Self-Renewal and Differentiation in Hematopoietic Stem and Progenitor Cells Is Controlled By the APC/C Coactivator Cdh1

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2370-2370
Author(s):  
Daniel Ewerth ◽  
Stefanie Kreutmair ◽  
Birgit Kügelgen ◽  
Dagmar Wider ◽  
Julia Felthaus ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Research Funding ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Nsg Mice ◽  
Human Cd34 ◽  
Cd34 Cells ◽  
Stem And Progenitor Cells

Abstract Introduction: Hematopoietic stem and progenitor cells (HSPCs) represent the lifelong source of all blood cells and continuously renew the hematopoietic system by differentiation into mature blood cells. The process of differentiation is predominantly initiated in G1 phase of the cell cycle when stem cells leave their quiescent state. During G1 the anaphase-promoting complex or cyclosome (APC/C) associated with the coactivator Cdh1 is highly active and marks proteins for proteasomal degradation to regulate proliferation. In addition, Cdh1 has been shown to control terminal differentiation in neurons, muscle cells or osteoblasts. Here we show that Cdh1 is also a critical regulator of human HSPC differentiation and self-renewal. Methods: Human CD34+ cells were collected from peripheral blood (PB) of G-CSF mobilized donors and cultured in the presence of different cytokine combinations. To analyze cell division and self-renewal versus differentiation, CFSE staining was used in combination with flow cytometric detection of CD34 expression. The knockdown and overexpression of Cdh1 was achieved by lentiviral delivery of suitable vectors into target cells. After cell sorting transduced (GFP+) CD34+ cells were used for in vitro differentiation in liquid culture or CFU assay. For in vivo experiments purified cells were transplanted into NSG mice. Results: G-CSF mobilized CD34+ cells showed effective differentiation into granulocytes (SCF, G-CSF), erythrocytes (SCF, EPO) or extended self-renewal (SCF, TPO, Flt3-L) when stimulated in vitro. The differentiation was characterized by a fast downregulation of Cdh1 on protein level, while Cdh1 remained expressed under self-renewal conditions. A detailed analysis of different subsets, both in vitro and in vivo, showed high Cdh1 level in CD34+ cells and low expression in myeloid cells. Analysis of proliferation revealed lowest division rates during self-renewal, accompanied by higher frequency of CD34+ cells. The fastest proliferation was found after induction of erythropoiesis. These experiments also showed a more rapid decrease of HSPCs' colony-forming ability and of CD34+ cells during granulopoiesis after 2-3 cell divisions in contrast to a moderate decline under self-renewal conditions. The depletion of Cdh1 (Cdh1-kd) had no effect on total cell numbers or proliferation detected by CFSE during differentiation and self-renewal, but showed an increase in S phase cells. These results were confirmed at the single cell level by measuring the cell cycle length of individual cells. Independent of cell cycle regulation, Cdh1-kd cells showed a significant maintenance of CD34+ cells under self-renewal conditions and during erythropoiesis with lower frequency of Glycophorin A+ cells. In CFU assays, the Cdh1-kd resulted in less primary colony formation, notably CFU-GM and BFU-E, but significantly more secondary colonies compared to control cells. These results suggest that the majority of cells reside in a more undifferentiated state due to Cdh1-kd. The overexpression of Cdh1 showed reversed results with less S phase cells and tendency to increased differentiation in liquid culture and CFU assays. To further validate our results in vivo, we have established a NSG xenotransplant mouse model. Human CD34+ cells depleted of Cdh1 engrafted to a much higher degree in the murine BM 8 and 12 weeks after injection as shown by higher frequencies of human CD45+ cells. Moreover, we also found an increased frequency of human CD19+ B cells after transplantation of CD34+ Cdh1-kd cells. These results suggest an enhanced in vivo repopulation capacity of human CD34+ HSCs in NSG mice when Cdh1 is depleted. Preliminary data in murine hematopoiesis support our hypothesis showing enhanced PB chimerism upon Cdh1-kd. Looking for a mediator of these effects, we found the Cdh1 target protein TRRAP, a cofactor of many HAT complexes, increased upon Cdh1-kd under self-renewal conditions. We use currently RT-qPCR to determine, if this is caused by a transcriptional or post-translational mechanism. Conclusions: Loss of the APC/C coactivator Cdh1 supports self-renewal of CD34+ cells, represses erythropoiesis in vitro and facilitates engraftment capacity and B cell development of human HSPCs in vivo. This work was supported by Josè Carreras Leukemia Foundation grant DCJLS R10/14 (to ME+RW) Disclosures Ewerth: Josè Carreras Leukemia Foundation: Research Funding. Wäsch:German Cancer Aid: Research Funding; Comprehensiv Cancer Center Freiburg: Research Funding; Janssen-Cilag: Research Funding; MSD: Research Funding.

scholarly journals Cytokine Rescue and Targeting of Inflammation-Sensitive RUNX1 Deficient Human CD34+ Hematopoietic Stem and Progenitor Cells

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 14-15
Author(s):  
Amy Fan ◽  
Armon Azizi ◽  
Kevin Nuno ◽  
Yusuke Nakauchi ◽  
Feifei Zhao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Publicly Traded ◽  
Hematopoietic Stem ◽  
The Past ◽  
Nsg Mice ◽  
Human Cd34 ◽  
Stem And Progenitor Cells

