搜索结果: 'NeuroCult Proliferation'

Erythropoiesis,the essential process of hematopoietic stem cell development into erythrocytes,is controlled by lineage-specific transcription factors that determine cell fate and differentiation and by the hormone erythropoietin that stimulates cell survival and proliferation. Here we identify the Sry-related high-mobility-group (HMG) box transcription factor Sox6 as an important enhancer of definitive erythropoiesis. Sox6 is highly expressed in proerythroblasts and erythroblasts in the fetal liver,neonatal spleen,and bone marrow. Mouse fetuses and pups lacking Sox6 develop erythroid cells slowly and feature misshapen,short-lived erythrocytes. They compensate for anemia by elevating the serum level of erythropoietin and progressively enlarging their erythropoietic tissues. Erythroid-specific inactivation of Sox6 causes the same phenotype,demonstrating cell-autonomous roles for Sox6 in erythroid cells. Sox6 potentiates the ability of erythropoietin signaling to promote proerythroblast survival and has an effect additive to that of erythropoietin in stimulating proerythroblast and erythroblast proliferation. Sox6 also critically facilitates erythroblast and reticulocyte maturation,including hemoglobinization,cell condensation,and enucleation,and ensures erythrocyte cytoskeleton long-term stability. It does not control adult globin and erythrocyte cytoskeleton genes but acts by stabilizing filamentous actin (F-actin) levels. Sox6 thus enhances erythroid cell development at multiple levels and thereby ensures adequate production and quality of red blood cells. View Publication

We have recently shown that conservation and differentiation of primitive human hematopoietic progenitors in in vitro long-term bone marrow cultures (LTBMC) occurs to a greater extent when hematopoietic cells are grown separated from the stromal layer than when grown in direct contact with the stroma. This finding suggests that hematopoiesis may depend mainly on soluble factors produced by the stroma. To define these soluble factors,we examine here whether a combination of defined early-acting cytokines can replace soluble stroma-derived biologic activities that induce conservation and differentiation of primitive progenitors. Normal human Lineage-/CD34+/HLA-DR- cells (DR-) were cultured either in the absence of a stromal layer (stroma-free") or in a culture system in which DR- cells were separated from the stromal layer by a microporous membrane ("stroma-noncontact"). Both culture systems were supplemented three times per week with or without cytokines. These studies show that culture of DR- cells for 5 weeks in a "stroma-free" culture supplemented with a combination of four early acting cytokines (Interleukin-3 [IL-3]� View Publication

Adipose tissue stem cells (ADSCs) would be an attractive autologous cell source. However,ADSCs require invasive procedures,and has potential complications. Recently,urine stem cells (USCs) have been proposed as an alternative stem cell source. In this study,we compared USCs and ADSCs collected from the same patients on stem cell characteristics and capacity to differentiate into various cell lineages to provide a useful guideline for selecting the appropriate type of cell source for use in clinical application. The urine samples were collected via urethral catheterization,and adipose tissue was obtained from subcutaneous fat tissue during elective laparoscopic kidney surgery from the same patient (n = 10). Both cells were plated for primary culture. Cell proliferation,colony formation,cell surface markers,immune modulation,chromosome stability and multi-lineage differentiation were analyzed for each USCs and ADSCs at cell passage 3,5,and 7. USCs showed high cell proliferation rate,enhanced colony forming ability,strong positive for stem cell markers expression,high efficiency for inhibition of immune cell activation compared to ADSCs at cell passage 3,5,and 7. In chromosome stability analysis,both cells showed normal karyotype through all passages. In analysis of multi-lineage capability,USCs showed higher myogenic,neurogenic,and endogenic differentiation rate,and lower osteogenic,adipogenic,and chondrogenic differentiation rate compared to ADSCs. Therefore,we expect that USC can be an alternative autologous stem cell source for muscle,neuron and endothelial tissue reconstruction instead of ADSCs. View Publication

