Objective: To investigate the expression and significance of caspase-3 protein in CD34^+ cells from cord blood (CB) during culture in vitro with different growth factors. Methods: RT-PCR, Western blot and flow cytomet...Objective: To investigate the expression and significance of caspase-3 protein in CD34^+ cells from cord blood (CB) during culture in vitro with different growth factors. Methods: RT-PCR, Western blot and flow cytometry techniques were used to detect the expression of caspase-3 in CD34^+ CB cells during culture in vitro. Results: Caspase-3 mRNA was constitutively expressed at a low level in freshly isolated CD34^+ cells. The expression of caspase-3 mRNA and protein was upregulated when these cellswere first expanded in suspension culture with growth factors for 3 days. However, only the 32 kDa inactive caspase-3 proenzyme was detected in the freshly isolated CD34^+ cells as well as during the first 3 days expansion with cytokines. With longer culture time in vitro, especially in the presence of the combination of IL-3, IL-6 and GM-CSF, caspase-3 was activated and a cleavage product of 20 kDa became detectable.Conclusion: Caspase-3 is involved in apoptosis of primitive CB CD34^+ cells during expansion in vitro.展开更多
CD34+ cells from human umbilical cord blood were purified by Dynal beads M-450 CD34 immunoselection system and cultured in the presence of various cytokines alone or in combination, including stem cell factor (SCF), i...CD34+ cells from human umbilical cord blood were purified by Dynal beads M-450 CD34 immunoselection system and cultured in the presence of various cytokines alone or in combination, including stem cell factor (SCF), interleukin-6 (IL-6) and erythropoietin (EPO). The results revealed that: (D In methylcellulose culture, the plating efficiencies of purified cord blood CD34+ cells were much different when stimulated by various cytokines. IL-6 alone had the lowest colo-ny yield, while the combination of SCF, IL-6 and EPO had the highest yield. ② In the suspension culture, IL-6 alone or IL-6 + EPO had little expanding effect on cord blood CD34+ celis, the other cytokine combinations could expand cord blood CD34+ celis at different Ievels. Among them, the combination of SCF, IL-6 and EPO had the maximal expanding effect on cord blood CD34+ celis, the number of progenitor celis peaked at day 21, about 29-fold increase and nucleated celis increased approximately 3676-fold at day 28. The expanding effect of展开更多
This study investigated the correlation between and compared the effects of reactive oxygen species(ROS) and p38 mitogen-activated protein kinase α(p38MAPKα) in the ex vivo expanded umbilical cord blood(hUCB) ...This study investigated the correlation between and compared the effects of reactive oxygen species(ROS) and p38 mitogen-activated protein kinase α(p38MAPKα) in the ex vivo expanded umbilical cord blood(hUCB) CD133+ cells.hUCB CD133+ cells were cultured in the hematopoietic stem cells(HSCs) culture medium with N-acetylcysteine(NAC,an anti-oxidant),p38MAPKα-specific inhibitor(SB203580) or their combination.The levels of ROS and expression of phosphorylated p38MAPKα(p-p38) in CD133+ cells were flow cytometrically detected.The efficacy of ex vivo expansion was evaluated by the density of CD133+ cell sub-group colony-forming cells(CFC) and cobblestone area-forming cells(CAFC) assay.Our results showed decreased ROS levels in NAC,SB203580,and their combination treatment groups were almost 37%,48%,and 85%,respectively.Furthermore,SB203580 abrogated the activation of p38MAPKα more obviously than NAC.Moreover,the CD133+ cells in SB203580 treatment group had a 21.93±1.36-fold increase,and 14.50±1.19-fold increase in NAC treatment group,but only 10.13±0.57-fold increase in control group.In addition,SB203580 treatment led a higher level increase in the number of CFU and CAFC than NAC did.These findings suggested that,in expanded CD133+ cells,ROS activates p38MAPKα,which,in turn,induces ROS production,and p38MAPKα might be the most suitable regulator in ROS-p38MAPKα pathway for the promotion of HSCs ex vivo expansion.展开更多
