Project description:The goal was to compare the transcriptome profiling of different human hematopoietic stem and progenitor populations to uncover the molecular mechanism involved in stemnes maintenance. Overall design: We isolated by flow cytomtery 5 highly purified populations (long term hematopoietic stem cells (LT-HSCs), short term hematopoietic stem cells (ST-HSCs), multipotent progenitors (MPPs), common myeloid progenitor (CMPs), granulocyte and monocyte progenitors (GMPs), multilymphoid progenitors (MLPs)) from 3 to 4 cord blood pools. We extracted RNA from all these populations and performed RNA-sequencing. Raw data files will be uploaded to EGA.
Project description:Genome-wide DNA methylation (DNAm) studies have proven extremely useful to understand human hematopoiesis. Due to their active DNA content, nucleated red blood cells (nRBCs) contribute to epigenetic and transcriptomic studies derived from whole cord blood. Genomic studies of cord blood hematopoietic cells isolated by fluorescence-activated cell sorting (FACS) may be significantly altered by heterotopic interactions with nRBCs during conventional cell sorting.We report that cord blood T cells, and to a lesser extent monocytes and B cells, physically engage with nRBCs during FACS. These heterotopic interactions resulted in significant cross-contamination of genome-wide epigenetic and transcriptomic data. Formal exclusion of erythroid lineage-specific markers yielded DNAm profiles (measured by the Illumina 450K array) of cord blood CD4 and CD8 T lymphocytes, B lymphocytes, natural killer (NK) cells, granulocytes, monocytes, and nRBCs that were more consistent with expected hematopoietic lineage relationships. Additionally, we identified eight highly differentially methylated CpG sites in nRBCs (false detection rate <5 %, |??| >0.50) that can be used to detect nRBC contamination of purified hematopoietic cells or to assess the impact of nRBCs on whole cord blood DNAm profiles. Several of these erythroid markers are located in or near genes involved in erythropoiesis (ZFPM1, HDAC4) or immune function (MAP3K14, IFIT1B), reinforcing a possible immune regulatory role for nRBCs in early life.Heterotopic interactions between erythroid cells and white blood cells can result in contaminated cell populations if not properly excluded during cell sorting. Cord blood nRBCs have a distinct DNAm profile that can significantly skew epigenetic studies. Our findings have major implications for the design and interpretation of genome-wide epigenetic and transcriptomic studies using human cord blood.
Project description:<h4>Background</h4>Premature infants are highly vulnerable to infection. This is partly attributable to the preterm immune system, which differs from that of the term neonate in cell composition and function. Multiple studies have found differential DNA methylation (DNAm) between preterm and term infants' cord blood; however, interpretation of these studies is limited by the confounding factor of blood cell composition. This study evaluates the epigenetic impact of preterm birth in isolated hematopoietic cell populations, reducing the concern of cell composition differences.<h4>Methods</h4>Genome-wide DNAm was measured using the Illumina 450K array in T cells, monocytes, granulocytes, and nucleated red blood cells (nRBCs) isolated from cord blood of 5 term and 5 preterm (<31 weeks gestational age) newborns. DNAm of hematopoietic cells was compared globally across the 450K array and through site-specific linear modeling.<h4>Results</h4>Nucleated red blood cells (nRBCs) showed the most extensive changes in DNAm, with 9258 differentially methylated (DM) sites (FDR?<?5%, |??|?>?0.10) discovered between preterm and term infants compared to the <1000 prematurity-DM sites identified in white blood cell populations. The direction of DNAm change with gestational age at these prematurity-DM sites followed known patterns of hematopoietic differentiation, suggesting that term hematopoietic cell populations are more epigenetically mature than their preterm counterparts. Consistent shifts in DNAm between preterm and term cells were observed at 25 CpG sites, with many of these sites located in genes involved in growth and proliferation, hematopoietic lineage commitment, and the cytoskeleton. DNAm in preterm and term hematopoietic cells conformed to previously identified DNAm signatures of fetal liver and bone marrow, respectively.<h4>Conclusions</h4>This study presents the first genome-wide mapping of epigenetic differences in hematopoietic cells across the late gestational period. DNAm differences in hematopoietic cells between term and <31 weeks were consistent with the hematopoietic origin of these cells during ontogeny, reflecting an important role of DNAm in their regulation. Due to the limited sample size and the high coincidence of prematurity and multiple births, the relationship between cause of preterm birth and DNAm could not be evaluated. These findings highlight gene regulatory mechanisms at both cell-specific and systemic levels that may be involved in fetal immune system maturation.
