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.

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.

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.

Homing and Engraftment of Mobilized Hematopoietic Stem Cells: Involvement of VLA-5.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4943-4943
Author(s):  
Pieter K. Wierenga ◽  
Gerald de Haan ◽  
Bert Dontje ◽  
Ellen Weersing ◽  
Ronald van Os
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Peripheral Blood ◽  
Hematopoietic Stem ◽  
Post Transplant ◽  
Hematopoietic Reconstitution

Abstract VLA-5 has been implicated in the adhesive interactions of stem and progenitor cells with the bone marrow extracellular matrix and stromal cells and is therefore considered to play an important role in the hematopoietic reconstitution 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-GSF, the number of VLA-5 expressing cells in mobilized peripheral blood cells (MPB) decreases to 38±3%. Despite this low frequency of VLA-5+ cells, however, even when equal numbers of progenitor cells are transplanted MPB cells provide a much faster hematopoietic recovery compared to BM cells. To shed more light on the role of VLA-5 in the process of homing and engraftment, we investigated whether differences in homing potential of the stem cell subsets might be responsible for this enhanced reconstitution. At 3 hours post-transplant, however, no differences in homing efficiency of progenitor and stem cells from MPB and BM grafts in both bone marrow and spleen could be detected. It should be realized that MPB and BM grafts demonstrate different ratios of stem/progenitor cells which might be another explanation for the observed differences in repopulation potential. Furthermore, MPB cells migrating in vitro towards SDF-1α showed potent reconstitution while VLA-5 expression was reduced on these cells. In fact, in vitro treatment with SDF-1α showed further decrease in VLA-5 expressing cells (from 38% to 4%) in the lin- fraction. When equal numbers of MPB were transplanted with and without SDF-1α pretreatment, no difference in hematopoietic reconstitution was observed suggesting a minor role of VLA-5 in homing and engraftment. On the other hand, after VLA-5 blocking an inhibition of 59±7% in the homing of MPB progenitor cells in the bone marrow could be found, whereas homing in the spleen of the the recipients is only inhibited by 11±4%. To elucidate whether the observed enhanced reconstitution could be explained by a selective homing of VLA-5+ cells or a rapid upregulation of VLA-5 expression, cells were labelled with PKH67-GL and transplanted in lethally irradiated recipients. It could be demonstrated that at 3 hours post-transplant cells from MPB grafts showed a rapid increase from 38±3% up to 66±9% of VLA-5+ cells in the bone marrow of the recipient. In the spleen no significant increase in VLA-5+ cells was observed. When MPB cells were transplanted after pretreatment with SDF-1α an increase from 2±1% up to 33±5% of VLA-5+ cells in the bone marrow was detected. When calculating the number of cells recovered from bone marrow, a selective homing of VLA-5+ cells cannot be excluded. Therefore, we also assessed the number of VLA-5+ cells in the PKH+ fraction in peripheral blood from the recipient immediately (½-1 hour) after transplantation but found no increase during that time period. So far it can be concluded that MPB cells show low number of VLA-5+ cells but these cells possess an enhanced hematopoietic reconstitution potential. Homing of progenitor cells to the spleen seems to be less dependent on VLA-5 expression than homing to the bone marrow. A rapid upregulation of VLA-5 expression on engrafting MPB cells early after transplantation does not occur and hence our data are suggestive for the preferential homing of VLA-5+ cells in the bone marrow after transplantation.

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

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.

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.

Donor Origin of Multipotent Adult Progenitor Cells in Radiation Chimeras.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1395-1395
Author(s):  
Morayma Reyes ◽  
Jeffrey S. Chamberlain
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Y Chromosome ◽  
Stromal Cells ◽  
Mononuclear Cells ◽  
Multipotent Adult Progenitor Cells