Objective To evaluate the feasibility and safety of peripheral CD34+ cell mobilization in patients with severe autoimmune disease. Methods Forty-two patients underwent a total of 46 mobilizations by the regimen of cyc...Objective To evaluate the feasibility and safety of peripheral CD34+ cell mobilization in patients with severe autoimmune disease. Methods Forty-two patients underwent a total of 46 mobilizations by the regimen of cyclophosphamide 2-3 g/m2 +recombinant human granulocyte colony stimulating factor (rhG-CSF) 5 μg·kg-1·d-1. The positive selection of CD34+ cell was performed through the CliniMACS. Results In 8.1±2.3 days after administration of cyclophosphamide, the peripheral white blood cell and mononuclear cell (MNC) decreased to the lowest level. In 3.7±1.6 days after injection of rhG-CSF, the peripheral absolute MNC and CD34+ cell counts were 0.95×109/L and 0.035×109/L, respectively. After 2.4±0.6 times of leukapheresis, there gained 4.46×108/kg of MNC and 5.26×106/kg of CD34+, respectively. After mobilization, the underlying diseases were ameliorated more or less. In systemic lupus erythematosus (SLE) patients, SLE Disease Activity Index (SLEDAI) decreased from a median of 17 to 3 (P<0.01). In rheumatic arthritis patients, an American College of Rheumatology criteria for 20%(ACR20) response was achieved in all five patients. Totally, 17.4% of patients whose absolute neutrophil count <0.5×109/L suffered infection, and 31.0% of patients had bone pain after the injection of rhG-CSF. Two patients suffered severe complications, one with acute renal failure and recovered by hemodialysis, the other died of thrombotic thrombocytopenic purpura. Failed mobilization occurred in three patients. Conclusions Sufficient CD34+ cells can be mobilized by low dose of cyclophosphamide and rhG-CSF. CD34+ cell mobilization for treatment of severe autoimmune disease not only is appropriate in both effectiveness and safety but ameliorates disease also.展开更多
BACKGROUND There is no established treatment to impede the progression or restore kidney function in human chronic kidney disease(CKD).AIM To examine the efficacy of cultured human CD34+cells with enhanced proliferati...BACKGROUND There is no established treatment to impede the progression or restore kidney function in human chronic kidney disease(CKD).AIM To examine the efficacy of cultured human CD34+cells with enhanced proliferating potential in kidney injury in mice.METHODS Human umbilical cord blood(UCB)-derived CD34+cells were incubated for one week in vasculogenic conditioning medium.Vasculogenic culture significantly increased the number of CD34+cells and their ability to form endothelial progenitor cell colony-forming units.Adenineinduced tubulointerstitial injury of the kidney was induced in immunodeficient non-obese diabetic/severe combined immunodeficiency mice,and cultured human UCB-CD34+cells were administered at a dose of 1×106/mouse on days 7,14,and 21 after the start of adenine diet.RESULTS Repetitive administration of cultured UCB-CD34+cells significantly improved the time-course of kidney dysfunction in the cell therapy group compared with that in the control group.Both interstitial fibrosis and tubular damage were significantly reduced in the cell therapy group compared with those in the control group(P<0.01).Microvasculature integrity was significantly preserved(P<0.01)and macrophage infiltration into kidney tissue was dramatically decreased in the cell therapy group compared with those in the control group(P<0.001).CONCLUSION Early intervention using human cultured CD34+cells significantly improved the progression of tubulointerstitial kidney injury.Repetitive administration of cultured human UCB-CD34+cells significantly improved tubulointerstitial damage in adenine-induced kidney injury in mice via vasculoprotective and anti-inflammatory effects.展开更多
The changes of CD4^+CD25^+ regulatory T cells (CD4^+CD25^+ Treg) and Foxp3 mRNA in peripheral blood mononuclear cells (PBMCs) from patients with asthma were investigated in order to elucidate the possible role...The changes of CD4^+CD25^+ regulatory T cells (CD4^+CD25^+ Treg) and Foxp3 mRNA in peripheral blood mononuclear cells (PBMCs) from patients with asthma were investigated in order to elucidate the possible roles of CD4^+CD25^+ Treg in the development of asthma. The peripheral blood samples were collected from 29 healthy controls (normal control group) and 78 patients with asthma which included 30 patients in exacerbation group, 25 patients in persistent group, and 23 patients