Introduction: Loss-of-function mutations in Runt-related transcription factor 1 (RUNX1) are commonly found in both germline and somatic hematopoietic malignancies and confer particularly poor prognosis in AML. However, it remains unclear how RUNX1 functions during hematopoietic and leukemic development, particularly because RUNX1 mutations alone are not sufficient to cause myeloid malignancy and some models show that RUNX1 mutations confer hematopoietic stem cell defects. Recently, mouse models have shown that RUNX1-deficient neutrophils upregulate NFκB activity, and hematopoietic stem and progenitor cells (HSPCs) with overactive inflammatory pathways gain competitive advantage under chronic inflammation. Thus, we hypothesized that while RUNX1 mutations impair normal HSPC function, inflammation may select for or rescue RUNX1 mutant HSPCs. Methods: To interrogate the effect of RUNX1 loss in human CD34+ HSPCs, we disrupted the RUNX1 locus using CRISPR/Cas9 and AAV6-mediated homology directed repair. Importantly, by using an AAV6 vector that carries arms of homology flanking a fluorescent reporter expression cassette, we are able to track and isolate cells edited at the RUNX1 locus for in vitro and in vivo functional analyses and for molecular characterization using RNA-seq and ATAC-seq. Results: First, we used this system to evaluate the functional consequences of RUNX1 knockout (KO) in human CD34+ HSPCs. Loss of RUNX1 caused early erythroid-megakaryocytic differentiation arrest and skewing toward monocytic differentiation. RUNX1 KO cells demonstrated decreased proliferation, cell cycle arrest, and reduction in serial replating potential in vitro. In competitive transplantation experiments in NSG mice, RUNX1 KO engraftment decreased over time in both primary and secondary transplant, revealing a competitive disadvantage. Second, ATAC-seq peak motif analysis showed that PU.1 and NFκB motifs are more accessible upon RUNX1 KO whereas GATA, TAL1, and RUNX motifs were less accessible. Similarly, gene set enrichment analysis of transcriptional data confirmed the broad upregulation of NFκB-mediated inflammatory programs; downregulation of GATA1-dependent heme metabolism and platelet development pathways; and downregulation of MYC- and E2F-dependent cell cycle programs. These observations imply that RUNX1 directs cell fate decisions by recruiting and activating lineage-specific hematopoietic transcription factors and augmenting stem cell proliferation programs. We next sought to determine which cytokines are sufficient to drive RUNX1 KO cell expansion. RUNX1 KO cells not only expanded preferentially in NSG mice expressing human SCF, GM-CSF, and IL-3 (NSGS mice), but also were no longer defective in competitive transplants in these mice. Further, treatment with IL-3 was sufficient to significantly expand RUNX1 KO cells in vitro. Flow cytometry revealed that the IL-3 receptor CD123 is upregulated in RUNX1 KO cells compared to control. Similarly, RUNX1-mutant AML patient samples express higher levels of CD123 than RUNX1-wildtype AML patient samples. Finally, evaluation of publicly available RUNX1 ChIP-seq of bone marrow CD34+ HSPCs revealed that RUNX1 directly binds the promoter of CD123. Ongoing efforts are aimed at determining whether targeting CD123 and IL-3 signaling may be a viable therapeutic approach for the prevention or treatment of RUNX1-mutant myeloid malignancies. Conclusion: In summary, we established a RUNX1-deficient human HSPC model not only to evaluate the role of RUNX1 in hematopoiesis, but also to characterize intrinsic and extrinsic factors involved in RUNX1-deficient clonal expansion and leukemic transformation. We show that RUNX1 KO causes monocytic skew at the expense of erythro-megakaryocytic potential and severely limits HSC engraftment and expansion in vivo. Molecular profiling reveals that these effects are associated with dysregulation of both transcription factor activity and cytokine signaling. However, exposure to IL-3 rescues RUNX1-deficient cell proliferative defects in vitro and competitive engraftment defects in vivo. This hypersensitivity to IL-3 signaling is mediated in part by increased expression of the IL-3 receptor CD123. These findings reveal how RUNX1 mutations may initially behave in a deleterious manner but can ultimately confer an advantage to HSPCs under certain environmental conditions. Disclosures Majeti: CD47 Inc.: Divested equity in a private or publicly-traded company in the past 24 months; Gilead Sciences: Divested equity in a private or publicly-traded company in the past 24 months, Patents & Royalties; Kodikaz Therapeutic Solutions Inc: Membership on an entity's Board of Directors or advisory committees.

scholarly journals The APC/C Coactivator Cdh1 Controls Self-Renewal and Differentiation of Human and Murine HSPCs

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2650-2650
Author(s):  
Daniel Ewerth ◽  
Stefanie Kreutmair ◽  
Andrea Schmidts ◽  
Marie Follo ◽  
Dagmar Wider ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
Research Funding ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Cell Fate Decisions ◽  
Cd34 Cells

