| 1. |
- Adolfsson, Jörgen, et al.
(författare)
-
Identification of Flt3(+) lympho-myeloid stem cells lacking erythro-megakaryocytic potential: A revised road map for adult blood lineage commitment
- 2005
-
Ingår i: Cell. - : Elsevier (Cell Press). - 0092-8674 .- 1097-4172. ; 121:2, s. 295-306
-
Tidskriftsartikel (refereegranskat)abstract
- All blood cell lineages derive from a common hematopoietic stem cell (HSC). The current model implicates that the first lineage commitment step of adult pluripotent HSCs results in a strict separation into common lymphoid and common myeloid precursors. We present evidence for a population of cells which, although sustaining a high proliferative and combined lympho-myeloid differentiation potential, have lost the ability to adopt erythroid and megakaryocyte lineage fates. Cells in the Lin-Sca-1+c-kit+ HSC compartment coexpressing high levels of the tyrosine kinase receptor Flt3 sustain granulocyte, monocyte, and B and T cell potentials but in contrast to Lin-Sca-1(+)ckit(+)Flt3(-) HSCs fail to produce significant erythroid and megakaryocytic progeny. This distinct lineage restriction site is accompanied by downregulation of genes for regulators of erythroid and megakaryocyte development. In agreement with representing a lymphoid primed progenitor, Lin(-)Sca-l(+)c-kit(+)CD34(+)Flt3(+) cells display upregulated IL-7 receptor gene expression. Based on these observations, we propose a revised road map for adult blood lineage development.
|
|
| 2. |
- Azzoni, Emanuele, et al.
(författare)
-
The onset of circulation triggers a metabolic switch required for endothelial to hematopoietic transition
- 2021
-
Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 37:11
-
Tidskriftsartikel (refereegranskat)abstract
- Hematopoietic stem cells (HSCs) emerge during development from the vascular wall of the main embryonic arteries. The onset of circulation triggers several processes that provide critical external factors for HSC generation. Nevertheless, it is not fully understood how and when the onset of circulation affects HSC emergence. Here we show that in Ncx1−/− mouse embryos devoid of circulation the HSC lineage develops until the phenotypic pro-HSC stage. However, these cells reside in an abnormal microenvironment, fail to activate the hematopoietic program downstream of Runx1, and are functionally impaired. Single-cell transcriptomics shows that during the endothelial-to-hematopoietic transition, Ncx1−/− cells fail to undergo a glycolysis to oxidative phosphorylation metabolic switch present in wild-type cells. Interestingly, experimental activation of glycolysis results in decreased intraembryonic hematopoiesis. Our results suggest that the onset of circulation triggers metabolic changes that allow HSC generation to proceed.
|
|
| 3. |
- Broeske, Ann-Marie, et al.
(författare)
-
DNA methylation protects hematopoietic stem cell multipotency from myeloerythroid restriction
- 2009
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:11, s. 69-1207
-
Tidskriftsartikel (refereegranskat)abstract
- DNA methylation is a dynamic epigenetic mark that undergoes extensive changes during differentiation of self-renewing stem cells. However, whether these changes are the cause or consequence of stem cell fate remains unknown. Here, we show that alternative functional programs of hematopoietic stem cells (HSCs) are governed by gradual differences in methylation levels. Constitutive methylation is essential for HSC self-renewal but dispensable for homing, cell cycle control and suppression of apoptosis. Notably, HSCs from mice with reduced DNA methyltransferase 1 activity cannot suppress key myeloerythroid regulators and thus can differentiate into myeloerythroid, but not lymphoid, progeny. A similar methylation dosage effect controls stem cell function in leukemia. These data identify DNA methylation as an essential epigenetic mechanism to protect stem cells from premature activation of predominant differentiation programs and suggest that methylation dynamics determine stem cell functions in tissue homeostasis and cancer.
|
|
| 4. |
- Bryder, David, et al.
(författare)
-
Deficiency of oncoretrovirally transduced hematopoietic stem cells and correction through ex vivo expansion.
- 2005
-
Ingår i: Journal of Gene Medicine. - : Wiley. - 1521-2254 .- 1099-498X. ; 7:2, s. 137-144
-
Tidskriftsartikel (refereegranskat)abstract
- Background Extensive efforts to develop hematopoietic stem cell (HSC) based gene therapy have been hampered by low gene marking. Major emphasis has so far been directed at improving gene transfer efficiency, but low gene marking in transplanted recipients might equally well reflect compromised repopulating activity of transduced cells, competing for reconstitution with endogenous and unmanipulated stem cells. Methods The autologous settings of clinical gene therapy protocols preclude evaluation of changes in repopulating ability following transduction; however, using a congenic mouse model, allowing for direct evaluation of gene marking of lympho-myeloid progeny, we show here that these issues can be accurately addressed. Results We demonstrate that conditions supporting in vitro stem cell self-renewal efficiently promote oncoretroviral-mediated gene transfer to multipotent adult bone marrow stem cells, without prior in vivo conditioning. Despite using optimized culture conditions, transduction resulted in striking losses of repopulating activity, translating into low numbers of gene marked cells in competitively repopulated mice. Subjecting transduced HSCs to an ex vivo expansion protocol following the transduction procedure could partially reverse this loss. Conclusions These studies suggest that loss of repopulating ability of transduced HSCs rather than low gene transfer efficiency might be the main problem in clinical gene therapy protocols, and that a clinically feasible ex vivo expansion approach post-transduction can markedly improve reconstitution with gene marked stem cells.
|
|
| 5. |
- Bryder, David, et al.