TLRs are involved in innate cell activation by conserved structures expressed by microorganisms. Human T cells express the mRNA encoding most of TLRs. Therefore,we tested whether some TLR ligands may modulate the function of highly purified human CD4+ T lymphocytes. We report that,in the absence of APCs,flagellin (a TLR5 ligand) and R-848 (a TLR7/8 ligand) synergized with suboptimal concentrations of TCR-dependent (anti-CD3 mAb) or -independent stimuli (anti-CD2 mAbs or IL-2) to up-regulate proliferation and IFN-gamma,IL-8,and IL-10 but not IL-4 production by human CD4+ T cells. No effect of poly(I:C) and LPS,ligands for TLR3 and TLR4,respectively,was detected. We also observed that CD4+CD45RO+ memory T cell responses to TLR ligands were more potent than those observed with CD4+CD45RA+ naive T cells. Moreover,among the memory T cells,CCR7- effector cells were more sensitive to TLR ligands than CCR7+ central memory cells. These data demonstrate for the first time a direct effect of TLR5 and TLR7/8 ligands on human T cells,and highlight an innate arm in T cell functions. They also suggest that some components from invading microorganisms may directly stimulate effector memory T cells located in tissues by up-regulating cytokine and chemokine production. View Publication

In recent years,mesenchymal stem cells (MSCs) have been shown to inhibit T-lymphocyte proliferation induced by alloantigens or mitogens. However,no substantial information is available regarding their effect on natural killer (NK) cells. Here we show that MSCs sharply inhibit IL-2-induced proliferation of resting NK cells,whereas they only partially affect the proliferation of activated NK cells. In addition,we show that IL-2-activated NK cells (but not freshly isolated NK cells) efficiently lyse autologous and allogeneic MSCs. The activating NK receptors NKp30,NKG2D,and DNAM-1 represented the major receptors responsible for the induction of NK-mediated cytotoxicity against MSCs. Accordingly,MSCs expressed the known ligands for these activating NK receptors-ULBPs,PVR,and Nectin-2. Moreover,NK-mediated lysis was inhibited when IFN-gamma-exposed MSCs were used as target cells as a consequence of the up-regulation of HLA class I molecules at the MSC surface. The interaction between NK cells and MSCs resulted not only in the lysis of MSCs but also in cytokine production by NK cells. These results should be taken into account when evaluating the possible use of MSCs in novel therapeutic strategies designed to improve engraftment or to suppress graft-versus-host disease (GVHD) in bone marrow transplantation. View Publication

Background Cancer has been considered a serious global health problem and a leading cause of morbidity and mortality worldwide. Despite recent advances in cancer therapy,treatments of advance stage cancers are mostly ineffective resulting in poor survival of patients. Recent evidences suggest that multipotent human mesenchymal stem cells (hMSCs) play important roles in growth and metastasis of several cancers by enhancing their engraftment and inducing tumor neovascularization. However,the effect of hMSCs on cancer cells is still controversial because there are also evidences demonstrating that hMSCs inhibited growth and metastasis of some cancers. Methods In this study,we investigated the effects of bioactive molecules released from bone marrow and gestational tissue-derived hMSCs on the proliferation of various human cancer cells,including C3A,HT29,A549,Saos-2,and U251. We also characterized the hMSC-derived factors that inhibit cancer cell proliferation by protein fractionation and mass spectrometry analysis. Results We herein make a direct comparison and show that the effects of hMSCs on cancer cell proliferation and migration depend on both hMSC sources and cancer cell types and cancer-derived bioactive molecules did not affect the cancer suppressive capacity of hMSCs. Moreover,hMSCs use distinct combination of bioactive molecules to suppress the proliferation of human hepatoblastoma and colorectal cancer cells. Using protein fractionation and mass spectrometry analysis,we have identified several novel hMSC-derived factors that might be able to suppress cancer cell proliferation. Conclusion We believe that the procedure developed in this study could be used to discover other therapeutically useful molecules released by various hMSC sources for a future in vivo study. View Publication

