The Roles of RUNX1 in Human Hematopoiesis and Megakaryopoiesis Revealed By Genome-Targeted Human iPSCs and an Improved Hematopoietic Differentiation Model

Abstract The RUNX1 gene (also called AML1), one of the most mutated genes in acute myeloid leukemia (AML), was first identified decades ago that encodes a key regulatory transcriptional factor. Numerous studies using mouse and zebrafish models show that RUNX1 is essential for definitive hematopoiesis. In mice, its homozygous knock-out (KO) in hematopoietic stem/progenitor cells also causes defects in lymphoid and megakaryocytic (MK) development. However, heterozygous Runx1 gene mutations in laboratory mouse and zebrafish had little effects on development of hematopoietic stem/progenitor cells (HSPCs) or the MK cell lineage. In contrast, heterozygous germline mutations in RUNX1 were found in patients with familial platelet disorder (FPD) with predisposition to AML and MDS. The mechanisms underlying the observed differences between humans and small animal models remain unclear. In the past decade, we and others have utilized human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) to investigate human hematopoiesis including the roles of the RUNX1 gene. Using a feeder-free culture system, we generated human CD34+CD45+ HSPCs cells from human ESCs and iPSCs around 11-14 days after embryoid body (EB) formation. The CD34+CD45+ HSPCs were capable to form multiple types of hematopoietic cells such as myeloid, erythroid, and polyploid MK cells (Connelly et al., 2014; Liu et al., 2015). We also reported that human iPSCs derived from FPD patients containing a heterozygous RUNX1 mutation were defective in MK formation, and targeted correction of the mutated RUNX1 allele by genome editing restored the MK potential (Connelly et al., 2014). Since then, we have extended our studies by precise genomic targeting in human wildtype iPSCs to ablate exon 5 that is common in all 3 isoforms of the RUNX1 gene, or exon 1B that is unique to the RUNX1c isoform. Bi-allelic KO of RUNX1 at exon 5 completely abolished the formation of hematopoietic cells at days 11-14 after EB formation. Complete disruption of exon 1B showed little effect, indicating that the RUNX1c isoform is dispensable for definitive hematopoiesis in the presence of the RUNX1a and RUNX1b isoforms transcribed from the downstream P2 promoter. Detailed analysis of EBs at days 6-8 revealed that bi-allelic RUNX1 KO at exon 5 (ablating all 3 isoforms) did not affect the formation of CD34+/CD31+/CD144+ endothelial-like cells. However, the endothelial-to-hematopoietic transition (EHT) was completely blocked and no CD45+ hematopoietic cells emerged from the EHT culture supplemented with hematopoietic cytokines. To elucidate the functions of different RUNX1 isoforms in early steps of human hematopoiesis, we adapted the EHT culture system that uses CD34+ cells isolated from earlier stages of EB formation (day 6-8), before definite hematopoiesis was observable (after day 8, Bai et al., 2015). Two different iPSCs clones with homozygous or bi-allelic RUNX1 KO at exon 5 both failed to form CD45+ hematopoietic cells after EHT culture. Because constitutive transgene expression of RUNX1b or RUNX1c (but not RUNX1a) cDNA in human iPSCs inhibits hematopoietic differentiation, we transduced the day 6 EB cells at the beginning of the EHT culture with RUNX1-expressing vectors. Lentiviral vectors constitutively express RUNX1b or RUNX1c (but not RUNX1a) cDNA partially restored the EHT and hematopoietic (CD45+) cell formation after 4-5 days in EHT culture. We further used a lentiviral vector in which RUNX1c (as an ER fusion protein) can be conditionally activated by 4-HT induction. Induction starting at day 4 and lasting for 3 days rendered the maximal effect of hematopoietic cell formation in the EHT culture using CD34+ cells isolated at day 6 of EB formation. Our data corroborate with limited in vivo data using human fetal tissues on the possible roles of RUNX1 in definitive hematopoiesis. At present we are analyzing iPSC clones with mono-allelic disruption of exon 5 in a wild type iPSC line, comparing to iPSCs derived from FPD patients. The current study of using isogenic human iPSCs will help to understand the roles of RUNX1 in human hematopoiesis and megakaryopoiesis, and offer an amenable system to study the RUNX1 gene functions and downstream target genes. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Heterogenous Nuclear Ribonucleoprotein L (hnRNPL) Is Required for the Functional Integrity of Hematopoietic Stem Cells.

Blood ◽

10.1182/blood.v114.22.1486.1486 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1486-1486

Author(s):

Marie-Claude Gaudreau ◽

Ehssan Sharif Askari ◽

Florian Heyd ◽

Tarik Moroy

Keyword(s):

