Effects of dendritic cell stimulation on cytotoxic activity of cord blood derived cytokine-induced killer cells,natural killer cells and CD45RO expression in CIK cells

AIM: To investigate the efficacy of dendritic cells (DCs) that augments the cytotoxic activity of cytokine-induced killer (CIK) cells, natural killer (NK) cells from a same donor and the CD45RO expression on CIK cells. METHODS: The expanded killer cells were divided into two groups: group A was pre-cocultured with DCs for 6 days, group B was the control that without any stimulation. Cytotoxicity of CIK and NK cells was measured at different effect-target ratio against K562 and HL-60. CD45RO and CD45RA expression on CIK cells in different groups were detected by flow cytometry. RESULTS: Cytotoxicity of CB derived killer cells was positive correlation with effect-target ratio. The cytotoxicity of group A against HL-60 was higher than that of group B significantly. At 20∶1 effector-target ratio, the lytic activity of group A CIK, NK cells against K562 was higher than that of group B significantly, but no significant difference between them at 10∶1 effector-target ratio. The CD45RO expression on CIK cells in groups A was significantly higher than that in groups B. CONCLUSION: CIK and NK cells cocultured with DCs can augment the killer's cytotoxicity against tumor cells and promote the CD45RO expression on CIK cells.     

Effects of IL-6 and IL-11 on differentiation of cord blood CD34+ cells towards megakaryocytes

AIM: To investigate the effects of interleukin-6 (IL-6) and interleukin-11 (IL-11) on differentiation of cord blood CD34+ cells towards megakaryocytes and platelet production in vitro.METHODS: The CD34+ cells from fresh umbilical cord blood samples were cultured in serum-free culture medium with thrombopoietin (TPO) 50 μg/L,IL-3 10 μg/L,stem cell factor (SCF) 50 μg/L as control groups,then 10 μg/L IL-6 or IL-11 or IL-6＋IL-11 respectively was added as treatment groups.Mononuclear cells (MNCs) in cultured cells were detected by cell counter,megakaryocytes (CD41+ cells) and platelets were measured by flow cytometry,respectively.Platelet agglutination after thrombin induced was observed by microscopy and flow cytometry.RESULTS: Compared with the control group,the number of MNCs was not significantly different（P>0.05）,but the numbers of CD41+ cells and platelets were increased significantly (P<0.05) in treatment groups.There were more platelet particles in treatment groups than those in control group by microscopy and the results also showed that the cytoplasmic fragments from the cultures responded to thrombin induction.CONCLUSION: It is concluded that both IL-6 and IL-11 induce the cord blood CD34+ cells to differentiate towards megakaryocytes and produce platelets.     

Construction of recombinant retrovirus vector carrying hTERT and transfected to MSCs in human cord blood

AIM:To construct a recombinant retrovirus vector carrying hTERT for establishing UCBMSCs with hTERT (hTERT-MSCs) to overcome their limited life span and detecting whether telomerized UCBMSCs line maintained long-term self-renewal and differentiation capacity. METHODS:The whole cDNA was generated by PCR amplifications from the plasmid pEGFP-hTERT-C1. The hTERT segments were subcloned into pLNCX2. The target cells were infected with these retroviral particles. The stably transfected cells were selected by neomycin and expanded life span which were designated hTERT-MSCs was observed. The expression of hTERT in mRNA level was detected by RT-PCR and the telomerase activity was measured by TRAP (PCR)-ELISA assay. The hTERT-MSCs were induced with 5-azacytidine to cardiac muscle cells and the specific marker of myocardiocyte was detected. RESULTS:The constructed plasmids were digested with restriction endonucleases (BglⅡand NotⅠ). Two characteristic segments including 6.1 kb and 3.6 kb were obtained. The hTERT-MSCs expressed hTERT in mRNA level. The telomerase activity of hTERT-MSCs was positive. The growth kinetics of hTERT-MSCs was higher than those in UCBMSCs. The hTERT-MSCs were induced to myocardiocyte. CONCLUSION:The hTERT recombinant retrovirus vector has been successfully constructed. The hTERT gene activates the telomerase and prolongs the life-span of cells. No effect of hTERT gene on some type of differentiation potential of MSCs is present.     