An urgent need exists to devise strategies to augment antiviral immune responses in patients with HIV who are virologically well controlled and immunologically stable on highly active antiretroviral therapy (HAART). The objective of this study was to compare the immunomodulatory effects of the cytokines interleukin (IL)-21 with IL-15 on CD8 T cells in patients with HIV RNA of less than 50 copies/mL and CD4 counts greater than 200 cells/mm.(3) Patient CD8 T cells displayed skewed maturation and decreased perforin expression compared with healthy controls. Culture of freshly isolated patient peripheral-blood mononuclear cells (PBMCs) for 5 hours to 5 days with IL-21 resulted in up-regulation of perforin in CD8 T cells,including memory and effector subsets and virus-specific T cells. IL-21 did not induce T-cell activation or proliferation,nor did it augment T-cell receptor (TCR)-induced degranulation. Treatment of patient PBMCs with IL-15 resulted in induction of perforin in association with lymphocyte proliferation and augmentation of TCR-induced degranulation. Patient CD8 T cells were more responsive to cytokine effects than the cells of healthy volunteers. We conclude that CD8 T cells of patients with HIV can be modulated by IL-21 to increase perforin expression without undergoing overt cellular activation. IL-21 could potentially be useful for its perforin-enhancing properties in anti-HIV immunotherapy. View Publication

Human embryonic stem cells (hESCs) exhibit unique cell cycle structure,self-renewal and pluripotency. The Forkhead box transcription factor M1 (FOXM1) is critically required for the maintenance of pluripotency in mouse embryonic stem cells and mouse embryonal carcinoma cells,but its role in hESCs remains unclear. Here,we show that FOXM1 expression was enriched in undifferentiated hESCs and was regulated in a cell cycle-dependent manner with peak levels detected at the G2/M phase. Expression of FOXM1 did not correlate with OCT4 and NANOG during in vitro differentiation of hESCs. Importantly,knockdown of FOXM1 expression led to aberrant cell cycle distribution with impairment in mitotic progression but showed no profound effect on the undifferentiated state. Interestingly,FOXM1 depletion sensitized hESCs to oxidative stress. Moreover,genome-wide analysis of FOXM1 targets by ChIP-seq identified genes important for M phase including CCNB1 and CDK1,which were subsequently confirmed by ChIP and RNA interference analyses. Further peak set comparison against a differentiating hESC line and a cancer cell line revealed a substantial difference in the genomic binding profile of FOXM1 in hESCs. Taken together,our findings provide the first evidence to support FOXM1 as an important regulator of cell cycle progression and defense against oxidative stress in hESCs. View Publication

The constitutive activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway commonly occurs in cancers and is a crucial event in tumorigenesis. Chronic myelogenous leukemia (CML) is characterized by a reciprocal chromosomal translocation (9;22) that generates the Bcr-Abl fusion gene. The PI3K/Akt pathway is activated by Bcr-Abl chimera protein and mediates the leukemogenesis in CML. However,the mechanism by which Bcr-Abl activates the PI3K/Akt pathway is not completely understood. In the present study,we found that pleckstrin homology domain leucine-rich repeat protein phosphatases 1 and 2 (PHLPP1 and PHLPP2) were depleted in CML cells. We investigated the interaction between PHLPPs and Bcr-Abl in CML cell lines and Bcr-Abl+ progenitor cells from CML patients. The Abl kinase inhibitors and depletion of Bcr-Abl induced the expression of PHLPP1 and PHLPP2,which dephosphorylated Ser-473 on Akt1,-2,and -3,resulting in inhibited proliferation of CML cells. The reduction of PHLPP1 and PHLPP2 expression by short interfering RNA in CML cells weakened the Abl kinase inhibitor-mediated inhibition of proliferation. In colony-forming unit-granulocyte,erythroid,macrophage,megakaryocyte; colony-forming unit-granulocyte,macrophage; and burst-forming unit-erythroid,treatment with the Abl kinase inhibitors and depletion of Bcr-Abl induced PHLPP1 and PHLPP2 expression and inhibited colony formation of Bcr-Abl+ progenitor cells,whereas depletion of PHLPP1 and PHLPP2 weakened the inhibition of colony formation activity by the Abl kinase inhibitors in Bcr-Abl+ progenitor cells. Thus,Bcr-Abl represses the expression of PHLPP1 and PHLPP2 and continuously activates Akt1,-2,and -3 via phosphorylation on Ser-473,resulting in the proliferation of CML cells. View Publication