in remission group. By using flow cytometry and RT-PCR, the CD4^+CD25^+ Treg ratio and Foxp3 mRNA in PBMCs were detected. The CD4^+CD25^+ Treg ratio and Foxp3 mRNA in PBMCs of exacerbation and persistent groups were lower than that of remission and normal control groups (P〈0.05). Although the CD4^+CD25^+ Treg ratio and Foxp3 mRNA of remission group were also lower than that of normal control group, there was no significant difference between them (P〉0.05). As compared with persistent group, exacerbation group had lower CD4^+CD25^+ Treg ratio and Foxp3 mRNA (P〈0.05). It was indicated that the decrease of CD4^+CD25^+ Treg ratio and its function in PBMCs may be responsible for pathogenesis of asthma.展开更多
The cell surface expression and functional status of the CD95/Fas antigen on primitive hematopoietic progenitors isolated from human cord blood (CB) were studied. The CD34 + cells freshly isolated from CB displayed ...The cell surface expression and functional status of the CD95/Fas antigen on primitive hematopoietic progenitors isolated from human cord blood (CB) were studied. The CD34 + cells freshly isolated from CB displayed low CD95 expression. The combinations of cytokines such as SCF+FL could up regulate the expression of CD95 in vitro culture and tumor necrosis factor α (TNF α) and interon γ (IFN γ) further increased the CD95 expression induced by positive cytokines. The functional status of CD95 mediated apoptosis were analyzed by incubation of CD34 +CB cells in the presence of anti CD95 monoclonal antibodies (McAbs). The effects of anti CD95 McAbs were measured by viable cell counting, flow cytometry, LTIC and CFU C assays. A decrease of viable cells, CFU C and LTIC numbers were observed in the presence of anti CD95 McAbs and TNF α or IFN γ. However, growth factor deprivation or the early acting cytokine such as SCF and FL cross linking to CD95 caused low apoptosis of CD34 + cells. The correlation of increased intracytoplasmic levels of bcl 2 and the presence of CD95 on fresh CB CD34 + cells suggested that bcl 2 might be involved in protecting against CD95 mediated apoptosis of CB CD34 + cells.展开更多
Objective: To explore the effect of homoharringtonine (HHT) on bone morrow CD34^+CD7^+ cells in chronic granulocytic leukemia (CGL). Methods: The changes of bone morrow CD34^+CD7^+ cells were observed after ...Objective: To explore the effect of homoharringtonine (HHT) on bone morrow CD34^+CD7^+ cells in chronic granulocytic leukemia (CGL). Methods: The changes of bone morrow CD34^+CD7^+ cells were observed after the treatment of HHT in 23 cases with CGL. The proliferation and apoptosis of CD34^+CD7^+ cells treated with HHT in vitro were studied. Results: The proportion of CD34^+CD7^+ cells in CGL (0.145±0.021) was higher than that of normal control (0.052±0.013). The proportion of CD34^+CD7^+ cells in patients who got cytogenetic responses to HHT (0.072±0.020) decreased remarkably, but not in those patients who did not got cytogenetic responses to HHT, (0.137±0.023). the proliferation of CD34^+ cells was inhibited and the proportion of CD34^+CD7^+ cells decreased after cultured with HHT (0.134 in 24 h, 0.126 in 48 h and 0.102 in 72). The apoptosis rate of CD34^+CD7^+ cells was higher than that in CD34^+CDT cells (35.39%±4.39% versus 24.57%±4.01%, P〈0.05) 72 h after culture with HHT. Conclusion: The proportion of CD34^+CD7^+ cells in CGL was higher than that of normal control and HHT may inhibit the proliferation and induce apoptosis of bone marrow CD34^+CD7^+ cells.展开更多
To induce the growth and differentiation of dendritic cells (DCs) from human cord blood, CD34 + cells isolated from human cord blood by mini MACS were cultured in a liquid culture system with rhSCF, rhGM CSF, rhTNF α...To induce the growth and differentiation of dendritic cells (DCs) from human cord blood, CD34 + cells isolated from human cord blood by mini MACS were cultured in a liquid culture system with rhSCF, rhGM CSF, rhTNF α and rhFL for 10 days. Then the induced cells were characterized by DC′s morphological and phenotypic properties. In addition, they stimulated the proliferation of allogeneic T cells and possessed an efficient capacity for initiating T cell dependent antitumor immune responses in vitro. It is concluded that mature DCs could be obtained from human cord blood CD34 + cells.展开更多