Abstract Multipotent Adult Progenitor Cells (MAPC) are bone marrow derived stem cells that can be extensively expanded in vitro and can differentiate in vivo and in vitro into cells of all three germinal layers: ectoderm, mesoderm, endoderm. The origin of MAPC within bone marrow (BM) is unknown. MAPC are believed to be derived from the BM stroma compartment as they are isolated within the adherent cell component. Numerous studies of bone marrow chimeras in human and mouse point to a host origin of bone marrow stromal cells, including mesenchymal stem cells. We report here that following syngeneic bone marrow transplants into lethally irradiated C57Bl/6 mice, MAPC are of donor origin. When MAPC were isolated from BM chimeras (n=12, 4–12 weeks post-syngeneic BM transplant from a transgenic mouse ubiquitously expressing GFP), a mixture of large and small GFP-positive and GFP-negative cells were seen early in culture. While the large cells stained positive for stroma cell markers (smooth muscle actin), mesenchymal stem cell makers (CD73, CD105, CD44) or macrophages (CD45, CD14), the small cells were negative for all these markers and after 30 cell doublings, these cells displayed the classical phenotype of MAPC (CD45−,CD105−, CD44−, CD73−, FLK-1+(vascular endothelial growth factor receptor 2, VEGFR2), Sca-1+,CD13+). In a second experiment, BM obtained one month post BM transplant (n=3) was harvested and mononuclear cells were sorted as GFP-positive and GFP-negative cells and were cultured in MAPC expansion medium. MAPC grew from the GFP-positive fraction. These GFP positive cells displayed the typical MAPC-like immunophenotypes, displayed a normal diploid karyotype and were expanded for more than 50 cell doublings and differentiated into endothelial cells, hepatocytes and neurons. To rule out the possibility that MAPC are the product of cell fusion between a host and a donor cell either in vivo or in our in vitro culture conditions, we performed sex mismatched transplants of female GFP donor BM cells into a male host. BM from 5 chimeras were harvested 4 weeks after transplant and MAPC cultures were established. MAPC colonies were then sorted as GFP-positive and GFP- negative and analyzed for the presence of Y-chromosome by FISH analysis. As expected all GFP-negative (host cells) contained the Y-chromosome whereas all GFP-positive cells (donor cells) were negative for the Y-chromosome by FISH. This proves that MAPC are not derived from an in vitro or in vivo fusion event. In a third study, BM mononuclear cells from mice that had been previously BM-transplanted with syngeneic GFP-positive donors (n=3) were transplanted into a second set of syngeneic recipients (n=9). Two months after the second transplant, BM was harvested and mononuclear cells were cultured in MAPC medium. The secondary recipients also contained GFP-positive MAPC. This is the first demonstration that BM transplantation leads to the transfer of cells that upon isolation in vitro generate MAPCs and, whatever the identity of this cell may be, is eliminated by irradiation. We believe this is an important observation as MAPC hold great clinical potential for stem cell and/or gene therapy and, thus, BM transplant may serve as a way to deliver and reconstitute the MAPC population. In addition, this study provides insight into the nature of MAPC. The capacity to be transplantable within unfractionated BM transplant renders a functional and physiological distinction between MAPC and BM stromal cells. This study validates the use of unfractionated BM transplants to study the nature and possible in vivo role of MAPC in the BM.

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.

Cripto Selectively Expands a Distinct Population of Hematopoietic Stem Cells Expressing the Cell Surface Receptor GRP78 and Strongly Induces An Immature Phenotype In Vivo After Ex Vivo Culture

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 405-405
Author(s):  
Kenichi Miharada ◽  
Göran Karlsson ◽  
Jonas Larsson ◽  
Emma Larsson ◽  
Kavitha Siva ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Peripheral Blood ◽  
Distinct Population ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Total Bone Marrow

