Project description:We previously identified endothelial cell-selective adhesion molecule (ESAM) as a novel functional marker of hematopoietic stem cells (HSCs) in mice. To examine ESAM expression in human, we analyzed diverse HSC sources using flow cytometry. From mononuclear cells of collagenase-treated human hip bones, we obtained two ESAM positive populations in CD34(+) CD38(-) fraction, referred to as ESAM(High) and ESAM(Bright). Then we conducted microarray analyses comparing gene expression signatures between these two populations. Trabecular tissues of the femora were treated with collagenase IV and DNase. Mononuclear cells were collected, and CD34(+) CD38(-) ESAM(High) or ESAM(Bright) cells were sorted.
Project description:Cord blood (CB) samples from normal donors were obtained with informed consent. Fresh CB samples were processed within 18-34h after collection. Mononuclear cells were isolated and CD34+ fraction was separated. CB CD34+ enriched fraction was lineage depleted by staining with purified anti-human CD2, CD3, CD4, CD7, CD8a, CD11b, CD14, CD19, CD20, CD56, CD235a followed by Qdot 605 conjugated goat F(ab')2 anti-mouse IgG (H+L). Cells were also stained with anti-human CD38-FITC, CD45RA-PE or -BV650, CD123-PE Cy7, CD90-biotin, CD34- PerCP and CD10-APC. Finally, cells were incubated with streptavidin-conjugated APC-eF780 and Hoechst 33258 (Invitrogen, final concentration: 1 g/ml). Populations were defined, as follows: HSC - Lin-CD34+CD38-CD90+CD45RA-CD10-, MPP - Lin-CD34+CD38-CD90-CD45RA-CD10-, LMPP - Lin-CD34+CD38-CD90-/loCD45RA+CD10-, MLP - Lin-CD34+CD38-CD90-/loCD45RA+CD10+, GMP - Lin-CD34+CD38+CD123+CD45RA+CD10-, CMP - Lin-CD34+CD38+CD123+CD45RA-CD10-, MEP - Lin-CD34+CD38+CD123-CD45RA-CD10-.
Project description:Comparison of the CD34+CD38- versus CD34+CD38+ fractions of human umbilical cord blood and comparison of the slow-dividing fraction versus the fast dividing fraction of the CD34+/CD38- population.
Project description:The t(8;21) Acute Myeloid Leukaemia (AML) Kasumi-1cell line with N822K KIT mutation, is a model system for leukemogenesis. As AML initiating cells reside in the CD34+CD38- fraction, we addressed the refined cytogenomic characterization and miRNA expression of Kasumi-1 cell line and its FACS-sorted subpopulations focussing on this compartment. By conventional cytogenetics, Spectral Karyotyping and array-CGH the cytogenomic profile of Kasumi-1 cells evidenced only subtle regions differentially represented in CD34+CD38- cells. Expression profiling by a miRNA platform showed a set of miRNA differentially expressed in paired subpopulations and the signature of miR-584 and miR-182 upregulation in the CD34+CD38- fraction.
Project description:Leukemic stem cells (LSC) might be the source for leukemic disease self-renewal and account for disease relapse after treatment, which makes them a critical target for further therapeutic options. Leukemia associated antigens (LAA) might be suitable structures to be attacked by immunotherapeutic agents. We performed primary AML sample enrichment and microarray studies to define LAA expression levels in AML. We compared the LAA expression in the enriched CD34+CD38- AML fraction to that of enriched HSC of healthy donors and AML bulk cells (CD34+CD38+, CD34-CD38+ and CD34-CD38). Furthermore, we investigated the expression patterns of co-stimulatory molecules in LSC, bulk AML cells and enriched HSC, Conclusion: We demonstrated the differential expression of several LAA in LSC, and their suitability as target structures. We enriched primary AML samples using CD34 and CD38 as markers to compare LAA expression levels of LSC, HSC and AML bulk. LAA expression profiles comparing LSC, HSC and leukemic bulk AML citation: Leukemic progenitor cells are susceptible to targeting by stimulated cytotoxic T cells against immunogenic leukemia-associated antigens Vanessa Schneider, Lu Zhang, Markus Rojewski, Natalie Fekete, Hubert Schrezenmeier, Alexander Erle, Lars Bullinger, Susanne Hofmann, Marlies Götz, Konstanze Döhner, Susann Ihme, Hartmut Döhner, Christian Buske, Michaela Feuring-Buske, Jochen Greiner
