor cells (CPCs) and increased plasma markers of angiogenesis [vascular endothelial growth factor (VEGF) and the angiopoietins (Ang‐1 and ‐2)] may be evidence of this damage. Treatment with hydroxy‐methyl‐glutaryl (HMG‐CoA) reductase inhibitors (‘statins’) improves outcomes in patients with vascular disease, including diabetic patients. We hypothesized that 80 mg per day atorvastatin influences CPC counts of VEGF and the angiopoietins in patients with atherosclerotic CVD with or without diabetes mellitus. Methods. Cardiovascular disease patients with diabetes mellitus (Group A, n = 14) and nondiabetic patients with CVD only (Group B, n = 10) took atorvastatin 80 mg per day for a period of 8–10 weeks. CPCs (CD34+/CD133+/CD45?) were defined by flow cytometry, plasma levels VEGF and Ang‐1 and Ang‐2 by ELISA). Results. Circulating progenitor cell counts increased (P < 0.001) in Group A compared with a nonsignificant change in Group B (P = 0.37). VEGF levels fell significantly in Group A (P = 0.04) but no significant change was seen in Group B (P = 0.16). Whilst Ang‐1 remained unchanged (P = 0.41), Ang‐2 levels increased markedly in both groups (P < 0.05). These effects were independent of LDL and total cholesterol changes but were associated with HDL changes Conclusion. High‐dose atorvastatin increased circulating CPCs, reduced VEGF and increased Ang‐2 in patients with diabetes and CVD, providing another possible pathophysiological mechanism for the beneficial effects of statins in CVD.     

Isolation and characterization of CD133+CD34+VEGFR-2+CD45- fetal endothelial cells from human term placenta

The phenotypes and functions of endothelial cells (EC), a heterogeneous cell population, vary along the vascular tree and even in the same organ between different vessels. The placenta is an organ with abundant vessels. To enhance further knowledge concerning placenta derived EC, we develop a new method for isolation, purification and culture of these EC. Moreover, in order to investigate the peculiarity of placenta derived EC we compare their phenotypic and functional characteristics with human dermal lymphatic endothelial cells (HDLEC) and human umbilical vein endothelial cells (HUVEC). Freshly isolated placenta derived EC displayed an elongated shape with pale cytoplasm and showed the typical cobblestone pattern of EC but also a swirling pattern when confluent. FISH-analyses of the isolated EC from placentae of male fetus revealed an XY genotype strongly indicating their fetal origin. Characterisation of placenta derived fetal EC (fEC) underlined their blood vessel phenotype by the expression of vWF, Ulex europaeus lectin-1, HLA-class I molecules, CD31, CD34, CD36, CD51/61, CD54, CD62E, CD105, CD106, CD133, CD141, CD143, CD144, CD146, VEGFR-1, VEGFR-2, EN-4, PAL-E, BMA120, Tie-1, Tie-2 and α-Tubulin. In contrast to previous reports the expression of lymphatic markers, like VEGFR-3, LYVE-1, Prox-1 and Podoplanin was consistently negative. Haematopoietic surface markers like CD45 and CD14 were also always negative. Various functional tests (Dil-Ac-LDL uptake, Matrigel assay and TNF-α induced upregulation of CD62E and CD54) substantiated the endothelial nature of propagated fEC. At the ultrastructural level, fEC harboured numerous microvilli, micropinocytic vesicles at their basis, were rich in intermediate filaments and possessed typical Weibel - Palade bodies. In conclusion, the placenta is a plentiful source of fetal, microvascular, blood EC with an expression profile (CD34+, CD133+, VEGFR-2+, CD45-) suggestive of an endothelial progenitor phenotype.     

