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ABSTRACT: Formation of the hematopoietic stem cell (HSC) niche in bone marrow (BM) is tightly associated with endochondral ossification, but little is known about the mechanisms involved. We used the oc/oc mouse, a mouse model with impaired endochondral ossification caused by a loss of osteoclast (OCL) activity, to investigate the role of osteoblasts (OBLs) and OCLs in the HSC niche formation. The absence of OCL activity resulted in a defective HSC niche associated with an increased proportion of mesenchymal progenitors but reduced osteoblastic differentiation, leading to impaired HSC homing to the BM. Restoration of OCL activity reversed the defect in HSC niche formation. Our data demonstrate that OBLs are required for establishing HSC niches and that osteoblastic development is induced by OCLs. These findings broaden our knowledge of the HSC niche formation, which is critical for understanding normal and pathological hematopoiesis.
Journal of Experimental Medicine 02/2012; 209(3):537-49. · 13.85 Impact Factor
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ABSTRACT: The earliest stages of natural killer (NK)-cell development are not well characterized. In this study, we investigated in different fetal hematopoietic tissues how NK-cell progenitors and their mature NK-cell progeny emerge and expand during fetal development. Here we demonstrate, for the first time, that the counterpart of adult BM Lin(-)CD122(+)NK1.1(-)DX5(-) NK-cell progenitor (NKP) emerges in the fetal liver at E13.5. After NKP expansion, immature NK cells emerge at E14.5 in the liver and E15.5 in the spleen. Thymic NK cells arise at E15.5, whereas functionally competent cytotoxic NK cells were present in the liver and spleen at E16.5 and E17.5, respectively. Fetal NKPs failed to produce B and myeloid cells but sustained combined NK- and T-lineage potential at the single-cell level. NKPs were also found in the fetal blood, spleen, and thymus. These findings show the emergence and expansion of bipotent NK/T-cell progenitor during fetal and adult lymphopoiesis, further supporting that NK/T-lineage restriction is taking place prethymically. Uncovering the earliest NK-cell developmental stages will provide important clues, helping to understand the origin of diverse NK-cell subsets, their progenitors, and key regulators.
Blood 11/2011; 120(1):63-75. · 9.90 Impact Factor
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Shabnam Kharazi,
Adam J Mead,
Anna Mansour,
Anne Hultquist,
Charlotta Böiers,
Sidinh Luc,
Natalija Buza-Vidas,
Zhi Ma,
Helen Ferry,
Debbie Atkinson,
Kristian Reckzeh,
Kristina Masson,
Jörg Cammenga,
Lars Rönnstrand,
Fumio Arai,
Toshio Suda,
Claus Nerlov, Ewa Sitnicka,
Sten Eirik W Jacobsen
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ABSTRACT: Acquisition of homozygous activating growth factor receptor mutations might accelerate cancer progression through a simple gene-dosage effect. Internal tandem duplications (ITDs) of FLT3 occur in approximately 25% cases of acute myeloid leukemia and induce ligand-independent constitutive signaling. Homozygous FLT3-ITDs confer an adverse prognosis and are frequently detected at relapse. Using a mouse knockin model of Flt3-internal tandem duplication (Flt3-ITD)-induced myeloproliferation, we herein demonstrate that the enhanced myeloid phenotype and expansion of granulocyte-monocyte and primitive Lin(-)Sca1(+)c-Kit(+) progenitors in Flt3-ITD homozygous mice can in part be mediated through the loss of the second wild-type allele. Further, whereas autocrine FLT3 ligand production has been implicated in FLT3-ITD myeloid malignancies and resistance to FLT3 inhibitors, we demonstrate here that the mouse Flt3(ITD/ITD) myeloid phenotype is FLT3 ligand-independent.
