scholarly journals Lymphoid reconstitution of the human fetal thymus in SCID mice with CD34+ precursor cells.

1991 ◽  
Vol 174 (5) ◽  
pp. 1283-1286 ◽  
Author(s):  
B Péault ◽  
I L Weissman ◽  
C Baum ◽  
J M McCune ◽  
A Tsukamoto
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
T Cells ◽  
Bone Marrow Cells ◽  
Fetal Liver ◽  
Precursor Cell ◽  
Scid Mice ◽  
Hematopoietic Stem ◽  
Fetal Thymus

The search for human hematopoietic stem cells has been hampered by the lack of appropriate assay systems. Demonstration of the ability of precursor cell candidates to give rise to T cells is of significant difficulty since dissociated in vitro cultured thymus stroma cells lose their ability to sustain thymocyte maturation. To define further the differentiative capacities of the rare human fetal liver and bone marrow cells that express the CD34 surface antigen and exhibit in vitro myeloid and pre-B cell activities, we have microinjected them into HLA-mismatched fetal thymus fragments, partially depleted of hematopoietic cells by low temperature culture. In vitro colonized thymuses have then been allowed to develop upon engraftment into immunodeficient SCID mice. Using this modification of the SCID-hu system, we show that low numbers of fetal CD34+ progenitor cells can repopulate the lymphoid compartment in the human thymus.

scholarly journals High levels of interleukin 10 production in vivo are associated with tolerance in SCID patients transplanted with HLA mismatched hematopoietic stem cells.

1994 ◽  
Vol 179 (2) ◽  
pp. 493-502 ◽  
Author(s):  
R Bacchetta ◽  
M Bigler ◽  
J L Touraine ◽  
R Parkman ◽  
P A Tovo ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
T Cell ◽  
Mrna Expression ◽  
Fetal Liver ◽  
Hla Antigens ◽  
Interleukin 10 ◽  
Hematopoietic Stem

Transplantation of HLA mismatched hematopoietic stem cells in patients with severe combined immunodeficiency (SCID) can result in a selective engraftment of T cells of donor origin with complete immunologic reconstitution and in vivo tolerance. The latter may occur in the absence of clonal deletion of donor T lymphocytes able to recognize the host HLA antigens. The activity of these host-reactive T cells is suppressed in vivo, since no graft-vs. -host disease is observed in these human chimeras. Here it is shown that the CD4+ host-reactive T cell clones isolated from a SCID patient transplanted with fetal liver stem cells produce unusually high quantities of interleukin 10 (IL-10) and very low amounts of IL-2 after antigen-specific stimulation in vitro. The specific proliferative responses of the host-reactive T cell clones were considerably enhanced in the presence of neutralizing concentrations of an anti-IL-10 monoclonal antibody, suggesting that high levels of endogenous IL-10 suppress the activity of these cells. These in vitro data correlate with observations made in vivo. Semi-quantitative polymerase chain reaction analysis carried out on freshly isolated peripheral blood mononuclear cells (PBMC) of the patient indicated that the levels of IL-10 messenger RNA (mRNA) expression were strongly enhanced, whereas IL-2 mRNA expression was much lower than that in PBMC of healthy donors. In vivo IL-10 mRNA expression was not only high in the T cells, but also in the non-T cell fraction, indicating that host cells also contributed to the high levels of IL-10 in vivo. Patient-derived monocytes were found to be major IL-10 producers. Although no circulating IL-10 could be detected, freshly isolated monocytes of the patient showed a reduced expression of class II HLA antigens. However, their capacity to stimulate T cells of normal donors in primary mixed lymphocyte cultures was within the normal range. Interestingly, similar high in vivo IL-10 mRNA expressions in the T and non-T cell compartment were also observed in three SCID patients transplanted with fetal liver stem cells and in four SCID patients transplanted with T cell-depleted haploidentical bone marrow stem cells. Taken together, these data indicate that high endogenous IL-10 production is a general phenomenon in SCID patients in whom allogenic stem cell transplantation results in immunologic reconstitution and induction of tolerance. Both donor T cells and host accessory cells contribute to these high levels of IL-10, which would suppress the activity of host-reactive T cell in vivo.

