The Experts below are selected from a list of 2202 Experts worldwide ranked by ideXlab platform
James A. Thomson - One of the best experts on this subject based on the ideXlab platform.
-
an expandable inducible hemangioblast state regulated by fibroblast growth factor
Stem cell reports, 2014Co-Authors: David T Vereide, Vernella Vickerman, Brian E Mcintosh, Scott Swanson, James A. ThomsonAbstract:During development, the hematopoietic and vascular lineages are thought to descend from common mesodermal progenitors called Hemangioblasts. Here we identify six transcription factors, Gata2, Lmo2, Mycn, Pitx2, Sox17, and Tal1, that “trap” murine cells in a proliferative state and endow them with a hemangioblast potential. These “expandable” Hemangioblasts (eHBs) are capable, once released from the control of the ectopic factors, to give rise to functional endothelial cells, multilineage hematopoietic cells, and smooth muscle cells. The eHBs can be derived from embryonic stem cells, from fetal liver cells, or poorly from fibroblasts. The eHBs reveal a central role for fibroblast growth factor, which not only promotes their expansion, but also facilitates their ability to give rise to endothelial cells and leukocytes, but not erythrocytes. This study serves as a demonstration that ephemeral progenitor states can be harnessed in vitro, enabling the creation of tractable progenitor cell lines.
George Q. Daley - One of the best experts on this subject based on the ideXlab platform.
-
a role for thrombopoietin in hemangioblast development
Stem Cells, 2003Co-Authors: Rita C. R. Perlingeiro, Susan Bodie, Michael Kyba, George Q. DaleyAbstract:Vascular endothelial growth factor (VEGF) and stem cell factor (SCF) act as growth factors for the hemangioblast, an embryonic progenitor of the hematopoietic and endothelial lineages. Because thrombopoietin (TPO) and its receptor, c-Mpl, regulate primitive hematopoietic populations, including bone marrow hematopoietic stem cells, we investigated whether TPO acts on the Hemangioblasts that derive from differentiation of embryonic stem cells in vitro. Reverse transcriptase polymerase chain reaction analysis detected expression of c-Mpl beginning on day 3 of embryoid body differentiation when the hemangioblast first arises. In assays of the hemangioblast colony-forming cell (BL-CFC), TPO alone supported BL-CFC formation and nearly doubled the number of BL-CFC when added together with VEGF and SCF. When replated under the appropriate conditions, TPO-stimulated BL-CFC gave rise to secondary hematopoietic colonies, as well as endothelial cells, confirming their nature as Hemangioblasts. Addition of a neutralizing anti-VEGF antibody did not block TPO enhancement of BL-CFC formation, suggesting that TPO acts independently of VEGF. These results establish that Mpl signaling plays a role in the earliest stages of hematopoietic development and that TPO represents a third growth factor influencing hemangioblast formation.
Gordon Keller - One of the best experts on this subject based on the ideXlab platform.
-
numb mediates the interaction between wnt and notch to modulate primitive erythropoietic specification from the hemangioblast
Cell Research, 2008Co-Authors: Xin Cheng, Cristina M Nostro, Tara L Huber, Gordon Keller, Paul GadueAbstract:NUMB mediates the interaction between Wnt and Notch to modulate primitive erythropoietic specification from the hemangioblast
-
development of the hemangioblast defines the onset of hematopoiesis in human es cell differentiation cultures
Blood, 2007Co-Authors: Marion Kennedy, Sunita L Dsouza, Macarena Lynchkattman, Staci Schwantz, Gordon KellerAbstract:The onset of hematopoiesis in the mouse embryo and in the embryonic stem (ES) cell differentiation model is defined by the emergence of the hemangioblast, a progenitor with both hematopoietic and vascular potential. While there is evidence for the existence of a hemangioblast in the mouse, it is unclear if this progenitor develops during the establishment of the human hematopoietic system. In this report, we have mapped hematopoietic development in human ES cell (hESC) differentiation cultures and demonstrated that a comparable hemangioblast population exists. The human Hemangioblasts were identified by their capacity to generate blast colonies that display both hematopoietic and vascular potential. These colony-forming cells express the receptor tyrosine kinase KDR (VEGF receptor 2) and represent a transient population that develops in BMP-4–stimulated embryoid bodies (EBs) between 72 and 96 hours of differentiation, prior to the onset of the primitive erythroid program. Two distinct types of Hemangioblasts were identified, those that give rise to primitive erythroid cells, macrophages, and endothelial cells and those that generate only the primitive erythroid population and endothelial cells. These findings demonstrate for the first time the existence of the human hemangioblast and in doing so identify the earliest stage of hematopoietic commitment.