Blood 08/2011; 118(13):3613-21. · 9.90 Impact Factor
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Ewa Sitnicka
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ABSTRACT: Natural killer (NK) cells are large granular lymphocytes that are components of the innate immune system. These cells are key players in the defense against viral and other microbial infections and cancer and have an important function during pregnancy, autoimmunity and allergy. Furthermore, NK cells play important roles in hematopoietic stem cell (HSC) transplantation by providing the graft versus leukemia effect and preventing the development of graft versus host disease. Thus, understanding the developmental pathway(s) from multipotent HSCs to the NK cell lineage-restricted progenitors is of significant clinical value. However, despite extensive progress in the delineation of mature blood cell development, including the B- and T-cell lineages, the early stages of NK cell lineage commitment and development have been less well established and characterized. Here, I review the progress made thus far in dissecting the developmental stages, from HSCs in the bone marrow to the lineage-committed NK cells in mouse.
Journal of Innate Immunity 03/2011; 3(4):329-36. · 4.21 Impact Factor
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ABSTRACT: Although bone marrow (BM) is the main site of natural killer (NK)-cell development in adult mice, recent studies have identified a distinct thymic-dependent NK pathway, implicating a possible close link between NK- and T-cell development in adult hematopoiesis. To investigate whether a potential NK-/T-lineage restriction of multipotent progenitors might take place already in the BM, we tested the full lineage potentials of NK-cell progenitors in adult BM. Notably, although Lin(-)CD122(+)NK1.1(-)DX5(-) NK-cell progenitors failed to commit to the B and myeloid lineages, they sustained a combined NK- and T-cell potential in vivo and in vitro at the single-cell level. Whereas T-cell development from NK/T progenitors is Notch-dependent, their contribution to thymic and BM NK cells remains Notch-independent. These findings demonstrate the existence of bipotent NK-/T-cell progenitors in adult BM.
Blood 07/2010; 116(2):183-92. · 9.90 Impact Factor
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ABSTRACT: Mice deficient in c-fms-like tyrosine kinase 3 (FLT3) signaling have reductions in early multipotent and lymphoid progenitors, whereas no evident myeloid phenotype has been reported. However, activating mutations of Flt3 are among the most common genetic events in acute myeloid leukemia and mice harboring internal tandem duplications within Flt3 (Flt3-ITD) develop myeloproliferative disease, with characteristic expansion of granulocyte-monocyte (GM) progenitors (GMP), possibly compatible with FLT3-ITD promoting a myeloid fate of multipotent progenitors. Alternatively, FLT3 might be expressed at the earliest stages of GM development. Herein, we investigated the expression, function, and role of FLT3 in recently identified early GMPs. Flt3-cre fate-mapping established that most progenitors and mature progeny of the GM lineage are derived from Flt3-expressing progenitors. A higher expression of FLT3 was found in preGMP compared with GMP, and preGMPs were more responsive to stimulation with FLT3 ligand (FL). Whereas preGMPs and GMPs were reduced in Fl(-/-) mice, megakaryocyte-erythroid progenitors were unaffected and lacked FLT3 expression. Notably, mice deficient in both thrombopoietin (THPO) and FL had a more pronounced GMP phenotype than Thpo(-/-) mice, establishing a role of FL in THPO-dependent and -independent regulation of GMPs, of likely significance for myeloid malignancies with Flt3-ITD mutations.
Blood 06/2010; 115(24):5061-8. · 9.90 Impact Factor
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ABSTRACT: Although bone marrow (BM) represents the main site for postnatal NK cell development, recently a distinct thymic-dependent NK cell pathway was identified. These studies were designed to investigate the role of cytokines in regulation of thymic NK cells and to compare with established regulatory pathways of BM-dependent NK cell compartment. The common cytokine receptor gamma-chain (Il2rg) essential for IL-15-induced signaling, and FMS-like tyrosine kinase 3 (FLT3) receptor ligand (Flt3l) were previously identified as important regulatory pathways of the BM NK cell compartment based on lack of function studies in mice, however their complementary action remains unknown. By investigating mice double-deficient in Il2rg and Flt3l (Flt3l(-/-) Il2rg(-/-)), we demonstrate that FLT3L is important for IL2Rg-independent maintenance of both immature BM as well as peripheral NK cells. In contrast to IL-7, which is dispensable for BM but important for thymic NK cells, IL-15 has a direct and important role in both thymic and BM NK cell compartments. Although thymic NK cells were not affected in Flt3l(-/-) mice, Flt3l(-/-)Il2rg(-/-) mice lacked detectable thymic NK cells, suggesting that FLT3L is also important for IL-2Rg-independent maintenance of thymic NK cells. Thus, IL-2Rg cytokines and FLT3L play complementary roles and are indispensable for homeostasis of both BM and thymic dependent NK cell development, suggesting that the cytokine pathways crucial for these two distinct NK cell pathways are largely overlapping.
