Sociology of Normal Stem and Progenitor Cells in CML Niche

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1234-1234
Author(s):  
Robert S Welner ◽  
Giovanni Amabile ◽  
Deepak Bararia ◽  
Philipp B. Staber ◽  
Akos G. Czibere ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mouse Model ◽  
Progenitor Cells ◽  
Conflicts Of Interest ◽  
Hematopoietic Progenitor Cells ◽  
Quiescent State ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem ◽  
Stem And Progenitor Cells

Abstract Abstract 1234 Specialized bone marrow (BM) microenvironment niches are essential for hematopoietic stem and progenitor cell maintenance, and recent publications have focused on the leukemic stem cells interaction and placement within those sites. Surprisingly, little is known about how the integrity of this leukemic niche changes the normal stem and progenitor cells behavior and functionality. To address this issue, we started by studying the kinetics and differentiation of normal hematopoietic stem and progenitor cells in mice with Chronic Myeloid Leukemia (CML). CML accounts for ∼15% of all adult leukemias and is characterized by the BCR-ABL t(9;22) translocation. Therefore, we used a novel SCL-tTA BCR/ABL inducible mouse model of CML-chronic phase to investigate these issues. To this end, BM from leukemic and normal mice were mixed and co-transplanted into hosts. Although normal hematopoiesis was increasingly suppressed during the disease progression, the leukemic microenvironment imposed distinct effects on hematopoietic progenitor cells predisposing them toward the myeloid lineage. Indeed, normal hematopoietic progenitor cells from this leukemic environment demonstrated accelerated proliferation with a lack of lymphoid potential, similar to that of the companion leukemic population. Meanwhile, the leukemic-exposed normal hematopoietic stem cells were kept in a more quiescent state, but remained functional on transplantation with only modest changes in both engraftment and homing. Further analysis of the microenvironment identified several cytokines that were found to be dysregulated in the leukemia and potentially responsible for these bystander responses. We investigated a few of these cytokines and found IL-6 to play a crucial role in the perturbation of normal stem and progenitor cells observed in the leukemic environment. Interestingly, mice treated with anti-IL-6 monoclonal antibody reduced both the myeloid bias and proliferation defects of normal stem and progenitor cells. Results obtained with this mouse model were similarly validated using specimens obtained from CML patients. Co-culture of primary CML patient samples and GFP labeled human CD34+CD38- adult stem cells resulted in selective proliferation of the normal primitive progenitors compared to mixed cultures containing unlabeled normal bone marrow. Proliferation was blocked by adding anti-IL-6 neutralizing antibody to these co-cultures. Therefore, our current study provides definitive support and an underlying crucial mechanism for the hematopoietic perturbation of normal stem and progenitor cells during leukemogenesis. We believe our study to have important implications for cancer prevention and novel therapeutic approach for leukemia patients. We conclude that changes in cytokine levels and in particular those of IL-6 in the CML microenvironment are responsible for altered differentiation and functionality of normal stem cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Identification of BCR/ABL-negative primitive hematopoietic progenitor cells within chronic myeloid leukemia marrow

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 801-807 ◽  
Author(s):  
T Leemhuis ◽  
D Leibowitz ◽  
G Cox ◽  
R Silver ◽  
EF Srour ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Chronic Myeloid Leukemia ◽  
Progenitor Cells ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Polymerase Chain Reaction Analysis ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem

Chronic myeloid leukemia (CML) is a malignant disorder of the hematopoietic stem cell. It has been shown that normal stem cells coexist with malignant stem cells in the bone marrow of patients with chronic-phase CML. To characterize the primitive hematopoietic progenitor cells within CML marrow, CD34+DR- and CD34+DR+ cells were isolated using centrifugal elutriation, monoclonal antibody labeling, and flow cytometric cell sorting. Polymerase chain reaction analysis of RNA samples from these CD34+ subpopulations was used to detect the presence of the BCR/ABL translocation characteristic of CML. The CD34+DR+ subpopulation contained BCR/ABL(+) cells in 11 of 12 marrow samples studied, whereas the CD34+DR- subpopulation contained BCR/ABL(+) cells in 6 of 9 CML marrow specimens. These cell populations were assayed for hematopoietic progenitor cells, and individual hematopoietic colonies were analyzed by PCR for their BCR/ABL status. Results from six patients showed that nearly half of the myeloid colonies cloned from CD34+DR- cells were BCR/ABL(+), although the CD34+DR- subpopulation contained significantly fewer BCR/ABL(+) progenitor cells than either low-density bone marrow (LDBM) or the CD34+DR+ fraction. These CD34+ cells were also used to establish stromal cell-free long-term bone marrow cultures to assess the BCR/ABL status of hematopoietic stem cells within these CML marrow populations. After 28 days in culture, three of five cultures initiated with CD34+DR- cells produced BCR/ABL(-) cells. By contrast, only one of eight cultures initiated with CD34+DR+ cells were BCR/ABL(-) after 28 days. These results indicate that the CD34+DR- subpopulation of CML marrow still contains leukemic progenitor cells, although to a lesser extent than either LDBM or CD34+DR+ cells.

scholarly journals Identification of BCR/ABL-negative primitive hematopoietic progenitor cells within chronic myeloid leukemia marrow

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 801-807 ◽  
Author(s):  
T Leemhuis ◽  
D Leibowitz ◽  
G Cox ◽  
R Silver ◽  
EF Srour ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Chronic Myeloid Leukemia ◽  
Progenitor Cells ◽  
Myeloid Leukemia ◽  
Chronic Phase ◽  
Polymerase Chain Reaction Analysis ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem

Abstract Chronic myeloid leukemia (CML) is a malignant disorder of the hematopoietic stem cell. It has been shown that normal stem cells coexist with malignant stem cells in the bone marrow of patients with chronic-phase CML. To characterize the primitive hematopoietic progenitor cells within CML marrow, CD34+DR- and CD34+DR+ cells were isolated using centrifugal elutriation, monoclonal antibody labeling, and flow cytometric cell sorting. Polymerase chain reaction analysis of RNA samples from these CD34+ subpopulations was used to detect the presence of the BCR/ABL translocation characteristic of CML. The CD34+DR+ subpopulation contained BCR/ABL(+) cells in 11 of 12 marrow samples studied, whereas the CD34+DR- subpopulation contained BCR/ABL(+) cells in 6 of 9 CML marrow specimens. These cell populations were assayed for hematopoietic progenitor cells, and individual hematopoietic colonies were analyzed by PCR for their BCR/ABL status. Results from six patients showed that nearly half of the myeloid colonies cloned from CD34+DR- cells were BCR/ABL(+), although the CD34+DR- subpopulation contained significantly fewer BCR/ABL(+) progenitor cells than either low-density bone marrow (LDBM) or the CD34+DR+ fraction. These CD34+ cells were also used to establish stromal cell-free long-term bone marrow cultures to assess the BCR/ABL status of hematopoietic stem cells within these CML marrow populations. After 28 days in culture, three of five cultures initiated with CD34+DR- cells produced BCR/ABL(-) cells. By contrast, only one of eight cultures initiated with CD34+DR+ cells were BCR/ABL(-) after 28 days. These results indicate that the CD34+DR- subpopulation of CML marrow still contains leukemic progenitor cells, although to a lesser extent than either LDBM or CD34+DR+ cells.

scholarly journals Differential Effects of TLR1/2 and TLR2/6 Signaling on Normal and Premalignant Hematopoietic Stem and Progenitor Cells

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1806-1806
Author(s):  
Darlene A. Monlish ◽  
Zev J. Greenberg ◽  
Sima T. Bhatt ◽  
Dagmar Ralphs ◽  
John L. Keller ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mouse Model ◽  
Progenitor Cells ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
White Blood Cells ◽  
Hematopoietic Stem ◽  
Specific Effects ◽  
Stem And Progenitor Cells ◽  
Cell Cycling