Bone marrow-derived mesenchymal stem cells inhibit T follicular helper cell in lupus-prone mice

Lupus ◽  
2017 ◽  
Vol 27 (1) ◽  
pp. 49-59 ◽  
Author(s):  
X Yang ◽  
J Yang ◽  
X Li ◽  
W Ma ◽  
H Zou
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Flow Cytometry ◽  
T Cells ◽  
Lupus Nephritis ◽  
Bone Marrow Cells ◽  
Tfh Cells ◽  
Follicular Helper

Background The objective of this paper is to analyze the role of bone marrow-derived mesenchymal stem cells (BM-MSCs) on the differentiation of T follicular helper (Tfh) cells in lupus-prone mice. Methods Bone marrow cells were isolated from C57BL/6 (B6) mice and cultured in vitro, and surface markers were identified by flow cytometry. Naïve CD4+ T cells, splenocytes and Tfh cells were isolated from B6 mice spleens and co-cultured with BM-MSCs. The proliferation and the differentiation of CD4+ T cells and Tfh cells were analyzed by flow cytometry. Lupus-prone MRL/Mp-lpr/lpr (MRL/lpr) mice were treated via intravenous injection with expanded BM-MSCs, the differentiation of Tfh cells was detected, and the relief of lupus nephritis was analyzed. Results MSCs could be successfully induced from bone marrow cells, and cultured BM-MSCs could inhibit T cell proliferation dose-dependently. BM-MSCs could prevent Tfh cell development from naïve CD4+ T cells and splenocytes. BM-MSCs could inhibit IL-21 gene expression and cytokine production and inhibit isolated Tfh cells and STAT3 phosphorylation. In vivo study proved that BM-MSCs intravenous injection could effectively inhibit Tfh cell expansion and IL-21 production, alleviate lupus nephritis, and prolong the survival rate of lupus-prone mice. Conclusions BM-MSCs could effectively inhibit the differentiation of Tfh cells both in vitro and in vivo. BM-MSC treatment could relieve lupus nephritis, which indicates that BM-MSCs might be a promising therapeutic method for the treatment of SLE.

scholarly journals Molecular Modulation of Fetal Liver Hematopoietic Stem Cell Mobilization into Fetal Bone Marrow in Mice

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Huihong Zeng ◽  
Jiaoqi Cheng ◽  
Ying Fan ◽  
Yingying Luan ◽  
Juan Yang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Vascular Endothelial Cells ◽  
Fetal Liver ◽  
Bone Marrow Niche ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Fetal Bone

Development of hematopoietic stem cells is a complex process, which has been extensively investigated. Hematopoietic stem cells (HSCs) in mouse fetal liver are highly expanded to prepare for mobilization of HSCs into the fetal bone marrow. It is not completely known how the fetal liver niche regulates HSC expansion without loss of self-renewal ability. We reviewed current progress about the effects of fetal liver niche, chemokine, cytokine, and signaling pathways on HSC self-renewal, proliferation, and expansion. We discussed the molecular regulations of fetal HSC expansion in mouse and zebrafish. It is also unknown how HSCs from the fetal liver mobilize, circulate, and reside into the fetal bone marrow niche. We reviewed how extrinsic and intrinsic factors regulate mobilization of fetal liver HSCs into the fetal bone marrow, which provides tools to improve HSC engraftment efficiency during HSC transplantation. Understanding the regulation of fetal liver HSC mobilization into the fetal bone marrow will help us to design proper clinical therapeutic protocol for disease treatment like leukemia during pregnancy. We prospect that fetal cells, including hepatocytes and endothelial and hematopoietic cells, might regulate fetal liver HSC expansion. Components from vascular endothelial cells and bones might also modulate the lodging of fetal liver HSCs into the bone marrow. The current review holds great potential to deeply understand the molecular regulations of HSCs in the fetal liver and bone marrow in mammals, which will be helpful to efficiently expand HSCs in vitro.

scholarly journals Age-Associated Characteristics of Murine Hematopoietic Stem Cells

2000 ◽  
Vol 192 (9) ◽  
pp. 1273-1280 ◽  
Author(s):  
Kazuhiro Sudo ◽  
Hideo Ema ◽  
Yohei Morita ◽  
Hiromitsu Nakauchi
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Bone Marrow Cells ◽  
Lymphoid Cells ◽  
Differentiation Potential ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Functional Changes

