scholarly journals Regulatory Systems in Bone Marrow for Hematopoietic Stem/Progenitor Cells Mobilization and Homing

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
P. Alvarez ◽  
E. Carrillo ◽  
C. Vélez ◽  
F. Hita-Contreras ◽  
A. Martínez-Amat ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Proteolytic Enzymes ◽  
Influential Factors ◽  
Hematopoietic Stem ◽  
Cell Therapies ◽  
Cord Injury ◽  
Cell Release ◽  
Stromal Cell Derived Factor

Regulation of hematopoietic stem cell release, migration, and homing from the bone marrow (BM) and of the mobilization pathway involves a complex interaction among adhesion molecules, cytokines, proteolytic enzymes, stromal cells, and hematopoietic cells. The identification of new mechanisms that regulate the trafficking of hematopoietic stem/progenitor cells (HSPCs) cells has important implications, not only for hematopoietic transplantation but also for cell therapies in regenerative medicine for patients with acute myocardial infarction, spinal cord injury, and stroke, among others. This paper reviews the regulation mechanisms underlying the homing and mobilization of BM hematopoietic stem/progenitor cells, investigating the following issues: (a) the role of different factors, such as stromal cell derived factor-1 (SDF-1), granulocyte colony-stimulating factor (G-CSF), and vascular cell adhesion molecule-1 (VCAM-1), among other ligands; (b) the stem cell count in peripheral blood and BM and influential factors; (c) the therapeutic utilization of this phenomenon in lesions in different tissues, examining the agents involved in HSPCs mobilization, such as the different forms of G-CSF, plerixafor, and natalizumab; and (d) the effects of this mobilization on BM-derived stem/progenitor cells in clinical trials of patients with different diseases.

The histone lysine acetyltransferase HBO1 (KAT7) regulates hematopoietic stem cell quiescence and self-renewal

Blood ◽  
2021 ◽  
Author(s):  
Yuqing Yang ◽  
Andrew J Kueh ◽  
Zoe Grant ◽  
Waruni Abeysekera ◽  
Alexandra L Garnham ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Hematopoietic Stem Cell ◽  
Cell Function ◽  
Bone Marrow Cells ◽  
High Rate ◽  
Embryonic Patterning ◽  
Self Renewal ◽  
Hematopoietic Stem

The histone acetyltransferase HBO1 (MYST2, KAT7) is indispensable for postgastrulation development, histone H3 lysine 14 acetylation (H3K14Ac) and the expression of embryonic patterning genes. In this study, we report the role of HBO1 in regulating hematopoietic stem cell function in adult hematopoiesis. We used two complementary cre-recombinase transgenes to conditionally delete Hbo1 (Mx1-Cre and Rosa26-CreERT2). Hbo1 null mice became moribund due to hematopoietic failure with pancytopenia in the blood and bone marrow two to six weeks after Hbo1 deletion. Hbo1 deleted bone marrow cells failed to repopulate hemoablated recipients in competitive transplantation experiments. Hbo1 deletion caused a rapid loss of hematopoietic progenitors (HPCs). The numbers of lineage-restricted progenitors for the erythroid, myeloid, B-and T-cell lineages were reduced. Loss of HBO1 resulted in an abnormally high rate of recruitment of quiescent hematopoietic stem cells (HSCs) into the cell cycle. Cycling HSCs produced progenitors at the expense of self-renewal, which led to the exhaustion of the HSC pool. Mechanistically, genes important for HSC functions were downregulated in HSC-enriched cell populations after Hbo1 deletion, including genes essential for HSC quiescence and self-renewal, such as Mpl, Tek(Tie-2), Gfi1b, Egr1, Tal1(Scl), Gata2, Erg, Pbx1, Meis1 and Hox9, as well as genes important for multipotent progenitor cells and lineage-specific progenitor cells, such as Gata1. HBO1 was required for H3K14Ac through the genome and particularly at gene loci required for HSC quiescence and self-renewal. Our data indicate that HBO1 promotes the expression of a transcription factor network essential for HSC maintenance and self-renewal in adult hematopoiesis.