Stem Cells ◽

Alternative Splicing ◽

Hematopoietic Stem Cells ◽

Hematopoietic Cells ◽

Regulation Of Transcription ◽

Hematopoietic Differentiation ◽

Short Term ◽

Hematopoietic Stem ◽

Functional Integrity ◽

Nuclear Ribonucleoprotein

Abstract Abstract 1486 Poster Board I-509 Hematopoietic differentiation has to be tightly regulated since uncontrolled or exaggerated development of blood cells may lead to the development of leukemia or autoimmune diseases. Many mechanisms exist to control hematopoiesis on a molecular level, including the regulation of transcription, which has been intensely studied. However, new evidence suggests the process of alternative splicing to be an important regulator of the maturation and activation of blood- and immune effector cells. One of the factors that has been identified as a potential regulator of the immune response and controls alternative splicing is “heterogenous nuclear ribonucleoprotein L” (hnRNP L). This factor affects among others the alternative splicing of the CD45 gene, which encodes the major tyrosine phosphatase expressed on all hematopoietic cells. To investigate the biological role of hnRNP L as a regulator of alternative splicing in hematopoiesis, we have generated conditional hnRNP L knockout (KO) mice carrying floxed alleles that can be deleted by co expression of Cre recombinase. Both the inducible MxCre transgene or Vav-Cre transgene, which is active in all hematopoietic cells were introduced into hnRNP Lfl/fl mice. We found that the conditional deletion of hnRNP L by the Vav Cre transgene led to early mortality before birth (at stage E17.5) and flow cytometric analysis of fetal liver of hnRNP Lfl/fl, Vav-Cre mice or bone marrow from pIpC induced hnRNP Lfl/fl Mx-Cre mice showed a deficit in erythrocyte maturation. In addition, fetal thymi from hnRNP Lfl/fl X Vav-Cre mice were severely reduced in cellularity and showed disturbed T cell maturation. Moreover, the deletion of hnRNP L results in reduced numbers of Lin−Sca1+ckit+ (LSK) cells, common lymphoid progenitors (CLPs), common myeloid progenitors (CMPs), granulocyte-monocyte progenitors (GMPs) and megakaryocyte-erythrocyte progenitors (MEPs). Strikingly, while most of the progenitors and the short-term hematopoietic stem cells (HSCs) were affected by the deletion of hnRNP L, the population of long term HSCs was not reduced. We found a high percentage of Annexin V positive cells in the LSK population suggesting that the loss of progenitors and short term HSCs in hnRNP L deficient mice is due to an accelerated cell death. To test whether stem cells lacking hnRNP L were still functional, we sorted Lin−Sca1+ckit+ (LSK) cells and cultured them on either methylcellulose or the feeder cell lines OP9 and OP9-DL1. The co-culture with OP9 or OP9-DL1 cells demonstrated that hnRNP L−/− LSK cells had lost their potential to differentiate into B and T lymphocytes. Similarly, hnRNP L deficient LSK cells were unable to give rise to lymphoid, myeloid or erythroid colonies on methylcellulose. This suggests that hnRNP L is required to maintain not only the numbers of hematopoietic stem cells, but also their ability for multilineage differentiation. We conclude that the regulation of alternative splicing is an essential component of the regulatory network required to maintain hematopoietic differentiation and the functional integrity of hematopoietic stem cells. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Induced Hematopoietic Differentiation Of Common Marmoset Embryonic Stem Cells By LYL1 Can Give Rise To Hematopoietic Stem Cells Having The Enhanced Bone Marrow Reconstitution Capability

Blood ◽

10.1182/blood.v122.21.1192.1192 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1192-1192

Author(s):

Hirotaka Kawano ◽

Tomotoshi Marumoto ◽

Takafumi Hiramoto ◽

Michiyo Okada ◽

Tomoko Inoue ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Lymphoblastic Leukemia ◽

Embryonic Stem ◽

Hematopoietic Differentiation ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Hsc Transplantation