本研究旨在观察几种不同细胞因子组合通过体外培养以诱导造血干/祖细胞增殖和向巨核细胞/血小板分化。应用无血清培养基(S tem Span(SFEM)体外扩增脐血CD34+细胞并向巨核细胞/血小板定向分化,将不同细胞因子组合分为3个阶段培养,并比较...本研究旨在观察几种不同细胞因子组合通过体外培养以诱导造血干/祖细胞增殖和向巨核细胞/血小板分化。应用无血清培养基(S tem Span(SFEM)体外扩增脐血CD34+细胞并向巨核细胞/血小板定向分化,将不同细胞因子组合分为3个阶段培养,并比较其培养效果。结果表明,在第一阶段的第14天时,SCF+TPO+FL+IL-3组细胞扩增倍数最高为11 000±1 000,显著高于SCF+TPO+FL组,但与SCF+TPO+IL-3组及SCF+TPO+FL+IL-3+羟皮质激素组相比较无显著差异;在第二培养阶段的第7天时,SCF+TPO+FL+IL-11组巨核细胞系扩增倍数为204666.7±11718.9,显著高于SCF+TPO+FL+IL-3组,与SCF+TPO+FL+IL1-1+BM P4+VEGF组比较并无显著差异。在第三阶段中,SCF+TPO+FL+IL-11和SCF+TPO+FL+IL-11+BM P4+VEGF2组的CD41+血小板样细胞所占比例显著高于SCF+TPO+FL+IL-3组。结论:SCF+TPO+FL+IL-3因子组合可显著提高造血干/祖细胞的扩增倍数,SCF+TPO+FL+IL-11组合有利于巨核细胞的扩增成熟及分化,为下一步的体外培养巨核细胞/血小板体系的建立奠定了一定的基础。展开更多
基金The study was supported by a grant from the National Natural Science Foundation of China(No.39928010)
文摘Objective: To investigate the expression and significance of caspase-3 protein in CD34^+ cells from cord blood (CB) during culture in vitro with different growth factors. Methods: RT-PCR, Western blot and flow cytometry techniques were used to detect the expression of caspase-3 in CD34^+ CB cells during culture in vitro. Results: Caspase-3 mRNA was constitutively expressed at a low level in freshly isolated CD34^+ cells. The expression of caspase-3 mRNA and protein was upregulated when these cellswere first expanded in suspension culture with growth factors for 3 days. However, only the 32 kDa inactive caspase-3 proenzyme was detected in the freshly isolated CD34^+ cells as well as during the first 3 days expansion with cytokines. With longer culture time in vitro, especially in the presence of the combination of IL-3, IL-6 and GM-CSF, caspase-3 was activated and a cleavage product of 20 kDa became detectable.Conclusion: Caspase-3 is involved in apoptosis of primitive CB CD34^+ cells during expansion in vitro.
文摘CD34+ cells from human umbilical cord blood were purified by Dynal beads M-450 CD34 immunoselection system and cultured in the presence of various cytokines alone or in combination, including stem cell factor (SCF), interleukin-6 (IL-6) and erythropoietin (EPO). The results revealed that: (D In methylcellulose culture, the plating efficiencies of purified cord blood CD34+ cells were much different when stimulated by various cytokines. IL-6 alone had the lowest colo-ny yield, while the combination of SCF, IL-6 and EPO had the highest yield. ② In the suspension culture, IL-6 alone or IL-6 + EPO had little expanding effect on cord blood CD34+ celis, the other cytokine combinations could expand cord blood CD34+ celis at different Ievels. Among them, the combination of SCF, IL-6 and EPO had the maximal expanding effect on cord blood CD34+ celis, the number of progenitor celis peaked at day 21, about 29-fold increase and nucleated celis increased approximately 3676-fold at day 28. The expanding effect of
基金supported by a grant from the National Natural Science Foundation of China (No. 30871097)
文摘This study investigated the correlation between and compared the effects of reactive oxygen species(ROS) and p38 mitogen-activated protein kinase α(p38MAPKα) in the ex vivo expanded umbilical cord blood(hUCB) CD133+ cells.hUCB CD133+ cells were cultured in the hematopoietic stem cells(HSCs) culture medium with N-acetylcysteine(NAC,an anti-oxidant),p38MAPKα-specific inhibitor(SB203580) or their combination.The levels of ROS and expression of phosphorylated p38MAPKα(p-p38) in CD133+ cells were flow cytometrically detected.The efficacy of ex vivo expansion was evaluated by the density of CD133+ cell sub-group colony-forming cells(CFC) and cobblestone area-forming cells(CAFC) assay.Our results showed decreased ROS levels in NAC,SB203580,and their combination treatment groups were almost 37%,48%,and 85%,respectively.Furthermore,SB203580 abrogated the activation of p38MAPKα more obviously than NAC.Moreover,the CD133+ cells in SB203580 treatment group had a 21.93±1.36-fold increase,and 14.50±1.19-fold increase in NAC treatment group,but only 10.13±0.57-fold increase in control group.In addition,SB203580 treatment led a higher level increase in the number of CFU and CAFC than NAC did.These findings suggested that,in expanded CD133+ cells,ROS activates p38MAPKα,which,in turn,induces ROS production,and p38MAPKα might be the most suitable regulator in ROS-p38MAPKα pathway for the promotion of HSCs ex vivo expansion.