Project description:We isolated by fluorescence-activated cell sorting highly purified populations (long term hematopoietic stem cells (LT-HSCs), short term hematopoietic stem cells (ST-HSCs), multipotent progenitors (MPPs), common myeloid progenitor (CMPs), granulocyte and monocyte progenitors (GMPs), multilymphoid progenitors (MLPs), Myeloid-erythorid Progenitor (MEP), Granulocytes, Monocytes, B cells, T cells, Dendritic cells, Natural Killer cells and Erythrocyte Progenitors from 3 to 4 cord blood pools. We extracted RNA from 5K cells of each population and performed RNA-sequencing.
Project description:Experiments using xenografts show that some solid tumours and leukemias are organized as cellular hierarchies sustained by cancer stem cells (CSC). Despite promise, the relevance of the CSC model to human disease remains uncertain. Here we show that acute myeloid leukemia (AML) follows a CSC model based on sorting multiple populations from each of 16 primary human AML samples and identifying which contain leukemia stem cells (LSC) using a sensitive xenograft assay. Analysis of gene expression from all functionally validated populations yielded an LSC-specific signature. Similarly, a hematopoietic stem cell (HSC) gene signature was established. Bioinformatic analysis identified a core transcriptional program shared by LSC and HSC, revealing the molecular machinery underlying stemness properties. Both stem cell programs were highly significant independent predictors of patient survival and also found in existing prognostic signatures. Thus, determinants of stemness influence clinical outcome of AML establishing that LSC are clinically relevant and not mere artifacts of xenotransplantation. Analysis of gene expression in FACS sorted cord blood fractions that were functionally determined to be enriched for HSC or not (6 and 6 respectively). 12 samples were hybridized to Affymetrix HG_U133A microarray [HG_U133A] or Affymetrix HG_U133B microarray [HC_U133B]
Project description:Mouse hematopoiesis is initiated by long-term hematopoietic stem cells (HSC) that differentiate into a series of multipotent progenitors that exhibit progressively diminished self-renewal ability. In human hematopoiesis, populations enriched for HSC activity have been identified, as have downstream lineage-committed progenitors, but multipotent progenitor activity has not been uniquely isolated. Previous reports indicate that human HSC are enriched in Lin-CD34+CD38- cord blood and bone marrow and express CD90. We demonstrate that the Lin-CD34+CD38- fraction of cord blood and bone marrow can be subdivided into three subpopulations: CD90+CD45RA-, CD90-CD45RA-, and CD90-CD45RA+. Utilizing in vivo transplantation studies and complementary in vitro assays, we demonstrate that the Lin-CD34+CD38-CD90+CD45RA- cord blood fraction contains HSC and isolate this activity to as few as 10 purified cells. Furthermore, we report the first prospective isolation of a population of candidate human multipotent progenitors, Lin-CD34+CD38-CD90-CD45RA- cord blood.
Project description:Natural killer (NK) cells derived or isolated from different sources have been gaining in importance for cancer therapies. In this study, we evaluate and compare key characteristics between NK cells derived or isolated from umbilical cord blood, umbilical cord blood hematopoietic stem/progenitor cells, peripheral blood, and induced pluripotent stem cells (iPSCs). Specifically, we find CD56+ NK cells isolated and expanded directly from umbilical cord blood (UCB56) and NK cells derived from CD34+ hematopoietic stem/progenitors in umbilical cord blood (UCB34) differ in their expression of markers associated with differentiation including CD16, CD2, and killer Ig-like receptors (KIRs). UCB56-NK cells also displayed a more potent cytotoxicity compared to UCB34-NK cells. NK cells derived from iPSCs (iPSC-NK cells) were found to have variable KIR expression, with certain iPSC-NK cell populations expressing high levels of KIRs and others not expressing KIRs. Notably, KIR expression on UCB56 and iPSC-NK cells had limited effect on cytotoxic activity when stimulated by tumor target cells that express high levels of cognate HLA class I, suggesting that in vitro differentiation and expansion may override the KIR-HLA class I mediated inhibition when used across HLA barriers. Together our results give a better understanding of the cell surface receptor, transcriptional, and functional differences between NK cells present in umbilical cord blood and hematopoietic progenitor-derived NK cells which may prove important in selecting the most active NK cell populations for treatment of cancer or other therapies.