Little is known of age-associated functional changes in hematopoietic stem cells (HSCs). We studied aging HSCs at the clonal level by isolating CD34−/lowc-Kit+Sca-1+ lineage marker–negative (CD34−KSL) cells from the bone marrow of C57BL/6 mice. A population of CD34−KSL cells gradually expanded as age increased. Regardless of age, these cells formed in vitro colonies with stem cell factor and interleukin (IL)-3 but not with IL-3 alone. They did not form day 12 colony-forming unit (CFU)-S, indicating that they are primitive cells with myeloid differentiation potential. An in vivo limiting dilution assay revealed that numbers of multilineage repopulating cells increased twofold from 2 to 18 mo of age within a population of CD34−KSL cells as well as among unseparated bone marrow cells. In addition, we detected another compartment of repopulating cells, which differed from HSCs, among CD34−KSL cells of 18-mo-old mice. These repopulating cells showed less differentiation potential toward lymphoid cells but retained self-renewal potential, as suggested by secondary transplantation. We propose that HSCs gradually accumulate with age, accompanied by cells with less lymphoid differentiation potential, as a result of repeated self-renewal of HSCs.

scholarly journals In vivo and in vitro stem cell function of c-kit- and Sca-1-positive murine hematopoietic cells

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3044-3050 ◽  
Author(s):  
S Okada ◽  
H Nakauchi ◽  
K Nagayoshi ◽  
S Nishikawa ◽  
Y Miura ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Cell Function ◽  
Bone Marrow Cells ◽  
Synergistic Effects ◽  
Single Cells ◽  
Hematopoietic Stem

c-kit is expressed on hematopoietic stem cells and progenitor cells, but not on lymphohematopoietic differentiated cells. Lineage marker- negative, c-kit-positive (Lin-c-kit+) bone marrow cells were fractionated by means of Ly6A/E or Sca-1 expression. Lin-c-kit+Sca-1+ cells, which consisted of 0.08% of bone marrow nucleated cells, did not contain day-8 colony-forming units-spleen (CFU-S), but 80% were day-12 CFU-S. One hundred cells rescued the lethally irradiated mice and reconstituted hematopoiesis. On the other hand, 2 x 10(3) of Lin-c- kit+Sca-1- cells formed 20 day-8 and 11 day-12 spleen colonies, but they could not rescue the lethally irradiated mice. These data indicate that Lin-c-kit+Sca-1+ cells are primitive hematopoietic stem cells and that Sca-1-cells do not contain stem cells that reconstitute hematopoiesis. Lin-c-kit+Sca-1+ cells formed no colonies in the presence of stem cell factor (SCF) or interleukin-6 (IL-6), and only 10% of them formed colonies in the presence of IL-3. However, approximately 50% of them formed large colonies in the presence of IL-3, IL-6, and SCF. Moreover, when single cells were deposited into culture medium by fluorescence-activated cell sorter clone sorting system, 40% of them proliferated on a stromal cell line (PA-6) and proliferated for more than 2 weeks. In contrast, 15% of the Lin-c- kit+Sca-1-cells formed colonies in the presence of IL-3, but no synergistic effects were observed in combination with SCF plus IL-6 and/or IL-3. Approximately 10% proliferated on PA-6, but most of them degenerated within 2 weeks. The population ratio of c-kit+Sca-1+ to c-kit+Sca-1- increased 2 and 4 days after exposure to 5-fluorouracil (5-FU). These results are consistent with the relative enrichment of highly proliferative colony-forming cells by 5-FU. These data show that, although c-kit is found both on the primitive hematopoietic stem cells and progenitors, Sca-1+ cells are more primitive and respond better than Sca-1- cells to a combination of hematopoietic factors, including SCF and stromal cells.