Role of c-kit/Kit ligand signaling in regulating vasculogenesis

2003 ◽  
Vol 90 (10) ◽  
pp. 570-576 ◽  
Author(s):  
Beate Heissig ◽  
Zena Werb ◽  
Shahin Rafii ◽  
Koichi Hattori
Keyword(s):  
Bone Marrow ◽  
Growth Factor ◽  
Progenitor Cells ◽  
International Workshop ◽  
Medical Science ◽  
Vascular Diseases ◽  
Hematopoietic Stem ◽  
Tumor Bed ◽  
Kit Ligand ◽  
Stromal Cell Derived Factor

SummaryMobilization into peripheral blood of bone marrow-derived cells including hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs), is regulated by chemokines/cytokines. These cells can contribute to the formation of new blood vessels (vasculogenesis) under pathological conditions including atherosclerosis, wound healing and tumor growth. We will review how these cells are mobilized into circulation, and supplied to the sites, where vessel formation is needed (i.e. ischemic tissue or tumor bed).We will give evidence that matrix metalloproteinase-9 mediated Kit ligand (Stem cell factor) processing is essential for cell mobilization induced by chemo-/cyto-kines, like vascular endothelial growth factor (VEGF), Placental growth factor (PlGF), stromal cell derived factor-1 (SDF-1). These studies may provide the basis for the development of new therapeutic strategies for vascular diseases through targeting kit ligand mediated mobilization and homing of bone marrow-derived progenitor cells for cell therapy and cancer therapy.This publication was partially financed by Serono Foundation for the Advancement of Medical Science. Financial support: This work was supported by a grant from the Japanese Society for the Promotion of Science (B.H.) and by funds from the National Institutes of Health (CA 72006 and AR46238 to ZW). Part of this paper was originally presented at the 2nd International Workshop on New Therapeutic Targets in Vascular Biology from February 6-9, 2003 in Geneva, Switzerland.

Cell surface peptidase CD26/DPPIV mediates G-CSF mobilization of mouse progenitor cells

Blood ◽  
2003 ◽  
Vol 101 (12) ◽  
pp. 4680-4686 ◽  
Author(s):  
Kent W. Christopherson ◽  
Scott Cooper ◽  
Hal E. Broxmeyer
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Mouse Bone Marrow ◽  
Peptidase Activity ◽  
Hematopoietic Stem ◽  
Migratory Response ◽  
Stromal Cell Derived Factor ◽  
Marrow Cells

AbstractCXC ligand 12 (CXCL12; also known as stromal cell–derived factor 1α/SDF-1α) chemoattracts hematopoietic stem and progenitor cells (HSCs/HPCs) and is thought to play a crucial role in the mobilization of HSCs/HPCs from the bone marrow. CD26 (dipeptidylpeptidase IV [DPPIV]) is a membrane-bound extracellular peptidase that cleaves dipeptides from the N-terminus of polypeptide chains. CD26 has the ability to cleave CXCL12 at its position-2 proline. We found by flow cytometry that CD26 is expressed on a subpopulation of normal Sca-1+c-kit+lin— hematopoietic cells isolated from mouse bone marrow, as well as Sca-1+c-kit—lin— cells, and that these cells possess CD26 peptidase activity. To test the functional role of CD26 in CXCL12-mediated normal HSC/HPC migration, chemotaxis assays were performed. The CD26 truncated CXCL12(3-68) showed an inability to induce the migration of sorted Sca-1+c-kit+lin— or Sca-1+c-kit—lin— mouse marrow cells compared with the normal CXCL12. In addition, CXCL12(3-68) acts as an antagonist, resulting in the reduction of migratory response to normal CXCL12. Treatment of Sca-1+c-kit+lin— mouse marrow cells, and myeloid progenitors within this population, or Sca-1+c-kit—lin— cells with a specific CD26 inhibitor, enhanced the migratory response of these cells to CXCL12. Finally, to test for potential in vivo relevance of these in vitro observations, mice were treated with CD26 inhibitors during granulocyte colony-stimulating factor (G-CSF)–induced mobilization. This treatment resulted in a reduction in the number of progenitor cells in the periphery as compared with the G-CSF regimen alone. This suggests that a mechanism of action of G-CSF mobilization involves CD26.