Project description:T cells develop from progenitors that migrate from the bone marrow into the thymus. Thymocytes are subdivided roughly as being double negative (DN), double positive (DP), or single positive (SP), based on the expression of the CD4 and CD8 coreceptors. The DN stage is heterogeneous and can be subdivided into four distinct subsets in mice based on the expression of CD44 and CD25. In human, three distinct DN stages can be recognized: a CD34+CD38−CD1a− stage that represents the most immature thymic subset and the consecutive CD34+CD38+CD1a− and CD34+CD38+CD1a+ stages. Human DN thymocytes mature via an immature single positive (ISP CD4+) and a DP stage into CD4+ or CD8+ SP T cells that express functional T cell receptors (TCR) and that exit the thymus. In this study, gene expression was measured in each of these nine stages. Overall design: CD34+ lineage negative “stem cell-like” cells were obtained from umbilical cord blood (UCB) and CD34+CD38− CD1a−, CD34+CD38+CD1a−, CD34+CD38+CD1a+, ISP CD4+, DP CD3−, DP CD3+, SP CD4+, and SP CD8+ subpopulations were obtained from thymi which represented consecutive stages of T cell development. Thymi were obtained as surgical tissue discards from children aged 7 wk to 3 yr (median of 6 mo) undergoing cardiac surgery at the Erasmus MC Rotterdam, with informed consent from the parents. The children did not have immunological abnormalities. Thymocytes were isolated by cutting the thymic lobes into small pieces and squeezing them through a metal mesh, and stored at +-80C until further analyses. Mononuclear cells (MNCs) were isolated by Ficoll-Paque (Amersham Biosciences) density centrifugation from human umbilical cord blood (UCB) obtained from full-term normal deliveries and from peripheral blood of healthy volunteers. All samples were obtained according to the guidelines of the Medical Ethical Committee of the Erasmus MC that also approved the human studies. For the isolation of CD34+ lineage (lin)- UCB cells and thymocyte subsets, total MNCs or thymocytes from five donors were pooled to reduce intrasample variation. After thawing, pooling, and Ficoll density separation, thymocytes were labeled with fluorochromeconjugated monoclonal antibodies. To isolate the CD34+ lin- UCB cells, CD34+CD38-CD1a-, CD34+CD38+CD1a-, and CD34+CD38+CD1a+ thymocytes, magnetic beads were used to enrich for CD34+ cells. For isolation of the ISP population, thymocytes were depleted of CD3-expressing cells using magnetic beads. All magnetic beads were used according to the manufacturer’s protocol. After MACS sorting, the enriched cells were labeled with fluorochrome-conjugated monoclonal antibodies for further purification by high speed cell sorting. All cell sorting was performed on a FACS DiVa cell sorter (BD Biosciences). Monoclonal antibodies used, with the clone in brackets: CD4-FITC (SK3), CD38-FITC (HB7), TCRGD- FITC (WT31), CD1a-RDI (T6), CD3-PE (SK7), CD16-PE (B73.1), CD19-PE (4G7), CD56-PE (M431), TCRGD-PE (11F2), CD3-PerCP (SK7), CD8- PerCP (SK1), CD19-PerCP (SJ25C1), CD3-APC (SK7), CD8-APC (SK1) and CD34-APC (8G12) (all obtained from BD Biosciences), CD13- RDI (MY7), and CD33-RDI (906) (obtained from Beckman Coulter). Purity of sorted population was determined on the FACS Calibur (BD Biosciences) and shown to be >95% for all populations. All populations were sorted twice using different donors for each sort.