Ex vivo expansion CD34+/AC133+ - selected autologous peripheral blood progenitor cells (PBPC) in high-risk breast cancer patients receiving intensive chemotherapy

AC133 antibody provides an alternative to CD34 for the selection and characterization of cells necessary for engraftment in transplant situations. We studied the effect of stem cell factor (SCF), interleukin 3 (IL-3) and interleukin 11 (IL-11) on the ex vivo expansion of human CD34⁺/AC133⁺ progenitors isolated from leukapheresis products from chemotherapy plus granulocyte-colony-stimulating factor (G-CSF) -mobilized adult donors. MiniMACS AC133⁺ isolated cells contained a mean of 85% (80-90) AC133⁺ cells. Enriched AC133⁺ cells co-expressed CD34⁺ 80%, CD71^low 36.6 % and CD33⁺ 6.6 %. After a seven-day ex vivo expansion in the presence of SCF + IL-3 + IL-11, the number of cells increased 19 times. These cells expressed a mean 12% CD34⁺ and 74% CD71⁺ (23% CD 71^high) and 59% CD33⁺. This means that the absolute number of CD34⁺ cells increased slightly, the number of CD33⁺ increased 100 times and cells with high density CD71^high (23%) appeared. These cells represent the cells committed to erythroid differentiation. The increase in the number of CFU-GM with various combinations of cytokines SCF + Il-3 + IL-11 will be discussed. The number of CFU-GM in culture after a seven-day ex vivo expansion in the presence of SCF + IL-3 + IL-11 increased 45 times.     

CD133-enriched CD34(-) (CD33/CD38/CD71)(-) cord blood cells acquire CD34 prior to cell division and hematopoietic activity is exclusively associated with CD34 expression

We compared the cell division behavior of CD34(-) and CD34(+) (CD33/CD38/CD71)-negative (Lin(-)) CD133(+) cord blood cells stimulated with the cytokines Flt3-ligand, stem cell factor, and thrombopoietin. Within a 4-day time frame, Lin(-)CD34(-) CD133(+) (CD34(-)) cells underwent more cell divisions in serum-free culture than their Lin(-)CD34(+) CD133(+) (CD34(+)) counterparts. The majority of CD34(-) cells acquired expression of CD34 in vitro, including most undivided cells. Moreover, hematopoietic activity from both CD34(-) and CD34(+) cells was exclusively retained within the cell fraction expressing CD34 after 4 days in culture. Most strikingly, in cultures from Lin(-)CD34(-) cells hematopoietic activity was associated with the fraction of divided cells, whereas in cultures of CD34(+) cells, hematopoietic activity associated with the undivided cell fraction. Therefore, clonogenic CD34(+) cells either do not divide or lose their clonogenic capacity upon cell division in vitro, while CD34(-) cells divide and retain this capacity under the same specific conditions. In conclusion, we demonstrate that CD133-enriched Lin(-)CD34(-) cord blood cells acquire CD34 prior to cell division and that long-term hematopoietic activity is associated exclusively with expression of CD34.     