Fluorescence-Based Selection of Gene-Corrected Hematopoietic Stem and Progenitor Cells From Acid Sphingomyelinase-Deficient Mice: Implications for Niemann-Pick Disease Gene Therapy and the Development of Improved Stem Cell Gene Transfer Procedures

Blood ◽  
1999 ◽  
Vol 93 (1) ◽  
pp. 80-86 ◽  
Author(s):  
Shai Erlich ◽  
Silvia R.P. Miranda ◽  
Jan W.M. Visser ◽  
Arie Dagan ◽  
Shimon Gatt ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Gene Transfer ◽  
Progenitor Cells ◽  
Fetal Liver ◽  
Acid Sphingomyelinase ◽  
Hematopoietic Stem

Abstract The general utility of a novel, fluorescence-based procedure for assessing gene transfer and expression has been demonstrated using hematopoietic stem and progenitor cells. Lineage-depleted hematopoietic cells were isolated from the bone marrow or fetal livers of acid sphingomyelinase–deficient mice, and retrovirally transduced with amphotropic or ecotropic vectors encoding a normal acid sphingomyelinase (ASM) cDNA. Anti–c-Kit antibodies were then used to label stem- and progenitor-enriched cell populations, and the Bodipy fluorescence was analyzed in each group after incubation with a Bodipy-conjugated sphingomyelin. Only cells expressing the functional ASM (ie, transduced) could degrade the sphingomyelin, thereby reducing their Bodipy fluorescence as compared with nontransduced cells. The usefulness of this procedure for the in vitro assessment of gene transfer into hematopoietic stem cells was evaluated, as well as its ability to provide an enrichment of transduced stem cells in vivo. To show the value of this method for in vitro analysis, the effects of retroviral transduction using ecotropic versus amphotropic vectors, various growth factor combinations, and adult bone marrow versus fetal liver stem cells were assessed. The results of these studies confirmed the fact that ecotropic vectors were much more efficient at transducing murine stem cells than amphotropic vectors, and that among the three most commonly used growth factors (stem cell factor [SCF] and interleukins 3 and 6 [IL-3 and IL-6]), SCF had the most significant effect on the transduction of stem cells, whereas IL-6 had the most significant effect on progenitor cells. In addition, it was determined that fetal liver stem cells were only approximately twofold more “transducible” than stem cells from adult bone marrow. Transplantation of Bodipy-selected bone marrow cells into lethally irradiated mice showed that the number of spleen colony-forming units that were positive for the retroviral vector (as determined by polymerase chain reaction) was 76%, as compared with 32% in animals that were transplanted with cells that were nonselected. The methods described within this manuscript are particularly useful for evaluating hematopoietic stem cell gene transfer in vivo because the marker gene used in the procedure (ASM) encodes a naturally occurring mammalian enzyme that has no known adverse effects, and the fluorescent compound used for selection (Bodipy sphingomyelin) is removed from the cells before transplantation.

Hepatogenic Potential of Stem Cells and Lymphoid Precursors.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1696-1696
Author(s):  
Yasuhiro Yamada ◽  
Hirosada Miyake ◽  
Eishi Nishimoto ◽  
Hiroaki Mitsuya ◽  
Yuji Yonemura
Keyword(s):  
Stem Cells ◽  
Bone Marrow Cells ◽  
Fetal Liver ◽  
Green Fluorescence Protein ◽  
Type I ◽  
Tyrosinaemia Type ◽  
Hematopoietic Stem ◽  
Titration Assay

Abstract Several research groups have recently reported that certain bone marrow cells (BMCs) differentiate into hepatocytes in vitro as well as in vivo in rodents through both transdifferentiation and cell fusion. Hematopoietic myelomonocytic cells are thought to be the major source of hepatocyte fusion partners in the tyrosinaemia type I mouce transplantation model. Transdifferentiation of murine BMCs can be induced with various cytokines and extracellular matrix. We previously reported that when Sca-1+ BMCs were co-cultured with fetal liver cells (FLCs) on laminin-coated dishes, alpha-fetoprotein (AFP)-expressing BMCs became completely adherent by day 4 and expressed albumin as assessed with immunochemistry and RNA-PCR (Yamada et al., Exp Hematol. in press). In the present study, we attempted to further delineate the characteristics of BMCs that differentiate into hepatic-like cells. It was found that AFP-expressing cells were in CD5+ or B220+ lymphoid lineage, mostly Sca-1+CD5+ lineage and that CD5+CD4−CD8− and CD5+CD4+CD8+ thymocytes expressed AFP. When cKit+Sca-1+ lineage BMCs (KSLs) which did not express AFP, CD5+ BMCs, and CD5+ thymocytes, all from green fluorescence protein (GFP)-expressing transgenic mice, were co-cultured with FLCs from ROSA26 mice (X-gal+ FLCs), fractionated cells gave rise to adherent hepatic-like cells, which expressed albumin and cytokeratin 8 (CK 8) as assessed with immunochemistry and AFP, albumin, transthyretin and dipeptidylpeptidase IV as examined with RNA-PCR. The hepatic-like cells from KSLs, CD5+ BMCs and CD5+ thymocytes emerged at the frequency of 1 in 50, 1x103 and 3.5x105 by titration assay. These data suggest that AFP-expressing cells in BMCs were derived from hematopoietic stem cells and that lymphoid precursors differentiated into hepatic-like cells and their hepatogenic ability could diminish over lymphoid maturation.