(författare)
-
Self-renewal of multipotent long-term repopulating hematopoietic stem cells is negatively regulated by Fas and tumor necrosis factor receptor activation
- 2001
-
Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 194:7, s. 941-952
-
Tidskriftsartikel (refereegranskat)abstract
- Multipotent self-renewing hematopoietic stem cells (HSCs) are responsible for reconstitution of all blood cell lineages. Whereas growth stimulatory cytokines have been demonstrated to promote HSC self-renewal, the potential role of negative regulators remains elusive. Receptors for tumor necrosis factor (TNF) and Fas ligand have been implicated as regulators of steady-state hematopoiesis, and if overexpressed mediate bone marrow failure. However, it has been proposed that hematopoietic progenitors rather than stem cells might be targeted by Fas activation. Here, murine Lin(-)Sca1(+)c-kit(+) stem cells revealed little or no constitutive expression of Fas and failed to respond to an agonistic anti-Fas antibody. However, if induced to undergo self-renewal in the presence of TNF-alpha, the entire short and long-term repopulating HSC pool acquired Fas expression at high levels and concomitant activation of Fas suppressed in vitro growth of Lin(-)Sca1(+)c-kit(+) cells cultured at the single cell level. Moreover, Lin(-)Sca1(+)c-kit(+) stem cells undergoing self-renewal divisions in vitro were severely and irreversibly compromised in their short- and long-term multilineage reconstituting ability if activated by TNF-alpha or through Fas, providing the first evidence for negative regulators of HSC self-renewal.
|
|
| 6. |
- Buza-Vidas, Natalija, et al.
(författare)
-
FLT3 receptor and ligand are dispensable for maintenance and posttransplantation expansion of mouse hematopoietic stem cells
- 2009
-
Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 113:15, s. 3453-3460
-
Tidskriftsartikel (refereegranskat)abstract
- Originally cloned from hematopoietic stem cell (HSC) populations and its ligand being extensively used to promote ex vivo HSC expansion, the FMS-like tyrosine kinase 3 (FLT3; also called FLK2) receptor and its ligand (FL) were expected to emerge as an important physiologic regulator of HSC maintenance and expansion. However, the role of FLT3 receptor and ligand in HSC regulation remains unclear and disputed. Herein, using Fl-deficient mice, we establish for the first time that HSC expansion in fetal liver and after transplantation is FL independent. Because previous findings in Flk2(-/-) mice were compatible with an important role of FLT3 receptor in HSC regulation and because alternative ligands might potentially interact directly or indirectly with FLT3 receptor, we here also characterized HSCs in Flk2(-/-) mice. Advanced phenotypic as well as functional evaluation of Flk2(-/-) HSCs showed that the FLT3 receptor is dispensable for HSC steady-state maintenance and expansion after transplantation. Taken together, these studies show that the FLT3 receptor and ligand are not critical regulators of mouse HSCs, neither in steady state nor during fetal or posttransplantation expansion. (Blood. 2009; 113: 3453-3460)
|
|
| 7. |
- Castor, Anders, et al.
(författare)
-
Distinct patterns of hematopoietic stem cell involvement in acute lymphoblastic leukemia
- 2005
-
Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 11:6, s. 630-637
-
Tidskriftsartikel (refereegranskat)abstract
- The cellular targets of primary mutations and malignant transformation remain elusive in most cancers. Here, we show that clinically and genetically different subtypes of acute lymphoblastic leukemia (ALL) originate and transform at distinct stages of hematopoietic development. Primary ETV6-RUNX1 (also known as TEL-AML1) fusions and subsequent leukemic transformations were targeted to committed B-cell progenitors. Major breakpoint BCR-ABL1 fusions (encoding P210 BCR-ABL1) originated in hematopoietic stem cells (HSCs), whereas minor BCR-ABL1 fusions (encoding P190 BCR-ABL1) had a B-cell progenitor origin, suggesting that P190 and P210 BCR-ABL1 ALLs represent largely distinct tumor biological and clinical entities. The transformed leukemia-initiating stem cells in both P190 and P210 BCR-ABL1 ALLs had, as in ETV6-RUNX1 ALLs, a committed B progenitor phenotype. In all patients, normal and leukemic repopulating stem cells could successfully be separated prospectively, and notably, the size of the normal HSC compartment in ETV6-RUNX1 and P190 BCR-ABL1 ALLs was found to be unaffected by the expansive leukemic stem cell population.
|
|
| 8. |
|
|
| 9. |
- Jacobsen, Sten Eirik W
(författare)
-
Bytte mellom legemidler - nok en gang
- 2008
-
Ingår i: Tidsskrift for den Norske Laegeforening. - 0807-7096. ; 128:2, s. 204-205
-
Tidskriftsartikel (refereegranskat)
|
|
| 10. |
- Jacobsen, Sten Eirik W
(författare)
-
Defining 'stemness': Notch and Wnt join forces?
- 2005
-
Ingår i: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 6:3, s. 234-236
-
Tidskriftsartikel (refereegranskat)
|
|