循环CD133+/KDR+内皮祖细胞水平与急性缺血性卒中患者转归的相关性

目的 探讨急性缺血性卒中患者循环CD133+/KDR+内皮祖细胞(endothelial progenitor cells,EPCs)水平与转归的关系.方法 纳入发病24 h内的首次急性缺血性卒中住院患者以及年龄和性别相匹配的健康体检者.收集患者人口统计学和临床资料.采用流式细胞术检测CD133+/KDR+EPCs水平.在发病后90 d时对所有患者进行随访,采用改良Rankin量表评价临床转归,0~2分定义为转归良好,>2分定义为转归不良.结果 共纳入连续126例缺血性卒中患者以及60例年龄和性别相匹配的健康体检者.在缺血性卒中患者中,大动脉粥样硬化(large artery atherosclerosis,LAA) 33例(26.19%),小动脉闭塞(small artery occlusion,SAO)74例(58.73%),心源性栓塞(cardioembolism,CE)19例(15.08%);82例(65.08%)转归良好,44例(34.92%)转归不良.LAA型(0.071%±0.018%)、CE型(0.068%±0.016%)和SAO型(0.118%±0.012%)患者基线循环EPCs数量均显著低于对照组(0.246%±0.052%;P均<0.05);CE型(P=0.028)和LAA型(P=0.037)均显著低于SAO型;CE型低于LAA型,但差异无统计学意义(P=0.762).转归不良组LAA型(40.91%对18.29%;χ2=7.577,P=0.006)和CE型(29.55%对7.32%;χ2=11.049,P=0.001)和心房颤动(29.55%对10.98%;χ2=6.582,P=0.009)患者的构成比以及年龄[(69.64±9.62)岁对 (61.12±7.31)岁;t=5.570,P<0.001]、基线NIHSS评分[(14.16±4.22)分对 (6.96±2.04)分;t=12.919,P<0.001]、基线收缩压[(176.06±13.42)mmHg对 (164.12±11.69)mmHg,1 mmHg=0.133 kPa;t=5.187,P<0.001]、低密度脂蛋白胆固醇[(2.92±0.52)mmol/L对 (2.49±0.36)mmol/L;t=5.447,P<0.001]、空腹血糖[(8.76±2.88)mmol/L对 (6.82±2.24)mmol/L;t=4.185,P<0.001]、C反应蛋白[(7.62±1.82)mg/L对 (4.57±1.58)mg/L;t=9.790,P<0.001]和D-二聚体[(1.14±0.08)mg/L对 (0.97±0.22)mg/L;t=4.946,P<0.001]水平均显著高于转归良好组,而SAO型患者构成比(29.55%对74.39%;χ2=23.759,P<0.001)以及高密度脂蛋白胆固醇[(0.94±0.68)mmol/L对 (1.16±0.14)mmol/L;t=2.829,P=0.005]和基线EPCs(0.069%±0.018%对0.098%±0.021%;t=7.755,P<0.001)水平显著低于转归良好组.多变量logistic回归分析显示,基线NIHSS评分较高(优势比1.242,95%可信区间1.126~1.372;P<0.001)、CE型(优势比3.460,95%可信区间1.312~5.146;P=0.016)和基线EPCs数量较低(优势比1.632,95%可信区间1.006~3.024;P<0.001)是急性缺血性卒中患者转归不良的独立危险因素.结论 急性缺血性卒中患者循环EPCs水平显著降低,基线EPCs水平较低是缺血性卒中患者90 d时转归不良的独立预测因素.     

Quantification of circulating CD34/KDR/CD45 endothelial progenitor cells: Analytical considerations

The discovery of peripheral circulating cells that contribute to vasculogenesis and endothelial repair was one of the most fascinating breakthroughs in the domain of vascular research during the last two decades. The population of vasculogenic cells however, is heterogeneous and can be analyzed using different approaches including in vitro culture and flow cytometry. Circulating CD34⁺/KDR⁺/CD45^dim endothelial progenitor cells (EPC) have a great potential as biomarkers in various cardiovascular diseases. With the expanding interest in this field, the development of standardized protocols is critical.     

Expression of VEGFR-2 and AC133 by circulating human CD34(+) cells identifies a population of functional endothelial precursors

Emerging data suggest that a subset of circulating human CD34(+) cells have phenotypic features of endothelial cells. Whether these cells are sloughed mature endothelial cells or functional circulating endothelial precursors (CEPs) is not known. Using monoclonal antibodies (MoAbs) to the extracellular domain of the human vascular endothelial receptor-2 (VEGFR-2), we have shown that 1.2 +/- 0.3% of CD34(+) cells isolated from fetal liver (FL), 2 +/- 0.5% from mobilized peripheral blood, and 1.4 +/- 0.5% from cord blood were VEGFR-2(+). In addition, most CD34(+)VEGFR-2(+) cells express hematopoietic stem cell marker AC133. Because mature endothelial cells do not express AC133, coexpression of VEGFR-2 and AC133 on CD34(+) cells phenotypically identifies a unique population of CEPs. CD34(+)VEGFR-2(+) cells express endothelial-specific markers, including VE-cadherin and E-selectin. Also, virtually all CD34(+)VEGFR-2(+) cells express the chemokine receptor CXCR4 and migrate in response to stromal-derived factor (SDF)-1 or VEGF. To quantitate the plating efficiency of CD34(+) cells that give rise to endothelial colonies, CD34(+) cells derived from FL were incubated with VEGF and fibroblast growth factor (FGF)-2. Subsequent isolation and plating of nonadherent FL-derived VEGFR-2(+) cells with VEGF and FGF-2 resulted in differentiation of AC133(+ )VEGFR-2(+) cells into adherent AC133(-)VEGFR-2(+)Ac-LDL(+ )(acetylated low-density lipoprotein) colonies (plating efficiency of 3%). In an in vivo human model, we have found that the neo-intima formed on the surface of left ventricular assist devices is colonized with AC133(+)VEGFR-2(+) cells. These data suggest that circulating CD34(+) cells expressing VEGFR-2 and AC133 constitute a phenotypically and functionally distinct population of circulating endothelial cells that may play a role in neo-angiogenesis.     