The Journal of Immunology 03/2009; 182(3):1460-8. · 5.79 Impact Factor
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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 03/2009; 113(15):3453-60. · 9.90 Impact Factor
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Ewa Sitnicka
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ABSTRACT: The thymus produces new T cells throughout life but has no self-renewing ability and requires replenishment and recruitment of progenitors derived from the bone marrow. Despite the progress in delineation of mature blood cell development several questions remain regarding T lymphopoiesis. Understanding the developmental stages from multipotent hematopoietic stem cells (HSCs) to the T-cell lineage-restricted progenitors has many potential clinical implications as it is important for understanding malignant transformation in T-cell cancer, accelerating T-cell regeneration after bone marrow transplantation and chemotherapy, and establishing new therapies to treat T-cell immune deficiencies. This review focuses on the steps leading from the HSCs in the bone marrow to the lineage committed T cells inside the thymus.
Critical Reviews in Immunology 01/2009; 29(6):487-530. · 3.32 Impact Factor
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ABSTRACT: Phenotypically and functionally distinct progenitors and developmental pathways have been proposed to exist for fetally derived B-1 and conventional B-2 cells. Although IL-7 appears to be the primary cytokine regulator of fetal and adult B lymphopoiesis in mice, considerable fetal B lymphopoiesis and postnatal B cells are sustained in the absence of IL-7; in humans, B-cell generation is suggested to be largely IL-7-independent, as severe combined immune-deficient patients with IL-7 deficiency appear to have normal B-cell numbers. However, the role of other cytokines in IL-7-independent B lymphopoiesis remains to be established. Although thymic stromal lymphopoietin (TSLP) has been proposed to be the main factor driving IL-7-independent B lymphopoiesis and to distinguish fetal from adult B-cell progenitor development in mice, recent studies failed to support a primary role of TSLP in IL-7-independent fetal B-cell development. However, the role of TSLP in IL-7-independent adult B lymphopoiesis and in particular in regulation of B-1 cells remains to be established. Here we demonstrate that, rather than TSLP, IL-7 and FLT3 ligand are combined responsible for all B-cell generation in mice, including recently identified B-1-specified cell progenitors. Thus, the same IL-7- and FLT3 ligand-mediated signal-ing regulates alternative pathways of fetal and adult B-1 and B-2 lymphopoiesis.
Blood 07/2008; 112(6):2297-304. · 9.90 Impact Factor
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ABSTRACT: Although several cytokines have been demonstrated to be critical regulators of development of multiple blood cell lineages, it remains disputed to what degree they act through instructive or permissive mechanisms. Signaling through the FMS-like tyrosine kinase 3 (FLT3) receptor and the hematopoietin IL-7 receptor alpha (IL-7Ralpha) has been demonstrated to be of critical importance for sustained thymopoiesis. Signaling triggered by IL-7 and thymic stromal lymphopoietin (TSLP) is dependent on IL-7Ralpha, and both ligands have been implicated in T-cell development. However, we demonstrate that, whereas thymopoiesis is abolished in adult mice doubly deficient in IL-7 and FLT3 ligand (FLT3L), TSLP does not play a key role in IL-7-independent or FLT3L-independent T lymphopoiesis. Furthermore, whereas previous studies implicated that the role of other cytokine tyrosine kinase receptors in T lymphopoiesis might not involve permissive actions, we demonstrate that ectopic expression of BCL2 is sufficient not only to partially correct the T-cell phenotype of Flt3l(-/-) mice but also to rescue the virtually complete loss of all discernable stages of early T lymphopoiesis in Flt3l(-/-)Il7r(-/-) mice. These findings implicate a permissive role of cytokine receptors of the hematopoietin and tyrosine kinase families in early T lymphopoiesis.