Project description:Differences in chemo-sensitivity of subpopulations of AML stem cells could have important clinical implications. Using in vitro cytotoxicity, xenograft models and colony forming assays, we compared chemotherapy sensitivity between Lineage (Lin-)CD34-CD38-, Lin-CD34-CD38+, Lin-CD34+CD38- and Lin-CD34+CD38+ populations from 26 primary AMLs (19 paediatric and 7 adult). We identified a common recurring pattern of chemo-response associated with a poor clinical outcome: In each of 16/26 (62%) AMLs, Lin-CD34-CD38- cells were the most chemoresistant of the four subpopulations to daunorubicin in vitro. Cytarabine-resistant colonies formed only from Lin-CD34-CD38- populations following tertiary passages through both NOG mice and methylcellulose in these AMLs The presence of chemo-resistant Lin-CD34-CD38- populations was signficantly associated with reduced relapse-free survival in childhood AML. Consistently, CD34 negativity was significantly associated with an increased risk of relapse in a larger retropsective cohort (n=89). Samples enriched for chemo-resistant Lin-CD34-CD38- LSCs with a stem cell profile and an undifferentiated genotype revealed pathways likely to confer chemo-resistance, These strongly indicated dependence of chemo-resistant Lin-CD34-CD38- LSCs on their niche environment as well as deregulated DNA damage responses, lipid and Notch1 signalling, Our findings have major implications for the risk stratification of childhood AML and could lead to the development of novel therapeutic approaches. 3 subpopulations of leukemia stem cells from 9 patients with primary childhood AML were analysed. We compared gene expression profiles of Lin-CD34+CD38- (Q1), Lin-CD34+CD38+ (Q2) and Lin-CD34-CD38- (Q3) cells between 3 AMLs in which the CD34+ cells were most chemo-resistant (AML-1P, AML-6P and AML-10P) and the same cells from the remaining AMLs in which the Lin-CD34-CD38- cells were the most chemo-resistant population. We also compared the gene expression profiles of Lin-CD34-CD38- (Q3) cells in the 3 samples with the highest LC50 values (AML-15P, AML-17P and AML-19P) with that of the 3 AMLs exhibiting the lowest LC50 values (AML-2P, AML-5P and AML-11P).
Project description:We recently found that the tetraspanin family member, CD82, which is aberrantly expressed in chemotherapy-resistant CD34+/CD38− acute myelogenous leukemia (AML) cells, negatively regulates matrix metalloproteinase 9, and plays an important role in enabling CD34+/CD38− AML cells to adhere to the bone marrow microenvironment. This study explored novel functions of CD82 that contribute to AML progression. We employed microarray analysis comparing the gene expression profiles between CD34+/CD38− AML cells transduced with CD82 shRNA and CD34+/CD38− AML cells transduced with control shRNA. Real-time RT-PCR and western blot analysis were performed to examine the effect of CD82 knockdown on the expression of the polycomb group member, enhancer of zeste homolog 2 (EZH2), in leukemia cells. A chromatin immunoprecipitation assay was performed to examine the effect of CD82 expression on the amount of EZH2 bound to the promoter regions of tumor suppressor genes in leukemia cells. We also utilized methylation-specific PCR to examine whether CD82 expression influences the methylation status of the tumor suppressor gene promoter regions in leukemia cells. Microarray analysis revealed that levels of EZH2 decreased after shRNA-mediated depletion of CD82 in CD34+/CD38− AML cells. Moreover, the antibody-mediated blockade of CD82 in leukemia cells lowered EZH2 expression via activation of p38 MAPK signaling, decreased the amount of EZH2 bound to the promoter regions of the tumor suppressor genes, and inhibited histone H3 lysine 27 trimethylation in these promoter regions, resulting in upregulation of the tumor suppressors at both the mRNA and protein levels. The aim of this study was to explore the biological functions of a tetraspanin family protein––CD82–– expressed aberrantly in chemotherapy-resistant CD34+/CD38- acute myelogenous leukemia (AML) cells. Microarray analysis of patient-isolated CD34+/CD38- AML cells revealed that the levels of anti-apoptotic protein BCL2L12 were downregulated after CD82 depletion by specific shRNA. Western blot analysis indicated that BCL2L12 was aberrantly expressed in patient-isolated AML cells and AML cell lines. Furthermore, CD82 blockade by a specific antibody downregulated BCL2L12 in parallel with de-phosphorylation of STAT5 and AKT, while pharmacological inhibition of STAT5 and AKT activation decreased BCL2L12 expression in leukemia cells. In addition, shRNA-mediated downregulation of BCL2L12 increased the levels of cleaved caspase 3and suppressed proliferation of leukemia cells, impairing their engraftment in immunodeficient mice. Taken together, our results indicate that CD82 regulated BCL2L12 expression via STAT5A and AKT signaling and stimulated proliferation and engrafting of leukemia cells, suggesting that CD82 and BCL2L12 may be promising therapeutic targets in AML. Overall design: Two-condition experiment, 3 control shRNA-transduced CD34+CD38- AML cells (CS2) vs 3 CD82 shRNA-transduced CD34+CD38- AML cells (CD82). 3 control shRNA-transduced CD34+CD38- AML cells (CS2) vs 3 STAT5A shRNA-transduced CD34+CD38- AML cells (00-2).