Abstract Hematopoietic stem cell (HSC) transplantation is the most successful cellular therapy for the malignant hematopoietic diseases such as leukemia, and early recovery of host’s hematopoiesis after HSC transplantation has eagerly been expected to reduce the regimen related toxicity for many years. For the establishment of the safer and more efficient cell source for allogeneic or autologous HSC transplantation, HSCs differentiated from embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) that show indefinite proliferation in an undifferentiated state and pluripotency, are considered to be one of the best candidates. Unfortunately, despite many recent efforts, the HSC-specific differentiation from ESCs and iPSCs remains poor [Kaufman, DS et al., 2001][Ledran MH et al., 2008]. In this study, we developed the new method to differentiate HSC from non-human primate ESC/iPSC. It has been reported that common marmoset (CM), a non-human primate, is a suitable experimental animal for the preclinical studies of HSC therapy [Hibino H et al., 1999]. We have been investigated the hematopoietic differentiation of CM ESCs into HSCs, and previously reported that the induction of CD34+ cells having a blood colony forming capacity from CM ESCs were promoted by lentiviral transduction of TAL1 cDNA [Kurita R et al., 2006]. However, those CD34+ cells did not have a bone marrow reconstituting ability in irradiated NOG (NOD/Shi-scid/IL-2Rγnull) mice, suggesting that transduction of TAL1 gene was not sufficient to induce functional HSCs which have self-renewal capability and multipotency. Thus, we tried to find other hematopoietic genes being able to promote hematopoietic differetiation more efficiently than TAL1. We selected 6 genes (LYL1, HOXB4, BMI1, GATA2, c-MYB and LMO2) as candidates for factors that induce the differentiation of ESCs into HSCs, based on the previous study of hematopoietic differentiation from human and mouse ESCs. And CM ESCs (Cj11) lentivirally transduced with the respective candidate gene were processed for embryoid body (EB) formation to induce their differentiation into HSCs for 9 days. We found that lentiviral transduction of LYL1 (lymphoblastic leukemia 1), a basic helix-loop-helix transcription factor, in EBs markedly increased the proportion of cells positive for CD34 (approximately 20% of LYL1-transduced cells). RT-PCR showed that LYL1-transduced EBs expressed various hematopoietic genes, such as TAL1, RUNX1 and c-KIT. To examine whether these CD34+ cells have the ability to differentiate into hematopoietic cells in vitro, we performed colony-forming unit (CFU) assay, and found that CD34+ cells in LYL1-transduced EBs could form multi-lineage blood colonies. Furthermore the number of blood colonies originated from CD34+CD45+ cells in LYL1-transduced EBs was almost the same as that from CD34+CD45+ cells derived from CM bone marrow. These results suggested that enforced expression of LYL1 in CM ESCs promoted the emergence of HSCs by EB formation in vitro. The LYL1 was originally identified as the factor of a chromosomal translocation, resulting in T cell acute lymphoblastic leukemia [Mellentin JD et al., 1989]. The Lyl1-deficient mice display the reduction of B cells and impaired long-term hematopoietic reconstitution capacity [Capron C et al., 2006]. And, transduction of Lyl1 in mouse bone marrow cells induced the increase of HSCs and lymphocytes in vitro and in vivo [Lukov GL et al., 2011]. Therefore we hypothesized that LYL1 may play essential roles in bone marrow reconstitution by HSCs differentiated from CM ESCs. To examine this, we transplanted CD34+ cells derived from LYL1-transduced CM ESCs into bone marrow of sublethally irradiated NOG mice, and found that about 7% of CD45+ cells derived from CM ESCs were detected in peripheral blood (PB) of recipient mice at 8 weeks after transplant (n=4). Although CM CD45+ cells disappeared at 12 weeks after transplant, CD34+ cells (about 3%) were still found in bone marrow at the same time point. Given that TAL1-transduced EBs derived from CM ESCs could not reconstitute bone marrow of irradiated mice at all, LYL1 rather than TAL1 might be a more appropriate transcription factor that can give rise to CD34+ HSCs having the enhanced capability of bone marrow reconstitution from CM ESCs. We are planning to do in vivo study to prove this hypothesis in CM. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Optimization Of Stepwise Hematopoietic Differentiation Of Human iPSCs

Blood ◽

10.1182/blood.v122.21.4840.4840 ◽

2013 ◽

Vol 122 (21) ◽

pp. 4840-4840

Author(s):

Friedrich Schuening ◽

Narasimhachar Srinivasakumar ◽

Michail Zaboikin ◽

Tatiana Zaboikina

Keyword(s):

Stem Cells ◽

Conflicts Of Interest ◽

Single Cells ◽

Retroviral Vectors ◽

Dermal Fibroblasts ◽

Hematopoietic Differentiation ◽

In Vitro Differentiation ◽

Hematopoietic Stem ◽

Human Ipscs

Abstract Since their discovery in 2006, induced pluripotent stem cells (iPSCs) with their ES cell-like self-renewal and differentiation capability, are set to revolutionize the field of regenerative medicine. There is tremendous interest in the field of hematology for derivation of hematopoietic stem cells (HSCs) and hematopoietic progenitors (HPCs) by in vitro differentiation of IPSCs. IPSCs can be differentiated into HSC/HPCs by coculture on feeder cells, such as OP9, or by using stepwise differentiation protocols on defined media. Neither approach produces high yields of HSCs or HPCs. With an intention to improve this, we systematically investigated various parameters for in vitro differentiation of iPSCs into HPCs. iPSCs were derived from human adult dermal fibroblasts by transduction with the Yamanaka retroviral vectors (encoding human Klf4, Oct3/4, Sox2 and cMyc) or by electroporation with the Yamanaka Epstein–Barr virus-based episomal plasmid vectors (encoding Klf4, Oct3/4, Sox2, L-Myc and p53 targeting shRNA). One iPSC clone of each variety was then subjected to a stepwise differentiation protocol described by Niwa and coworkers [PLoSOne. (2011); 6(7):e22261] followed by hematopoietic colony forming (CFU) assays in MethoCult (STEMCELL Technologies, Vancouver, Canada). The original protocol calls for the use of Stemline II serum-free medium (Sigma, St. Louis, MO) supplemented with various growth factors/cytokines. We investigated the use of APEL medium described by Ng and coworkers [Nature Protocols. (2008); 3(5): 768] as a possible substitute for Stemline II. We also tested the effect of varying the number of colonies seeded in 6-well plates and the efficiency of hematopoietic differentiation after seeding iPSCs as single cells. The results, based on the number of hematopoietic colonies obtained in MethoCult following differentiation, showed that the APEL medium (>100 CFU/100,000 cells) was a superior substitute to the Stemline II medium (<10 CFU/100,000). When IPSCs were seeded as single cells, at initial densities of 10, 100 or 1,000 cells/cm2 in the presence of Y-27632 Rock inhibitor, only the cells at starting density higher than 1,000 per cm2survived but did not yield hematopoietic CFUs in MethoCult. When seeded as colony fragments, lower density of seeding in 6-well plates (< 20 colonies/well) was superior to higher density (>50 colonies/well) for obtaining HPCs. Other parameters that can affect differentiation, such as bone-morphopoietic protein (BMP) and O2 concentration, are being investigated. Figure A. Cellular markers detected at different time points of stepwise hematopoietic differentiation. B. CFUs in MethoCult. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Vitamin K2 Supports Hematopoiesis through Acting on Bone Marrow Mesenchymal Stromal/Stem Cells