Involvement of the Integrin Alpha 6 Receptor in the Homing and Engraftment of Hematopoietic Stem and Progenitor Cells to Bone Marrow.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1293-1293
Author(s):  
Hong Qian ◽  
Sten Eirik W. Jacobsen ◽  
Marja Ekblom
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Bone Marrow Cells ◽  
Hematopoietic Stem ◽  
Stem And Progenitor Cells ◽  
Functional Blocking

Abstract Within the bone marrow environment, adhesive interactions between stromal cells and extracellular matrix molecules are required for stem and progenitor cell survival, proliferation and differentiation as well as their transmigration between bone marrow (BM) and the circulation. This regulation is mediated by cell surface adhesion receptors. In experimental mouse stem cell transplantation models, several classes of cell adhesion receptors have been shown to be involved in the homing and engraftment of stem and progenitor cells in BM. We have previously found that integrin a6 mediates human hematopoietic stem and progenitor cell adhesion to and migration on its specific ligands, laminin-8 and laminin-10/11 in vitro (Gu et al, Blood, 2003; 101:877). Using FACS analysis, the integrin a6 chain was now found to be ubiquitously (>95%) expressed in mouse hematopoietic stem and progenitor cells (lin−Sca-1+c-Kit+, lin−Sca-1+c-Kit+CD34+) both in adult bone marrow and in fetal liver. In vitro, about 70% of mouse BM lin−Sca-1+c-Kit+ cells adhered to laminin-10/11 and 40% adhered to laminin-8. This adhesion was mediated by integrin a6b1 receptor, as shown by functional blocking monoclonal antibodies. We also used a functional blocking monoclonal antibody (GoH3) against integrin a6 to analyse the role of the integrin a6 receptor for the in vivo homing of hematopoietic stem and progenitor cells. We found that the integrin a6 antibody inhibited the homing of bone marrow progenitors (CFU-C) into BM of lethally irradiated recipients. The number of homed CFU-C was reduced by about 40% as compared to cells incubated with an isotype matched control antibody. To study homing of long-term repopulating stem cells (LTR), antibody treated bone marrow cells were first injected intravenously into lethally irradiated primary recipients. After three hours, bone marrow cells of the primary recipients were analysed by competitive repopulation assay in secondary recipients. Blood analysis 16 weeks after transplantation revealed an 80% reduction of stem cell activity of integrin a6 antibody treated cells as compared to cells treated with control antibody. These results suggest that integrin a6 plays an important role for hematopoietic stem and progenitor cell homing in vivo.

Integrin alpha 6 Is Essential for Fetal Hematopoietic Progenitor, but Not Fetal Stem Cell Homing to Bone Marrow.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1387-1387
Author(s):  
Hong Qian ◽  
Sten Eirik W. Jacobsen ◽  
Marja Ekblom
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Fetal Liver ◽  
Hematopoietic Stem ◽  
Stem And Progenitor Cells ◽  
Integrin Alpha 6