Abstract Introduction: The balance between differentiation and self-renewal in hematopoietic stem and progenitor cells (HSPCs) is crucial for homeostasis and lifelong blood cell production. Differentiation is predominantly initiated in the G1 phase of the cell cycle when the E3 ligase anaphase-promoting complex or cyclosome (APC/C) is highly active. Its coactivator Cdh1 determines substrate specificity and mediates proteasomal degradation. Relevant target proteins are associated with cell fate decisions in G1/G0, and there is growing evidence that Cdh1 is an important regulator of differentiation. While this has already been demonstrated in neurons, muscle cells or osteoblasts, little is known about the role of APC/CCdh1 in hematopoiesis. Here we report on the function of Cdh1 in human and murine HSPCs in vitro and in vivo. Methods: Human CD34+ cells from the peripheral blood of G-CSF mobilized donors were exposed to different cytokine combinations and gains or losses of surface marker expression during cell division were determined. By using the established culture conditions Cdh1 expression was detected in distinct hematopoietic lineages and developmental states. CD34+ cells were transduced with a lentivirus to deplete Cdh1 by stably expressing shRNA and was then used for in vitro differentiation in liquid culture or CFU assay. In a second miR-based RNAi approach murine BM cells were depleted of Cdh1 and used for competitive transplantation assays. Complementary xenotransplantation of human Cdh1-depleted CD34+cells was carried out with NSG mice. Results: The stimulation of freshly thawed CD34+ cells with cytokines led to cell cycle entry and proliferation. Self-renewing cells preserved CD34 expression for up to 7 cell divisions with a low proliferation rate. In contrast, during granulopoiesis and erythropoiesis cells divided more frequently with rapid down-regulation of CD34. Cdh1 expression was tightly connected to differentiation status and proliferation properties. In vitro cultured CD34+ cellsand those from BM of healthy human donors showed the highest Cdh1 level compared to moderate or low expression in lymphoid and myeloid cells. Cdh1 is highly expressed at the transcriptional and translational level during both self-renewal and also when cells were directed toward erythroid differentiation. Therefore, high Cdh1 expression is characteristic of immature hematopoietic cells and differentiating precursors. The knockdown of Cdh1 (Cdh1-kd) did not affect proliferation or viability as detected by CFSE staining and measuring the cell cycle length via live-cell imaging. However, Cdh1-kd cells showed a significant maintenance of CD34+ cells under self-renewal conditions and during erythropoiesis with a lower frequency of glycophorin A+ cells. The functional relevance of Cdh1 depletion was verified in CFU assays. Cells with Cdh1-kd formed fewer primary colonies but significantly more secondary colonies, indicating a preference for self-renewal over differentiation. After competitive transplantation Cdh1-depleted murine BM cells showed a significant enhancement in the repopulation of PB, BM and spleen at week 3, while there was no change in cell cycle properties. However, after 8 weeks chimerism in each of the compartments was reduced to that of the control cells. Accordingly, higher LK and LSK frequencies supported the engraftment of Cdh1-depleted cells at week 3, but there was a significant decrease at week 8 compared to control cells, suggestive of stem cell exhaustion. The Cdh1 level also affected cell differentiation in vivo. After 8 weeks the population of B cells (B220+) was increased in transplanted Cdh1-kd cells and the frequency of mature granulocytes (CD11b+ Gr1high) was reduced. Consistently, human Cdh1-depleted CD34+ cells engrafted to a much higher degree in the murine BM 8 and 12 weeks after xenotransplantation, as shown by a higher frequency of human CD45+ cells. Moreover, the increase of human CD19+ B cells with Cdh1-kd confirmed the results of the competitive transplantation. Conclusions: Loss of the APC/C coactivator Cdh1 supports repopulation of murine HSPCs after transplantation with a lymphoid-biased differentiation, and was confirmed in xenotranplantation experiments. In the long-term, Cdh1 loss led to exhaustion of primitive LK and LSK population, highlighting the role of Cdh1 as a critical regulator of HSPC self-renewal and differentiation. Disclosures Engelhardt: Janssen: Research Funding; Amgen: Research Funding; MSD: Research Funding; Celgene: Research Funding.

Enforced Expression of GATA-2 Confers Quiescence on Human Hematopoietic Stem and Progenitor Cells In Vitro and In Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 83-83
Author(s):  
Alex J. Tipping ◽  
Cristina Pina ◽  
Anders Castor ◽  
Ann Atzberger ◽  
Dengli Hong ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Progenitor Cells ◽  
Zinc Finger ◽  
Human Cord Blood ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Stem And Progenitor Cells ◽  
Colony Number

Abstract Hematopoietic stem cells (HSCs) in adults are largely quiescent, periodically entering and exiting cell cycle to replenish the progenitor pool or to self-renew, without exhausting their number. Expression profiling of quiescent HSCs in our and other laboratories suggests that high expression of the zinc finger transcription factor GATA-2 correlates with quiescence. We show here that TGFβ1-induced quiescence of wild-type human cord blood CD34+ cells in vitro correlated with induction of endogenous GATA-2 expression. To directly test if GATA-2 has a causative role in HSC quiescence we constitutively expressed GATA-2 in human cord blood stem and progenitor cells using lentiviral vectors, and assessed the functional output from these cells. In both CD34+ and CD34+ CD38− populations, enforced GATA-2 expression conferred increased quiescence as assessed by Hoechst/Pyronin Y staining. CD34+ cells with enforced GATA-2 expression showed reductions in both colony number and size when assessed in multipotential CFC assays. In CFC assays conducted with more primitive CD34+ CD38− cells, colony number and size were also reduced, with myeloid and mixed colony number more reduced than erythroid colonies. Reduced CFC activity was not due to increased apoptosis, as judged by Annexin V staining of GATA-2-transduced CD34+ or CD34+ CD38− cells. To the contrary, in vitro cultures from GATA-2-transduced CD34+ CD38− cells showed increased protection from apoptosis. In vitro, proliferation of CD34+ CD38− cells was severely impaired by constitutive expression of GATA-2. Real-time PCR analysis showed no upregulation of classic cell cycle inhibitors such as p21, p57 or p16INK4A. However GATA-2 expression did cause repression of cyclin D3, EGR2, E2F4, ANGPT1 and C/EBPα. In stem cell assays, CD34+ CD38− cells constitutively expressing GATA-2 showed little or no LTC-IC activity. In xenografted NOD/SCID mice, transduced CD34+ CD38−cells expressing high levels of GATA-2 did not contribute to hematopoiesis, although cells expressing lower levels of GATA-2 did. This threshold effect is presumably due to DNA binding by GATA-2, as a zinc-finger deletion variant of GATA-2 shows contribution to hematopoiesis from cells irrespective of expression level. These NOD/SCID data suggest that levels of GATA-2 may play a part in the in vivo control of stem and progenitor cell proliferation. Taken together, our data demonstrate that GATA-2 enforces a transcriptional program on stem and progenitor cells which suppresses their responses to proliferative stimuli with the result that they remain quiescent in vitro and in vivo.