Blood ◽

10.1182/blood.v126.23.1192.1192 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1192-1192 ◽

Cited By ~ 2

Author(s):

Aya Fujishiro ◽

Yasuo Miura ◽

Masaki Iwasa ◽

Sumie Fujii ◽

Akihiro Tamura ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Flow Cytometric Analysis ◽

Hematopoietic Cells ◽

Vitamin K2 ◽

Therapeutic Effects ◽

Dependent Manner ◽

Hematopoietic Stem ◽

Gm Csf ◽

Cd34 Cells

Abstract [Background] Myelodysplastic syndrome is an intractable disorder characterized by ineffective hematopoiesis. Although allogeneic hematopoietic stem cell transplantation is the only curative therapy for eligible patients, hematopoiesis-supportive pharmacotherapy is practically important for transplant-ineligible patients to overcome transfusion dependency and infections. Vitamin K2 (VK2, menatetrenone) is a drug used to aim at improvement of hematopoiesis in MDS patients (Leukemia 14: 1156, 2000). However, the exact mechanism how VK2 improves hematopoiesis remains largely unknown. It was reported that VK2 induces MDS cells to undergo apoptosis (Leukemia 13: 1399, 1999). Here, we investigated our hypothesis that VK2 exerts its hematopoiesis-supportive effects through acting on mesenchymal stem/stromal cells (BM-MSCs) in the bone marrow microenvironment. [Methods] Normal bone marrow (BM) samples from healthy adult volunteers were purchased from AllCells (Emeryville, CA). BM-CD34+ cells were isolated from BM-mononuclear cells using anti-CD34 immunomagnetic microbeads (Miltenyi Biotec, Bergisch Gladbach, Germany). Human BM-MSCs were isolated according to our previously published methods (Stem Cells 32:2245, 2014). In co-culture experiments, BM-MSCs with or without VK2 treatment were seeded on a 24-well culture plate. BM-CD34+ cells were applied on the MSC-grown plate and co-cultured in SFEM (StemCell Technologies, Vancouver, Canada) supplemented with 100 ng/mL SCF, 100 ng/mL Flt-3 ligand, 50 ng/mL TPO and 20 ng/mL IL-3. After 10 days of co-culture, the number and surface marker expression of the expanded hematopoietic cells were examined by flow cytometric analysis. [Results] We first tested the direct effect of VK2 on BM-CD34+ cells. BM-CD34+ cells were treated with VK2 at various concentrations ranged from 0 µM to 10 µM for 24 hours and then cultured in SFEM in combinations with cytokines. Surprisingly, viable hematopoietic cells were hardly detected in the expansion culture of BM-CD34+ cells treated with 10 µM VK2. Even with 1 µM treatment, the number of CD45+ cells was decreased, as compared to that of expansion culture of untreated BM-CD34+ cells. The apoptosis analysis showed that the percentage of AnnexinV+ PI+ cells in the expanded hematopoietic cells is increased by VK2 treatment. We next examined the effect of VK2 on the hematopoiesis-supportive capability of BM-MSCs. BM-MSCs were pretreated with VK2 at various concentrations and then co-cultured with BM-CD34+ cells. The numbers of CD34+ cells and CD45+ cells were increased in a VK2 dose-dependent manner. These results demonstrated that VK2 shows different effects on distinct stem/progenitor cells: the induction of apoptosis in BM-CD34+ cells and the enhancement of hematopoiesis-supportive capability of BM-MSCs. We then investigated whether apoptosis-related cell death of BM-CD34+ cells by VK2 treatment is ameliorated in the presence of BM-MSCs. Both BM-CD34+ cells and BM-MSCs were treated with VK2 for 24 hours, and then co-cultured. The number of CD34+ cells was not decreased significantly in contrast to its severe decrease in single culture of VK2-treated BM-CD34+ cells. We further analyzed the effect of VK2 on BM-MSCs. Subpopulation analysis in co-culture of CD34+ cells with VK2-treated BM-MSCs showed that the expansion efficacy of CD34+CD38+ cells is higher in comparison to that of CD34+CD38- cells. In addition, the percentages of CD34-CD33+ cells and CD34-CD13+ cells were higher than those in co-cultures with untreated BM-MSCs. Therefore, VK2-treated BM-MSCs supported the expanded CD34+ cells to skew their phenotype toward myeloid lineage. The presence of a transwell in the co-culture system was unrelated to the expansion pattern of CD34+ cells, which suggested the involvement of soluble factors with respect to the underlining mechanism. We therefore compared the levels of hematopoiesis-supporting cytokine mRNA expression in VK2-treated and untreated BM-MSCs: VK2-treated BM-MSCs showed lower expression of CXCL12/SDF-1 mRNA and a trend toward higher expression of GM-CSF mRNA. [Summary] VK2 acted on BM-MSCs to support their ability to enhance expansion and myeloid differentiation of BM-CD34+ cells probably via altered GM-CSF and CXCL12/SDF-1 expression in MSCs. These findings may help to identify the mechanisms of therapeutic effects of VK2 in patients with MDS (Figure). Disclosures No relevant conflicts of interest to declare.