Hematopoietic Stem Cell Engraftment in Bone Marrow Is Dependent upon Gsα.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 857-857
Author(s):  
Gregor B. Adams ◽  
Ian R. Alley ◽  
Karissa T. Chabner ◽  
Ung-il Chung ◽  
Emily S. Marsters ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Bone Marrow Cells ◽  
Fetal Liver ◽  
Conditional Knockout ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Cell Engraftment

Abstract During development, hematopoietic stem cells (HSCs) translocate from the fetal liver to the bone marrow, which remains the site of hematopoiesis throughout adulthood. In the bone marrow the HSCs are located at the endosteal surface, where the osteoblasts are a key component of the stem cell niche. The exogenous signals that specifically direct HSCs to the bone marrow have been thought to include stimulation of the chemokine receptor CXCR4 by its cognate ligand stromal derived factor-1α (SDF-1α or CXCL12). However, experiments in which CXCR4−/− fetal liver hematopoietic cells were transplanted into wild-type hosts demonstrated efficient engraftment of the HSCs in the bone marrow. In addition, treatment of HSCs with inhibitors of Gαi-coupled signaling, which blocks transmigration towards SDF-1αin vitro, does not affect bone marrow homing and engraftment in vivo. Therefore, we examined whether Gsα-coupled mechanisms play a key role in the engraftment of the HSCs in the bone marrow environment. Utilizing an inducible-conditional knockout of Gsα, we found that deletion of the gene in hematopoietic bone marrow cells did not affect their ability to perform in the in vitro primitive CFU-C or LTC-IC assay systems. However, Gsα−/− cells were unable to establish effective hematopoiesis in the bone marrow microenvironment in vivo in a competitive repopulation assay (41.1% contribution from wild-type cells versus 1.4% from knockout cells). These effects were not due to an inability of the cells to function in the bone marrow in vivo as deletion of Gsα following establishment of hematopoiesis had no effects on the HSCs. Examining the ability of the HSCs to home to the bone marrow, though, demonstrated that deletion of Gsα resulted in a marked impairment of the ability of the stem cells to localize to the marrow space (approximately 9-fold reduction in the level of primitive cell homing). Furthermore, treatment of BM MNCs with an activator of Gsα augmented the cells homing and thus engraftment potential. These studies demonstrate that Gsα is critical to the localization of HSCs to the bone marrow. Which receptors utilize this pathway in this context remains unknown. However, Gsα represents a previously unrecognized signaling pathway for homing and engraftment of HSCs to bone marrow. Pharmacologic activation of Gsα in HSC ex vivo prior to transplantation offers a potential method for enhancing stem cell engraftment efficiency.

In Vitro Myelo-Lymphoid Colony Formation by Mouse Hematopoietic Stem Cells

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3861-3861
Author(s):  
Jun Ooehara ◽  
Hina Takano ◽  
Shin-ichiro Takayanagi ◽  
Hiromitsu Nakauchi ◽  
Hideo Ema
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Bone Marrow Cells ◽  
Culture Conditions ◽  
Differentiation Potential ◽  
Hematopoietic Stem ◽  
Lymphoid Progenitors ◽  
Marrow Cells