Abstract Prior studies from our lab and others have demonstrated a role for Toll-like receptor 2 (TLR2) in regulating both normal and premalignant hematopoietic stem and progenitor cells (HSPCs), however the contributions of its binding partners, TLR1 and TLR6, remain unknown. In CD34+ bone marrow cells of patients with myelodysplastic syndrome (MDS), increased TLR2 was associated with lower-risk disease, elevated rates of apoptosis associated with improved prognosis, and enhanced survival. Conversely, increased levels of TLR6, but not TLR1, was associated with higher-risk disease and an increased percentage of bone marrow blasts (Zeng et al., Exp Cell Res 2016 and Wei et al., Leukemia 2013). These data suggest that there may be heterodimer-specific effects of TLR2 signaling on HSPCs influencing disease progression. To elucidate the unique contributions of the heterodimer pairs in MDS pathogenesis and leukemogenesis, we utilized a well-established mouse model of MDS that expresses the NUP98-HOXD13 fusion from the hematopoietic Vav-1 promoter. The "NHD13" mice recapitulate many of the salient features of human MDS and succumb to cytopenias or leukemia by 14 months of age (Lin et al., Blood 2005). Importantly, we observed significantly increased expression of TLRs 1, 2, and 6 on the c-Kit+, Sca-1+, Lineage- ("KSL") HSPCs of the NHD13 mice, similar to the increased expression of these TLRs on CD34+ cells of MDS patients. To begin to delineate the heterodimeric differences, NHD13 mice were treated chronically with either PAM2CSK4 (PAM2), a TLR2/6-specific agonist, or PAM3CSK4 (PAM3), a TLR1/2-specific agonist, to assess the effects on cytopenias and survival. After five months of treatment, a significant increase was observed in the total number of white blood cells in NHD13 mice treated with PAM2 (p=0.007), but not PAM3 (vs. vehicle (water)-treated controls), a finding that was not recapitulated in wild-type (WT) controls. On the contrary, a significant decrease in the total number of platelets in both NHD13 and WT mice treated with PAM3 was observed as compared to vehicle-treated controls (p=0.024 and p=0.011, respectively). Further supporting the existence of heterodimer-specific differences, death was expedited in NHD13 mice treated with PAM2 as compared to those treated with PAM3 (p=0.019), with a median survival of 243 days vs. 338 for the PAM3-treated cohort. The cause of death, as determined by a hematopathologist based on cytology and blast percentage, was most often due to leukemia. To investigate the potential mechanism through which enhanced TLR2/6 signaling accelerates leukemogenesis and death in NHD13 mice, the HSPCs of premalignant NHD13 mice treated with PAM2 or PAM3 were characterized by flow cytometry and evaluated for cell cycling and cell death. Both the total number and frequency of KSL cells were significantly increased in NHD13 mice treated with PAM2 (p=0.007 and p<0.0001, respectively), but not PAM3, vs. water-treated controls. No significant changes were noted in either cell cycling or apoptosis following agonist treatment. A microarray of bone marrow KSL cells revealed that stimulation of the TLR2/6 pathway is associated with an activated c-Myc signature, suggesting that enhanced signaling through this pathway, but not TLR1/2, may enhance leukemogenesis via Myc activation. Further, the expression levels of six downstream targets of c-Myc, including BAX, APEX1, ODC1, FKBP4, NCL, and HSPD1, were significantly increased in both WT and NHD13 mice following PAM2 treatment. Evaluation of serum cytokines also revealed heterodimer-specific alterations, including increased IL-6 levels in NHD13 mice treated with PAM2, but not PAM3. These data corroborate numerous previous reports linking IL-6 to MDS pathogenesis and transformation to acute myeloid leukemia. Ongoing studies involving mass cytometry, IL-6knockout mice, and pharmacological inhibitors of both IL-6 and c-Myc aim to further elucidate the mechanism through which TLR2/6-specific activation accelerates leukemogenesis and death in the NHD13 mouse model of MDS. These studies hope to inform more targeted therapeutics that could potentially delay MDS progression and reduce off-target effects. Disclosures No relevant conflicts of interest to declare.