-
smad1 expands the hemangioblast population within a limited developmental window
Blood, 2007Co-Authors: Brian T Zafonte, Marion Kennedy, Macarena Lynchkattman, Ingrid Torregroza, Luke Benvenuto, Gordon Keller, Todd EvansAbstract:Bone morphogenetic protein (BMP) signaling is an important regulator of hematovascular development. However, the progenitor population that responds to BMP signaling is undefined, and the relative role of downstream mediators including Smad1 is unclear. We find that Smad1 shows a distinctive expression profile as embryonic stem (ES) cells undergo differentiation in the embryoid body (EB) system, with peak levels in cell populations enriched for the hemangioblast. To test the functional relevance of this observation, we generated an ES cell line that allows temporal control of ectopic Smad1 expression. Continuous expression of Smad1 from day 2 of EB culture does not disturb hematopoiesis, according to colony assays. In contrast, a pulse of Smad1 expression exclusively between day 2 and day 2.25 expands the population of progenitors for primitive erythroblasts and other hematopoietic lineages. This effect correlates with increased levels of transcripts encoding markers for the hemangioblast, including Runx1, Scl, and Gata2. Indeed, the pulse of Smad1 induction also expands the blast colony-forming cell (BL-CFC) population at a level that is fully sufficient to explain subsequent increases in hematopoiesis. Our data demonstrate that Smad1 expression is sufficient to expand the number of cells that commit to hemangioblast fate.
-
regulation of hemangioblast development
Annals of the New York Academy of Sciences, 2006Co-Authors: Georges Lacaud, Marion Kennedy, Scott M Robertson, James Palis, Gordon KellerAbstract:: The in vitro differentiation of embryonic stem (ES) cells provides a powerful approach for studying the earliest events involved in the commitment of the hematopoietic and endothelial lineages. Using this model system, we have identified a precursor with the potential to generate both primitive and definitive hematopoietic cells as well as cells with endothelial characteristics. The developmental potential of this precursor suggests that it represents the in vitro equivalent of the hemangioblast, a common stem cell for both lineages. ES cells deficient for the transcription factor scl/tal-1 are unable to generate Hemangioblasts, while those deficient for Runx1 generate reduced numbers of these precursors. These findings indicate that both genes play pivotal roles at the earliest stages of hematopoietic and endothelial development. In addition, they highlight the strength of this model system in studying the function of genes in embryonic development.