Abstract Abstract 405 Cripto is a member of the EGF-CFC soluble protein family and has been identified as an important factor for the proliferation/self-renewal of ES and several types of tumor cells. The role for Cripto in the regulation of hematopoietic cells has been unknown. Here we show that Cripto is a potential new candidate factor to increase self-renewal and expand hematopoietic stem cells (HSCs) in vitro. The expression level of Cripto was analyzed by qRT-PCR in several purified murine hematopoietic cell populations. The findings demonstrated that purified CD34-KSL cells, known as highly concentrated HSC population, had higher expression levels than other hematopoietic progenitor populations including CD34+KSL cells. We asked how Cripto regulates HSCs by using recombinant mouse Cripto (rmCripto) for in vitro and in vivo experiments. First we tested the effects of rmCripto on purified hematopoietic stem cells (CD34-LSK) in vitro. After two weeks culture in serum free media supplemented with 100ng/ml of SCF, TPO and 500ng/ml of rmCripto, 30 of CD34-KSL cells formed over 1,300 of colonies, including over 60 of GEMM colonies, while control cultures without rmCripto generated few colonies and no GEMM colonies (p<0.001). Next, 20 of CD34-KSL cells were cultured with or without rmCripto for 2 weeks and transplanted to lethally irradiated mice in a competitive setting. Cripto treated donor cells showed a low level of reconstitution (4–12%) in the peripheral blood, while cells cultured without rmCripto failed to reconstitute. To define the target population and the mechanism of Cripto action, we analyzed two cell surface proteins, GRP78 and Glypican-1, as potential receptor candidates for Cripto regulation of HSC. Surprisingly, CD34-KSL cells were divided into two distinct populations where HSC expressing GRP78 exhibited robust expansion of CFU-GEMM progenitor mediated by rmCripto in CFU-assay whereas GRP78- HSC did not respond (1/3 of CD34-KSL cells were GRP78+). Furthermore, a neutralization antibody for GRP78 completely inhibited the effect of Cripto in both CFU-assay and transplantation assay. In contrast, all lineage negative cells were Glypican-1 positive. These results suggest that GRP78 must be the functional receptor for Cripto on HSC. We therefore sorted these two GRP78+CD34-KSL (GRP78+HSC) and GRP78-CD34-KSL (GRP78-HSC) populations and transplanted to lethally irradiated mice using freshly isolated cells and cells cultured with or without rmCripto for 2 weeks. Interestingly, fresh GRP78-HSCs showed higher reconstitution than GRP78+HSCs (58–82% and 8–40%, p=0.0038) and the reconstitution level in peripheral blood increased rapidly. In contrast, GRP78+HSC reconstituted the peripheral blood slowly, still at a lower level than GRP78-HSC 4 months after transplantation. However, rmCripto selectively expanded (or maintained) GRP78+HSCs but not GRP78-HSCs after culture and generated a similar level of reconstitution as freshly transplanted cells (12–35%). Finally, bone marrow cells of engrafted recipient mice were analyzed at 5 months after transplantation. Surprisingly, GRP78+HSC cultured with rmCripto showed higher reconstitution of the CD34-KSL population in the recipients' bone marrow (45–54%, p=0.0026), while the reconstitution in peripheral blood and in total bone marrow was almost the same. Additionally, most reconstituted CD34-KSL population was GRP78+. Interestingly freshly transplanted sorted GRP78+HSC and GRP78-HSC can produce the GRP78− and GRP78+ populations in the bone marrow and the ratio of GRP78+/− cells that were regenerated have the same proportion as the original donor mice. Compared to cultured cells, the level of reconstitution (peripheral blood, total bone marrow, HSC) in the recipient mice was almost similar. These results indicate that the GRP78 expression on HSC is reversible, but it seems to be “fixed” into an immature stage and differentiate with lower efficiency toward mature cells after long/strong exposure to Cripto signaling. Based on these findings, we propose that Cripto is a novel factor that maintains HSC in an immature state and may be a potent candidate for expansion of a distinct population of GRP78 expressing HSC. Disclosures: No relevant conflicts of interest to declare.

Stem Cell Factor Sall4 Regulates Normal and Malignant Hematopoiesis In an Isoform-Specific Manner

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3728-3728
Author(s):  
Samuel Milanovich ◽  
Jeremy Allred ◽  
Jonathan Peterson ◽  
Cary Stelloh ◽  
Sridhar Rao
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem ◽  
Empty Vector ◽  
Bmi1 Expression ◽  
Colony Forming Units ◽  
Colony Forming Capacity