Cyclooxygenase-2 Derived Prostaglandin E2 Is Required for Dendritic Cell Differentiation From Hematopoietic Progenitor Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1499-1499
Author(s):  
Pratibha Singh ◽  
Jonathan Hoggatt ◽  
Jennifer M. Speth ◽  
Louis M. Pelus
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Progenitor Cells ◽  
Hematopoietic Progenitor Cells ◽  
Flt3 Ligand ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem ◽  
Plasmacytoid Dcs ◽  
Cox 2 ◽  
Cox 1

Abstract Abstract 1499 Poster Board I-522 Dendritic cells (DCs) are an attractive target for therapeutic manipulation of the immune system due to their potent antigen presentation capacity and ability to induce effective immune response. In steady-state conditions different DC subsets including myeloid DCs (CD11c+CD11b+B220neg) and plasmacytoid DCs (CD11c+CD11bnegB220+) are generated in bone-marrow (BM) from hematopoietic stem cells through a series of differentiation steps. We recently demonstrated that prostaglandin (PGE2), the predominant metabolite of arachidonic acid metabolism by cyclooxygenase (COX) enzymes, enhances the homing, survival and proliferation of hematopoietic stem cells (Hoggatt et. al., Blood 2009). In this study, we examined the requirement of prostaglandins in development of DCs from hematopoietic progenitor cells. In vivo treatment of mice for 4 days with the non-steroidal anti-inflammatory drug (NSAID) indomethacin (2.5 mg/kg/bid), a dual COX1/COX2 inhibitor, produced a 59.5±17.8 % (p<0.02) reduction in total bone-marrow DC number compared to control mice treated with vehicle alone. Interestingly, indomethacin selectively decreased marrow CD11c+CD11b+B220neg myeloid DCs without affecting CD11c+CD11bnegB220+ plasmacytoid DCs. To determine whether fewer DCs in the bone marrow of indomethacin treated mice was due to the impairment of DC differentiation from their hematopoietic progenitor cells, we stimulated differentiation of DCs from lineage depleted (CD5−,CD45R−, CD11b−, Anti-Gr-1−, 7-4− and Ter-119−) bone marrow cells using Flt-3 ligand for 9 days in vitro and treated cultures with indomethacin (1 microM), SC-560 (10 microM), a selective COX-1 inhibitor or NS-398 (10 microM), a selective COX-2 inhibitor. Indomethacin produced a 1.98±0.38 fold, (p<0.02) reduction and the COX-2 inhibitor NS-398 produced a 1.52±0.04 fold, (p<0.05) reduction in CD11c+CD11b+B220neg myeloid DC generation compared to control, while the COX-1 specific inhibitor SC-560 was without effect. As expected, Flt-3-ligand induced plasmacytoid DC (CD11c+CD11bnegB220+) differentiation was not affected by selective COX inhibitors. Indomethacin also impaired generation of CD11a+CD14neg Langerhans DC from human umbilical cord blood CD34+ cells. Measurement of PGE2 production in culture supernatants from DC-producing cultures demonstrated detectable PGE2 after 6 days of culture and DC generation from BM progenitors in these cultures was impaired when PGE2 synthesis was blocked on day 6 by indomethacin administration. Indomethacin treatment during the first 5 days of Flt3-ligand stimulated DC differentiation cultures did not decrease DC production. To identify mechanisms responsible for this impairment in Flt-3 ligand-induced DC generation from hematopoietic progenitor cells, we analyzed the effect of indomethacin on DC-committed precursor cell proliferation and survival. Survival of DC-committed precursors defined as CD11clow CD11bbrightMHCIIlow was reduced 35±2.5% (p<0.05) in indomethacin treated cultures compared to control. However, indomethacin did not affect DC precursor proliferation as measured by BrdU incorporation assay. To elucidate the signaling mechanisms by which indomethacin impaired the survival of DC precursors, we added selective receptor agonists to each of known PGE receptors, EP1-4, during Flt3-ligand induced DC differentiation. The EP1/EP3 agonist 17-phenyl trinor PGE2 rescued the DC precursors from indomethacin mediated death, whereas Butaprost, a specific EP2 agonist and L902688, a selective EP4 agonist, failed to rescue DC precursor death. DCs developed in the presence of prostaglandin inhibitors did not show any defect in LPS-induced activation and expressed CD40, CD80, CD86 and MHCII levels similar to control as measured by flow cytometry. In addition, DC developed in the absence of endogenous PGE2 production successfully induced T-cell activation as measured by mix lymphocyte reaction assay (MLR). In conclusion, COX-2 mediated prostaglandin production by DC-committed hematopoietic precursors confers resistance to cell death via signaling through EP1/EP3 receptors and promotes dendritic cell development. Disclosures: No relevant conflicts of interest to declare.

