1. |
- Adolfsson, Jörgen, et al.
(author)
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Identification of Flt3(+) lympho-myeloid stem cells lacking erythro-megakaryocytic potential: A revised road map for adult blood lineage commitment
- 2005
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In: Cell. - : Elsevier (Cell Press). - 0092-8674 .- 1097-4172. ; 121:2, s. 295-306
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Journal article (peer-reviewed)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.
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2. |
- Hernandez-Andrade, Edgar, et al.
(author)
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Perinatal adaptive response of the adrenal and carotid blood flow in sheep fetuses subjected to total cord occlusion
- 2005
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In: Journal of Maternal-Fetal & Neonatal Medicine. - 1476-7058. ; 17:2, s. 101-109
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Journal article (peer-reviewed)abstract
- Objective. To investigate the perinatal adaptive response of the adrenal blood flow/adrenal fractional moving blood volume (AFMBV) and carotid blood flow (CBF), in sheep fetuses subjected to severe acute intrauterine hypoxia/asphyxia induced by total cord occlusion.Methods. Adrenal blood flow velocity, AFMBV and CBF were measured in 13 exteriorized fetal sheep; eight of them underwent total umbilical cord occlusion to induce severe acute hypoxia/asphyxia. Five lambs were used as sham controls. Middle adrenal artery pulsatility index (MAAPI) and mean velocity (MAAMV) were recorded with pulsed Doppler ultrasound. AFMBV was estimated using power Doppler ultrasound. CBF was recorded with a transonic flowmeter. In the neonatal period, after resuscitation all lambs were followed for a 4-hour period and AFMBV and CBF were recorded. Mean arterial blood pressure (MABP) and fetal heart rate were recorded continuously. Arterial cortisol levels were measured at the beginning and at the end of the fetal and neonatal periods.Results. Following the total cord occlusion, there was a significant reduction in the CBF, MABP, and heart rate and adrenal flow/AFMBV after 2, 4 and 5?min, respectively. Cortisol levels in the asphyctic lambs at the end of the cord occlusion were significantly lower than those in controls. After resuscitation, the asphyctic lambs showed increased AFMBV and cortisol levels, and reduced MABP as compared to control lambs. No differences were found in CBF, MAAPI and MAAMV. Thereafter, no differences were observed between the two groups in any of the studied parameters. At the end of the cord occlusion period, there was a significant correlation between AFMBV and MABP (r?=?0.69), between AFMBV and CBF (r?=?0.65) and between CBF and MABP (r?=?0.89).Conclusion. During severe acute intrauterine hypoxia, the fetal lamb is able to maintain the blood flow to the brain and the adrenal gland for 3-5?min. Changes in the AFMBV and the CBF were highly correlated to the changes in MABP. Adrenal FMBV and cortisol levels were higher in lamb neonates exposed to severe intrauterine asphyxia.
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3. |
- Jensen, Christina, et al.
(author)
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TSLP-mediated fetal B lymphopoiesis?
- 2007
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In: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 8:9, s. 897-897
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Journal article (peer-reviewed)
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4. |
- Liuba, Karina
(author)
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Hematopoietic stem and progenitor cells and potentials for application in fetal cell replacement therapy
- 2009
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Doctoral thesis (other academic/artistic)abstract
- Fetal cell replacement therapy or in utero hematopoietic cell transplantation (IUHCT) is proposed as a non-myeloablative alternative to bone marrow transplantation (BMT) for a number of inborn immunologic, hematologic and metabolic disorders. IUHCT represents the method through which variable amounts of natural or genetically modified hematopoietic cells can be transferred to the fetal recipient in hope of correcting the disorder and preventing postnatal permanent organ damage. Although proof-of-principle has been achieved by succesful correction of X linked severe combined immune deficiency (X-SCID), in the majority of target diseases treated with IUHCT engraftment was insufficient for clinical benefit. Thus, the therapeutical promise of IUHCT remains unfullfilled and many challenges stand. In the present thesis we investigate the optimal cell population for IUHCT by first identifying a novel commitment/differentiation step of hematopoietic stem cells (HSCs) in adult murine hematopoiesis and then evaluating the therapeutical potential of the lymphoid primed multipotent progenitors (LMPPs) for immune reconstitution in a model of fetal X-SCID transplantation. We find that LMPPs generate rapid and sustained lymphoid reconstitution with polyclonal T cells, but that HSCs are most likely required for long term engraftment. We also find that the fetal microenvironment is apparently more receptive to donor HSCs (but also LMPPs) as it allows higher levels of chimerism after IUHCT then after BMT in neonatal or adult age. In the last part we investigate in adult and fetal animal models the proposed plasticity of HSCs, a feature that holds promise for clinical BMT (or IUHCT) to non-hematopoietic disorders. We find that HSCs plasticity is a result of heterotypic cell fusion, probably induced by inflammation/injury in the target tissue. We also show that heterotypic cell fusion is not a physiological frequently occuring event during development and we demonstrate that not only myeloid, but also lymphoid cells are efficient fusogenic partners to non-hematopoietic tissues.
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5. |
- Liuba, Karina, et al.