Interferon-γ Perturbs Key Signaling Pathways Induced By Thrombopoietin, but Not Eltrombopag, in Human Hematopoietic Stem/Progenitor Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3870-3870 ◽  
Author(s):  
Hai Cheng ◽  
Patali S. Cheruku ◽  
Luigi Alvarado ◽  
Ayla Cash ◽  
Cynthia E. Dunbar ◽  
...  
Keyword(s):  
Cell Signaling ◽  
Signaling Pathways ◽  
Research Funding ◽  
Fold Increase ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Nsg Mice ◽  
Human Cd34 ◽  
Inflammatory Conditions ◽  
Cd34 Cells

Abstract Thrombopoietin (TPO) is the main regulator of hematopoietic stem and progenitor cell (HSPC) self-renewal and survival. Upon binding to its receptor, c-MPL, TPO activates cell signaling, through JAK-STAT and other pathways, which is tightly balanced by negative regulatory signaling processes. Recent studies indicate that chronic exposure of HSPCs to IFNγ, as exemplified in subjects with severe aplastic anemia (SAA), impairs self-renewal by perturbing TPO signaling pathways. Despite elevated levels of TPO in subjects with SAA, the TPO receptor agonist Eltrombopag (Epag) improves trilineage hematopoiesis in refractory SAA, suggesting that it may activate signaling within HSPC in a way that is distinct from TPO under inflammatory conditions. To address the paradox of Epag efficacy despite high endogenous TPO levels in bone marrow failure, G-CSF mobilized human CD34+ cells from 6 healthy donors were cultured in the presence of SCF, FLT3 and either TPO 5 ng/ml (TPO5) or Epag 3 μg/ml (Epag), with or without IFNγ 100 ng/ml. After 7 days in culture, cells were characterized via flow cytometry, CFU assay and transplantation in immunodeficient (NSG) mice. The percentages of CD34+ cells in cultures containing TPO5 or Epag alone were similar (83.3 ± 9.7% and 87.6 ± 7.1%, respectively), but were better preserved with Epag than TPO5 in the presence of IFNγ (46.7 ± 16.1% and 24.6 ± 15.0% respectively, p<0.05). Accordingly, when comparing 7-day cultures with and without IFNγ, the absolute numbers of CD34+ cells were markedly reduced with TPO5 (average 7.6-fold, p<0.005) but only minimally decreased with Epag (average 1.6-fold, p = n.s.). The adjusted numbers of CFUs after 7 days in the presence of IFNγ similarly decreased 2.7-fold with TPO5 but remained unchanged with Epag compared to cultures without IFNγ. When the 7-day expanded progeny of an equal starting number of CD34+ cells was transplanted in NSG mice, human cell engraftment was superior with Epag (34 ± 3.8% human CD45+ cells) than with TPO5 (21 ± 1.8% human CD45+ cells, p<0.05) cultures in the presence of IFNγ, suggesting an impact of Epag on the most primitive long-term repopulating HSPCs. To investigate potential mechanisms by which Epag positively affects maintenance of HSPCs under inflammatory conditions, we examined cell signaling pathways induced upon binding of TPO, Epag and IFNγ to their respective receptors in human CD34+ cells. At a concentration of 5ng/mL, TPO induced a rapid (peak < 1 hour) and high potency rise in STAT5 phosphorylation followed by a rapid (< 2 hours) decay in signal. In contrast, Epag induced a slow (peak 4 hours) low potency rise in STAT5 phosphorylation, and the signal persisted for at least 10 hours. The difference in cell signaling potency and kinetics between TPO and Epag is likely related to their binding to distinct regions of c-MPL, resulting in alternate receptor conformational changes. We next investigated the impact of IFNγ on TPO and Epag-induced STAT5 phosphorylation at the signal peak (<1 and 4 hours, respectively). As previously shown in murine HSPCs, IFNγ impaired TPO signaling in human HSPCs (Figure, panels A, C). In contrast, Epag-induced STAT5 phosphorylation was preserved or increased in the presence of IFNγ (Figure, panels B, C). When Epag and TPO were combined, inhibition of TPO signaling by IFNγ was partially restored (Figure, panel D). By reducing the dose of TPO from 5 to 1ng/mL, and therefore reducing the potency of signaling to levels similar to Epag, the inhibitory effect of IFNγ on TPO signaling was abolished (Figure, panel E). Activation of IFNγ receptor by its ligand induces phosphorylation of STAT1 and subsequent expression of suppressor of cytokine signaling-1 (SOCS-1), a negative regulator of both IFNγ and c-MPL receptors via inhibition of STAT1 and STAT5 phosphorylation, respectively. We found that IFNγ-induced phosphorylation of STAT1 was increased in the presence of TPO 5ng/mL (1.5-fold increase, p<0.05) but unaffected by Epag (1.1-fold increase, p = n.s.) or TPO 1ng/mL (1.1-fold increase, p = n.s.). Our data indicate that Epag counters IFNγ-induced perturbation of TPO signaling in human HSPCs. Epag produces an unopposed low potency, slow kinetic positive signal and activates c-Mpl above a threshold level critical for HSPC self-renewal. Epag's evasion of IFN blockade of a critical pathway of growth factor cell signaling may explain its efficacy in improving hematopoiesis in SAA. Figure Figure. Disclosures Cheng: Novartis: Research Funding. Cheruku:Novartis: Research Funding. Alvarado:Novartis: Research Funding. Cash:Novartis: Research Funding. Dunbar:Novartis: Research Funding. Young:Novartis: Research Funding. Larochelle:Novartis: Research Funding.