The Combination of AMD3100 + G-CSF Restores the Ineffective Hematopoietic Stem Cell Mobilization with G-CSF Alone in a Thalassemic Mouse Model.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3234-3234
Author(s):  
Evangelia Yannaki ◽  
Nikoleta Psatha ◽  
Maria Demertzi ◽  
Evangelia Athanasiou ◽  
Eleni Sgouramali ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Steady State ◽  
Mouse Model ◽  
Progenitor Cells ◽  
State Condition ◽  
Hematopoietic Stem ◽  
Steady State Condition ◽  
Cd34 Cells ◽  
Stem And Progenitor Cells

Abstract Abstract 3234 Poster Board III-171 Gene therapy has been recently postulated as a realistic therapeutic potential for thalassemia and the mobilized autologous hematopoietic stem cells (HSCs) may represent the preferable source of stem cells for genetic modification due to the higher yield of HSCs compared to conventional bone marrow (bm) harvest. We have previously shown (manuscript under revision) that G-CSF mobilization in the HBBth-3 thalassemic mouse model is less efficient compared to normal C57Bl6 strain, mainly due to increased trapping of hematopoietic stem (Lin-sca-1+ckit+–LSK) and progenitor cells (CFU-GM) in the enlarged thalassemic spleen. The novel mobilizer, AMD3100 (plerixafor, mozobil), has been shown to reversibly bind to CXCR4 and inhibit the interaction between SDF-1 and CXCR4 within the bm microenvironment, resulting in the egress of CD34+ cells into the circulation of healthy donors and cancer patients. The addition of AMD to G-CSF results in even greater increases in circulating CD34+cells. We explored in the current study whether AMD alone or in combination with G-CSF improves the mobilization efficiency of thalassemic mice. C57 and HBBth-3 mice received G-CSF-alone at 250microgr/kgX7 days, AMD-alone at 5mg/kgX3 days or the combination of two with AMD administered in the evening of days 5-7 of G-CSF administration. Hematopoietic tissues (blood, bm, spleen) were collected and the absolute LSK and CFU-GM numbers were calculated based on their frequency within tissues (by FCM and clonogenic assays) in relation to the individual cell count per tissue. AMD-alone didn't significantly affect the HSC yield as compared to G-CSF mobilization in thal mice (LSK/μl blood: 103±85 vs 69±26 p=ns), although it significantly increased the circulating Colony Forming Cells (CFU-GM/ml blood: 1205±533 vs 330±87, p=0,05). In contrast, the AMD+G-CSF combination significantly improved the mobilization efficiency of HBBth-3 mice over the G-CSF-treated group (LSK cells/μl blood: 224±104 vs 69±26 p=0,04, CFU-GM/ml blood: 1671±984 vs 330±87 p=0,05, respectively) at levels comparable to normal mice treated with G-CSF (LSK cells/ μl blood: 241±167, CFU-GM/ml blood: 1235±1140, respectively). AMD induced a “detachment” of stem cells from the bm because reduced numbers of bm LSK cells were counted in the AMD-alone group as compared to the untreated group (LSK/2 femurs×103: 692±429 vs 1687±1016, respectively, p=0,05). This was in contrast to the marrow hyperplasia caused by G-CSF over the steady-state condition (LSK/2 femurs×103: 2684±1743 vs 1687±1016 p=0,02 / CFU-GM/2femurs:111.841±15.391 vs 76.774±31.728 p=0,01). Consequently, the combination of AMD+G-CSF resulted in increased numbers of circulating stem and progenitor cells without inducing marrow hyperplasia as compared to steady-state condition (LSK/2femurs×103: 1681±862 vs 1686±1017, p=ns / CFU-GM/2femurs: 76.774±31.728 vs 82.905±26.277, p=ns). AMD, also in contrast to G-CSF, did not cause increased trapping of stem and progenitor cells in the spleen compared to the untreated condition (LSK cells/spleen×103: 4738±2970 vs 8303±4166 p=ns / CFU-GM/spleen:146.269±93.174 vs 98.518±25.549, p=ns). However, the combination of AMD+G-CSF still resulted in splenic sequestration of progenitor cells (CFU-GM/spleen: 412.176±157.417 vs 98.518±25.549, p=0,0003) but not of LSK cells (LSK cells/spleen×103: 10.200±7.260 vs 8.300±4.166 p=ns). Overall, the combination of AMD3100+G-CSF seems to restore the less efficient mobilization in a thalassemic mouse model. This combination may prove beneficial in a GT setting for obtaining the high numbers of HSCs needed for genetic correction. In addition, the combination of AMD3100+G-CSF, by avoiding the marrow hyperplasia induced by G-CSF alone, indicates a better safety profile because it will not further burden the hyperplastic –due to the increased erythroid demand and the intramarrow destruction of erythroblasts-thalassemic bone marrow. Disclosures No relevant conflicts of interest to declare.