文摘Objective To evaluate the feasibility and safety of peripheral CD34+ cell mobilization in patients with severe autoimmune disease. Methods Forty-two patients underwent a total of 46 mobilizations by the regimen of cyclophosphamide 2-3 g/m2 +recombinant human granulocyte colony stimulating factor (rhG-CSF) 5 μg·kg-1·d-1. The positive selection of CD34+ cell was performed through the CliniMACS. Results In 8.1±2.3 days after administration of cyclophosphamide, the peripheral white blood cell and mononuclear cell (MNC) decreased to the lowest level. In 3.7±1.6 days after injection of rhG-CSF, the peripheral absolute MNC and CD34+ cell counts were 0.95×109/L and 0.035×109/L, respectively. After 2.4±0.6 times of leukapheresis, there gained 4.46×108/kg of MNC and 5.26×106/kg of CD34+, respectively. After mobilization, the underlying diseases were ameliorated more or less. In systemic lupus erythematosus (SLE) patients, SLE Disease Activity Index (SLEDAI) decreased from a median of 17 to 3 (P<0.01). In rheumatic arthritis patients, an American College of Rheumatology criteria for 20%(ACR20) response was achieved in all five patients. Totally, 17.4% of patients whose absolute neutrophil count <0.5×109/L suffered infection, and 31.0% of patients had bone pain after the injection of rhG-CSF. Two patients suffered severe complications, one with acute renal failure and recovered by hemodialysis, the other died of thrombotic thrombocytopenic purpura. Failed mobilization occurred in three patients. Conclusions Sufficient CD34+ cells can be mobilized by low dose of cyclophosphamide and rhG-CSF. CD34+ cell mobilization for treatment of severe autoimmune disease not only is appropriate in both effectiveness and safety but ameliorates disease also.
文摘BACKGROUND There is no established treatment to impede the progression or restore kidney function in human chronic kidney disease(CKD).AIM To examine the efficacy of cultured human CD34+cells with enhanced proliferating potential in kidney injury in mice.METHODS Human umbilical cord blood(UCB)-derived CD34+cells were incubated for one week in vasculogenic conditioning medium.Vasculogenic culture significantly increased the number of CD34+cells and their ability to form endothelial progenitor cell colony-forming units.Adenineinduced tubulointerstitial injury of the kidney was induced in immunodeficient non-obese diabetic/severe combined immunodeficiency mice,and cultured human UCB-CD34+cells were administered at a dose of 1×106/mouse on days 7,14,and 21 after the start of adenine diet.RESULTS Repetitive administration of cultured UCB-CD34+cells significantly improved the time-course of kidney dysfunction in the cell therapy group compared with that in the control group.Both interstitial fibrosis and tubular damage were significantly reduced in the cell therapy group compared with those in the control group(P<0.01).Microvasculature integrity was significantly preserved(P<0.01)and macrophage infiltration into kidney tissue was dramatically decreased in the cell therapy group compared with those in the control group(P<0.001).CONCLUSION Early intervention using human cultured CD34+cells significantly improved the progression of tubulointerstitial kidney injury.Repetitive administration of cultured human UCB-CD34+cells significantly improved tubulointerstitial damage in adenine-induced kidney injury in mice via vasculoprotective and anti-inflammatory effects.
基金This project was supported by a program of Science Project of Hubei Province (No.2003AA301C10).