Cyclin C Regulates the Quiescence of Human CD34+CD38- Hematopoietic Stem Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1273-1273
Author(s):  
Yasuhiko Miyata ◽  
Yan Liu ◽  
Vladimir Jankovic ◽  
Goro Sashida ◽  
Silvia Menendez ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Fold Increase ◽  
Human Cord Blood ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Human Cd34 ◽  
Cd34 Cells ◽  
Cyclin C

Abstract The relative quiescence of adult hematopoietic stem cells (HSCs) at steady state represents an important regulatory mechanism for maintaining their self-renewal and engraftment capacity, as well as their resistance to cytotoxic insults. However, the specific mechanisms regulating the intermittent entry of HSCs into the cell cycle are not well characterized. Here we provide the evidence that cyclin C (CCNC) specifically promotes the G0/G1 transition of human CD34+CD38- HSCs, and thus can significantly affect the loss of HSC self-renewal capacity in in vitro culture. Based on the recently hypothesized specific function of CCNC in G0 exit of human fibroblasts, we have analyzed the effects of CCNC loss on the behavior of human cord blood HSCs. We achieved a highly efficient knockdown of CCNC expression (>90%) using lentiviral shRNA (shCCNC) transduction of freshly isolated human cord blood CD34+ cells, allowing the in vitro assessment of early cell cycle regulation in HSCs. First, we observed a 3-fold increase in the G0 fraction of shCCNC transduced CD34+ cells compared to the empty vector control, based on the Pyronin Y and Hoechst 33342 staining 72h after infection. The depletion of CCNC did not prevent cell cycle progression beyond the G1 entry, as we observed no significant changes in the G1/S/G2-M distribution, indicating that critical CCNC activities may be restricted to the G0 checkpoint. Consistent with the reported enrichment of functional HSCs in the G0 fraction, CCNC knockdown (CCNC KD) cells showed increased activity in all surrogate in vitro assays of stem cell-ness tested: a ∼3 fold increase in CD34+ population after long term culture, a ∼2.5 fold increase in long-term culture initiating cells (LTC-ICs) and a ∼3.5 fold increase in cobblestone area forming cells (CAFCs). In contrast, CFU assays using freshly sorted shCCNC cells (and cells obtained after one-week culture in cytokines) showed only a minimal decrease in total colony number, with no difference in colony composition or morphology, indicating no significant effect on hematopoietic progenitor cell differentiation. However, we did observe a prominent effect on secondary CFUs after 2 and 3 weeks in liquid culture (i.e. using the delta assay), namely a 2-fold and 30-fold increase in shCCNC over control culture respectively, again indicating a specific function of CCNC on the more primitive cells. Consistently, CCNC KD robustly enhanced CD34 expression and secondary CFU maintenance in sorted CD34+CD38- cells (HSCs); both markers of hematopoietic cell immaturity were rapidly lost in CD34+CD38+ cells (i.e. the committed progenitor cells) with no detectable effect of shCCNC transduction. Finally, we have found that these effects of CCNC depletion are likely the result of its initial loss of function, as transient CCNC KD, using siRNA transfection of CD34+ cells, produced similar biological effects as the constitutive lentiviral shCCNC expression. Collectively, these data indicate a cell context-dependent effect of CCNC KD on the initial rate of cell cycle entry by quiescent HSCs and suggest that this approach could be used to preserve their functional capacity in culture, potentially enhancing the ex vivo expansion of HSCs, as well as their use in gene therapy protocols. Transplantation of transduced CD34+ cells into sublethally irradiated immunodeficient mice is now under way to establish the potentially beneficial effects of CCNC KD on the engraftment and repopulating capability of cultured HSCs.

scholarly journals Human Thrombopoietin Knockin Mice Efficiently Support Human Hematopoiesis In Vivo

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 403-403
Author(s):  
Anthony Rongvaux ◽  
Tim Willinger ◽  
Hitoshi Takizawa ◽  
Chozhavendan Rathinam ◽  
Elizabeth E. Eynon ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Humanized Mice ◽  
Multilineage Differentiation ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Human Cd34 ◽  
Cd34 Cells ◽  
Stem And Progenitor Cells