Lack of the Transcription Factor NFAT (Nuclear Factor of Activated T cells) c2 in Hematopoietic Progenitor Cells Results in Profound Hematological Abnormalities in Mice

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1296-1296
Author(s):  
Laleh S. Arabanian ◽  
Michael Haase ◽  
Ivonne Habermann ◽  
Malte von Bonin ◽  
Claudia Waskow ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Transcription Factor ◽  
Progenitor Cells ◽  
Conflicts Of Interest ◽  
Extramedullary Hematopoiesis ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem ◽  
Hematological Abnormalities

Abstract Abstract 1296 Understanding the transcriptional mechanisms that control hematopoiesis and the interaction between hematopoietic stem cells and the bone marrow microenvironment in vivo is of considerable interest. We have previously shown that aged mice lacking the transcription factor NFATc2 develop bone marrow hypoplasia, anemia, and extramedullary hematopoiesis in spleen and liver. The proliferation and differentiation of NFATc2-deficient hematopoietic progenitor cells (HPC) ex vivo, however, was found to be intact. It remained therefore unclear whether the disturbed hematopoiesis in NFATc2-deficient mice was caused by the hematopoietic or the stroma component of the bone marrow hematopoietic niche. In the current study we dissected the relative contribution of hematopoietic and stroma cells to the phenotype of the NFATc2-deficent mice by transplanting immunomagnetically purified NFATc2-deficient (ko) HPCs to lethally irradiated wildtype (wt) mice, and vice versa. After a posttransplantation period of 6–8 months, peripheral blood, bone marrow as well as spleen and liver of the transplanted animals were analyzed and compared to wt and ko mice transplanted with control cells. Transplantation of NFATc2-deficient HPCs into wt recipients (ko → wt) induced similar hematological abnormalities as those occurring in non-transplanted ko mice or in ko mice transplanted with ko cells (ko → ko). Compared to wt mice transplanted with wt cells (wt → wt), ko → wt mice showed evidence of anemia, thrombocytopenia and a significantly reduced number of hematopoietic cells in their bone marrow. Likewise, ko → wt mice developped clear signs of extramedullary hematopoiesis in spleen and liver, which was not the case in wt → wt control animals. Our data demonstrate for the first time, that NFAT transcription factors directly regulate the intrinsic function of hematopoietic progenitor cells in vivo. The transcriptional targets for NFAT in these cells are yet unknown and are the focus of further investigations. Disclosures: No relevant conflicts of interest to declare.