Blood 03/2008; 111(4):2083-90. · 9.90 Impact Factor
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ABSTRACT: The chemokine CCL25 is constitutively expressed in the thymus, and its receptor CCR9 is expressed on subsets of developing thymocytes. Nevertheless, the function of CCL25/CCR9 in adult thymopoiesis remains unclear. Here, we demonstrate that purified CCR9(-/-) hematopoietic stem cells are deficient in their ability to generate all major thymocyte subsets including double-negative 1 (DN1) cells in competitive transfers. CCR9(-/-) bone marrow contained normal numbers of lineage(-) Sca-1+c-kit+, common lymphoid progenitors, and lymphoid-primed multipotent progenitors (LMPP), and CCR9(-/-) LMPP showed similar T cell potential as their wild-type (WT) counterparts when cultured on OP9-delta-like 1 stromal cells. In contrast, early thymic progenitor and DN2 thymocyte numbers were reduced in the thymus of adult CCR9(-/-) mice. In fetal thymic organ cultures (FTOC), CCR9(-/-) DN1 cells were as efficient as WT DN1 cells in generating double-positive (DP) thymocytes; however, under competitive FTOC, CCR9(-/-) DP cell numbers were reduced significantly. Similarly, following intrathymic injection into sublethally irradiated recipients, CCR9(-/-) DN cells were out-competed by WT DN cells in generating DP thymocytes. Finally, in competitive reaggregation thymic organ cultures, CCR9(-/-) preselection DP thymocytes were disadvantaged significantly in their ability to generate CD4 single-positive (SP) thymocytes, a finding that correlated with a reduced ability to form TCR-MHC-dependent conjugates with thymic epithelial cells. Together, these results highlight a role for CCR9 at several stages of adult thymopoiesis: in hematopoietic progenitor seeding of the thymus, in the DN-DP thymocyte transition, and in the generation of CD4 SP thymocytes.
Journal of Leukocyte Biology 02/2008; 83(1):156-64. · 4.99 Impact Factor
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Ewa Sitnicka,
Natalija Buza-Vidas,
Henrik Ahlenius,
Corrado M Cilio,
Christos Gekas,
Jens M Nygren,
Robert Månsson,
Min Cheng,
Christina T Jensen,
Marcus Svensson,
Karin Leandersson,
William W Agace,
Mikael Sigvardsson,
Sten Eirik W Jacobsen
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ABSTRACT: The molecular pathways regulating lymphoid priming, fate, and development of multipotent bone marrow (BM) stem/progenitor cells that continuously replace thymic progenitors remain largely unknown. Herein, we show that fms-like tyrosine kinase 3 (Flt3) ligand (Fl)-deficient mice have distinct reductions in the earliest thymic progenitors in fetal, postnatal, and adult thymus. A critical role of FL in thymopoiesis was particularly evident in the absence of interleukin-7 receptor alpha (IL-7Ralpha) signaling. Fl-/-Il-7r-/- mice have extensive reductions in fetal and postnatal thymic progenitors that result in a loss of active thymopoiesis in adult mice, demonstrating an indispensable role of FL in IL-7Ralpha-independent fetal and adult T lymphopoiesis. Moreover, we establish a unique and critical role of FL, distinct from that of IL-7Ralpha, in regulation of the earliest lineage-negative (Lin(-)) Lin(-)SCA1+KIT+ (LSK) FLT3(hi) lymphoid-primed multipotent progenitors in BM, demonstrating a key role of FLT3 signaling in regulating the very earliest stages of lymphoid progenitors.