Abstract Abstract 403 Hematopoietic stem cells (HSCs) both self-renew and give rise to all blood cells for the lifetime of an individual. Xenogeneic mouse models are currently broadly used to experimentally study human hematopoietic stem and progenitor cell biology in vivo. However, maintenance, differentiation, and function of human hematopoietic cells are suboptimal in these hosts. More specifically, (i) human cell engraftment is only transient, not lasting for the life of recipient mice, (ii) there is an unphysiological bias towards the lymphoid lineage as well as poor differentiation of myeloid cells, and (iii) there is an important variability in the engraftment levels between different individual animals. Thrombopoietin (TPO) has been demonstrated as a crucial cytokine supporting maintenance and self-renewal of HSCs. Although TPO is mouse to human cross-reactive at supraphysiological levels, we speculated that species differences would lead to insufficient TPO activity on human cells in the xenogeneic environment. We thus generated RAG2−/−γc−/− mice in which we replaced the gene encoding mouse TPO by its human homologue. This led to the expression of human TPO at human physiological levels in the serum and tissues of TPO knockin mice. Homozygous humanization of TPO (TPOh/h) led to significantly increased levels of human engraftment in the bone marrow of the hosts (an approximately 2-fold increase). TPOh/h recipients also displayed a lower engraftment variability, with an at least 80% human chimerism in 75% of the mice, and engraftment levels were maintained for longer periods of time, up to 6–7 months, while they declined after 4 months in control recipient mice. Multilineage differentiation of hematopoietic cells was also improved, with an increased ratio between granulocytes versus and lymphocytes that better reflects the physiological human blood composition. Thus, TPOh/h recipient mice provide significant improvements compared to previously available models in all three limitations listed above. Importantly, we performed phenotypical and functional analyses of human hematopoietic stem and progenitor cells in TPOh/h compared to control recipients. We observed a significant increase in the fraction of human Lin−CD34+CD38loCD90+CD45RA− cells, a population previously identified as highly enriched in functional long-term HSC. Because serial transplantation is the most stringent protocol to functionally measure the self-renewal capacity of HSCs, we purified human CD34+ cells from TPOh/h and control primary recipients and transplanted them into secondary recipients. Human CD34+ cells isolated from control primary recipients had a very low capacity to serially engraft (with human CD45+ cells detected in only 2 of 11 secondary recipients). By contrast, CD34+ cells isolated from TPOh/h primary recipients had an increased capacity to efficiently engraft secondary recipients (with human CD45+ cells present in the bone marrow of 15 of 19 secondary recipients). This result indicates that the presence of human TPO in the primary recipient favored the maintenance of human cells with enhanced self-renewal capacity. In conclusion, we demonstrate here that RAG2−/−γc−/− TPO-humanized mice efficiently support a population of cells immunophenotypically and functionally enriched in hematopoietic stem and progenitor cells. This leads to enhanced engraftment levels, better maintenance of human chimerism and improved multilineage differentiation. Therefore, RAG2−/−γc−/− TPO-humanized mice represent a novel model to study human hematopoiesis in vivo. We anticipate that this model will be useful to study human hematopoietic stem cells in vivo, with applications in the fields of hematopoiesis, hematology and hematolo-oncology. Disclosures: Stevens: Regeneron Pharmaceuticals: Employment; AnaptysBio Inc: Employment.

scholarly journals Crispr Engineering in CD34+ Progenitors Reveals Cis-Acting Regulatory Regions Mediating 3D Interactions and Stem Cell Fate Decisions

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1466-1466
Author(s):  
Mira Jeong ◽  
Yong Lei ◽  
Ivan Bochkov ◽  
Muhammad S Shamim ◽  
Anna G Guzman ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Stem Cells ◽  
T Cells ◽  
Hoxa Cluster ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Nsg Mice ◽  
Human Cd34 ◽  
Cd34 Cells

Abstract DNA methylation is a critical regulator of cis-regulatory elements that can impact the distribution of epigenetic regulators and transcription factors. We have mapped DNA methylation changes in human CD34+ cells and downstream progeny to detect changes in DNA methylation with differentiation. Some large regions of low DNA methylation emerge with differentiation, which we call dynamic (d-) canyons. In order to determine whether these correlate with changes in the 3D genome, we generated 6 high-resolution Hi-C contact maps from CD34+CD38- cells, Adult bone marrow CD34+ cells, 7 days cultured CD34+ cells, CD71+CD36+CD235+ Erythroid cells, CD4+ T cells and AML patient blast cells. We generated ~ 1 billion mapped reads in order to create each 3D map of the genome at kilobase resolution. We identified several sites of d-canyons which correlate with changes in Hi-C loops. To study the functional role of d-canyons, we performed CRISPR/CAS9 mediated genome engineering targeting three sites of interest in CD34+ progenitors. We designed sgRNAs to delete several d-canyon regions that exhibited cell-type specific methylation and dynamic H3K27ac marking. First, we targeted a novel putative regulatory region of the RUNX1 gene, a critical master regulator of hematopoiesis that is frequently mutated in human leukemia. From genome-wide DNA methylation profiling, we identified a d-canyon located in the first intron of RUNX1, which overlaped with a H3K27ac peak in human CD34+CD38- hematopoietic progenitor cells. DNA methylation in this region is further depleted in T cells and increased in AML cells, suggesting a role for regulating RUNX1 in specific cell types. To study its function, we designed 2 sgRNAs to delete a 1.8 kb d-canyon. CRISPR/Cas9-mediated deletion of this region resulted in ablation of RUNX1 expression in cord blood hematopoietic stem cells and a significant decrease of engraftment activity in NSG mice along with an increase of erythroid colony forming ability in in vitro assays. In addition, we identified d-canyons upstream of the master regulators GATA2 and in the HOXA cluster. We deleted 1.7kb d-canyon upstream of GATA2 gene, finding that it resulted in increased self-renewal of CD34+CD38- cells in NSG xenografts. In contrast, when we deleted one a d-canyon located ~2Mb upstream of the HOXA cluster, within a HiC loop signal present only in CD34+CD38- cells, we observed in decreased CD34+CD38- cell self-renewal but a significant increase of CD34+CD38+ differentiated progenitors in an in vitro culture system, as well as in NSG mice. Colony forming assay showed decreased colony size and numbers. Finally, we identified a d-canyon associated with TCF3, also known as E2A, a transcription factor involved in B and T cell lineage differentiation. We designed 4 sgRNAs to delete 1.5kb d-canyon edge regions within the second intron of TCF3. Removal of this region resulted in a significant decrease of CD19+ B cells, but an increase of CD3+ T cells in NSG mice. Taken together, these results suggest the functional importance of d-canyons for orchestrating genome architecture and fate decisions of hematopoietic stem cells. These findings advance our understanding of the relationship between DNA methylation changes and loop interactions, providing new insights into the potential impact of potential aberrant DNA methylation and chromatin structure. Disclosures No relevant conflicts of interest to declare.