Fbxw11 Variants Control the Quiescence of HSCs

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5052-5052
Author(s):  
Lina Wang ◽  
Wenli Feng ◽  
Xiao Yang ◽  
Feifei Yang ◽  
Rong Wang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Progenitor Cells ◽  
Conflicts Of Interest ◽  
Hematopoietic Progenitor Cells ◽  
Control Vector ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem ◽  
The Impact

Abstract Ubiquitination is a posttranslational mechanism that controls diverse cellular processes. Fbxw11, a constituent of the SCF (Skp1-Cul1-F-box) ubiquitin ligase complex, targets for degradation of several important transcription factors, including NF-κB, β-cantenin and ATF4. Fbxw11 may play pivotal roles in many aspects of hematopoiesis through regulating various signal transduction pathways. However, the role of Fbxw11 on HSCs quiescence remains largely unknown. In this study, we cloned three transcript variants (Fbxw11a, Fbxw11c and Fbxw11d) to study the biological function of Fbxw11 in hematopoiesis. To elucidate Fbxw11 distribution in hematopoietic system, hematopoietic cell populations at different stages of differentiation were isolated from bone marrow of 8 week-old mice and Fbxw11 expression was studied by real-time PCR. Expression of Fbxw11 were lower in purified long term hematopoietic stem cells (LT-HSC, LSK CD34- Flt3-), but higher in short term hematopoietic stem cells (ST-HSC, LSK CD34+ Flt3-), hematopoietic stem and progenitor cells (LSK), and various hematopoietic progenitor cells. The results reveal that Fbxw11 is preferentially expressed in more mature progenitor cells. The expression of Fbxw11 in mature blood cells was also studied showing that Fbxw11 was expressed at lower level in neutrophils, higher level in B and T lymphocytes, and moderate level in monocytes. To assess the impact of Fbxw11 on reconstitution capacity of LT-HSCs, we cloned Fbxw11a, Fbxw11c and Fbxw11d into retrovirus system, respectively. LSK cells were infected with MSCV-Fbxw11a/Fbxw11c/Fbxw11d-IRES-GFP or the blank control vector MSCV-GFP. Competitive repopulation assays we performed 48h later after infection, and reconstitution in peripheral blood (PB) was analyzed every 4 weeks. Repopulation of donor cells expressing high level of Fbxw11 variants was significantly lower than those infected with control vector at 1 and 4 months in PB and at 4 months in BM after transplantation. These data indicate that Fbxw11 is negative for the long-term repopulating capacity of HSCs. To further confirm the effects of Fbxw11 variants in hematopoiesis, the effect of Fbxw11 variants on the growth and enumeration of hematopoietic progenitor cells was detected by colony-forming cell assay (CFC). The number of CFU-G, CFU-GM, CFU-GEMM and the total number of CFU were lower in LSK over-expressing Fbxw11 variants when compared with LSK control. To determine the cell-cycle distribution of HSC cells, Hoechst 33342 and Ki67 staining were performed showing that G0 phase LSK cells were decreased when they over-expressing Fbxw11 variants. In conclusion, our data reveal unrecognized roles for Fbxw11 in the regulation of HSPCs. Our findings suggest that Fbxw11 variants have negative effect on reconstitution capacity of LT-HSCs. Fbxw11 variants decrease the reconstitution capacity through promoting cell proliferation, which results in loss of hematopoietic stem cell quiescence. We anticipate that our experiments will facilitate the understanding of hematopoiesis through which Fbxw11-mediated signals control HSC quiescence and functions. The work was supported by the Grants 81300376, 81370634, 81570153 from the National Natural Science Foundation of China (NSFC); 14JCQNJC10600 from the Tianjin Science and Technology Programs; Disclosures No relevant conflicts of interest to declare.