Blood 11/2007; 110(8):2955-64. · 9.90 Impact Factor
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ABSTRACT: Almost 5 decades after the first clinical transplantations, delayed immune reconstitution remains a considerable hurdle in bone marrow transplantation, and the mechanisms regulating immune reconstitution after transplantation remain to be established. Whereas adult fms-like tyrosine kinase 3 ligand-deficient (FL(-/-)) mice have reduced numbers of early B- and T-cell progenitors, they sustain close to normal levels of mature B and T cells. Herein, we demonstrate that adult bone marrow cells fail to reconstitute B-cell progenitors and conventional B cells in lethally irradiated FL(-/-) recipients, which also display delayed kinetics of T-cell reconstitution. Similarly, FL is essential for B-cell regeneration after chemotherapy-induced myeloablation. In contrast, fetal progenitors reconstitute B lymphopoiesis in FL(-/-) mice, albeit at reduced levels. A critical role of FL in adult B lymphopoiesis is further substantiated by an age-progressive decline in peripheral conventional B cells in FL(-/-) mice, whereas fetally and early postnatally derived B1 and marginal zone B cells are sustained in a FL-independent manner. Thus, FL plays a crucial role in sustaining conventional B lymphopoiesis in adult mice and, as a consequence, our findings implicate a critical role of FL in promoting immune reconstitution after myeloablation and bone marrow transplantation.
Blood 08/2007; 110(1):424-32. · 9.90 Impact Factor
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Jörgen Adolfsson,
Robert Månsson,
Natalija Buza-Vidas,
Anne Hultquist,
Karina Liuba,
Christina T Jensen,
David Bryder,
Liping Yang,
Ole-Johan Borge,
Lina A M Thoren,
Kristina Anderson, Ewa Sitnicka,
Yutaka Sasaki,
Mikael Sigvardsson,
Sten Eirik W Jacobsen
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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+c-kit+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-1+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.
Cell 05/2005; 121(2):295-306. · 32.40 Impact Factor
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ABSTRACT: Whereas multiple growth-promoting cytokines have been demonstrated to be involved in regulation of the hemopoietic stem cell (HSC) pool, the potential role of negative regulators is less clear. However, IFN-gamma, if overexpressed, can mediate bone marrow suppression and has been directly implicated in a number of bone marrow failure syndromes, including graft-vs-host disease. Whether IFN-gamma might directly affect the function of repopulating HSCs has, however, not been investigated. In the present study, we used in vitro conditions promoting self-renewing divisions of human HSCs to investigate the effect of IFN-gamma on HSC maintenance and function. Although purified cord blood CD34(+)CD38(-) cells underwent cell divisions in the presence of IFN-gamma, cycling HSCs exposed to IFN-gamma in vitro were severely compromised in their ability to reconstitute long-term cultures in vitro and multilineage engraft NOD-SCID mice in vivo (>90% reduced activity in both HSC assays). In vitro studies suggested that IFN-gamma accelerated differentiation of targeted human stem and progenitor cells. These results demonstrate that IFN-gamma can negatively affect human HSC self-renewal.
The Journal of Immunology 01/2005; 174(2):752-7. · 5.79 Impact Factor
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Ewa Sitnicka,
Cord Brakebusch,
Inga-Lill Martensson,
Marcus Svensson,
William W Agace,
Mikael Sigvardsson,
Natalija Buza-Vidas,
David Bryder,
Corrado M Cilio,
Henrik Ahlenius,
Eugene Maraskovsky,
Jacques J Peschon,
Sten Eirik W Jacobsen
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ABSTRACT: Extensive studies of mice deficient in one or several cytokine receptors have failed to support an indispensable role of cytokines in development of multiple blood cell lineages. Whereas B1 B cells and Igs are sustained at normal levels throughout life of mice deficient in IL-7, IL-7Ralpha, common cytokine receptor gamma chain, or flt3 ligand (FL), we report here that adult mice double deficient in IL-7Ralpha and FL completely lack visible LNs, conventional IgM+ B cells, IgA+ plasma cells, and B1 cells, and consequently produce no Igs. All stages of committed B cell progenitors are undetectable in FL-/- x IL-7Ralpha-/- BM that also lacks expression of the B cell commitment factor Pax5 and its direct target genes. Furthermore, in contrast to IL-7Ralpha-/- mice, FL-/- x IL-7Ralpha-/- mice also lack mature B cells and detectable committed B cell progenitors during fetal development. Thus, signaling through the cytokine tyrosine kinase receptor flt3 and IL-7Ralpha are indispensable for fetal and adult B cell development.