Biological characteristics of JAK2 transduced CD34+ cells from cord blood during ex vivo expansion

AIM: To explore the feasibility and biological characterization of long-term regulated expansion of JAK2 transduced human CD34⁺ cord blood cells in vitro.METHODS: A retrovirus (RV) vector which contains JAK2 catalytic domain and two binding sites for a chemical inducer,dimerization (AP20187),was cloned (designated MGI-F₂JAK2).CD34⁺cells were enriched from cord blood with a MiniMACS system.The purified CD34⁺ cells were transfected with supernatant from the retrovirus packaging cell line that expressed JAK2.Following transduction,cells were expanded into four groups: AP20187 alone,FL alone,TPO,alone,AP20187+FL+TPO,respectively.The expanded cells were monitored by GFP expression,immunophenotyping,progenitor colony assay,karyotype analysis as well as tumorigenesis in nude mice.RESULTS: The purity of selected CD34⁺ cells was over 91% and gene transfer rate was 49.32%±6.21%.Only the group of AP20187 +FL+ TPO was obtained a significant sustained outgrowth of the transduced CD34⁺ cord blood cells.The percentage of GFP+ cells consistently produced a rise to the 90% peak level by the end of 8th week of culture.Flow cytometry analysis showed that the phenotype of the expanded cells was CD33⁺,CD61⁺ and Gly-A⁺ partial positive;CD38⁺ and HLA-DR⁺ strong positive,while CD2,CD7 and CD19 were almost negative.Colony assays performed in methycelluos,which can give rise to BFU-E,CFU-GM and CFU-Mix,the CFU-GM was predominantly in all colonies.The tumor was not observed in nude mice and the karyotype analysis was normal from expanded cells.CONCLUSION: The results demonstrate that AP20187-mediated activation of JAK2 signaling is capable of stimulating expansion JAK2 transduced CB CD34⁺ cells in combination with FL and TPO.This system may have applications for studies in signaling transduction,hematopoiesis,and for gene and cell therapy.     

Biological characters of mesenchymal stem cells of human umbilical cord blood

AIM：To study the isolation,expansion and purification of mesenchymal stem cells (MSCs) from human umbilical cord blood (UCB),and investigate some biological identities of MSCs.METHODS：(1) MSCs of UCB,adult bone marrow (BM) and fetus BM were isolated by centrifugation with Ficoll,and the different kinds of MSCs were observed everyday.(2) Surface markers of MSCs were identified by flow cytometry.(3) The level of HGFs (TPO,SCF,FLT-3L,IL-6) secreted by different sources of MSCs was checked by ELISA method.RESULTS：(1) No difference in morphology of the colonies between UCB MSCs and BM MSCs was observed.However,the mononuclear cells needed in culture of UCB MSCs was about 3 times more than that in culture of BM MSCs.The times of UCB MSCs colony formation and confluencing were longer than that of BM in primary culture.(2) After passaged,there was no significant difference in the proliferation rates of 3 kinds of MSCs.Only 4 of 15 UCB samples contained a homogeneous population of MSCs.(3) UCB MSCs shared the same markers with BM MSCs.Neither hematopoietic marker nor immunologic recognition antigens were expressed.(4) The level of hematopoietic growth factors (HGFs) secreted by 3 kinds of MSCs was similar.CONCLUSIONS：(1) MSCs were isolated from UCB,but the amount of MSCs in UCB was smaller than that in BM,and just seldom samples of UCB contained homogeneous MSCs.(2) MSCs from UCB and BM shared the same biological characteristics,such as proliferation ability,surface markers,immunophenotypes and HGFs secretion.     

Effects of monocyte-endothelium interaction on the expression of CD36 in monocytes

AIM: To examine the effects of monocyte-endothelium interaction on the expression of CD36 in monocytes and observe the functions of cytokines in this process. METHODS: The monocytes and endothelial cells were cultured alone or cocultured together to form different cell culture conditions. The level of M-CSF in culture medium was determined by enzyme linked immune sandwich assay(ELISA) technique, and the expression of CD36 in monocytes was determined by flow cytometry. RESULTS: The expression of CD36 in monocytes was low in monocytes cultured alone but increased signiFcantly when monocytes and endothelial cells were cocultumd(P<0.05).M-CSF and PDGF -BB played certain roles in increasing expression of CD36 in monocytes, but they didn't seize the principal positions. CONCLUSION: The monocyte-endothelium interaction increased the expression of CD36 in monocytes through various mechanisms and may participate in the pathogenesis of atherosclerosis.     