(author)
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Polyclonal T-cell reconstitution of X-SCID recipients after in utero transplantation of lymphoid-primed multipotent progenitors
- 2009
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In: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 113:19, s. 4790-4798
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Journal article (peer-reviewed)abstract
- Although successful in utero hematopoietic cell transplantation (IUHCT) of X-linked severe combined immune deficiency (X-SCID) with enriched stem and progenitor cells was achieved more than a decade ago, it remains applied only in rare cases. Although this in part reflects that postnatal transplantations have overall given good results, there are no direct comparisons between IUHCT and postnatal transplantations of X-SCID. The proposed tolerance of the fetal immune system to foreign human leukocyte antigen early in gestation, a main rationale behind IUHCT, has recently been challenged by evidence for a considerable immune barrier against in utero transplanted allogeneic bone marrow cells. Consequently, there is need for further exploring the application of purified stem and progenitor cells to overcome this barrier also in IUHCT. Herein, we demonstrate in a congenic setting that recently identified lymphoid-primed multipotent progenitors are superior to hematopoietic stem cells in providing rapid lymphoid reconstitution after IUHCT of X-SCID recipients, and sustain in the long-term B cells, polyclonal T cells, as well as short-lived B-cell progenitors and thymic T-cell precursors. We further provide evidence for IUHCT of hematopoietic stem cells giving superior B- and T-cell reconstitution in fetal X-SCID recipients compared with neonatal and adolescent recipients. (Blood. 2009;113:4790-4798)
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6. |
- Månsson, Robert, et al.
(author)
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Molecular evidence for hierarchical transcriptional lineage priming in fetal and adult stem cells and multipotent progenitors
- 2007
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In: Immunity. - : Elsevier BV. - 1074-7613 .- 1097-4180. ; 26:4, s. 407-419
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Journal article (peer-reviewed)abstract
- Recent studies implicated the existence of adult lymphoid-primed multipotent progenitors (LMPPs) with little or no megakaryocyte-erythroid potential, questioning common myeloid and lymphoid progenitors as obligate intermediates in hematopoietic stem cell (HSC) lineage commitment. However, the existence of LMPPs remains contentious. Herein, global and single-cell analyses revealed a hierarchical organization of transcriptional lineage programs, with downregulation of megakaryocyte-erythroid genes from HSCs to LMPPs, sustained granulocyte-monocyte priming, and upregulation of common lymphoid (but not B and T cell-specific) genes. These biological and molecular relationships, implicating almost mutual exclusion of megakaryocyte-erythroid and lymphoid pathways, are established already in fetal hematopoiesis, as evidenced by existence of LMPPs in fetal liver. The identification of LMPPs and hierarchically ordered transcriptional activation and downregulation of distinct lineage programs is compatible with a model for HSC lineage commitment in which the probability for undergoing different lineage commitment fates changes gradually when progressing from HSCs to LMPPs.
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7. |
- Nygren, Jens Martin, 1976-, et al.
(author)
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Myeloid and lymphoid contribution to non-haematopoietic lineages through irradiation-induced heterotypic cell fusion
- 2008
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In: Nature Cell Biology. - London : Nature Publishing Group. - 1465-7392 .- 1476-4679. ; 10:5, s. 584-92
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Journal article (peer-reviewed)abstract
- Recent studies have suggested that regeneration of non-haematopoietic cell lineages can occur through heterotypic cell fusion with haematopoietic cells of the myeloid lineage. Here we show that lymphocytes also form heterotypic-fusion hybrids with cardiomyocytes, skeletal muscle, hepatocytes and Purkinje neurons. However, through lineage fate-mapping we demonstrate that such in vivo fusion of lymphoid and myeloid blood cells does not occur to an appreciable extent in steady-state adult tissues or during normal development. Rather, fusion of blood cells with different non-haematopoietic cell types is induced by organ-specific injuries or whole-body irradiation, which has been used in previous studies to condition recipients of bone marrow transplants. Our findings demonstrate that blood cells of the lymphoid and myeloid lineages contribute to various non-haematopoietic tissues by forming rare fusion hybrids, but almost exclusively in response to injuries or inflammation.
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8. |
- Thorén, Lina, et al.
(author)
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Kit regulates maintenance of quiescent hematopoietic stem cells
- 2008
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In: Journal of Immunology. - Bethesda, MD : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 180:4, s. 2045-2053
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Journal article (peer-reviewed)abstract
- Hematopoietic stem cell (HSC) numbers are tightly regulated and maintained in postnatal hematopoiesis. Extensive studies have supported a role of the cytokine tyrosine kinase receptor Kit in sustaining cycling HSCs when competing with wild-type HSCs posttransplantation, but not in maintenance of quiescent HSCs in steady state adult bone marrow. In this study, we investigated HSC regulation in White Spotting 41 (Kit(W41/W41)) mice, with a partial loss of function of Kit. Although the extensive fetal HSC expansion was Kit-independent, adult Kit(W41/W41) mice had an almost 2-fold reduction in long-term HSCs, reflecting a loss of roughly 10,000 Lin(-)Sca-1(+)Kit(high) (LSK)CD34(-)Flt3(-) long-term HSCs by 12 wk of age, whereas LSKCD34(+)Flt3(-) short-term HSCs and LSKCD34(+)Flt3(+) multipotent progenitors were less affected. Whereas homing and initial reconstitution of Kit(W41/W41) bone marrow cells in myeloablated recipients were close to normal, self-renewing Kit(W41/W41) HSCs were progressively depleted in not only competitive but also noncompetitive transplantation assays. Overexpression of the anti-apoptotic regulator BCL-2 partially rescued the posttransplantation Kit(W41/W41) HSC deficiency, suggesting that Kit might at least in the posttransplantation setting in part sustain HSC numbers by promoting HSC survival. Most notably, accelerated in vivo BrdU incorporation and cell cycle kinetics implicated a previously unrecognized role of Kit in maintaining quiescent HSCs in steady state adult hematopoiesis.
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