Abstract Homing of transplanted hematopoietic stem cells (HSC) in the bone marrow (BM) is a prerequisite for establishment of hematopoiesis following transplantation. However, although multiple adhesive interactions of HSCs with BM microenviroment are thought to critically influence their homing and subsequently their engraftment, the molecular pathways that control the homing of transplanted HSCs, in particular, of fetal HSCs are still not well understood. In experimental mouse stem cell transplantation models, several integrins have been shown to be involved in the homing and engraftment of both adult and fetal stem and progenitor cells in BM. We have previously found that integrin a6 mediates human hematopoietic stem and progenitor cell adhesion to and migration on its specific ligands, laminin-8 and laminin-10/11 in vitro (Gu et al, Blood, 2003; 101:877). Furthermore, integrin a6 is required for adult mouse HSC homing to BM in vivo (Qian et al., Abstract American Society of Hematology, Blood 2004 ). We have now found that the integrin a6 chain like in adult HSC is ubiquitously (>99%) expressed also in fetal liver hematopoietic stem and progenitor cells (lin−Sca-1+c-Kit+, LSK ). In vitro, fetal liver LSK cells adhere to laminin-10/11 and laminin-8 in an integrin a6b1 receptor-dependent manner, as shown by function blocking monoclonal antibodies. We have now used a function blocking monoclonal antibody (GoH3) against integrin a6 to analyse the role of the integrin a6 receptor for the in vivo homing of fetal liver hematopoietic stem and progenitor cells to BM. The integrin a6 antibody inhibited homing of fetal liver progenitors (CFU-C) into BM of lethally irradiated recipients. The number of homed CFU-C in BM was reduced by about 40% as compared to the cells incubated with an isotype matched control antibody. To study homing of long-term repopulating stem cells, BM cells were first incubated with anti-integrin alpha 6 or anti-integrin alpha 4 or control antibody, and then injected intravenously into lethally irradiated primary recipients. After three hours, BM cells of the primary recipients were analysed by competitive repopulation assay in secondary recipients. Blood analysis up to 16 weeks after transplantation showed that no reduction of stem cell reconstitution from integrin a6 antibody treated cells as compared to cells treated with control antibody. In accordance with this, fetal liver HSC from integrin a6 gene deleted embryos did not show any impairment of homing and engraftment in BM as compared to normal littermates. These results suggest that integrin a6 plays an important developmentally regulated role for homing of distinct hematopoietic stem and progenitor cell populations in vivo.

Differential Role for VLA-5 in Mobilization of Heamotopoieic Stem Cells Toward Peripheral Blood and Homing to Bone Marrow and Spleen.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2190-2190 ◽  
Author(s):  
Pieter K. Wierenga ◽  
Ellen Weersing ◽  
Bert Dontje ◽  
Gerald de Haan ◽  
Ronald P. van Os
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Peripheral Blood ◽  
Hematopoietic Stem ◽  
Late Antigen ◽  
Cell Mobilization

Abstract Adhesion molecules have been implicated in the interactions of hematopoietic stem and progenitor cells with the bone marrow extracellular matrix and stromal cells. In this study we examined the role of very late antigen-5 (VLA-5) in the process of stem cell mobilization and homing after stem cell transplantation. In normal bone marrow (BM) from CBA/H mice 79±3 % of the cells in the lineage negative fraction express VLA-5. After mobilization with cyclophosphamide/G-CSF, the number of VLA-5 expressing cells in mobilized peripheral blood cells (MPB) decreases to 36±4%. The lineage negative fraction of MPB cells migrating in vitro towards SDF-1α (M-MPB) demonstrated a further decrease to 3±1% of VLA-5 expressing cells. These data are suggestive for a downregulation of VLA-5 on hematopoietic cells during mobilization. Next, MPB cells were labelled with PKH67-GL and transplanted in lethally irradiated recipients. Three hours after transplantation an increase in VLA-5 expressing cells was observed which remained stable until 24 hours post-transplant. When MPB cells were used the percentage PKH-67GL+ Lin− VLA-5+ cells increased from 36% to 88±4%. In the case of M-MPB cells the number increased from 3% to 33±5%. Although the increase might implicate an upregulation of VLA-5, we could not exclude selective homing of VLA-5+ cells as a possible explanation. Moreover, we determined the percentage of VLA-5 expressing cells immediately after transplantation in the peripheral blood of the recipients and were not able to observe any increase in VLA-5+ cells in the first three hours post-tranpslant. Finally, we separated the MPB cells in VLA-5+ and VLA-5− cells and plated these cells out in clonogenic assays for progenitor (CFU-GM) and stem cells (CAFC-day35). It could be demonstared that 98.8±0.5% of the progenitor cells and 99.4±0.7% of the stem cells were present in the VLA-5+ fraction. Hence, VLA-5 is not downregulated during the process of mobilization and the observed increase in VLA-5 expressing cells after transplantation is indeed caused by selective homing of VLA-5+ cells. To shed more light on the role of VLA-5 in the process of homing, BM and MPB cells were treated with an antibody to VLA-5. After VLA-5 blocking of MPB cells an inhibition of 59±7% in the homing of progenitor cells in bone marrow could be found, whereas homing of these subsets in the spleen of the recipients was only inhibited by 11±4%. For BM cells an inhibition of 60±12% in the bone marrow was observed. Homing of BM cells in the spleen was not affected at all after VLA-5 blocking. Based on these data we conclude that mobilization of hematopoietic progenitor/stem cells does not coincide with a downregulation of VLA-5. The observed increase in VLA-5 expressing cells after transplantation is caused by preferential homing of VLA-5+ cells. Homing of progenitor/stem cells to the bone marrow after transplantation apparantly requires adhesion interactions that can be inhibited by blocking VLA-5 expression. Homing to the spleen seems to be independent of VLA-5 expression. These data are indicative for different adhesive pathways in the process of homing to bone marrow or spleen.