Biological characterics of human fetal cord blood mesenchymal stem cells

AIM: To investigate the biological characterics of human second-trimester fetal cord blood mesenchymal stem cells (MSC) and its application prospects in utero gene transfer/therapy (IUGT). METHODS: Nuclear cells separated from cord blood were cultured in DMEM medium. Surface antigens of the MSC were analyzed by the FACScan flow cytometry. Adipogenic and osteogenic mediums were used to assess the differentiation ability of the cells. Adenovirus vector deliver green fluorescent protein gene (Ad-GFP) was used to transfected the MSC and the expressing of GFP was detected by fluorescent microscope. The MSC were injected into the liver of newborn rat. The immunofluorescence analysis was conducted to determine the presence of double-positive CD105⁺/CD166⁺ cells in different organs of rats. MSC were subcutaneous injected into the human-nonobese diabetes/severe combined immunodeficiency disease (NOD/SCID) mice and carcinogenesises of the MSC in vivo were detected by pathological diagnosis. RESULTS: MSC could be separated from fetal cord blood. These cells were uniformly positive for CD29, CD44, CD59, CD105, CD166 and negative for CD34, CD45, CD80, CD86, HLA-DR. The cells had the abilities to differentiate into adipogenic and osteogenic cells in vitro, expressed the GFP at high levels (56.32%±3.28%). The MSC were located at different organs after injected into the newborn rats and didn't have carcinogenicity in vivo. CONCLUSION: Human second-trimester fetal cord blood MSC is an promising target cells in fetal IUGT.     

The ex vivo expansion characteristic of endothelial progenitor cells

AIM: To explore the ex vivo expansion characteristics of the endothelial progenitor cells (EPCs). METHODS: CD34⁺ cells were selected from umbilical cord blood mononuclear cells (MNC) by MiniMACS system, expanded at the same conditions as that for total MNC, coincubation of CD34⁺ and CD34^- from the same donation for EPCs. In addition, we tested the effect of vessel endothelial growth factor (VEGF) and passage on cell differentiation, expansion kinetics and apoptosis. EPCs were determined and quantified by immunocytochemistry and flow cytometry. RESULTS: Coculture of CD34⁺ and CD34^-,total MNC led to a significant increase in the expansion of CD34⁺ cells compared with CD34 enrichment (P＜0.05). There was a trend toward decreased apoptosis in cultures when early passage was performed once the linear cord like structures appeared. There was no significant effect on apoptosis between with VEGF and without VEGF group (P＞0.05). These differentiated EPCs were stained positive for CD34⁺, von Willebrand factor (vWF), KDR, CD31 and incorporate acetylated low-density lipoprotein (LDL). CD34⁺ and AC133⁺cells accounted for 68.2%±6.3% (n=6) and 57.2%±9.8% (n=6) of attaching (AT) cells at day 7 of culture, respectively. CONCLUSIONS: Coculture of CD34⁺ and CD34^- or culture of MNC enhances ex vivo expansion of EPCs. Early passage decreases apoptosis rate, VEGF has no significant effect on ex vivo expansion of EPCs.     

Vascular endothelial growth factor on function of endothelial progenitor cells from peripheral blood

AIM: To investigate the effect of vascular endothelial growth factor(VEGF) on the biological function of peripheral endothelial progenitor cells (EPCs) and to find the suitable concentration to promote the growth of EPCs.METHODS: Total mononuclear cells (MNCs) were isolated from peripheral blood by density gradient centrifugation,and then the cells were plated on fibronectin-coated culture dishes.After culture for 4 days,attached cells were incubated with VEGF in a series of concentrations (0,10,20 and 50 μg/L) for 72 h,then attached cells were characterized with immunohistochemistry.EPC proliferation and migration activity were assayed with MTT assay and modified Boyden chamber assay,respectively.EPC adhesion assay was performed by replating MNCs on fibronectin-coated dishes,and then the adherent cells were counted.RESULTS: The EPCs from MNCs were successfully isolated and were differentiated to endothelial cells (ECs).Incubation of isolated human MNCs with VEGF increased the proliferative,migratory and adhesive capacities of EPCs,and this effect was most prominent when the concentration of VEGF was 20 μg/L after 72 hours.At the same concentration of VEGF,the functions of EPCs from patients with masculine coronary arteriography were lower than those of EPCs from patients with negative coronary arteriography.CONCLUSION: Functional activities of EPCs are decreased in patients with masculine coronary arteriography.The results suggest that the low concentration of VEGF may improve functional activities of EPCs.     