文摘The changes of CD4^+CD25^+ regulatory T cells (CD4^+CD25^+ Treg) and Foxp3 mRNA in peripheral blood mononuclear cells (PBMCs) from patients with asthma were investigated in order to elucidate the possible roles of CD4^+CD25^+ Treg in the development of asthma. The peripheral blood samples were collected from 29 healthy controls (normal control group) and 78 patients with asthma which included 30 patients in exacerbation group, 25 patients in persistent group, and 23 patients in remission group. By using flow cytometry and RT-PCR, the CD4^+CD25^+ Treg ratio and Foxp3 mRNA in PBMCs were detected. The CD4^+CD25^+ Treg ratio and Foxp3 mRNA in PBMCs of exacerbation and persistent groups were lower than that of remission and normal control groups (P〈0.05). Although the CD4^+CD25^+ Treg ratio and Foxp3 mRNA of remission group were also lower than that of normal control group, there was no significant difference between them (P〉0.05). As compared with persistent group, exacerbation group had lower CD4^+CD25^+ Treg ratio and Foxp3 mRNA (P〈0.05). It was indicated that the decrease of CD4^+CD25^+ Treg ratio and its function in PBMCs may be responsible for pathogenesis of asthma.
基金This project was supported by a grant from National Na-ture Science Foundation of China (No.3992 80 10 )
文摘The cell surface expression and functional status of the CD95/Fas antigen on primitive hematopoietic progenitors isolated from human cord blood (CB) were studied. The CD34 + cells freshly isolated from CB displayed low CD95 expression. The combinations of cytokines such as SCF+FL could up regulate the expression of CD95 in vitro culture and tumor necrosis factor α (TNF α) and interon γ (IFN γ) further increased the CD95 expression induced by positive cytokines. The functional status of CD95 mediated apoptosis were analyzed by incubation of CD34 +CB cells in the presence of anti CD95 monoclonal antibodies (McAbs). The effects of anti CD95 McAbs were measured by viable cell counting, flow cytometry, LTIC and CFU C assays. A decrease of viable cells, CFU C and LTIC numbers were observed in the presence of anti CD95 McAbs and TNF α or IFN γ. However, growth factor deprivation or the early acting cytokine such as SCF and FL cross linking to CD95 caused low apoptosis of CD34 + cells. The correlation of increased intracytoplasmic levels of bcl 2 and the presence of CD95 on fresh CB CD34 + cells suggested that bcl 2 might be involved in protecting against CD95 mediated apoptosis of CB CD34 + cells.
文摘Objective: To explore the effect of homoharringtonine (HHT) on bone morrow CD34^+CD7^+ cells in chronic granulocytic leukemia (CGL). Methods: The changes of bone morrow CD34^+CD7^+ cells were observed after the treatment of HHT in 23 cases with CGL. The proliferation and apoptosis of CD34^+CD7^+ cells treated with HHT in vitro were studied. Results: The proportion of CD34^+CD7^+ cells in CGL (0.145±0.021) was higher than that of normal control (0.052±0.013). The proportion of CD34^+CD7^+ cells in patients who got cytogenetic responses to HHT (0.072±0.020) decreased remarkably, but not in those patients who did not got cytogenetic responses to HHT, (0.137±0.023). the proliferation of CD34^+ cells was inhibited and the proportion of CD34^+CD7^+ cells decreased after cultured with HHT (0.134 in 24 h, 0.126 in 48 h and 0.102 in 72). The apoptosis rate of CD34^+CD7^+ cells was higher than that in CD34^+CDT cells (35.39%±4.39% versus 24.57%±4.01%, P〈0.05) 72 h after culture with HHT. Conclusion: The proportion of CD34^+CD7^+ cells in CGL was higher than that of normal control and HHT may inhibit the proliferation and induce apoptosis of bone marrow CD34^+CD7^+ cells.
文摘To induce the growth and differentiation of dendritic cells (DCs) from human cord blood, CD34 + cells isolated from human cord blood by mini MACS were cultured in a liquid culture system with rhSCF, rhGM CSF, rhTNF α and rhFL for 10 days. Then the induced cells were characterized by DC′s morphological and phenotypic properties. In addition, they stimulated the proliferation of allogeneic T cells and possessed an efficient capacity for initiating T cell dependent antitumor immune responses in vitro. It is concluded that mature DCs could be obtained from human cord blood CD34 + cells.