Muc1 Expression Identifies Human Self-Renewing Stem/Progenitor Populations and Is Elevated in AML CD34+ Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4040-4040
Author(s):  
Szabolcs Fatrai ◽  
Simon M.G.J. Daenen ◽  
Edo Vellenga ◽  
Jan J. Schuringa
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Fold Increase ◽  
Marrow Stromal Cells ◽  
Muc1 Expression ◽  
Hematopoietic Stem ◽  
Cd34 Cells

Abstract Mucin1 (Muc1) is a membrane glycoprotein which is expressed on most of the normal secretory epithelial cells as well as on hematopoietic cells. It is involved in migration, adhesion and intracellular signalling. Muc1 can be cleaved close to the membrane-proximal region, resulting in an intracellular Muc1 that can associate with or activate various signalling pathway components such as b-catenin, p53 and HIF1a. Based on these properties, Muc1 expression was analysed in human hematopoietic stem/progenitor cells. Muc1 mRNA expression was highest in the immature CD34+/CD38− cells and was reduced upon maturation towards the progenitor stage. Cord blood (CB) CD34+ cells were sorted into Muc1+ and Muc1− populations followed by CFC and LTC-IC assays and these experiments revealed that the stem and progenitor cells reside predominantly in the CD34+/Muc1+ fraction. Importantly, we observed strongly increased Muc1 expression in the CD34+ subfraction of AML mononuclear cells. These results tempted us to further study the role of Muc1 overexpression in human CD34+ stem/progenitor cells. Full-length Muc1 (Muc1F) and a Muc1 isoform with a deleted extracellular domain (DTR) were stably expressed in CB CD34+ cells using a retroviral approach. Upon coculture with MS5 bone marrow stromal cells, a two-fold increase in expansion of suspension cells was observed in both Muc1F and DTR cultures. In line with these results, we observed an increase in progenitor counts in the Muc1F and DTR group as determined by CFC assays in methylcellulose. Upon replating of CFC cultures, Muc1F and DTR were giving rise to secondary colonies in contrast to empty vector control groups, indicating that self-renewal was imposed on progenitors by expression of Muc1. A 3-fold and 2-fold increase in stem cell frequencies was observed in the DTR and Muc1F groups, respectively, as determined by LTC-IC assays. To determine whether the above mentioned phenotypes in MS5 co-cultures were stroma-dependent, we expanded Muc1F and DTR-transduced cells in cytokine-driven liquid cultures. However, no proliferative advantage or increase in CFC frequencies was observed suggesting that Muc1 requires bone marrow stromal cells. In conclusion, our data indicate that HSCs as well as AML cells are enriched for Muc1 expression, and that overexpression of Muc1 in CB cells is sufficient to increase both progenitor and stem cell frequencies.

Novel In Vivo Evidence That Not Only Androgens But Also Pituitary Gonadotropins and Prolactin Directly Stimulate Murine Bone Marrow Stem Cells – Implications For Potential Treatment Strategies In Aplastic Anemias

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2476-2476
Author(s):  
Kasia Mierzejewska ◽  
Ewa Suszynska ◽  
Sylwia Borkowska ◽  
Malwina Suszynska ◽  
Maja Maj ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Sex Hormones ◽  
Peripheral Blood ◽  
Hematopoietic Stem ◽  
Clonogenic Potential