Current data suggests an association between elevations in interleukin 1 (IL-1)α,IL-1β,and IL-6 and the proliferation of neural progenitor cells (NPCs) following brain injury. A limited amount of work implicates changes in these pro-inflammatory responses with diminished NPC proliferation observed as a function of aging. In the current study,adolescent (21day-old) and 1year-old CD-1 male mice were injected with trimethyltin (TMT,2.3mg/kg,i.p.) to produce acute apoptosis of hippocampal dentate granule cells. In this model,fewer 5-bromo-2'-deoxyuridine (BrdU)+ NPC were observed in both naive and injured adult hippocampus as compared to the corresponding number seen in adolescent mice. At 48h post-TMT,a similar level of neuronal death was observed across ages,yet activated ameboid microglia were observed in the adolescent and hypertrophic process-bearing microglia in the adult. IL-1α mRNA levels were elevated in the adolescent hippocampus; IL-6 mRNA levels were elevated in the adult. In subgranular zone (SGZ) isolated by laser-capture microdissection,IL-1β was detected but not elevated by TMT,IL-1a was elevated at both ages,while IL-6 was elevated only in the adult. Naïve NPCs isolated from the hippocampus expressed transcripts for IL-1R1,IL-6Rα,and gp130 with significantly higher levels of IL-6Rα mRNA in the adult. In vitro,IL-1α (150pg/ml) stimulated proliferation of adolescent NPCs; IL-6 (10ng/ml) inhibited proliferation of adolescent and adult NPCs. Microarray analysis of SGZ post-TMT indicated a prominence of IL-1a/IL-1R1 signaling in the adolescent and IL-6/gp130 signaling in the adult. View Publication

There has been a new interest in using aldehyde dehydrogenase (ALDH) activity as one marker for stem cells since the Aldefluor flow cytometry-based assay has become available. Diethylaminobenzaldehyde (DEAB),used in the Aldeflour assay,has been considered a specific inhibitor for ALDH1A1 isoform. In this study,we explore the effects of human ALDH isoenzymes,ALDH1A2 and ALDH2,on drug resistance and proliferation,and the specificity of DEAB as an inhibitor. We also screened for the expression of 19 ALDH isoenzymes in K562 cells using TaqMan Low Density Array (TLDA). We used lentiviral vectors containing the full cDNA length of either ALDH2 or ALDH1A2 to over express the enzymes in K562 leukemia and H1299 lung cancer cell lines. Successful expression was measured by activity assay,Western blot,RT-PCR,and Aldefluor assay. Both cell lines,with either ALDH1A2 or ALDH2,exhibited higher cell proliferation rates,higher clonal efficiency,and increased drug resistance to 4-hydroperoxycyclophosphamide and doxorubicin. In order to study the specificity of known ALDH activity inhibitors,DEAB and disulfiram,we incubated each cell line with either inhibitor and measured the remaining ALDH enzymatic activity. Both inhibitors reduced ALDH activity of both isoenzymes by 65-90%. Furthermore,our TLDA results revealed that ALDH1,ALDH7,ALDH3 and ALDH8 are expressed in K562 cells. We conclude that DEAB is not a specific inhibitor for ALDH1A1 and that Aldefluor assay is not specific for ALDH1A1 activity. In addition,other ALDH isoenzymes seem to play a major role in the biology and drug resistance of various malignant cells. View Publication