Kinetics of engraftment of CD34(-) and CD34(+) cells from mobilized blood differs from that of CD34(-) and CD34(+) cells from bone marrow

OBJECTIVE: Mobilized peripheral blood (PB) progenitors are increasingly used in autologous and allogeneic transplantation. However, the short- and long-term engraftment potential of mobilized PB or bone marrow (BM) has not been directly compared. Although several studies showed that BM-derived Lin(-)CD34(-) cells contain hemopoietic progenitors, no studies have addressed whether Lin(-)CD34(-) cells from mobilized PB contain hemopoietic progenitors. Here, we compared the short- and long-term engraftment potential of CD34(+) cells and Lin(-)CD34(-) cells in BM and PB of normal donors who received 5 days of granulocyte colony-stimulating factor (G-CSF). MATERIALS AND METHODS: 35 x 10(3) CD34(+) or Lin(-)CD34(-) cells from G-CSF mobilized BM and PB of normal donors were transplanted in 60-day-old fetal sheep. Animals were evaluated 2 and 6 months after transplantation for human hemopoietic cells. In addition, cells recovered after 2 months from fetal sheep were serially passaged to secondary and tertiary recipients to assess long-term engrafting cells. RESULTS: Mobilized PB CD34(+) cells supported earlier development of human hemopoiesis than BM CD34(+) cells. When serially transferred to secondary and tertiary recipients, earlier exhaustion of human hematopoiesis was seen for PB than BM CD34(+) cells. A similar degree of chimerism was seen for Lin(-)CD34(-) cells from PB or BM in primary recipients. We again observed earlier exhaustion of human hemopoiesis with serial transplantation of PB than BM Lin(-)CD34(-) cells. CONCLUSIONS: Differences exist in the short- and long-term repopulating ability of cells in PB and BM from G-CSF mobilized normal donors, and this is independent of the phenotype. Studies are ongoing to examine if this reflects intrinsic differences in the repopulating potential between progenitors from PB and BM, or a lower frequency of long-term repopulating cells in PB than BM CD34(+) and Lin(-)CD34(-) cells, that may not be apparent if larger numbers of cells are transplanted.     

Long-term culture of human CD34(+) progenitors with FLT3-ligand, thrombopoietin, and stem cell factor induces extensive amplification of a CD34(-)CD14(-) and a CD34(-)CD14(+) dendritic cell precursor

Current in vitro culture systems allow the generation of human dendritic cells (DCs), but the output of mature cells remains modest. This contrasts with the extensive amplification of hematopoietic progenitors achieved when culturing CD34(+) cells with FLT3-ligand and thrombopoietin. To test whether such cultures contained DC precursors, CD34(+) cord blood cells were incubated with the above cytokines, inducing on the mean a 250-fold and a 16,600-fold increase in total cell number after 4 and 8 weeks, respectively. The addition of stem cell factor induced a further fivefold increase in proliferation. The majority of the cells produced were CD34(-)CD1a- CD14(+) (p14(+)) and CD34(-)CD1a-CD14(-) (p14(-)) and did not display the morphology, surface markers, or allostimulatory capacity of DC. When cultured with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), both subsets differentiated without further proliferation into immature (CD1a+, CD14(-), CD83(-)) macropinocytic DC. Mature (CD1a+, CD14(-), CD83(+)) DCs with high allostimulatory activity were generated if such cultures were supplemented with tumor necrosis factor-alpha (TNF). In addition, p14(-) cells generated CD14(+) cells with GM-CSF and TNF, which in turn, differentiated into DC when exposed to GM-CSF and IL-4. Similar results were obtained with frozen DC precursors and also when using pooled human serum AB+ instead of bovine serum, emphasizing that this system using CD34(+) cells may improve future prospects for immunotherapy.     