Abstract Background Hematopoietic stem/progenitor cells (HSPCs) are exposed in vivo to several growth factors, cytokines, chemokines, and bioactive lipids in bone marrow (BM) in addition to various sex hormones circulating in peripheral blood (PB). It is known that androgen hormones (e.g., danazol) is employed in the clinic to treat aplastic anemia patients. However, the exact mechanism of action of sex hormones secreted by the pituitary gland or gonads is not well understood. Therefore, we performed a complex series of experiments to address the influence of pregnant mare serum gonadotropin (PMSG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), androgen (danazol) and prolactin (PRL) on murine hematopoiesis. In particular, from a mechanistic view we were interested in whether this effect depends on stimulation of BM-residing stem cells or is mediated through the BM microenvironment. Materials and Methods To address this issue, normal 2-month-old C57Bl6 mice were exposed or not to daily injections of PMSG (10 IU/mice/10 days), LH (5 IU/mice/10 days), FSH (5 IU/mice/10 days), danazol (4 mg/kg/10 days) and PRL (1 mg/day/5days). Subsequently, we evaluated changes in the BM number of Sca-1+Lin–CD45– that are precursors of long term repopulating hematopoietic stem cells (LT-HSCs) (Leukemia 2011;25:1278–1285) and bone forming mesenchymal stem cells (Stem Cell & Dev. 2013;22:622-30) and Sca-1+Lin–CD45+ hematopoietic stem/progenitor cells (HSPC) cells by FACS, the number of clonogenic progenitors from all hematopoietic lineages, and changes in peripheral blood (PB) counts. In some of the experiments, mice were exposed to bromodeoxyuridine (BrdU) to evaluate whether sex hormones affect stem cell cycling. By employing RT-PCR, we also evaluated the expression of cell-surface and intracellular receptors for hormones in purified populations of murine BM stem cells. In parallel, we studied whether stimulation by sex hormones activates major signaling pathways (MAPKp42/44 and AKT) in HSPCs and evaluated the effect of sex hormones on the clonogenic potential of murine CFU-Mix, BFU-E, CFU-GM, and CFU-Meg in vitro. We also sublethally irradiated mice and studied whether administration of sex hormones accelerates recovery of peripheral blood parameters. Finally, we determined the influence of sex hormones on the motility of stem cells in direct chemotaxis assays as well as in direct in vivo stem cell mobilization studies. Results We found that 10-day administration of each of the sex hormones evaluated in this study directly stimulated expansion of HSPCs in BM, as measured by an increase in the number of these cells in BM (∼2–3x), and enhanced BrdU incorporation (the percentage of quiescent BrdU+Sca-1+Lin–CD45– cells increased from ∼2% to ∼15–35% and the percentage of BrdU+Sca-1+Lin–CD45+ cells increased from 24% to 43–58%, Figure 1). These increases paralleled an increase in the number of clonogenic progenitors in BM (∼2–3x). We also observed that murine Sca-1+Lin–CD45– and Sca-1+Lin–CD45+ cells express sex hormone receptors and respond by phosphorylation of MAPKp42/44 and AKT in response to exposure to PSMG, LH, FSH, danazol and PRL. We also observed that administration of sex hormones accelerated the recovery of PB cell counts in sublethally irradiated mice and slightly mobilized HSPCs into PB. Finally, in direct in vitro clonogenic experiments on purified murine SKL cells, we observed a stimulatory effect of sex hormones on clonogenic potential in the order: CFU-Mix > BFU-E > CFU-Meg > CFU-GM. Conclusions Our data indicate for the first time that not only danazol but also several pituitary-secreted sex hormones directly stimulate the expansion of stem cells in BM. This effect seems to be direct, as precursors of LT-HSCs and HSPCs express all the receptors for these hormones and respond to stimulation by phosphorylation of intracellular pathways involved in cell proliferation. These hormones also directly stimulated in vitro proliferation of purified HSPCs. In conclusion, our studies support the possibility that not only danazol but also several other upstream pituitary sex hormones could be employed to treat aplastic disorders and irradiation syndromes. Further dose- and time-optimizing mouse studies and studies with human cells are in progress in our laboratories. Disclosures: No relevant conflicts of interest to declare.