Journal of Experimental Medicine 12/2003; 198(10):1495-506. · 13.85 Impact Factor
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ABSTRACT: The cytokine tyrosine kinase receptors c-kit and flt3 are expressed and function in early mouse and human hematopoiesis. Through its ability to promote ex vivo expansion and oncoretroviral transduction of primitive human hematopoietic progenitors, the flt3 ligand (FL) has emerged as a key stimulator of candidate human hematopoietic stem cells (HSCs). However, recent studies in the mouse suggest that though it is present on short-term repopulating cells, flt3 is not expressed on bone marrow long-term reconstituting HSCs, the ultimate target for the development of cell replacement and gene therapy. Herein we demonstrate that though only a fraction of human adult bone marrow and cord blood CD34+long-term culture-initiating cells (LTC-ICs) express flt3, most cord blood lymphomyeloid HSCs capable of in vivo reconstituting nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice are flt3+. The striking difference in flt3 and c-kit expression on mouse and candidate human HSCs translated into a corresponding difference in flt3 and c-kit function because FL was more efficient than SCF at supporting the survival of candidate human HSCs. In contrast, SCF is far superior to FL as a viability factor for mouse HSCs. Thus, the present data provide compelling evidence for a contrasting expression and response pattern of flt3 and c-kit on mouse and human HSCs.
Blood 09/2003; 102(3):881-6. · 9.90 Impact Factor
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ABSTRACT: The first lineage commitment step of hematopoietic stem cells (HSC) results in separation into distinct lymphoid and myeloid differentiation pathways, reflected in the generation of common lymphoid and myeloid progenitors (CLP and CMP, respectively). In this report we present the first evidence for a nonredundant regulator of this process, in that adult mice deficient in expression of the flt3 ligand (FL) have severely (10-fold) reduced levels of the CLP, accompanied by reductions in the earliest identifiable B and T cell progenitors. In contrast, CMP and HSC are unaffected in FL-deficient mice. Noteworthy, CLP express high levels of both the flt3 receptor and ligand, indicating a potential autocrine role of FL in regulation of the earliest lymphoid commitment step from HSC.
Immunity 11/2002; 17(4):463-72. · 21.64 Impact Factor
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ABSTRACT: Recent developments of surrogate assays for human hematopoietic stem cells (HSC) have facilitated efforts at improving HSC gene transfer efficiency. Through the use of xenograft transplantation models, such as nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice, successful oncoretroviral gene transfer to transplantable hematopoietic cells has been achieved. However, because of the low frequency and/or homing efficiency of SCID repopulating cells (SRC) in bone marrow (BM), studies have primarily focused on cord blood (CB). The recently developed extended (> 60 days) long-term culture-initiating cell (ELTC-IC) assay detects an infrequent and highly quiescent candidate stem cell population in BM as well as CB of the CD34(+)CD38(-) phenotype. Although these characteristics suggest that ELTC-IC and SRC might be closely related, attempts to oncoretrovirally transduce ELTC-IC have been unsuccessful. Here, recently developed conditions (high concentrations of SCF + FL + Tpo in serum-free medium) supporting expansion of BM CD34(+)CD38(-) 12 week ELTC-IC promoted efficient oncoretroviral transduction of BM and CB ELTC-IC. Although SRC can be transduced with oncoretroviral vectors, this is frequently associated with loss of reconstituting activity, posing a problem for development of clinical HSC gene therapy. However, previous attempts at expanding transduced HSC posttransduction resulted in compromised rather than improved gene marking. Utilizing conditions promoting cell divisions and transduction of ELTC-IC we show that although 5 days of ex vivo culture is sufficient to obtain maximum gene transfer efficiency to SRC, extension of the expansion period to 12 days significantly enhances multilineage reconstitution activity of transduced SRC, supporting the feasibility of improving gene marking through ex vivo expansion.
Human Gene Therapy 06/2002; 13(9):1061-73. · 4.22 Impact Factor