-
hypoxia affects mesoderm and enhances hemangioblast specification during early development
Development, 2004Co-Authors: Diana L Ramirezbergeron, Anja Runge, Karen Cowden D Dahl, Hans Joerg Fehling, Gordon Keller, Celeste M SimonAbstract:Hypoxia Inducible Factor (HIF), consisting of HIF1α and ARNT (HIF1β) subunits, activates multiple genes in response to oxygen (O 2 ) deprivation. Arnt –/– mice exhibit substantial defects in blood cell and vessel development. We demonstrate that hypoxia accelerates the expression of Brachyury (a mesoderm-specific transcription factor), BMP4 (a mesoderm-promoting growth factor) and FLK1 (a marker of Hemangioblasts, the bipotential progenitor of endothelial and hematopoietic cells) in differentiating ES cell cultures. Significantly, proliferation of embryonic Hemangioblasts (BL-CFCs) is regulated by hypoxia, as Arnt +/+ ES cells generate increased numbers of FLK1 + cells, and BL-CFCs with accelerated kinetics in response to low O 2 . This response is HIF-dependent as Arnt –/– ES cells produce fewer FLK1 + cells and BL-CFCs, under both normoxic and hypoxic conditions. Interestingly, this defect is rescued when Arnt –/– ES cells are co-cultured with Arnt +/+ ES cells. Vegf +/– or Vegf –/– ES cells generate proper numbers of FLK1 + cells but fewer BL-CFCs, suggesting that additional factors regulated by HIF (other than VEGF) are involved in these early events. Thus, hypoxic responses are important for the establishment of various progenitor cells, including early mesoderm and its differentiation into Hemangioblasts. Together these data suggest that ineffective responses to hypoxia in Arnt –/– embryos abrogate proper cardiovascular development during early embryogenesis, including the pathways controlling hemangioblast differentiation.
Amin M Arnaout - One of the best experts on this subject based on the ideXlab platform.
-
differential role of the transcription factor zbp 89 in hemangioblast fate determination zbp 89 is a direct regulator of scl
Blood, 2007Co-Authors: Xiangen Li, C S Shelley, Amin M ArnaoutAbstract:Several molecular pathways have been identified that regulate distinct stages in the developmental progression from mesoderm to the formation of the hematopoietic and vascular lineages. Our previous work indicated that ectopic expression of the zinc finger transcription factor ZBP-89 promotes hematopoietic lineage development and represses endothelial cell lineage differentiation from Hemangioblasts in murine embryonic stem cells. Here we evaluated the functional consequences of stable knockdown of ZBP-89 in embryonic stem cells (ESC) on hematopoietic and vascular development. Stable knock down of ZBP-89 in ESC significantly decreased the number of Blast Colony Forming Cells (BL-CFC) Hemangioblasts, as well as primitive and definitive hematopoietic progenitor colonies BFU-E, GM-CFU, G-CFU, M-CFU and GEMM-CFU in vitro. In contrast, sprouting angiogenesis was markedly increased in EB cultures. Flow cytometric analysis of the lineages derived from ZBP-89 deficient EB cultures showed that the early (C-kit+Sca-1+) and definitive (CD45+) hematopoietic stem cells populations were reduced, but the endothelial cell population (CD31+ VE-Cadherin+) was increased. RT-PCR analysis of EB cultures revealed a direct correlation between the expression levels of ZBP-89 and hematopoietic markers (including SCL and Runx1) but an inverse correlation with the vascular marker CD31, with no change in Oct4 expression level. To investigate the mechanism underlying the role of ZBP-89 in hematopoiesis, the effect of ZBP-89 on expression of SCL, a master regulator of hematopoiesis, was examined. The murine SCL promoter transduced into the ZBP-89-expressing MEL cell line drove luciferase gene expression. ZBP-89 knockdown in MEL cells markedly reduced SCL expression. ChIP analysis showed that endogenous ZBP-89 protein bound directly to the murine SCL promoter in MEL cells. Thus ZBP-89 plays a central role in fate determination of Hemangioblasts; its induction suppresses angiogenesis but enhances differentiation of Hemangioblasts along the hematopoietic pathway, an effect mediated through the regulated expression of SCL.
Byoung S Kwon - One of the best experts on this subject based on the ideXlab platform.