Download Full-text

UM171 Regulates the Hematopoietic Differentiation of Human Acquired Aplastic Anemia-Derived Induced Pluripotent Stem Cells

Blood ◽

10.1182/blood-2019-127466 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2500-2500

Author(s):

Tellechea Maria Florencia ◽

Flavia S. Donaires ◽

Tiago C. Silva ◽

Lilian F. Moreira ◽

Yordanka Armenteros ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Pluripotent Stem Cells ◽

Patient Specific ◽

Hematopoietic Differentiation ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Induced Pluripotent

Aplastic anemia (AA) is characterized by a hypoplastic bone marrow associated with low peripheral blood counts. In acquired cases, the immune system promotes hematopoietic stem and progenitor cell (HSPC) depletion by the action of several pro-inflammatory Th1 cytokines. The current treatment options for severe cases consist of sibling-matched allogeneic hematopoietic stem cell transplantation (HSCT) and immunosuppressive therapy (IST) with anti-thymocyte globulin, cyclosporine, and eltrombopag. However, most patients are not eligible for HSCT and, although about 85% of patients respond to IST with eltrombopag, a proportion of patients eventually relapse, requiring further therapies. Failure to respond adequately to immunosuppression may be attributed to the scarcity of HSPCs at the time of diagnosis. Induced pluripotent stem cells (iPSCs) are potentially an alternative source of patient-specific hematopoietic cells. Patient-specific HSPCs derived from in vitro iPSC differentiation may serve as a tool to study the disease as well as a source of hematopoietic tissue for cell therapies. The pyrimidoindole molecule UM171 induces ex vivo expansion of HSCs of human cord and peripheral blood and bone marrow, but the pathways modulated by this molecule are not well understood. Here we evaluated the hematopoietic differentiation potential of iPSCs obtained from patients with acquired AA. We further determined the effects of UM171 on this differentiation process. First, we derived iPSCs from 3 patients with acquired AA after treatment (1 female; average age, 31 years; 2 partial responders, 1 complete responder) and 3 healthy subjects (3 females; average age, 61 years) and induced differentiation in vitro through the embryoid body system in cell feeder and serum-free medium supplemented with cytokines. The hematopoietic differentiation of healthy-iPSCs yielded 19% ± 8.1% (mean ± SEM) of CD34+cells after 16 days in culture, in contrast with 11% ± 4.9% of CD34+cells obtained from the differentiation of AA-iPSCs, which corresponds to a 1.7-fold reduction in CD34+cell yield. The total number of erythroid and myeloid CFUs was lower in the AA-iPSC group as compared to healthy-iPSCs (12±4.2 vs.24±7.2; respectively; p<0.03). These findings suggest that erythroid-derived AA-iPSC have an intrinsic defect in hematopoietic differentiation. Next, we tested whether UM171 modulated hematopoietic differentiation of AA-iPSCs. We found that UM171 significantly stimulated the differentiation of both healthy and AA-iPSCs. In the healthy-iPSC group, the percentage of CD34+cells was 1.9-fold higher when treated with UM171 compared to controls treated with DMSO (37% ± 7.8% vs.19% ± 8.1%; respectively; p<0.03) and in AA-iPSCs the increase was 3.9-fold (45% ± 11% vs. 11% ± 4.9%; p<0.07). The clonogenic capacity of progenitors to produce erythroid and myeloid colonies also was augmented in both groups in comparison to DMSO (28±11 vs. 23±7.2) for healthy-iPSCs and for AA-iPSCs (23±8.5 vs. 12±4.2, p<0.06). We then investigated the molecular pathways influenced by UM171. The transcriptional profile of differentiated CD34+cells showed that UM171 up-regulated genes involved in early hematopoiesis from mesoderm (BRACHYURY and MIXL1) and primitive streak specification (APELA and APLNR), to hemangioblasts and primitive hematopoietic progenitor commitment (TDGF1, SOX17, and KLF5). We also observed the up-regulation of pro-inflammatory NF-kB activators (MAP4K1, ZAP70, and CARD11) and the anti-inflammatory gene PROCR, a marker of cultured HSCs and an NF-kB inhibitor. This balanced network has been previously suggested to be modulated by UM171 (Chagraoui et. al. Cell Stem Cell 2019). Taken together, our results showed that acquired AA-iPSCs may have intrinsic defects that impair hematopoietic differentiation in vitro. This defect may be atavic to the cell or, alternatively, the consequence of epigenetic changes in erythroid precursors provoked by the immune attack. In addition, our findings demonstrate that UM171 significantly stimulate the hematopoietic differentiation of AA-iPSCs and identified a novel molecular mechanism for UM171 as an enhancer of early hematopoietic development programs. These observations may be valuable for improving the achievement of de novo hematopoietic cells. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Effect of Inhibition of Grb2 Expression on BCR-ABL Mediated Transformation of Primary Human Hematopoietic Cells.