Abstract Hematopoietic stem cells (HSCs) clonally differentiate into all myeloid, B-lymphoid, and T-lymphoid lineages. Mouse HSCs are known to form in vitro colonies comprised of morphologically identifiable myeloid cells such as neutrophils, macrophages, erythroblasts, and megakaryocytes. Whether HSCs are able to differentiate along B-and T-lymphoid lineages in such colonies remains obscure. The co-culture systems with stromal cells such as S17, OP9, OP9/Delta cells have been shown to support B- and T-cell development. These systems have been used to identify subclasses of progenitors with lymphoid potentials. However, neither B cells nor T cells have been successfully generated from HSCs in vitro. This is most likely due to the lack of culture conditions which support HSCs to differentiate into a certain stage of lymphoid progenitors. In this study, we attempted to use serum-free single-cell culture to identify cytokines which fill the developmental gap between HSCs and lymphoid progenitors. Here we show that myelo-lymphoid colonies are formed by HSCs in the presence of thrombopoietin (TPO), interleukin (IL)-11, or IL-12 together with stem cell factor (SCF). CD34-negative/low, c-Kit-positive, Sca-1-positive, lineage marker-negative (CD34-KSL) bone marrow cells were individually cultured with a combination of cytokines for 7 days. All cells in each colony were transplanted into each from a group of lethally irradiated mice, along with compromised bone marrow cells. The recipient mice were periodically analyzed after transplantation to detect transient myeloid and lymphoid reconstitution. All myeloid, B-, and T-lymphoid progenitor activities were detected in single colonies formed in the presence of SCF+TPO, SCF+IL-11, SCF+IL-12. Only myeloid progenitor activity was predominantly detected in single colonies formed in the presence of SCF+IL-3, consistent with previous observations in blast colony assays. All these combinations of cytokines support self-renewal in HSCs to varying degrees. We conclude that TPO, IL-11, and IL-12 directly act on HSCs and support them to differentiate into progenitors with lymphoid differentiation potential. Early differentiation pathways in HSCs are likely to be used in common by myeloid and lymphoid lineages and be supported in common by multiple cytokines.

Roles of Histone Acetyltransferase MORF and MOZ in Hematopoiesis.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2525-2525
Author(s):  
Takuo Katsumoto ◽  
Issay Kitabayashi
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Bone Marrow Cells ◽  
Fetal Liver ◽  
Liver Cells ◽  
Wild Type ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Fetal Liver Cells

Abstract Abstract 2525 Poster Board II-502 MOZ (MOnocytic leukemia Zinc finger protein) and MORF (MOz Related Factor), Myst-type histone acetyltransferases, are involved in chromosome translocations associated with FAB-M4/5 subtypes of acute myeloid leukemia. We have reported that MOZ is essential for hematopoietic cell development and self-renewal of hematopoietic stem cells. To explore the possibility MORF also plays important roles in hematopoiesis, we generated Morf-deficient mice with homologous recombination methods. Morf−/− mice were smaller than their wildtype littermates and died within 4 weeks after birth on C57BL/6 background. In MORF−/− fetal liver, Flt3-negative KSL (c-Kit+ Sca-1+ Lineage-) cells containing hematopoietic stem cells were decreased. When fetal liver cells were transplanted into irradiated recipient mice, MORF−/− cells less efficiently reconstituted hematopoiesis than wild-type cells. Additionally, bone marrow cells reconstituted with MORF−/− cells rarely contributed to hematopoiesis in secondary transplants. To reveal relationship between MORF and MOZ in hematopoiesis, we generated double heterozygous (Moz+/− Morf+/−) mouse. Double heterozygous mice were smaller than wild-type littermates and died at least 4 weeks after birth. Numbers of KSL cells, especially Flt3- KSL cells and common myeloid progenitors were decreased in the double heterozygous embryos. The double heterozygous fetal liver cells also displayed less activity to reconstitute hematopoiesis than MOZ+/− or MORF+/− cells. Since MORF−/− mice and MOZ/MORF double heterozygous mice were alive at adult on a mixed C57BL/6/DBA2 genetic background, we investigated adult hematopoiesis in these mice. MORF−/− or MOZ/MORF double heterozygous mice were smaller than their wild-type littermates and had small numbers of thymocytes and splenocytes. However, there were no significant differences in number of bone marrow cells and hematopoietic lineage population in MORF−/− or MOZ/MORF double heterozygous mice. These results suggest that MORF as well as MOZ plays important roles in self-renewal of hematopoietic stem cells. Disclosures: No relevant conflicts of interest to declare.

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