IL-12 indirectly enhances proliferation of 5-FU-treated human hematopoietic peripheral blood CD34+ cells

Interleukin-12 (IL-12) or natural killer cell stimulatory factor (NKSF), has multiple effects on T lymphocytes and natural killer cells. In this study, the effect of IL-12 on human hematopoiesis was studied by analyzing the growth of CD34⁺ peripheral blood stem cells (PBSC), in steady state. In the presence of Epo, IL-12 alone or in combination with IL-3 or SCF had no effect on the formation of colonies from CD34⁺ cells. In culture with Epo, G-CSF, and IL-3, the effect of Flt3-ligand (FL) on CD34⁺ PBSC was investigated in the presence or absence of IL-12. No additional effect of IL-12 was observed when combined with FL. We evaluated 5-FU-treated human CD34⁺ PBSC proliferation in cultures with Epo, G-CSF, and IL-3, in the presence or absence of IL-12. No cytokine combination enhanced colony formation from 5-FU-treated CD34⁺ cells. However, in cultures of 5-FU-treated human CD34⁺ cells, the most efficient combination was IL-3 + Epo + G-CSF + Accessory cells (CD34⁻). Furthermore, IL-12 enhanced this colony formation significantly. To investigate whether immature CD34⁺ cells were responsible for FL or SCF, 5-FU-treated human CD34⁺ cells were cultured with or without IL-12. Whereas no synergistic effect was observed in combination with IL-12, SCF alone significantly enhanced colony formation. However, the colony number was found to be smaller than with the potent combination of accessory cells in the presence of IL-12. These results indicate that accessory cells, lost in CD34⁺ cell purification, could be partly responsible for an IL-12 effect on immature human PBSC proliferation. J. Hematol. 58:183–188, 1998. © 1998 Wiley-Liss, Inc.     

IL-6 precludes the differentiation induced by IL-3 on expansion of CD34+ cells from cord blood

BACKGROUND AND OBJECTIVES: Ex vivo expansion of hematopoietic progenitor cells (HPC) from umbilical cord blood (UCB) is an interesting strategy to obtain a sufficient number of transplantable cells for adults. To define the optimal culture conditions allowing the generation of HPC that retain their proliferative capacity without loss of long-term culture-initiating cells (LTC-IC), the effect of different cytokine combinations on the expansion of CD34+ cells from UCB was assessed. DESIGN AND METHODS: CD34+ cells were cultured in serum-free culture medium with four cytokine combinations: stem cell factor plus thrombopoietin plus flk2/flt3 ligand (STF), STF plus interleukin-3 (IL-3), STF plus interleukin-6 (IL-6) and STF plus IL-6 plus IL-3. After a 1-week culture, the number of CD34+ and CD133+ cells, colony forming units (CFU), LTC-IC and telomerase activity were determined. RESULTS: The addition of IL-6 or IL-3 to the combination of STF significantly enhanced the expansion of CD34+, CD133+ cells and CFU. All cytokine combinations tested induced a slight increase in LTC-IC number except that composed by STF plus IL-3. The greatest induction of telomerase activity was observed with the combination of STF plus IL-3 or plus IL-3 plus IL-6. Decay of the activity along time was observed when the combination of STF plus IL-3 was used, and this effect was reverted by the addition of IL-6. INTERPRETATION AND CONCLUSIONS: Our results demonstrate that the inclusion of IL-6 in a serum-free short-term culture has a beneficial effect on HPC expansion from UCB, and precludes the negative effects induced by IL-3 on LTC-IC expansion and telomerase activity.     

Distribution of surface-membrane molecules on bone marrow and cord blood CD34+ hematopoietic cells.