Project description:The small number of hematopoietic stem and progenitor cells in cord blood units limits their widespread use in human transplant protocols. We identified a family of chemically related small molecules that stimulates the expansion ex vivo of human cord blood cells capable of reconstituting human hematopoiesis for at least 6 months in immunocompromised mice. The potent activity of these newly identified compounds, UM171 being the prototype, is independent of suppression of the aryl hydrocarbon receptor, which targets cells with more-limited regenerative potential. The properties of UM171 make it a potential candidate for hematopoietic stem cell transplantation and gene therapy.
Project description:Genome-wide DNA methylation (DNAm) studies have been extremely useful to understand hematopoiesis in humans. For cell-specific epigenetic studies, fluorescence-activated cell sorting (FACS) is the gold standard technique to isolate homogeneous cell populations of interest. However, in cord blood, the DNAm signature of isolated hematopoietic cells may be significantly altered by heterotopic interactions with nucleated red blood cells (nRBCs) that go undetected during conventional cell sorting. Using the Illumina 450K array, genome-wide DNAm profiles of the following cell types were obtained: (1) T lymphocytes, monocytes, and nRBCs isolated using a “standard” strategy lacking exclusion for erythroid lineage markers; and (2) CD4 and CD8 T lymphocytes, B lymphocytes, Natural Killer (NK) cells, granulocytes, monocytes, and nRBCs isolated using a “stringent” strategy formally excluding erythroid lineage-specific markers. DNAm profiles of cord blood cells isolated by the standard sorting strategy showed significant heterotopic cross-contamination between cell populations, whereas the cord blood cells sorted by the stringent strategy displayed DNAm profiles more consistent with their expected hematopoietic lineage relationships. Overall design: Bisulphite-converted DNA from 15 cord blood cell populations sorted by a standard FACS protocol with no erythroid exclusion (T cells, monocytes, and nucleated RBCs collected from 5 cord blood samples) and from 48 cord blood cell populations sorted by a stringent FACS protocol formally excluding erythroid lineage-specific marker CD235 (B cells, CD4 and CD8 T cells, granulocytes, monocytes, NK cells, and nucleated RBCs collected from 7 cord blood samples; CD8 T cells were not collected from one sample) were hybridized to the Illumina Infinium HumanMethylation450 BeadChip.
Project description:Hemogenic endothelium has been identified in embryonic dorsal aorta and in tissues generated from mouse embryonic stem cells, but to date there is no evidence for such bipotential cells in postnatal tissues or blood. Here we identify a cell population from human umbilical cord blood that gives rise to both endothelial cells and hematopoietic progenitors in vitro. Cord blood CD34+/CD133+ cells plated at high density in an endothelial basal medium formed an endothelial monolayer and a nonadherent cell population after 14-21 days. AML-1, a factor required for definitive hematopoiesis, was detected at low levels in adherent cells and at high levels in nonadherent cells. Nonadherent cells coexpressed the endothelial marker vascular endothelial (VE)-cadherin and the hematopoietic marker CD45, whereas adherent cells were composed primarily of VE-cadherin+/CD45- cells and a smaller fraction of VE-cadherin+/CD45+ cells. Both nonadherent and adherent cells produced hematopoietic colonies in methylcellulose, with the adherent cells yielding more colony-forming units (CFU)-GEMM compared with the nonadherent cells. To determine whether the adherent endothelial cells were producing hematopoietic progenitors, single cells from the adherent population were expanded in 96-well dishes for 14 days. The clonal populations expressed VE-cadherin, and a subset expressed AML-1, epsilon-globin, and gamma-globin. Three of 17 clonal cell populations gave rise to early CFU-GEMM hematopoietic progenitors and burst-forming unit-erythroid progenitors. These results provide evidence for hemogenic endothelial cells in human umbilical cord blood.