Blood ◽

10.1182/blood.v110.11.1020.1020 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1020-1020

Author(s):

Hardik Modi ◽

Liang Li ◽

Su Chu ◽

Ravi Bhatia

Keyword(s):

Stem Cells ◽

Hematopoietic Cells ◽

Retroviral Vectors ◽

Significant Inhibition ◽

Hematopoietic Stem ◽

Gfp Gene ◽

Human Cd34 ◽

Cd34 Cells ◽

Significant Difference ◽

Dsred Gene

Abstract The critical mechanisms underlying human hematopoietic stem cell (HSC) transformation by the BCR-ABL gene in chronic myeloid leukemia (CML) are still not well understood. Since treatment with imatinib fails to eliminate primitive CML hematopoietic cells, there is a pressing need to identify additional mechanisms that can be targeted to enhance elimination of CML stem cells. A tyrosine residue at position 177 (Y177) in the BCR-ABL protein binds the adapter protein Grb2 and appears to play an important role in BCR-ABL induced myeloid leukemogenesis in murine CML models. We have recently shown that a tyrosine to phenylalanine mutation of Y177 (Y177F) also results in significant reduction of abnormalities in proliferation and differentiation in BCR-ABL expressing human CD34+ cells and in BCR-ABL induced activation of Ras, Akt and STAT5 signaling (Cancer Res200767:7045). Since Grb2 signaling is implicated in several other human malignancies and likely plays an important role in signaling downstream of BCR-ABL, we were interested in investigating the role of Grb2 in BCR-ABL-mediated transformation of primary human hematopoietic cells. Cord blood (CB) CD34+ cells were transduced with bicistronic retrovirus vectors coexpressing wild type or Y177F mutated BCR-ABL genes with the GFP gene. Coimmunoprecipitation studies confirmed the association of Grb2 with BCR-ABL and was abrogated by the Y177F mutation. We next investigated the effect of inhibition of Grb2 expression in BCR-ABL transduced human CD34+ cells. CB CD34+ cells were co-transduced with retroviral vectors coexpressing the BCR-ABL and GFP genes or control vectors expressing the GFP gene alone together with lentivirus vectors coexpressing Grb2 shRNA constructs and the dsRed gene or the dsRed gene alone. Cells expressing CD34+, GFP and dsRed were selected using flow cytometry. Western blot analysis indicated that Grb2 levels were reduced by 80.8±14.5% (n=3, P < 0.014); in CD34+ cells transduced with BCR-ABL and Grb2 shRNA compared with cells expressing BCR-ABL alone. Expression of Grb2 shRNA resulted in significant reduction in expansion of BCR-ABL expressing CD34+ cells compared with cells expressing BCR-ABL alone after 7 days of culture in serum free medium (SFM) with low concentrations of growth factor similar to those present in bone marrow stroma conditioned medium (BA alone 48.5±7.7; BA+Grb2 shRNA, 16.7±4.7, n=3). Co-expression of Grb2 shRNA also resulted in significant reduction in the total number of colonies generated by BCR-ABL expressing CD34+ cells in methylcellulose progenitor culture (BA, 123±31; BA+Grb2, 40±9; n=3, p<0.03), with reduction being seen mainly for erythroid colonies. Expression of Grb2 shRNA also reduced cell expansion from control CD34+ expressing GFP alone but the difference was not statistically significant. Similarly Grb2 inhibition did not result in a significant difference in the number of colonies generated from control CD34+ cells. Grb2 inhibition was associated with reduced levels of P-MAPK, but not P-AKT in BCR-ABL expressing CD34+ cells. Interestingly Grb2 inhibition also results in decreased levels of P-STAT5 consistent with the observed reduction in erythroid colonies. In conclusion RNAi mediated inhibition of Grb2 expression results in significant inhibition of BCR-ABL induced proliferation of human CD34+ cells proliferation, indicating an important role for Grb2 in BCR-ABL mediated transformation of CML cells. These observations support further evaluation of inhibition of Grb2 signaling in targeting of CML stem cells.

Download Full-text

Hematopoietic Differentiation of Human Embryonic Stem Cells in Vitro : Comparison of Three Cell Lines

Blood ◽

10.1182/blood.v112.11.4787.4787 ◽

2008 ◽

Vol 112 (11) ◽

pp. 4787-4787

Author(s):

Marion Brenot ◽

Annelise Bennaceur-Griscelli ◽

Marc Peschanski ◽

Maria Teresa Mitjavila-Garcia

Keyword(s):

Stem Cells ◽

Embryonic Stem Cells ◽

Cell Lines ◽

Human Embryonic Stem Cells ◽

Hematopoietic Cells ◽

Embryonic Stem ◽

Embryoid Bodies ◽

Hematopoietic Differentiation ◽

Hematopoietic Stem

Abstract Human embryonic stem cells (hES) isolated from the inner cell mass of a blastocyst have the ability to self renew indefinitely while maintaining their pluripotency to differentiate into multiple cell lineages. Therefore, hES represent an important source of cells for perspective cell therapies and serve as an essential tool for fundamental research, specifically for understanding pathophysiological mechanisms of human diseases for the development of novel pharmacological drugs. The generation of hematopoietic stem cells from hES may serve as an alternative source of cells for hematopoietic reconstitution following bone marrow transplantation and an interesting approach to understand early stages of hematopoietic development which are difficult to study in human embryos. Using two different methods, we have differentiated three hES cell lines (SA01, H1 and H9) into hematopoietic cells by generating embryoid bodies and co-culturing on the murine Op9 cell line. In both experimental approaches, we obtain cells expressing CD34 and when cultured in hematopoietic conditions, SA01 and H1 cell lines differentiate into various hematopoietic lineages as demonstrated by BFU-E, CFU-GM and CFU-GEMM colony formation, whereas H9 have almost exclusively granulo-macrophage differentiation. Cells composing these hematopoietic colonies express CD45, CD11b, CD31, CD41 and CD235 and staining with May Grundwald-Giemsa demonstrate neutrophil and erythrocyte morphology. These results demonstrate the capacity of hES to differentiate into mature hematopoietic cells in vitro. Nevertheless, there exist some quantitative and qualitative differences about hematopoietic differentiation between the hES cell lines used. However, we still have to evaluate their capacity to reconstitute hematopoiesis in vivo in an immune deficient mouse model. We will also be interested in developing in vitro methods to expand these hematopoietic precursor cells derived from hES which may be used as a viable source for future cell therapy.