We have investigated the distribution of membrane molecules on CD34+ hematopoietic cells isolated from human bone marrow (BM) and cord blood (CB). A distinct CD10+ population was present in BM, but it was not detected in CB. Most CD34+ CD10+ cells in BM were B-cell precursors (BCP), because they expressed CD19. However, CD40 and CD37 were found on the majority of CD34+ cells from either BM or CB, demonstrating that these antigens are not restricted to B-lineage CD34+ cells. CD40 and CD37 were lost during culture of CD34+ cells in the presence of interleukin 3 (IL-3), indicating transient expression early in myeloid development. CD13 antigen was detected on virtually all CD34+ cells from BM and CB. Accordingly, CD13 was present on CD34+ CD10+ cells, demonstrating that this structure is not restricted to myeloid CD34+ cells. In contrast, myeloid CD33 antigen was not detected on CD34+ CD10+ cells. Expression levels of CD13 and of CD33 were heterogeneous in BM, reflecting diversity within the resident CD34+ population. CD25 and CD71 were found on a proportion of CD34+ cells from either BM or CB and maintained during culture in IL-3, consistent with a distribution on activated cells. Finally, a variety of adhesion receptors were present on CD34+ cells. These included the alpha 4 beta 1 (VLA-4), alpha 5 beta 1 (VLA-5), and alpha L beta 2 (LFA-1) integrins, as well as ICAM-1, LFA-3, H-CAM, and LAM-1. Expression of adhesion receptors was remarkably similar in BM and CB, and it followed an all-or-nothing pattern that failed to delineate CD34+ subsets. Taken together, our data show that although CD34+ cells from BM constitute a more heterogeneous population, resident and circulating CD34+ cells largely display the same cell-surface molecules.     

Sequential loss of CD34 and class II MHC antigens on purified cord blood hematopoietic progenitors cultured with IL-3: characterization of CD34-, HLA-DR+ cells

The expression of class II MHC and CD34 antigens on human cord blood hematopoietic progenitor cells (HPC) was investigated upon culturing in the presence of interleukin-3 (IL-3). HPC isolated by "panning" according to their expression of CD34 coexpressed HLA-DR and HLA-DP, and the majority of the CD34+ HPC also expressed HLA-DQ. In the presence of IL-3, the expression of CD34 and class II MHC antigens was found to be gradually lost in culture. Loss of CD34 expression preceded loss of HLA-DR expression. After eight days of culture, CD34-, HLA-DR+ blast cells were obtained that strongly proliferated in response to IL-3, GM-CSF, G-CSF, and M-CSF, and that had the capacity to generate macrophage and granulocyte colonies. After ten days of culture in IL-3, a population of CD34- cells that expressed low levels of HLA-DR (HLA-DRlo) was obtained by FACS-sorting. These CD34-, HLA-DRlo cells lacked colony-forming activity while the population expressing high levels of HLA-DR (HLA-DRhi) contained great numbers of colony-forming cells, and proliferated stronger in response to CSFs than the HLA-DRlo fraction. Finally CD34-, HLA-DR- cells that appeared later in the cultures (14 to 16 days) represented more differentiated cells with only marginal proliferative and no clonogenic capacity. These data indicate that whereas CD34 expression is associated with the multilineage potential of the HPC, HLA-DR expression correlates with overall proliferative capacity of hematopoietic cells during culture in IL-3.     

Interferon-gamma enhances factor-dependent myeloid proliferation of human CD34+ hematopoietic progenitor cells.

Numerous studies have shown that interferon-gamma (IFN gamma) inhibits the proliferative effects of colony-stimulating factors (CSFs) on human bone marrow cells. In the present study we investigated the effects of IFN gamma and other described inhibitory factors on the proliferation of highly purified CD34+ human hematopoietic progenitor cells (HPC) in response to recombinant CSFs. While transforming growth factor-beta (TGF beta) and IFN alpha were highly inhibitory, IFN gamma strongly potentiated interleukin-3 (IL-3) and, to a lesser extent, granulocyte-macrophage-CSF (GM-CSF) induced growth of CD34+ HPC. IFN gamma had no significant proliferative effect per se, and did not affect granulocyte-CSF (G-CSF)-dependent cell proliferation. Within 10 days the number of viable cells generated in the presence of IL-3 + IFN gamma was two times higher than in the presence of IL-3 alone. Limiting dilution analysis showed that IFN gamma acts directly on its target cell to increase the frequency of IL-3-responding cells without affecting the average size of the IL-3-dependent clones. Enhanced frequency of IL-3- and GM-CSF-responding cells was also observed in colony assays where the addition of IFN gamma increased by twofold to threefold the number of granulocyte colony-forming units (CFU-G), macrophage CFUs (CFU-M), granulocyte-macrophage CFUs (CFU-GM), and mixed erythroid (E-MIX). In contrast, IFN gamma did not affect the generation of erythroid burst-forming units (BFU-e) in such cultures. In longer-term culture, the combination of IFN gamma and IL-3 did not alter the lineage distribution of the cells when compared with IL-3 alone. However, after 15 days, when mature cells were present in the cultures, IFN gamma displayed cell concentration-related growth-inhibitory effects. Thus, IFN gamma appears to stimulate the early stage of myelopoiesis by enhancing the frequency of growth factor-responding cells but, unlike tumor necrosis factor alpha (TNF alpha), does not alter cell differentiation.     

