Zebrafish Cbfb Is Required For The Mobilization, But Not The Emergence, Of Hematopoietic Stem Cells In Embryos

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 464-464
Author(s):  
Erica Bresciani ◽  
Blake Carrington ◽  
Stephen Wincovitch ◽  
Aniket Gore ◽  
Brant M. Weinstein ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Notch Pathway ◽  
Targeted Mutagenesis ◽  
Dorsal Aorta ◽  
Human Leukemia ◽  
Hemogenic Endothelium ◽  
Hematopoietic Stem ◽  
Definitive Hematopoiesis

CBFβ and RUNX1 form a DNA-binding heterodimer that plays a crucial role during definitive hematopoiesis at the stage of hematopoietic stem cells (HSCs). Both of them are targets of recurrent chromosomal translocations in human leukemia. In mammals and zebrafish, RUNX1 is required for the emergence of definitive HSCs from the hemogenic endothelium. Mouse knockouts for either Runx1 or Cbfb show similar phenotypes with complete lack of definitive hematopoiesis. Therefore, the impairment of all definitive hematopoietic lineages in both Runx1-/- and Cbfb-/- embryos suggested that the CBF heterodimer is required for HSC formation. However the exact role of the CBF complex in the development of HSCs remains unclear. The cellular mechanisms and the genetic pathways driving the HSC generation are highly conserved across vertebrates. Thus, we used the zebrafish model to dissect the role of cbfb and the CBF complex in the emergence and the maintenance of HSCs. We generated two independent cbfb knockouts (cbfb-/-) by zinc-finger nuclease (ZFN) - mediated targeted mutagenesis. The analysis of cbfb-/- embryos revealed a previously unknown role of cbfb during definitive hematopoiesis. Similar to the published zebrafish runx1 mutant embryos (runx1W84X/W84X), cbfb-/- embryos underwent primitive hematopoiesis and developed erythromyeloid progenitors (EMPs), but they lacked definitive hematopoiesis as the expression of markers for differentiated blood lineages such as rag1, lplastin and αe1globin was completely abrogated. Moreover, circulating thrombocytes were almost undetectable in cbfb-/-/tg(cd41:GFP) embryos. Unlike the runx1 mutants in which HSCs are not formed, however, the emergence of runx1+/c-myb+ HSCs from the hemogenic endothelium along the ventral wall of the dorsal aorta was unaffected in the cbfb-/- mutants. Rather, the subsequent translocation of the HSCs from aorta-gonad-mesonephros (AGM) to the caudal hematopoietic tissue (CHT) was blocked, as evidenced by the accumulation of runx1+ HSCs in the AGM and the concomitant absence of such cells in the CHT. Live imaging analysis of cbfb-/-/tg(c-myb:eGFP) embryos confirmed that HSCs egressed from the dorsal aorta but did not enter circulation through the axial vein. Moreover, embryos treated with a specific inhibitor of RUNX1-CBFβ interaction, Ro5-3335, phenocopied the hematopoietic defects observed in the cbfb-/- mutants, confirming that the function of RUNX1 and CBFβ during HSC development could be uncoupled. The Notch-Runx1 pathway is critical for the initial specification of HSCs during definitive hematopoiesis. Therefore, in order to gain insight into the genetic mechanisms that regulate cbfb expression we investigated the Notch pathway. We found that transient Notch activation enhanced cbfb expression and expanded it ectopically. On the other hand, in the Notch signaling mutant mind bomb, cbfb expression in hematopoietic regions was abrogated. Thus, our results suggest that cbfb is also downstream of the Notch pathway during hematopoiesis. Overall our data indicate that CBFβ and functional CBFβ-RUNX1 heterodimers are not required for the emergence of HSCs, but are essential for the mobilization of HSCs during early definitive hematopoiesis. Disclosures: No relevant conflicts of interest to declare.