Download Full-text

Impaired Hematopoietic Differentiation of iPSCs Derived From Patients with FPD/AML

Blood ◽

10.1182/blood.v120.21.767.767 ◽

2012 ◽

Vol 120 (21) ◽

pp. 767-767

Author(s):

Masatoshi Sakurai ◽

Hiroyoshi Kunimoto ◽

Naohide Watanabe ◽

Yumi Fukuchi ◽

Ken Sadahira ◽

...

Keyword(s):

Stem Cells ◽

Flow Cytometry ◽

Acute Myeloid Leukemia ◽

Pluripotent Stem Cells ◽

Myeloid Leukemia ◽

Hematopoietic Differentiation ◽

Hematopoietic Stem ◽

Differentiation Capacity ◽

Cd34 Cells ◽

Acute Myeloid

Abstract Abstract 767 Somatic mutation of RUNX1 has been implicated in a variety of hematopoietic malignancies including myelodysplastic syndrome and acute myeloid leukemia, and previous studies using mouse models disclosed its critical roles in hematopoiesis. During embryonic development, Runx1 is absolutely essential in the emergence of hematopoietic stem and progenitor cells through hemogenic endothelium. In contrast, conditional disruption of Runx1 in adult hematopoietic system revealed that it was critical in the differentiation of megakaryocytes and lymphocytes as well as in the function of hematopoietic stem cells (HSCs). However, these results were derived from gene-disruption studies in mouse models, and the role of RUNX1 in human hematopoiesis has never been tested in experimental settings. Familial platelet disorder/ acute myeloid leukemia (FPD/AML) is a rare autosomal dominant disorder caused by germline mutation of RUNX1, marked by thrombocytopenia and propensity to acute leukemia. To investigate the physiological function of RUNX1 in human hematopoiesis and the pathophysiology of FPD/AML, we derived induced pluripotent stem cells (iPSCs) from three distinct FPD/AML pedigrees (FPD-iPSCs) and examined their defects in hematopoietic differentiation. These pedigrees have distinct heterozygous mutations in RUNX1 gene, two in the N-terminal RUNT domain affecting its DNA-binding activity and one in the C-terminal region affecting its transactivation capacity. After obtaining informed consent from the affected patients, we established iPSCs from their peripheral T cells by infecting Sendai viruses expressing four reprogramming factors (OCT3/4, SOX2, KLF4 and c-MYC). FPD-iPSCs could be established in comparable frequency as the one from normal individuals (WT-iPSCs). Initial characterization of FPD-iPSCs revealed that the established clones retained typical characteristics of pluripotent stem cells such as the expression of Nanog, Oct3/4, SSEA-3, SSEA-4, Tra-1-60 or Tra-1-81, and the teratoma formation in immunodeficient mice. Next we examined the hematopoietic differentiation capacity of FPD-iPSCs by co-culturing on AGMS-3 cells, a stromal cell line established from aorta-gonad-mesonephros (AGM) region. FPD-iPSCs and WT-iPSCs were dispersed and plated on inactivated AGM-S3 cells and were co-cultured in the presence of vascular endothelial growth factor. On day 10 through day 14 of co-culture, cells were collected and analyzed for the emergence of hematopoietic progenitors (HPCs) by flow cytometry. Interestingly, FPD-iPSCs generated CD34+ cells or CD45+ cells in significantly lower frequencies as compared to WT-iPSCs. To evaluate the differentiation capacity of HPCs generated from iPSCs, CD34+ cells were sorted by flow cytometry and subjected to colony forming assays. This revealed that CD34+ cells derived from FPD-iPSCs generated significantly fewer colonies as compared to those from WT-iPSCs in all colony types examined, showing that differentiation capacity of HPCs were impaired by RUNX1 mutation. Furthermore, CD34+ cells from FPD-iPSCs generated CD41a+CD42b+ megakaryocytes (MgK) in significantly lower frequencies as compared to WT in in vitro liquid culture with stem cell factor (SCF) and thrombopoietin (TPO). Of note, MgKs differentiated from FPD-iPSCs are smaller in size as evidenced by mean-FSC by flow cytometry. These results indicate that differentiation of MgKs is impaired both quantitatively and qualitatively. Importantly, all three FPD-iPSC lines share the same phenotype in the above-described assays, suggesting that N-terminal and C-terminal RUNX1 mutations impose similar defects in hematopoietic differentiation of FPD-iPSCs. Taken together, this study, for the first time, demonstrated that mutation of RUNX1 leads to the defective differentiation of hematopoietic cells in human settings. The phenotype observed in this study, at least in part, recapitulates the ones previously reported in Runx1-homozygously deficient mice, suggesting that the mutations of RUNX1 seen in FPD/AML indeed act in dominant negative manner. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Use of the NOD/SCID/γcnull Mouse Model To Assess the Hepatocyte-Producing Ability of Human Hematopoietic Cells.