In vitro differentiation of natural killer T cells from human cord blood CD34+ cells

Natural killer T (NKT) cells are involved in innate immune defence and also in the regulation of adaptive immune responses. However, the development of NKT cells in vitro has not been fully characterized and culture conditions have not been fully optimized. In the present study, we found that an NKT cell fraction developed during the in vitro culture of cord blood (CB) CD34+ cells, and this was subsequently characterized both phenotypically and morphologically. CD34+ cells purified from 10 human CB were cultured in the presence of several cytokines and analysed by flow cytometry, light microscopy and electron microscopy. The NKT cell fraction, defined phenotypically (CD3+CD16+CD56+CD94+) as expressing the invariant T-cell receptor Valpha24 and Vbeta11, appeared in the CD56hi fractions. Intracytoplasmic staining demonstrated that interferon-gamma and interleukin 4 (IL-4) were detected in the CD56hi fractions. IL-15 was essential and, in combination with either flt3-ligand (FL) or stem cell factor (SCF), was sufficient to induce the development of NKT cells. The phenotype of the NKT cell fraction was CD45RO+CD45RA- and CD4+CD8alpha+. Morphologically, they were very large, with either round or oval nuclei, moderately condensed chromatins, voluminous weakly basophilic cytoplasm and various cytoplasmic granules such as dense core granules, multivesicular bodies, and intermediate form granules. When CD34+ cells purified from bone marrow (BM) were compared with those from CB, the latter were consistently more efficient at generating CD56hi NKT cell fractions. In conclusion, IL-15 in combination with FL and/or SCF can induce the differentiation of NKT cells from human CB CD34+ cells.     

Caspase-3在脐血CD34+造血干/祖细胞中的表达及意义

目的：探讨脐血CD34^＋干／祖细胞在不同细胞因子支持下的体外扩增过程中Caspase-3表达及意义，方法：采用RT－PCR、Wester blot和流式细胞仪分析技术测定脐血CD34^ 细胞在体外扩增过程中的生物学特性及Caspase-3的表达。结果：Caspase-3 mRNA在新鲜分离的脐血CD34^ 细胞中低水平表达，在细胞因子支持下体外增养3d，扩增的CD34^ 细胞中Caspase-3 mRNA和蛋白质表达上调，但在该两种细胞中仅能检测到分子量为32000的无活性酶原形式的Caspase-3，随着体外培养时间的延长，在IL－3、IL－6和GM－CSF组合条件下，Caspase-3被激活，可检测到分子量为20000的裂解片段。结论：虽然造血干细胞的凋亡是个复杂的过程，但在脐血CD34^ 干／祖细胞体外扩增过程中，Caspase-3参与了凋亡事件并发挥着重要的作用。     

Ex vivo expansion of human umbilical cord blood and peripheral blood CD34(+) hematopoietic stem cells

The proliferation and expansion of human hematopoietic stem cells (HSC) in ex vivo culture was examined with the goal of generating a suitable clinical protocol for expanding HSC for patient transplantation.HSC were derived from umbilical cord blood (UCB) and adult patient peripheral blood stem cell collections. HSC were stimulated to proliferate ex vivo by a combination of two growth factors, flt-3 ligand (FL) and thrombopoietin/c-mpl ligand (TPO/ML), and assessed for expansion by flow cytometry.Ex vivo expansion cultures of UCB were maintained for prolonged periods (up to 16 weeks), and sufficient HSC were generated for adult transplantation. In contrast to UCB, FL + TPO/ML did not significantly increase CD34(+) peripheral blood stem cell (PBSC) numbers.UCB-HSC can be expanded in culture to numbers theoretically adequate for safe, rapid engraftment of adult patients. Additional studies are needed to establish the functional activity of expanded UCB-HSC.     