Abstract Stem cells play key roles in early normal development (e.g. embryonic stem cells (ESCs)), maintenance of adult organs (e.g. hematopoietic stem cells (HSCs)) and in some cancers (e.g. leukemia stem cells). To what degree these different types of stem cells rely upon shared versus distinct transcriptional programs remains controversial. Sall4 is a zinc finger transcription factor that exists in two distinct splice isoforms, Sall4a (long) and Sall4b (short). Sall4 has been implicated in embryonic, hematopoietic and malignant stem cell transcriptional regulation. Additionally, Sall4 has been proposed as a potential means of ex-vivo hematopoietic stem cell expansion prior to transplantation. Sall4 isoform-specific differences have been described in ESCs, with Sall4b shown to be critical for maintaining ESC “stemness”. Here we investigate the role of Sall4 isoforms in pediatric acute myeloid leukemia (AML) and murine hematopoiesis to unravel shared versus unique transcriptional programs across different stem cell types. Quantitative real time PCR shows that Sall4b is the predominant Sall4 isoform in murine HSCs and lin-, Sca1+, cKit+ (LSK) cells. Sall4b expression decreases in early lineage-committed progenitors, while Sall4a expression is minimal to absent across murine HSCs and progenitors. Next, we evaluated seven pediatric AML samples and found highly variable Sall4 expression across AML cases. All samples had measurable Sall4a and Sall4b; in 3/7 cases Sall4a and Sall4b expression was similar to that of ESCs, in the other 4 cases Sall4 expression was minimal (<3% of ESCs). To study overexpression of Sall4, we used a murine stem cell retrovirus system to express Sall4a or Sall4b. Bone marrow was harvested from C57/BL6 mice and lineage-committed cells were removed by magnetic column separation. Lineage-negative bone marrow was infected with either empty vector, Sall4a or Sall4b. Transduced bone marrow was then cultured in methylcellulose media to assess colony forming capacity and proliferation in vitro or transplanted in syngeneic mice to assess engraftment and hematopoietic reconstitution in vivo. Sall4a or Sall4b overexpression caused diminished colony forming capacity and cellular proliferation in vitro compared to bone marrow transduced with empty vector (Figure 1). In bone marrow transplant assays, all mice (4/4) transplanted with Sall4b-transduced bone marrow following lethal irradiation succumbed to bone marrow failure within 10 days of transplant. Transplantation of Sall4b-transduced bone marrow into sublethally irradiated mice failed to contribute to hematopoiesis as measured by peripheral blood leukocyte GFP expression (encoded by the viral vector). Together, this data shows that Sall4b-transduced hematopoietic cells fail to engraft and reconstitute hematopoiesis in vivo. We postulated that this phenotype might be mediated through the interaction of Sall4 with Bmi1. Bmi1 is a member of the polycomb complex necessary for normal hematopoiesis, and is known to be bound by Sall4. In preliminary experiments, we have found that overexpression of Sall4 leads to decreased Bmi1 expression at 48 hours post-infection compared to bone marrow infected with empty vector.Figure 1Lin- bone marrow expressing Sall4a, Sall4b or empty vector was cultured in methylcellulose; plates were flushed and replated out to three generations. Colony forming units were assessed (A) and viable cells were counted (B) after 7-10 days in culture.Figure 1. Lin- bone marrow expressing Sall4a, Sall4b or empty vector was cultured in methylcellulose; plates were flushed and replated out to three generations. Colony forming units were assessed (A) and viable cells were counted (B) after 7-10 days in culture. In conclusion, our data shows that Sall4b is expressed in murine hematopoietic stem cells and progenitors, suggesting that Sall4b but not Sall4a influences a hematopoietic cell fate. Additionally, Sall4 expression is variable in AML specimens, implicating a potential pathogenic role in some leukemias, while others are Sall4-independent. Lastly, Sall4 overexpression is associated with decreased expression of the critical hematopoietic gene Bmi1. Together this data suggests that hematopoiesis is dependent upon appropriately regulated Sall4 expression with alterations leading to impaired proliferation and self-renewal. These effects on hematopoiesis appear to be mediated at least in part through a dose-dependent effect on Bmi1 expression. Future studies will evaluate other genes targeted by Sall4 in hematopoiesis and leukemia to define Sall4-dependent gene signatures in normal versus malignant hematopoiesis. Disclosures: No relevant conflicts of interest to declare.

scholarly journals In vivo administration of stem cell factor to mice increases the absolute number of pluripotent hematopoietic stem cells

Blood ◽  
1993 ◽  
Vol 82 (2) ◽  
pp. 445-455 ◽  
Author(s):  
DM Bodine ◽  
NE Seidel ◽  
KM Zsebo ◽  
D Orlic
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Peripheral Blood ◽  
Stem Cell Factor ◽  
Absolute Number ◽  
Hematopoietic Stem ◽  
The Absolute ◽  
In Vivo Administration

We have examined the effects of administration of stem cell-factor (SCF) on the number and distribution of pluripotent hematopoietic stem cells (PHSC) in normal mice. Using the competitive repopulation assay we found that in vivo administration of SCF increases the absolute number of PHSC per mouse threefold. The increased numbers of PHSC are found in the peripheral blood and spleen of the SCF-treated animals. The spleen and peripheral blood stem cells completely repopulated the erythroid, myeloid, and lymphoid lineages of irradiated or W/Wv hosts, similar to bone marrow PHSC. PHSC from the peripheral blood of SCF- treated mice have a lineage marker-negative, c-kit-positive phenotype that is indistinguishable from that of bone marrow PHSC. The increase in the absolute number of spleen PHSC is associated with efficient gene transfer to these cells without prior treatment with 5-fluorouracil. This is a US government work. There are no restrictions on its use.

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