Blood ◽

10.1182/blood.v106.11.1695.1695 ◽

2005 ◽

Vol 106 (11) ◽

pp. 1695-1695

Author(s):

Hisanori Fujino ◽

Hidefumi Hiramatsu ◽

Atsunori Tsuchiya ◽

Haruyoshi Noma ◽

Mitsutaka Shiota ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Mouse Model ◽

Hematopoietic Stem Cells ◽

Liver Damage ◽

Hematopoietic Cells ◽

Human Albumin ◽

Hematopoietic Stem ◽

Hepatic Cells ◽

Cd34 Cells

Abstract Hematopoietic cells have been shown to generate nonhematopoietic cells, although the true plasticity of stem cells has been questioned. Here we used the NOD/SCID/γcnull mouse model, which permits efficient engraftment of human hematopoietic stem cells and their multi-lineage differentiation including T cells, to investigate whether human hematopoietic stem cells can differentiate into human hepatocytes. Freshly collected cord blood was depleted of phagocytes with Silica® followed by CD34 positive selection using auto MACS®. These cells were intravenously transplanted into irradiated mice, after which the liver was either undamaged or damaged by chemicals. The livers of these mice contained hepatocyte-specific (albumin, CYP family, TAT, alpha1AT, CPSI, prealbumin, transferrin and RBP4), cholangiocyte-specific (CK19) and vascular endothelial cell-specific (eNOS) human mRNAs. Immunohistochemistry detected the human hepatocyte specific antigens, albumin and alpha-1-antitrypsin-positive hepatocytes, cholangiocytes and CD68+ Kupffer cells. We also found human albumin in the murine bloodstream. Human albumin levels in the peripheral blood of transplanted mice correlate with the degree of PB chimerism and increase with time after transplantation. Furthermore, after obtaining liver cells by collagenase perfusion, flow cytometry revealed the presence of human albumin-positive cells that bear both human and murine MHC molecules, suggesting cell fusion occurs. All of the above phenomena were found in both liver-damaged and undamaged mice. In addition, we found human CD34+ cells are recruited from the murine bone marrow to the liver only in the case of acute liver injury but do not acquire hepatic stem/progenitor characteristics. Our observation suggests there are two pathways that yield hepatic cells from hematopoietic stem cells. The first requires liver damage that recruits CD34+ cells from the bone marrow via the circulation while the second pathway does not involve liver damage and appears to represent a constitutive default pathway of hematopoietic to nonhematopoietic transition. Our model is thus a versatile tool for investigating the development of functional human hepatic cells from hematopoietic cells and the feasibility of using hematopoietic cells in clinical situations.

Download Full-text

Robust generation of erythroid and multilineage hematopoietic progenitors from human iPSCs using a scalable monolayer culture system

10.1101/711267 ◽

2019 ◽

Author(s):

Juan Pablo Ruiz ◽

Guibin Chen ◽

Juan Jesus Haro Mora ◽

Keyvan Keyvanfar ◽

Chengyu Liu ◽

...

Keyword(s):

Stem Cells ◽

Vascular Endothelium ◽

Pluripotent Stem Cells ◽

Culture System ◽

Supernatant Fraction ◽

Erythroid Cells ◽

Hematopoietic Differentiation ◽

Hematopoietic Progenitors ◽

Erythroid Progenitors ◽

Human Ipscs

AbstractOne of the most promising objectives of clinical hematology is to derive engraftable autologous hematopoietic stem cells (HSCs) from human induced pluripotent stem cells (iPSCs). Progress in translating iPSC technologies to the clinic relies on the availability of scalable differentiation methodologies. In this study, human iPSCs were differentiated for 21 days using STEMdiff™, a monolayer-based approach for hematopoietic differentiation of human iPSCs that requires no replating, co-culture or embryoid body formation. Both monolayer and suspension cells were functionally characterized throughout differentiation. In the supernatant fraction, an early transient population of primitive CD235a+ erythroid cells first emerged, followed by hematopoietic progenitors with multilineage differentiation activity in vitro but no long-term engraftment potential in vivo. In later stages of differentiation, a nearly exclusive production of definitive erythroid progenitors was observed. In the adherent monolayer, we identified a prevalent population of mesenchymal stromal cells and limited arterial vascular endothelium (VE), suggesting that the cellular constitution of the monolayer may be inadequate to support the generation of HSCs with durable repopulating potential. Quantitative modulation of WNT/β-catenin and activin/nodal/TGFβ signaling pathways with CHIR/SB molecules during differentiation enhanced formation of arterial VE, definitive multilineage and erythroid progenitors, but was insufficient to orchestrate the generation of engrafting HSCs. Overall, STEMdiff™ provides a clinically-relevant and readily adaptable platform for the generation of erythroid and multilineage hematopoietic progenitors from human pluripotent stem cells.HighlightsRobust, scalable and clinically-relevant monolayer-based culture system for hematopoietic differentiation of human iPSCs.Successive emergence of primitive erythroid cells, definitive multilineage HSPCs and erythroid progenitors in the culture supernatant.Abundant mesenchymal cells and limited arterial vascular endothelium in the culture monolayer.CHIR/SB molecules increase arterial vascular endothelium formation, suppress primitive hematopoiesis and promote definitive multilineage and erythroid progenitors.

Download Full-text