The role of children's bone marrow mesenchymal stromal cells in the ex vivo expansion of autologous and allogeneic hematopoietic stem cells

2015 ◽  
Vol 39 (10) ◽  
pp. 1099-1110 ◽  
Author(s):  
Iordanis Pelagiadis ◽  
Eftichia Stiakaki ◽  
Christianna Choulaki ◽  
Maria Kalmanti ◽  
Helen Dimitriou
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Mesenchymal Stromal Cells ◽  
Stromal Cells ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Hematopoietic Stem

scholarly journals The Dynamic Interface Between the Bone Marrow Vascular Niche and Hematopoietic Stem Cells in Myeloid Malignancy

2021 ◽  
Vol 9 ◽  
Author(s):  
Laura Mosteo ◽  
Joanna Storer ◽  
Kiran Batta ◽  
Emma J. Searle ◽  
Delfim Duarte ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Hematopoietic Stem ◽  
Vascular Niche ◽  
Dynamic Interface ◽  
Bone Marrow Vascular Niche ◽  
Bidirectional Interactions ◽  
Vascular Compartment

Hematopoietic stem cells interact with bone marrow niches, including highly specialized blood vessels. Recent studies have revealed the phenotypic and functional heterogeneity of bone marrow endothelial cells. This has facilitated the analysis of the vascular microenvironment in steady state and malignant hematopoiesis. In this review, we provide an overview of the bone marrow microenvironment, focusing on refined analyses of the marrow vascular compartment performed in mouse studies. We also discuss the emerging role of the vascular niche in “inflamm-aging” and clonal hematopoiesis, and how the endothelial microenvironment influences, supports and interacts with hematopoietic cells in acute myeloid leukemia and myelodysplastic syndromes, as exemplar states of malignant myelopoiesis. Finally, we provide an overview of strategies for modulating these bidirectional interactions to therapeutic effect in myeloid malignancies.

scholarly journals Accessibility Over Transposable Elements Reveals Genetic Determinants of Stemness Properties in Normal and Leukemic Hematopoiesis

2021 ◽  
Author(s):  
Bettina Nadorp ◽  
Giacomo Grillo ◽  
Aditi Qamra ◽  
Amanda Mitchell ◽  
Christopher Arlidge ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Chromatin Accessibility ◽  
Genetic Determinants ◽  
Hematopoietic Stem ◽  
Transcription Regulators ◽  
Docking Sites ◽  
Cellular Hierarchy ◽  
Mutational Processes

AbstractDespite most acute myeloid leukemia (AML) patients achieving complete remission after induction chemotherapy, two thirds of patients will relapse with fatal disease within 5 years. AML is organized as a cellular hierarchy sustained by leukemia stem cells (LSC) at the apex, with LSC properties directly linked to tumor progression, therapy failure and disease relapse 1–5. Despite the central role of LSC in poor patient outcomes, little is known of the genetic determinants of their stemness properties 6–8. Although much AML research focuses on mutational processes and their impact on gene expression programs, the genetic determinants of cell state properties including stemness expand beyond mutations, relying on the genetic architecture captured in the chromatin of each cell 9–11. As LSCs share many functional and molecular properties with normal hematopoietic stem cells (HSC), we identified genetic determinants of primitive populations enriched for LSCs and HSCs in comparison with their downstream mature progeny by investigating their chromatin accessibility. Our work reveals how distinct transposable element (TE) subfamilies are used in primitive versus mature populations, functioning as docking sites for stem cell-associated regulators of genome topology, including CTCF, or lineage-specific transcription regulators in primitive and mature populations, respectively. We further show how TE subfamilies accessible in LSCs define docking sites for several oncogenic drivers in AML, namely FLI1, LYL1 and MEIS1. Using chromatin accessibility profiles from a cohort of AML patients, we further show the clinical utility of our TE accessibility-based LSCTE121 scoring scheme to identify patients with high rates of relapse. Collectively, our work reveals how different accessible TE subfamilies serve as genetic determinants of stemness properties in normal and leukemic hematopoietic stem cells.

scholarly journals Scl isoforms act downstream of etsrp to specify angioblasts and definitive hematopoietic stem cells

Blood ◽  
2010 ◽  
Vol 115 (26) ◽  
pp. 5338-5346 ◽  
Author(s):  
Xi Ren ◽  
Gustavo A. Gomez ◽  
Bo Zhang ◽  
Shuo Lin
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Vascular Endothelial ◽  
Hematopoietic Stem ◽  
Vegf Signaling ◽  
Endothelial Growth Factor ◽  
Endothelial Development ◽  
Definitive Hematopoiesis ◽  
Runx1 Expression