G-CSF- and GM-CSF-induced upregulation of CD26 peptidase downregulates the functional chemotactic response of CD34+CD38- human cord blood hematopoietic cells

OBJECTIVE: Cytokine treatment with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and stem cell factor (SCF) is a mainstay of current and future clinical and research protocols for peripheral blood stem cell mobilization, therapeutic care after hematopoietic stem cell transplantation (HSCT), and ex vivo hematopoietic stem and progenitor cell (HSC/HPC) expansion. We have previously shown that the peptidase CD26 (DPPIV/dipeptidylpeptidase IV) negatively regulates HSC/HPC and that inhibition of CD26 improves the chemotactic ability and trafficking of HSC/HPC. We set out to establish whether short-term in vitro G-CSF, GM-CSF, or SCF treatment upregulates CD26 and thereby has a detrimental effect on the chemotactic potential of HSC/HPC that could be reversed by CD26 inhibitor treatment. MATERIALS AND METHODS: CD34+ or CD34+CD38- cells, a population enriched in HSC, were isolated from human umbilical cord blood and subjected to G-CSF, GM-CSF, or SCF treatment. We then evaluated CD26 expression, CD26 activity, and CXCL12 (SDF-1)-induced migration in the presence or absence of a CD26 inhibitor, Diprotin A. RESULTS: Treatment with G-CSF and GM-CSF but not SCF upregulates CD26 expression and activity resulting in a CD26 inhibitor-reversible downregulation of CXCL12-induced chemotactic response. CONCLUSIONS: Short-term in vitro G-CSF and GM-CSF treatment upregulates the peptidase CD26, resulting in downregulation of the functional ability of CD34+CD38- cells to respond to the chemokine CXCL12. This suggests that current and future clinical protocols utilizing G-CSF and GM-CSF may have unforeseen detrimental effects on the trafficking of HSC/HPC during HSCT that can be overcome through the use of CD26 inhibitors.     

Functional maturation of myeloid cells during in vitro differentiation from human cord blood CD34+ cells

CD34+ cells purified from human cord blood were expanded in the presence of several cytokines. The cultured cells were assayed for myeloid effector functions, including phagocytic activity, respiratory burst and microbicidal activity. The results showed that phagocytic activity was observed as early as day 6, irrespective of the type of cytokines used. By contrast, respiratory burst and microbicidal activity peaked on day 15 and were dependent on the type of cytokines used. In particular, granulocyte-colony stimulating factor and interleukin-6 markedly enhanced respiratory burst and microbicidal activity.     

Aorta-associated CD34+ hematopoietic cells in the early human embryo

Hematopoiesis is established from circulating blood stem cells that seed the embryonic rudiments of blood-forming tissues, a basic notion in developmental hematology. However, the assumption that these stem cells originate from the extraembryonic mesoderm, where primitive hematopoiesis is initiated by intrinsic precursors, has been reconsidered after analysis of blood cell development in avian embryo chimeras: yolk-sac-derived stem cells do not contribute significantly to the definitive blood system, whose first forerunners develop independently along the ventral aspect of the embryonic aorta. Recently, the homologous intraembryonic tissues of the mouse have been submitted to sensitive in vivo and in vitro assays, which showed that they also harbor multipotential hematopoietic stem cells. We have now identified a dense population of hematogenous cells, marked by the surface expression of the CD34 glycoprotein, associated with the ventral endothelium of the aorta in the 5-week human embryo. Therefore, we extend to the human species the growing evidence that intraembryonic hematopoietic cells developing independently of the yolk sac might be the real stem of the whole blood system.     