-
in vitro development of a hemangioblast from a human embryonic stem cell snuhes 3
Life Sciences, 2009Co-Authors: Jaehyeog Choi, Byoung S KwonAbstract:AIMS: Recent reports demonstrated that a hemangioblast population emerged during hematopoietic development in both mouse and human embryonic stem cell (hESC) differentiation cultures. MAIN METHODS: In this study, a new uncharacterized hESC line, SNUhES#3, was studied for its capacity to proliferate with STO cells and differentiate into Hemangioblasts in co-culture with OP9 cells. KEY FINDINGS: We were able to obtain CD34(+)CD45(-) cells from SNUhES#3 cells after 12 days of in vitro culture, and this cell population could be maximized to 12.6% of the total. These cells, derived from SNUhES#3, showed the morphology of hematopoietic precursor cells and endothelial lineage cells with high efficiency. Reverse transcription polymerase chain reaction (RT-PCR) analysis showed that the hematopoietic markers CD34, GATA2, and LMO2 were co-expressed with the endothelial marker CD31 from day 8, whereas ES cell marker OCT4 no longer existed at an early stage. Moreover, we found that the efficacy of colony forming by SNUhES#3 cells is better than that of H9 cells. SIGNIFICANCE: These findings provide evidence that SNUhES#3 cells can be used as an established human ESC line, and co-culture with OP9 can induce SNUhES#3 cells to differentiate into Hemangioblasts, the common precursors of the hematopoietic and endothelial lineages.
-
In vitro development of a hemangioblast from a human embryonic stem cell, SNUhES#3.
Life Sciences, 2009Co-Authors: Jaehyeog Choi, Byoung S KwonAbstract:AIMS: Recent reports demonstrated that a hemangioblast population emerged during hematopoietic development in both mouse and human embryonic stem cell (hESC) differentiation cultures. MAIN METHODS: In this study, a new uncharacterized hESC line, SNUhES#3, was studied for its capacity to proliferate with STO cells and differentiate into Hemangioblasts in co-culture with OP9 cells. KEY FINDINGS: We were able to obtain CD34(+)CD45(-) cells from SNUhES#3 cells after 12 days of in vitro culture, and this cell population could be maximized to 12.6% of the total. These cells, derived from SNUhES#3, showed the morphology of hematopoietic precursor cells and endothelial lineage cells with high efficiency. Reverse transcription polymerase chain reaction (RT-PCR) analysis showed that the hematopoietic markers CD34, GATA2, and LMO2 were co-expressed with the endothelial marker CD31 from day 8, whereas ES cell marker OCT4 no longer existed at an early stage. Moreover, we found that the efficacy of colony forming by SNUhES#3 cells is better than that of H9 cells. SIGNIFICANCE: These findings provide evidence that SNUhES#3 cells can be used as an established human ESC line, and co-culture with OP9 can induce SNUhES#3 cells to differentiate into Hemangioblasts, the common precursors of the hematopoietic and endothelial lineages.
-
In vitro development of a hemangioblast from a human embryonic stem cell, SNUhES#3.
Life Sciences, 2009Co-Authors: Jaehyeog Choi, Young-shin Ryu, Koo-hee Kim, Yoo-ra Lee, Ki-won Cha, In-seob Han, Byoung S KwonAbstract:Recent reports demonstrated that a hemangioblast population emerged during hematopoietic development in both mouse and human embryonic stem cell (hESC) differentiation cultures. In this study, a new uncharacterized hESC line, SNUhES#3, was studied for its capacity to proliferate with STO cells and differentiate into Hemangioblasts in co-culture with OP9 cells. We were able to obtain CD34(+)CD45(-) cells from SNUhES#3 cells after 12 days of in vitro culture, and this cell population could be maximized to 12.6% of the total. These cells, derived from SNUhES#3, showed the morphology of hematopoietic precursor cells and endothelial lineage cells with high efficiency. Reverse transcription polymerase chain reaction (RT-PCR) analysis showed that the hematopoietic markers CD34, GATA2, and LMO2 were co-expressed with the endothelial marker CD31 from day 8, whereas ES cell marker OCT4 no longer existed at an early stage. Moreover, we found that the efficacy of colony forming by SNUhES#3 cells is better than that of H9 cells. These findings provide evidence that SNUhES#3 cells can be used as an established human ESC line, and co-culture with OP9 can induce SNUhES#3 cells to differentiate into Hemangioblasts, the common precursors of the hematopoietic and endothelial lineages.