Modeling Bone Marrow Failure and MDS in Shwachman Diamond Syndrome Using Induced Pluripotent Stem Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1496-1496 ◽  
Author(s):  
Melisa Ruiz-Gutierrez ◽  
Ozge Vargel Bolukbasi ◽  
Linda Vo ◽  
Ryohichi Sugimura ◽  
Marilyn Sanchez Bonilla ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Bone Marrow Failure ◽  
Clonal Evolution ◽  
Chromosome 7 ◽  
Stem Cell Markers ◽  
Hematopoietic Stem ◽  
Monosomy 7

Abstract Myelodysplastic syndrome (MDS) caused by monosomy 7 or del(7q) is a frequent clonal abnormality that arises in the context of inherited bone marrow failure syndromes, such as Shwachman Diamond Syndrome (SDS). Monosomy 7/del(7q) also develops in a subset of patients with acquired aplastic anemia or de novo MDS in the general population. Monosomy 7/del(7q) is associated with high grade MDS and a high risk of malignant transformation, most frequently to acute myelogenous leukemia (AML). Bone marrow failure and clonal evolution to MDS and AML remain major causes of morbidity and mortality for individuals with SDS. Currently, the only curative therapy for these hematological complications is a hematopoietic stem cell transplant. Prognosis is extremely poor once SDS patients develop leukemia. The basis for this propensity to develop monosomy 7 clones remains unclear. The longterm aim of this study is to understand the molecular mechanisms underlying leukemia predisposition and develop more effective treatments. Whether monosomy 7/del(7q) functions as a driver of MDS, or is merely an associated marker of clonal progression in bone marrow failure remains a critical question. The lack of synteny between murine versus human chromosome 7 has posed a major barrier to the development of mouse models of monosomy 7/del(7q). To study the biological and molecular consequences of monosomy 7/del(7q) in SDS, induced pluripotent stem cells (iPSCs) were generated from bone marrow mononuclear cells of two patients with SDS. Each patient harbored homozygous c.258+2 T>C mutations in the canonical splice donor site of intron 2 in the SBDS gene. The SDS-iPSCs retained the pathogenic homozygous IVS2+2 T>C SBDS mutations, expressed stem cell markers, formed teratomas, and expressed reduced levels of SBDS protein similar to levels noted in the primary patient samples. Proliferation of 4 distinct SDS-iPSC clones derived from two different patients was reduced relative to wild type controls without an increase in cell death. SDS-iPSC formed smaller embryoid bodies with reduced production of CD34+ hematopoietic stem/progenitor cells. Hematopoietic differentiation from CD34+ to CD45+ cells was also impaired. Preliminary data suggest that SDS-iPSCs retain the capacity to give rise to hematopoietic stem/progenitor cells and early myeloid progenitor cells in vitro. These populations were also observed in primary SDS patient-derived bone marrow samples. Because the number of CD34+ cells derived from SDS-iPSCs are limiting, a previously reported 5 transcrition factor re-specification system was used to expand multilineage hematopietic progenitors for further characterization. SDS iPSCs were able to differentiate into an expandable CD34+ population in vitro. Further studies to characterize the hematopoietic impairment in SDS iPSC and primary marrow samples are ongoing. To model del(7q) in SDS iPSCs, a deletion of the MDS-associated long arm of chromosome 7 was genomically engineered using a previously published modified Cre-Lox approach. The deletion of 7q at locus (11.2) was confirmed by karyotyping and by qPCR across chromosome 7. The SDS (del7q) iPSCs retained the SBDS pathogenic mutations, expressed stem cell markers, and formed teratomas. Proliferation of the SDS del(7q) iPSC was markedly impaired compared to isogenic SDS iPSCs. No increase in cell death was observed in the SDS del7q iPSCs. Studies are in progress to determine the effects of del7q on hematopoiesis. Investigation is ongoing to determine the molecular consequences of deleting 7q. These isogenic SDS+/- del(7q) iPS models provide a platform to study the role of 7q loss in clonal evolution from bone marrow failure and to screen for novel therapeutic compounds or pathways to treat bone marrow failure and MDS. Disclosures No relevant conflicts of interest to declare.

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