scholarly journals Mechanism of Action of Diallyl Sulphide in Ameliorating the Hematopoietic Radiation Injury

2021 ◽  
Author(s):  
Omika Katoch ◽  
Mrinalini Tiwari ◽  
Namita Kalra ◽  
Paban K. Agrawala
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Progenitor Cells ◽  
Hematopoietic Stem ◽  
Proliferation And Differentiation ◽  
Stem And Progenitor Cells ◽  
Radiation Induced ◽  
Medicinal Properties ◽  
Marrow Cellularity

AbstractDiallyl sulphide (DAS), the pungent component of garlic, is known to have several medicinal properties and has recently been shown to have radiomitigative properties. The present study was performed to better understand its mode of action in rendering radiomitigation. Evaluation of the colonogenic ability of hematopoietic progenitor cells (HPCs) on methocult media, proliferation and differentiation of hematopoietic stem cells (HSCs), and transplantation of stem cells were performed. The supporting tissue of HSCs was also evaluated by examining the histology of bone marrow and in vitro colony-forming unit–fibroblast (CFU-F) count. Alterations in the levels of IL-5, IL-6 and COX-2 were studied as a function of radiation or DAS treatment. It was observed that an increase in proliferation and differentiation of hematopoietic stem and progenitor cells occurred by postirradiation DAS administration. It also resulted in increased circulating and bone marrow homing of transplanted stem cells. Enhancement in bone marrow cellularity, CFU-F count, and cytokine IL-5 level were also evident. All those actions of DAS that could possibly add to its radiomitigative potential and can be attributed to its HDAC inhibitory properties, as was observed by the reversal radiation induced increase in histone acetylation.

scholarly journals Kinetics of normal hematopoietic stem and progenitor cells in a Notch1-induced leukemia model

Blood ◽  
2009 ◽  
Vol 114 (18) ◽  
pp. 3783-3792 ◽  
Author(s):  
Xiaoxia Hu ◽  
Hongmei Shen ◽  
Chen Tian ◽  
Hui Yu ◽  
Guoguang Zheng ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Progenitor Cells ◽  
Quiescent State ◽  
Hematopoietic Stem ◽  
Definitive Evidence ◽  
Accelerated Proliferation ◽  
Stem And Progenitor Cells ◽  
Underlying Mechanisms ◽  
The Impact

Abstract The predominant outgrowth of malignant cells over their normal counterparts in a given tissue is a shared feature for all types of cancer. However, the impact of a cancer environment on normal tissue stem and progenitor cells has not been thoroughly investigated. We began to address this important issue by studying the kinetics and functions of hematopoietic stem and progenitor cells in mice with Notch1-induced leukemia. Although hematopoiesis was progressively suppressed during leukemia development, the leukemic environment imposed distinct effects on hematopoietic stem and progenitor cells, thereby resulting in different outcomes. The normal hematopoietic stem cells in leukemic mice were kept in a more quiescent state but remained highly functional on transplantation to nonleukemic recipients. In contrast, the normal hematopoietic progenitor cells in leukemic mice demonstrated accelerated proliferation and exhaustion. Subsequent analyses on multiple cell-cycle parameters and known regulators (such as p21, p27, and p18) further support this paradigm. Therefore, our current study provides definitive evidence and plausible underlying mechanisms for hematopoietic disruption but reversible inhibition of normal hematopoietic stem cells in a leukemic environment. It may also have important implications for cancer prevention and treatment in general.

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