CD34+/CD105+ cells are enriched in primitive circulating progenitors residing in the G0 phase of the cell cycle and contain all bone marrow and cord blood CD34+/CD38low/- precursors

A subset of circulating CD34+ cells was found to express CD105 antigen. Sorting experiments showed that most granulocyte-macrophage colony-forming units (GM-CFU) and burst-forming units - erythroid (BFU-E) were retained in the CD34+/CD105- fraction, whereas rare GM-CFU/BFU-E were generated from CD34+/CD105+ cells. Megakaryocytic aggregates were entirely retained in the CD34+/CD105+ fraction. Neutralizing doses of an anti-TGF-beta1 antibody demonstrated CD34+/CD105+ cells capable of colony-forming activity without any significant effect on CD34+/CD105- cells. Cloning of secondary colonies revealed that CD34+/CD105+ cells had a significantly higher secondary cloning efficiency than CD34+/CD105- cells. CD34+/CD105+ cells had a significantly higher long-term culture-initiating cell (LTC-IC) frequency than CD34+/CD105- cells. Kinetic analysis showed that 75% of CD34+/CD105+ cells consisted of DNA 2n G0Ki-67- cells whereas 82% of CD34+/CD105- were DNA 2n G1Ki-67+ cells, and this latter subset showed a RNA content consistently higher than CD34+/CD105+ cells. CD34+/CD105+ progenitors were CD25+, whereas CD34+/CD105- contained a small CD25+ subset. Three-colour analysis of bone marrow and cord blood CD34+ cells demonstrated that all the CD34+/CD38low/- primitive precursors were contained in CD34+/CD105+ cells. Extensive characterization of these CD105+ precursors indicated that they have biological properties associated with primitive haematopoietic precursors.     

CD133-2 (AC141) expression analysis in acute leukemia immunophenotyping in correlation to CD34 and P-glycoprotein

A total of 49 newly diagnosed patients with acute leukemia were studied in order to assess the diagnostic value of clone AC141 of CD133 antibody by flow cytometry. AC141 expression was further compared to CD34 and P-glycoprotein, immunophenotype, morphology and cytogenetic/molecular data. Flow cytometry allowed for the detection of AC141 expression in 42.8% of the patients. A strong correlation with myeloid lineage was observed. All AC141(+) acute myeloid leukemia (AML) cases were of immature morphology and a strong concordance with CD34 expression was found. However, discordant patterns were also observed. Besides, AC141 expression correlated with CD7 in the absence of mature markers (CD14, CD15 and CD64). Similarly to CD34, P-glycoprotein levels were also significantly higher in AC141(+) AML cases. No correlation was found with cytogenetic/molecular data of the patients. In conclusion, membrane expression of AC141, in combination with other antigens, might facilitate a more precise immunologic characterization of acute leukemias and may serve as an alternative to CD34 for purging purposes in selected patients.     

Endothelial impairment and bone marrow‐derived CD34+/133+ cells in diabetic patients with erectile dysfunction

Aims/Introduction

The present study was undertaken to determine vascular endothelial impairment and endothelial progenitor cells (EPCs) in patients with type 2 diabetes mellitus and erectile dysfunction (ED).

Materials and Methods

A total of 100 type 2 diabetic men were enrolled. Flow‐mediated dilatation (FMD) and anaerobic threshold (AT) were measured. Also, EPCs in the peripheral blood were determined by flow cytometry.

Results

In the 42 ED diabetic patients, FMD and AT were significantly less than those in the 58 patients with normal erectile function (FMD 2.84 vs 3.82%, P = 0.038, and AT 11.2 vs 12.7 mL/kg/min, P = 0.022). Exercise tolerance significantly increased the number of EPCs in the patients with and without ED (49–60 cells/100 μL, P = 0.015, and 72–99 cells/100 μL, P = 0.003). In the diabetic patients without autonomic neuropathy, FMD was significantly reduced in the patients with ED than those without ED (P = 0.015). In response to exercise tolerance, the number of EPCs increased in both the diabetic patients with ED (P = 0.003) and without ED (P = 0.007). In contrast, in the diabetic patients with autonomic neuropathy, there was no difference in FMD between the patients with and without ED. The exercise tolerance increased the number of EPCs in the patients without ED (P = 0.023), but it disappeared in those with ED.