Function of dendritic cells in cord blood

AIM: To explore the function of dendritic cells in cord blood.METHODS: Dendritic cell precursor subsets pDC/pDC(CD11c+CD123- /CD11c-CD123+) in cord blood and adult peripheral blood were analyzed gated by CD34-Lin- HLA-DR+ cells and the levels of IL-12p40,IL-10,IFN-γ,IL-4 in the serums were tested by ELISA.RESULTS: The level of IL-12p40 in cord blood serum was higher than that in peripheral blood.pDC1/pDC2,IL-10,IFN-γ,IL-4 in cord blood were similar to that in peripheral blood.CONCLUSION: Function development of dendritic cells in cord blood may be consummate.     

Age-related changes in phenotypes of T lymphocytes in human peripheral blood

AIM:To investigate the details of age-related changes of T lymphocytes in order to seek for sensitive biomarker for immunosenesence.METHODS:Heparin anticoagulated venous blood was collected freshly from young (20-35 years) and elderly (50-75 years) volunteers and three or four color immunofluorescence staining was performed. The nucleated cells were acquired and the phenotypes of T lymphocyte subpopulations were analyzed with flow cytometry.RESULTS:There was no significant difference in percentages of pan-T (CD3⁺), helper T (CD4⁺) and cytotoxic (CD8^＋) T subsets between young and elderly, whereas the density of CD3 molecule (MFI) on T cells in elderly group decreased significantly. It was also found that the rates of CD44⁺ and CD62L⁺ T cell subsets in young group did not have statistical difference from elderly. However, the rates of CD95⁺ pan-T, helper T and cytotoxic T subsets of elderly group were all markedly higher than that in young group.CONCLUSIONS:The relative rates of T cell and its subsets displayed no age-related changes while the density of CD3 was down-regulated during aging in these groups investigated. Moreover, the expression percentage of CD95 (Fas) on T cells increased as aging, suggesting that it is a potential biomarker for evaluating immunosenescence.     

Effects of psychological stress on in vitro expression of activated surface molecules on T cells of peripheral blood from healthy persons

AIM: To study cellular and molecular mechanism involved in increasing susceptibility of infection in psychological stress persons. METHODS: Comparative studies were performed with double staining and flow cytometry analysis on immunophenotyping and in vitro expression of early activating surface molecule CD69 in response to mitogens on T cells from peripheral blood of 20 healthy college student volunteers before and after psychological stress. A series of term final examinations was defined as psychological stress. RESULTS: Immunophenotyping analysis showed no statistically significant difference in the percentage of CD2, CD3, CD4, CD8, CD19, CD20, CD16 and CD56 positive lymphocyte populations before and after psychological stress. There was a statistically significant decrease in the in vitro expression of CD69 in response to polyclonal stimulators on the T cells from persons after psychological stress than those before psychological stress. The percentage of CD69 expression (CD69⁺CD3⁺/CD3⁺%) in response to PHA and PDB in the whole blood culture for 72 hours decreased respectively from 28.1±4.1 and 80.7±6.8 on the T cells obtained before psychological stress to 17.6±3.8 and 65.8±7.9 on those obtained after psychological stress, while there was no statistically significant difference between the CD69 expression rates without stimulators on the T cells obtained before and after psychological stress. CONCLUSIONS: The effects of psychological stress to immune system is not on the level of changing proportions of the sub-populations within peripheral blood lymphocytes. Psychological stress can decrease the activating response of T cells in healthy persons, which may be responsible for the increase of susceptibility to infection in the psychological stress persons.     