Myeloperoxidase expression in CD34+ normal human hematopoietic cells

Bone marrow (BM), adult peripheral blood (aPB), and umbilical cord blood (CB) samples contain small proportions of CD34+ cells that include virtually all hematopoietic progenitor cells. Myeloperoxidase (MPO) is considered to be selectively expressed in cells committed to granulomonocytic differentiation. Using flow cytometry and an antibody against MPO, we studied at which stage of normal hematopoietic differentiation CD34+ cells being to express MPO. We consistently observed a characteristic MPO/CD34 staining pattern and found that 35% +/- 9% of CD34+ BM cells express MPO. The MPO+ CD34+ subset and the CD33+ CD34+ subset were of similar size and overlapped considerably. MPO+ CD34+ cells expressed high levels of HLA-D molecules, were weakly CD71/transferrin receptor positive to negative, were CD45RA+ and lacked the CD45RO isoform of the leukocyte common antigen. Additionally, MPO+ CD34+ cells were on average larger in size than MPO- CD34+ cells. Virtually identical phenotypic features have previously been described for in vitro colony-forming granulomonocytic progenitor cells. In vitro clonogenic assays performed with MPO-enriched and MPO-depleted fractions of CD34+ BM cells performed by us also suggest, but do not formally prove, that at least a portion of MPO+ CD34+ cells have in vitro cluster (10 to 50 cells/colony) or colony-forming unit granulocyte-macrophage (> or = 50 cells/colony) forming capacity. CD34+ cells from CB and aPB resembled CD34+ BM cells in that considerable proportions of them coexpressed CD33. However, in contrast to BM, CD34+ cells from CB and aPB samples lacked significant MPO expression and, in line with this, the majority of them (CB, 59% +/- 7%; aPB, 66% +/- 5%) coexpressed CD45RO.     

Differentiation and maintenance of mast cells from CD34(+) human cord blood cells

OBJECTIVE: Establishment of a stable umbilical cord blood CD34(+) (UCB CD34(+)) cell culture system and identification of the cells in the cobblestone area differentiated from UCB CD34(+) long-term culture cells. MATERIALS AND METHODS: Human UCB CD34(+) cells were cultured on MS-5 mouse stroma cells in the presence of stem cell factor (SCF), flt-3 ligand (FL), and thrombopoietin (TPO) for 4 to 16 weeks. Cells in the culture medium and in the cobblestone area were collected and characterized by flow cytometry and microscopy. RESULTS: CD34(+) cells were stably expanded by culturing on MS-5 stroma cells in the presence of SCF, FL, and TPO for more than 4 months. Cells highly expressing CD117 (c-kit) appeared in the cobblestone area after 2 weeks and stably expanded. Isolation of cells highly expressing CD117 by fluorescence-activated cell sorter (FACS) revealed the cells were tryptase-positive and Fc epsilon receptor 1-negative mast cells. They showed typical mast cell morphology and released histamine upon stimulation by substance P or compound 48/80 in vitro. CONCLUSION: Human UCB CD34(+) cells were stably expanded on MS-5 stroma cells in the presence of SCF, FL, and TPO. Under this condition, multipotent CD34(+) cells and mast cells differentiated from UCB CD34(+) cells were expanded in the cobblestone area. The expanded mast cells showed histamine release after substance P or compound 48/80 stimulation. These human mast cells will be useful as a source of human cells for evaluating the allergic effects of drugs.     

2型重组腺相关病毒对脐血CD34+造血干/祖细胞的转导条件的优化

目的:探索不同转导条件下2型重组腺相关病毒(rAAV-2)/绿色荧光蛋白(GFP)对人脐血CD34 细胞的转导效率。方法:人脐血CD34 细胞分别以IL-3加IL-6加干细胞因子(SCF)加Flt3配体(FL)(预刺激1组)或SCF加FL加血小板生长因子(预刺激2组)预刺激48 h后,转导rAAV-2/GFP,转导后2 d和7 d收集细胞,流式细胞仪检测GFP的表达,同时以金黄地鼠胚胎肾细胞(BHK-21)细胞作为阳性对照。结果:感染复数(MOI)为2×105病毒基因组(v.g)/cell时,rAAV-2/GFP能有效地转导CD34 细胞,2 d的GFP阳性率可达(28.05±4.47)%(S/F/T组),(27.44±4.99)%(3/6/S/F组),最高达43.36%,随着培养时间的延长,GFP表达有下降的趋势,但差异无统计学意义(P>0.05)。预刺激1组、预刺激2组与无预刺激组的GFP阳性率比较,差异有统计学意义(P<0.05),预刺激1组与预刺激2组比较差异无统计学意义(P>0.05)。结论:MOI 2×105v.g/cell时,采用细胞因子预刺激可得到rAAV-2/GFP对人脐血CD34 细胞的有效转导,但本实验采用的2种预刺激条件对转导效率的提高没有明显区别。     