Dissecting Stem Cell Proliferation and Differentiation In Association With The Central Cell Cycle Regulator APC/CCdh1In Vitro and In Vivo

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2446-2446
Author(s):  
Daniel Ewerth ◽  
Andrea Schmidts ◽  
Birgit Kuegelgen ◽  
Dagmar Wider ◽  
Julia Schüler ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cell ◽  
Cell Division ◽  
Target Cells ◽  
Self Renewal ◽  
Human Cd34 ◽  
Cell Cycle Entry ◽  
Cd34 Cells

Abstract Introduction Hematopoietic stem cells (HSCs) and multipotent progenitor cells continuously maintain hematopoiesis by self-renewal and differentiation. The stem cell fate is tightly connected with the cell cycle, where the major regulator anaphase-promoting complex or cyclosome (APC/C) with its co-activators Cdc20 and Cdh1 marks cell cycle regulatory proteins, such as cyclin A and B, for proteasomal degradation and thus controls their activity. Known targets of Cdh1 are involved in regulation of self-renewal and granulopoiesis. This raises the hypothesis that Cdh1 may be a critical mediator of HSC proliferation, self-renewal and differentiation. Methods CD34+ cells were collected from peripheral blood (PB) of G-CSF mobilized donors and cultured in the presence of different cytokines. To analyze cell division and self-renewal versus differentiation, CFSE staining was used in combination with CD34 detection. The knockdown (kd) of Cdh1 was achieved by lentiviral delivery of specific shRNA into target cells. Results In vitro cultivation of CD34+ cells under conditions resulting in either self-renewal (SCF, TPO, Flt3-l) or differentiation/granulopoiesis (SCF, G-CSF) showed impressive downregulation of Cdh1 during culture. A high Cdh1 expression in CD34+ cells and lower expression in myeloid cells (CD41a+, CD15+, Glycophorin A+) reflects the situation we found in vivo in bone marrow (BM) subsets. Western blotting also revealed inactivation of Cdh1 by its specific inhibitor Emi1 which stabilized the ubiquitin ligase Skp2 and promoted cell cycle entry and proliferation by degrading the Cdk inhibitor p27. In addition, the APC/CCdh1 target cyclin B was upregulated. These data indicate that initial Cdh1 downregulation is required to promote cell cycle entry and proliferation of CD34+ HSCs under conditions mediating both self-renewal as well as differentiation. When cultured under self-renewal conditions, CD34+ cells showed diminished proliferation with cells residing in lower generations, whereas during granulopoiesis, cells accumulated within higher generations. These experiments also revealed a more rapid decrease of CD34+ cells in granulopoiesis after three cell divisions in contrast to a moderate decline under self-renewal conditions. We also found a decreased colony-forming ability in cells divided more than twice during granulopoiesis, which correlates with their lower CD34 expression. This is consistent with more symmetric divisions into CD34+ daughter cells under self-renewal conditions and gradual commitment during granulopoiesis. Our current experiments extent these analyses to immunofluorescence of Numb distribution in individual cells to elucidate the impact of Cdh1 on symmetric/asymmetric cell division. We could already show that Cdh1-kd led to expansion of CD34+ HSCs in vitro. To further validate our results in vivo, we have established a NOD/SCID/IL-2Rγ chain-/- (NSG) xenotransplant mouse model. Human CD34+ cells depleted of Cdh1 engrafted to a much higher degree in the murine BM 8 and 12 weeks after injection as shown by higher frequencies of engrafted human CD45+ cells. Moreover, we also found an increased frequency of human CD19+ B cells after transplantation of CD34+ Cdh1-kd cells. Further analyses of the contributing subsets to the pool of CD45+ human cells are ongoing. These results suggest an enhanced in vivo repopulation capacity of human CD34+ HSCs in NSG mice when Cdh1 is depleted. Conclusions APC/CCdh1 mediates cell cycle entry and proliferation during self-renewal and differentiation in CD34+ HSCs in vitro and improves engraftment capacity in vivo. Disclosures: No relevant conflicts of interest to declare.