Abstract Recent lineage studies suggest that hematopoietic stem cells (HSCs) may be derived from endothelial cells. However, the genetic hierarchy governing the emergence of HSCs remains elusive. We report here that zebrafish ets1-related protein (etsrp), which is essential for vascular endothelial development, also plays a critical role in the initiation of definitive hematopoiesis by controlling the expression of 2 stem cell leukemia (scl) isoforms (scl-α and scl-β) in angioblasts. In etsrp morphants, which are deficient in endothelial and HSC development, scl-α alone partially rescues angioblast specification, arterial-venous differentiation, and the expression of HSC markers, runx1 and c-myb, whereas scl-β requires angioblast rescue by fli1a to restore runx1 expression. Interestingly, when vascular endothelial growth factor (Vegf) signaling is inhibited, HSC marker expression can still be restored by scl-α in etsrp morphants, whereas the rescue of arterial ephrinb2a expression is blocked. Furthermore, both scl isoforms partially rescue runx1 but not ephrinb2a expression in embryos deficient in Vegf signaling. Our data suggest that downstream of etsrp, scl-α and fli1a specify the angioblasts, whereas scl-β further initiates HSC specification from this angioblast population, and that Vegf signaling acts upstream of scl-β during definitive hematopoiesis.

The transcription factor Erg is essential for definitive hematopoiesis and the function of adult hematopoietic stem cells

2008 ◽  
Vol 9 (7) ◽  
pp. 810-819 ◽  
Author(s):  
Stephen J Loughran ◽  
Elizabeth A Kruse ◽  
Douglas F Hacking ◽  
Carolyn A de Graaf ◽  
Craig D Hyland ◽  
...  
Keyword(s):  
Stem Cells ◽  
Transcription Factor ◽  
Hematopoietic Stem Cells ◽  
Hematopoietic Stem ◽  
Definitive Hematopoiesis

scholarly journals Rapid and sustained hematopoietic recovery in lethally irradiated mice transplanted with purified Thy-1.1lo Lin-Sca-1+ hematopoietic stem cells

Blood ◽  
1994 ◽  
Vol 83 (12) ◽  
pp. 3758-3779 ◽  
Author(s):  
N Uchida ◽  
HL Aguila ◽  
WH Fleming ◽  
L Jerabek ◽  
IL Weissman
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Blood Cells ◽  
Critical Role ◽  
White Blood Cells ◽  
Cell Types ◽  
Dose Dependence ◽  
Hematopoietic Stem ◽  
Hematopoietic Recovery

Abstract Hematopoietic stem cells (HSCs) are believed to play a critical role in the sustained repopulation of all blood cells after bone marrow transplantation (BMT). However, understanding the role of HSCs versus other hematopoietic cells in the quantitative reconstitution of various blood cell types has awaited methods to isolate HSCs. A candidate population of mouse HSCs, Thy-1.1lo Lin-Sca-1+ cells, was isolated several years ago and, recently, this population has been shown to be the only population of BM cells that contains HSCs in C57BL/Ka-Thy-1.1 mice. As few as 100 of these cells can radioprotect 95% to 100% of irradiated mice, resulting long-term multilineage reconstitution. In this study, we examined the reconstitution potential of irradiated mice transplanted with purified Thy-1.1lo Lin-Sca-1+ BM cells. Donor-derived peripheral blood (PB) white blood cells were detected as early as day 9 or 10 when 100 to 1,000 Thy-1.1lo Lin-Sca-1+ cells were used, with minor dose-dependent differences. The reappearance of platelets by day 14 and thereafter was also seen at all HSC doses (100 to 1,000 cells), with a slight dose-dependence. All studied HSC doses also allowed RBC levels to recover, although at the 100 cell dose a delay in hematocrit recovery was observed at day 14. When irradiated mice were transplanted with 500 Thy-1.1lo Lin-Sca-1+ cells compared with 1 x 10(6) BM cells (the equivalent amount of cells that contain 500 Thy-1.1lo Lin-Sca-1+ cells as well as progenitor and mature cells), very little difference in the kinetics of recovery of PB, white blood cells, platelets, and hematocrit was observed. Surprisingly, even when 200 Thy1.1lo Lin-Sca- 1+ cells were mixed with 4 x 10(5) Sca-1- BM cells in a competitive repopulation assay, most of the early (days 11 and 14) PB myeloid cells were derived from the HSC genotype, indicating the superiority of the Thy-1.1lo Lin-Sca-1+ cells over Sca-1- cells even in the early phases of myeloid reconstitution. Within the Thy-1.1lo Lin-Sca-1+ population, the Rhodamine 123 (Rh123)hi subset dominates in PB myeloid reconstitution at 10 to 14 days, only to be overtaken by the Rh123lo subset at 3 weeks and thereafter. These findings indicate that HSCs can account for the early phase of hematopoietic recovery, as well as sustained hematopoiesis, and raise questions about the role of non-HSC BM populations in the setting of BMT.

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