Ex vivo large-scale generation of human red blood cells from cord blood CD34+ cells by co-culturing with macrophages

We generated red blood cells (RBC) from cord blood (CB) CD34⁺ cells using a four-phase culture system. We first cultured CB CD34⁺ cells on telomerase gene-transduced human stromal cells in serum-free medium containing stem cell factor (SCF), Flt-3/Flk-2 ligand, and thrombopoietin to expand CD34⁺ cells (980-fold) and the total cells (10,400-fold) (first phase). Expanded cells from the first phase were liquid-cultured with SCF, interleukin-3 (IL-3), and erythropoietin (EPO) to expand (113-fold) and differentiate them into erythroblasts (second phase). To obtain macrophages for the next phase, we expanded CD34⁺ cells from a different donor using the same co-culture system. Expanded cells from the first phase were liquid-cultured with granulocyte-macrophage colony stimulating factor, macrophage-colony stimulating factor (M-CSF), IL-3, and SCF to generate monocytes/macrophages (75-fold), which were incubated with type AB serum and M-CSF to fully differentiate them into macrophages. Erythroblasts were then co-cultured with macrophages in the presence of EPO to expand (threefold) and fully differentiate them (61% orthochromatic erythroblasts plus 39% RBC) (third phase). RBC were purified from erythroblasts and debris through a deleukocyting filter to generate 6.0 × 10¹² RBC from 1.0 unit of CB (3.0 transfusable units). Qualitatively, these RBC showed a hemoglobin content, oxygenation of hemoglobin, and in vivo clearance similar to those of adult peripheral RBC. Finally, an almost complete enucleation of orthochromatic erythroblasts (99.4%) was achieved by the cultivation method recently described by Miharada et al. in the absence of macrophages and cytokines (fourth phase). RBC were purified from remnant erythroblasts and debris by passage through a deleukocyting filter to generate 1.76 × 10¹³ RBC from 1.0 unit of CB (8.8 transfusable units), the highest yield ever reported. Thus, this method may be useful for generating an alternative RBC supply for transfusions, investigating infectious agents that target erythroid cells, and as a general in vitro hematopoietic model system.     

Alloantigen presenting function of normal human CD34+ hematopoietic cells

The identification of the CD34 molecule, expressed almost exclusively on human hematopoietic stem cells and committed progenitors, and the development of CD34-specific monoclonal antibodies have made procurement of relatively pure populations of CD34+ marrow cells for autologous transplantation feasible. Characterization of the immunogenicity of CD34+ marrow cells may facilitate the design of successful strategies to use these cells for allogeneic transplantation. CD34+ marrow cells from normal volunteers were enriched to greater than 98% purity by immunoaffinity chromatography on column followed by fluorescence-activated cell sorting. Purified CD34+ cells were tested for expression of HLA-DR and other accessory molecules, and function in hematopoietic colony growth and mixed leukocyte culture (MLC) assays. Greater than 95% CD34+ cells were positive for HLA-DR and 74% +/- 10% were highly positive for CD18, the common beta-chain of a leukointegrin family. CD34+/CD18- cells were small, agranular lymphocytes which contained the majority of precursors for colony-forming cells detected in long-term cultures. They produced almost no stimulation of purified T cells from HLA-DR-incompatible individuals in bulk MLC or in limiting dilution assay. In contrast, CD34+/CD18+ cells were large, were enriched for cells forming mixed colonies in short- but not long-term assays, and were capable of stimulating allogeneic T cells. CD86, a natural ligand for the T-cell activation molecule CD28, was coexpressed with CD18 in 6% +/- 3% of CD34+ cells. CD34+/CD86+ cells, but not CD34+/CD86- cells, exhibited strong alloantigen presenting function. Thus, pluripotent hematopoietic activity and alloantigen presenting function are attributes of distinct subsets of CD34+ marrow cells. CD34+/CD18- or CD34+/CD86- cells may be more effective than either the whole CD34+ population or unseparated marrow in engrafting allogeneic recipients and may also facilitate induction of tolerance.