Isolation and characterization of human CD34−Lin− and CD34+Lin− hematopoietic stem cells using cell surface markers AC133 and CD7

Blood ◽  
2000 ◽  
Vol 95 (9) ◽  
pp. 2813-2820 ◽  
Author(s):  
Lisa Gallacher ◽  
Barbara Murdoch ◽  
Dongmei M. Wu ◽  
Francis N. Karanu ◽  
Mike Keeney ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Surface Markers ◽  
Cell Surface Markers ◽  
Hematopoietic Stem ◽  
Human Cd34 ◽  
Cd34 Cells

Recent evidence indicates that human hematopoietic stem cell properties can be found among cells lacking CD34 and lineage commitment markers (CD34−Lin−). A major barrier in the further characterization of human CD34− stem cells is the inability to detect this population using in vitro assays because these cells only demonstrate hematopoietic activity in vivo. Using cell surface markers AC133 and CD7, subfractions were isolated within CD34−CD38−Lin− and CD34+CD38−Lin− cells derived from human cord blood. Although the majority of CD34−CD38−Lin− cells lack AC133 and express CD7, an extremely rare population of AC133+CD7− cells was identified at a frequency of 0.2%. Surprisingly, these AC133+CD7− cells were highly enriched for progenitor activity at a frequency equivalent to purified fractions of CD34+ stem cells, and they were the only subset among the CD34−CD38−Lin− population capable of giving rise to CD34+ cells in defined liquid cultures. Human cells were detected in the bone marrow of non-obese/severe combined immunodeficiency (NOD/SCID) mice 8 weeks after transplantation of ex vivo–cultured AC133+CD7− cells isolated from the CD34−CD38−Lin− population, whereas 400-fold greater numbers of the AC133−CD7− subset had no engraftment ability. These studies provide novel insights into the hierarchical relationship of the human stem cell compartment by identifying a rare population of primitive human CD34− cells that are detectable after transplantation in vivo, enriched for in vitro clonogenic capacity, and capable of differentiation into CD34+ cells.

Co-Stimulatory Blockade With CTLA4-Ig Permits Transplantation Of Human Hematopoietic Stem Cells and HLA Incompatible T Cells In NOD/SCID γ Null (NSG) Mouse Model

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1999-1999
Author(s):  
Annie L. Oh ◽  
Dolores Mahmud ◽  
Benedetta Nicolini ◽  
Nadim Mahmud ◽  
Elisa Bonetti ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Nsg Mice ◽  
Human Cd34 ◽  
Cd34 Cells

Abstract Our previous studies have shown the ability of human CD34+ cells to stimulate T cell alloproliferative responses in-vitro. Here, we investigated anti-CD34 T cell alloreactivity in-vivo by co-transplanting human CD34+ cells and allogeneic T cells of an incompatible individual into NSG mice. Human CD34+ cells (2x105/animal) were transplanted with allogeneic T cells at different ratios ranging from 1:50 to 1:0.5, or without T cells as a control. No xenogeneic GVHD was detected at 1:1 CD34:T cell ratio. Engraftment of human CD45+ (huCD45+) cells in mice marrow and spleen was analyzed by flow cytometry. Marrow engraftment of huCD45+ cells at 4 or 8 weeks was significantly decreased in mice transplanted with T cells compared to control mice that did not receive T cells. More importantly, transplantation of T cells at CD34:T cell ratios from 1:50 to 1:0.5 resulted in stem cell rejection since >98% huCD45+ cells detected were CD3+. In mice with stem cell rejection, human T cells had a normal CD4:CD8 ratio and CD4+ cells were mostly CD45RA+. The kinetics of human cell engraftment in the bone marrow and spleen was then analyzed in mice transplanted with CD34+ and allogeneic T cells at 1:1 ratio and sacrificed at 1, 2, or 4 weeks. At 2 weeks post transplant, the bone marrow showed CD34-derived myeloid cells, whereas the spleen showed only allo-T cells. At 4 weeks, all myeloid cells had been rejected and only T cells were detected both in the bone marrow and spleen. Based on our previous in-vitro studies showing that T cell alloreactivity against CD34+ cells is mainly due to B7:CD28 costimulatory activation, we injected the mice with CTLA4-Ig (Abatacept, Bristol Myers Squibb, New York, NY) from d-1 to d+28 post transplantation of CD34+ and allogeneic T cells. Treatment of mice with CTLA4-Ig prevented rejection and allowed CD34+ cells to fully engraft the marrow of NSG mice at 4 weeks with an overall 13± 7% engraftment of huCD45+ marrow cells (n=5) which included: 53±9% CD33+ cells, 22±3% CD14+ monocytes, 7±2% CD1c myeloid dendritic cells, and 4±1% CD34+ cells, while CD19+ B cells were only 3±1% and CD3+ T cells were 0.5±1%. We hypothesize that CTLA4-Ig may induce the apoptotic deletion of alloreactive T cells early in the post transplant period although we could not detect T cells in the spleen as early as 7 or 10 days after transplant. Here we demonstrate that costimulatory blockade with CTLA4-Ig at the time of transplant of human CD34+ cells and incompatible allogeneic T cells can prevent T cell mediated rejection. We also show that the NSG model can be utilized to test immunotherapy strategies aimed at engrafting human stem cells across HLA barriers in-vivo. These results will prompt the design of future clinical trials of CD34+ cell transplantation for patients with severe non-malignant disorders, such as sickle cell anemia, thalassemia, immunodeficiencies or aplastic anemia. Disclosures: No relevant conflicts of interest to declare.

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