Conclusions

ED diabetic patients have endothelial impairment during the early period of diabetic complications, whose deranged endothelial function is concomitantly repaired by promoting bone marrow‐derived EPCs.     

Extensive generation of human cord blood CD34(+) stem cells from Lin(-)CD34(-) cells in a long-term in vitro system

Human CD34(-) hematopoietic stem cells (HSCs) have been identified as potential precursors of CD34(+) HSCs by using xenogeneic transplantation systems. However, the properties of CD34(+) cells generated from CD34(-) cells have not been precisely analyzed due to the lack of an in vitro system in which CD34(+) cells are continuously produced from CD34(-) cells. We conducted this study to determine whether CD34(+) cells generated in vitro from CD34(-) cells have long-term multilineage reconstitution abilities. Lin(-)CD34(-) population isolated from human cord blood was cultured in the presence of murine bone marrow stroma cell line, HESS-5, and human cytokines, thrombopoietin, Flk2/Flt3 ligand, stem cell factor, granulocyte colony-stimulating factor, interleukin 3 (IL-3), and IL-6. They were analyzed weekly for their surface markers expressions, colony-forming cells, long-term culture initiating cells (LTC-IC), and SCID repopulating cells (SRC) abilities up to 30 days of culture.In this culture system, more than 10(7) CD34(+) cells can be continuously generated from 10(4) CD34(-) cells over 30 days. These CD34(+) cells produce colony-forming units, LTC-IC, and SRC with multi-lineage differentiation, all of which are characteristic features of hematopoietic stem/progenitor cells.These findings suggest that CD34(-) HSCs have extensive potential for the generation of CD34(+) HSCs in vitro. This system provides a novel and potentially useful procedure to generate CD34(+) cells for clinical transplantation and gene therapy.     

Cell cycle and functional differences between CD34+/CD38hi and CD34+/38lo human marrow cells after in vitro cytokine exposure

The proliferation kinetics and clonogenic activity of CD34+/38hi (CD38hi) and CD34+/38lo (CD38lo) human marrow cells were measured before and after culturing the cells in vitro over a 6-day period in serum-deprived medium containing recombinant growth factors (interleukin-1 [IL-1], IL-3, IL-6, granulocyte colony-stimulating factor [G-CSF], granulocyte-macrophage [GM]-CSF, kit ligand, and erythropoietin). Before in vitro culture, 3% +/- 3% of the CD38lo and 13% +/- 2% of the CD38hi cells were in the S-phase of the cell cycle. The clonogenic activity of CD38hi cells was twofold greater than that of the CD38lo cells, as measured by colony-forming units (CFU) in short- term assays. However, CD38hi cells contained fewer pre-CFU than did the CD38lo cells, generating only 3 +/- 2 colonies per 1,000 cells after 4 weeks of culture on competent stromal layers, compared with 107 +/- 46 colonies per 1,000 cells from the CD38lo population. CD38hi and CD38lo cells exhibited distinctly different responses when cultured in serum- deprived medium supplemented with recombinant growth factors. After culturing cells for 24 hours, CD38lo cells essentially remained a noncycling population with only 5.1% +/- 3.0% of the cells cycling, whereas 44.2% +/- 6.9% of the CD38hi cells were in DNA synthesis. Gradually CD38lo cells were recruited into cycle, such that by 72 hours, approximately 28% of the CD38lo cells were in S-phase. However, during 6 days of culture, the percentage of cycling CD38lo cells never exceeded the proliferative response observed for CD38hi cells. Phenotype analysis conducted at day 6 indicated that 86% of the CD38hi population were no longer phenotypically CD34+/38hi, while 60% of CD38lo cells maintained a CD34+/38lo phenotype. Long-term cultures initiated with 6-day in vitro-expanded CD38lo cells showed approximately a twofold decrease in clonogenic activity attributable to a loss of erythroid precursors and a decrease in GM colonies. Thus, a proportion of CD38lo cells capable of generating CFU was maintained even after exposure to growth factors.