Effects of exosomes derived from hypoxia-preconditioned umbilical cord mesenchymal stem cells on function of endothelial cells

AIM To investigate the effect of exosomes derived from hypoxia-preconditioned human umbilical cord mesenchymal stem cells (hUCMSCs) on proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs). METHODS hUCMSCs and HUVECs were isolated, cultured and identified. Exosomes derived from hUCMSCs were extracted by ultracentrifugation. The morphological change of exosomes was observed under transmission electron microscope. The particle size and concentration of exosomes were detected by nanoparticle tracking analysis, and the surface specific marker proteins of exosomes were determined by Western blot. hUCMSCs were divided into normoxia group and hypoxia group. The viability of hUCMSCs was measured by CCK-8 assay. HUVECs were divided into control group, normoxic exosome group and hypoxic exosome group. The proliferation of HUVECs was detected by EdU assay. The migration ability was detected by cell scratch assay and Transwell experiment. Tube formation ability was evaluated by tube formation experiment. RESULTS Compared with normoxia group, hypoxia pretreatment enhanced the viability and exosome release of hUCMSCs. Compared with normoxic exosome group, hypoxic exosomes enhanced the proliferation, migration and tube formation of HUVECs. CONCLUSION Exosomes derived from hUCMSCs under hypoxia enhances the proliferation, migration and tube formation of HUVECs.     

Effect of CD151 on biological characteristics of human umbilical cord mesenchymal stem cells

AIM：To study the effect of CD151 on the biological characteristics of human umbilical cord mesenchymal stem cells (hUC-MSCs). METHODS：CD151 expression on hUC-MSCs was interfered by siRNA. The cells were divided into siRNA-CD151 group and negative control group (treated with siRNA-NC). The efficiency of interference after 72 h and the changes of other surface markers were detected by flow cytometry. The ability of differentiation was assessed by oil red O and von Kossa staining. The cell cycle was analyzed by flow cytometry. The mRNA expression of CD151, hepatocyte growth factor (HGF), transforming growth factor β1 (TGF-β1), cyclooxygenase 2 (COX-2) and indoleamine 2, 3-dioxygenase (IDO) in hUC-MSCs was detected by real-time PCR. The secretion of HGF by hUC-MSCs was measured by ELISA. RESULTS：The results of flow cytometry showed that the expression of CD151 (11.97±2.63 vs 95.66±1.56, P<0.01) and CD105 (93.66±0.21 vs 83.37±0.71, P<0.05) on hUC-MSCs in siRNA-CD151 group was lower than that in negative control group. The consistent results were also achieved by using the method of real-time PCR. Treatment with siRNA-CD151 down-regulated the progress of the cell cycle as the G1 phase increased and the S phase decreased. The mRNA expression levels of HGF and TGF-β1 in hUC-MSCs in siRNA-CD151 group were lower than those in negative control group, and opposite result of COX-2 mRNA expression was observed. The IDO mRNA in hUC-MSCs was unchanged with IFN-γ stimulation for 24 h. HGF concentration in siRNA-CD151 group was decreased as compared with negative control group. CONCLUSION：Interfering CD151 expression on hUC-MSCs doesn’t change other surface markers except CD105, and maintains the capacity of adipogenic differentiation. However, it changes the osteogenic differentiation, proliferation and the expression of immunomodulatory cytokines.     

Injury effect of recombinant soluble human CD40 ligand on human umbilical vein endothelial cells

AIM: To investigate the damage in human umbilical vein endothelial cells (HUVECs) induced by recombinant soluble human CD40 ligand (rshCD40L). METHODS: The cultured HUVECs were treated with rshCD40L for 12 h. The survival activity of the HUVECs was observed by MTS assay. The expression of E-selectin, intercellular adhesion molecule (ICAM)-1, tissue factor (TF) and tissue factor pathway inhibitor (TFPI) was measured by ELISA. The activity of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) were detected by the methods of thibabituric acid (TBA). RESULTS: Compared with normal group, different concentrations of rshCD40L (0.5, 1, 2, 3 mg/L) had no obvious effect on the survival activity of the HUVECs (P>0.05). rshCD40L at concentration of 0.5 mg/L promoted the secretion of E-selectin, sICAM-1, TF and TFPI in the HUVECs (P<0.01). rshCD40L at concentration of 0.5 mg/L also increased MDA content and reduced the activity of SOD in the HUVECs (P<0.05). CONCLUSION: 0.5~3mg/L rshCD40L has no obvious effect on endothelial cell survival, but already causes endothelial dysfunction by increasing endothelial inflammation and exogenous coagulation reaction, inducing lipid peroxides injury and reducing antioxidant capacity.