Expansion of Murine Amniotic Fluid c-Kit High Lin- Cells Maintaining Their Hematopoietic Potential.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1475-1475
Author(s):  
Isabelle Andre-Schmutz ◽  
Andrea Ditadi ◽  
Amine Boudil ◽  
Sophie Ezine ◽  
Marina Cavazzana-Calvo
Keyword(s):  
Stem Cells ◽  
Amniotic Fluid ◽  
Conflicts Of Interest ◽  
Calf Serum ◽  
Embryonic Stem ◽  
Rt Pcr ◽  
Hematopoietic Stem ◽  
Serum Free

Abstract Abstract 1475 Poster Board I-498 We have recently described the hematopoietic potential of ckit+ Lin- cells from the murine and human amniotic fluid (1). These cells were able to generate all types of blood cells in vitro and as far as mice are concerned, to generate a complete hematopoietic system once transplanted to immunodeficient recipients. This strong hematopoietic potential was accompanied by a molecular signature measured by unicellular RT-PCR, characteristic of fetal hematopoietic progenitors. Indeed coexpression of Gata2, Lmo2 and Aml1 was found in 28% of ckit+Lin- AF cells. Intriguingly, murine ckit+Lin- AF cells can be subdivided into two fractions depending on the level of ckit expression (low or high). In in vitro assays, we demonstrated that hematopoietic potential was strictly restricted to the ckit high expressing fraction. The expansion of these cells would have great impact even in the clinical field as AF could be seen as a source of transplantable hematopoietic stem cells (HSCs). Many of the early studies that documented some expansion ability of HSCs included fetal calf serum in the protocol. Given the poorly defined combination of factors in serum and the variability between different serum lots, these protocols were often difficult to reproduce. Serum-free media supplied with specific inducers have been shown to bring several advances in driving direct differentiation of embryonic stem cells. Murine AF Lin-ckitlo and ckithi were cultured in serum- and feeder layer-free culture conditions. Lin-ckitlo AF cells died within a few days. Conversely, Lin-ckithi AF cells were maintained for up to 6 weeks, with a proliferation rate of more than 100 during the first three weeks. Their phenotype remained stable, ckithi CD45+ and Lin-. The hematopoietic potential tested in methylcellulose assays showed an increased frequency of mixed CFU-GEMM (from 24% to 84%). In vivo, CFU-S12 composed of erythroid, myeloid and Lin-ckit+Sca1+ progenitor cells were observed after the injection of AF ckithi in lethally irradiated recipients. Gene expression profile analyzed by single cell multiplex RT-PCR analysis correlated with the in vitro and in vivo results of differentiation. LMO2 was coexpressed with Gata2 and Aml1 in 66% of expanded cells, demonstrating the maintenance of an overall pattern of expression. Collectively, our results indicate that the hematopoietic potential of AF resides in the ckithi fraction and that these cells can be expanded in serum-free condition for prolonged periods of time without reduction of their hematopoietic potential. This strongly supports the idea that AF may be an excellent source of cells for therapeutic applications. 1. Ditadi 2009 Disclosures: No relevant conflicts of interest to declare.

A Subset of MicroRNAs and Genes Involved in AML Has a Pivotal Role in the in Vitro differentiation of Hematopoietic Stem Cell Precursors

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1290-1290
Author(s):  
Julian Pulecio ◽  
Leopoldo Laricchia-Robbio ◽  
Juan Carlos Izpisua ◽  
Montserrat Barragan ◽  
Marianna Vitaloni ◽  
...  
Keyword(s):  
Stem Cells ◽  
Conflicts Of Interest ◽  
Embryonic Stem ◽  
In Vitro Assays ◽  
Main Role ◽  
In Vitro Differentiation ◽  
Related Factors ◽  
Hematopoietic Stem

Abstract Abstract 1290 After the finding of a set of transcription factors capable of reprogram any somatic cell into an embryonic stem-like cell by Yamanaka's group a lot of effort has been put to differentiate and produce in-vitro engraftable cells that could replace and fix damaged tissues. One of the most attractive and promising fields is the differentiation towards blood, considering it is a tissue without a complex tridimensional structure and that the phenotypes of the different sublineages are already well characterized. Nonetheless, so far there are no reports of successful differentiation into blood progenitors which are able to completely recover functionally in vivo blood-depleted mice. We previously reported the differentiation from induced pluripotent stem cells (iPS) towards hematopoietic cells capable of distinguish into sub lineages in in vitro assays, while another group obtained blood precursors by transdifferentiation of fibroblasts; however a complete recovery of the hematopoietic lineages in vivo was not seen. Our hypothesis is that the gap missing in the current protocols to obtain repopulating blood stem cells can be filled by the microRNA profiling of Cord Blood (CB) progenitors, in order to find the key players in the maintenance of blood stemness. In particular, it has been shown that population with the highest capacity to be engrafted in mice is the CD34+/CD90+ from CB. Our preliminary results depict a set of miRNAs that are specifically overexpressed in the CD34+/CD90+ population from CB cells when compared against a less specific CD34+ population. These miRNAs are currently being tested as a tool to improve the efficiency of iPS differentiation and fibroblasts conversion towards blood progenitors by means of lentiviral infection of the miRNA precursors. Interestingly, we have found that these miRNAs have been previously reported to have a main role in the occurrence of Acute Myeloid Leukemia in humans and mice. These results led us to look for genes that are highly expressed in blood progenitors but also have been shown to be correlated with AML.As a safety study, we are currently evaluating the effect of overexpressing AML related factors (miRNAs and genes) when added to the established protocols to obtain blood progenitors from iPS and fibroblasts. Surprisingly, our initial results show that the overxpression of the above mentioned genes and miRNAs have an intrinsic potential to induce in vitro differentiation or conversion from iPS and fibroblasts towards blood progenitors. Disclosures: No relevant conflicts of interest to declare.

LYL1, Class II Basic Helix-Loop-Helix Transcription Factor, Induces the Differentiation of Common Marmoset Embryonic Stem Cells to Hematopoietic Stem Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2348-2348
Author(s):  
Hirotaka Kawano ◽  
Tomotoshi Marumoto ◽  
Michiyo Okada ◽  
Tomoko Inoue ◽  
Takenobu Nii ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Lymphoblastic Leukemia ◽  
Embryonic Stem ◽  
Common Marmoset ◽  
Hematopoietic Stem ◽  
Helix Loop Helix ◽  
Cd34 Cells

Abstract Abstract 2348 Since the successful establishment of human embryonic stem cells (ESCs) in 1998, transplantation of functional cells differentiated from ESCs to the specific impaired organ has been expected to cure its defective function [Thomson JA et al., Science 282:1145–47, 1998]. For the establishment of the regenerative medicine using ESCs, the preclinical studies utilizing animal model systems including non-human primates are essential. We have demonstrated that non-human primate of common marmoset (CM) is a suitable experimental animal for the preclinical studies of hematopoietic stem cells (HSCs) therapy [Hibino H et al., Blood 93:2839–48, 1999]. Since then we have continuously investigated the in vitro and in vivo differentiation of CM ESCs to hematopoietic cells by the exogenous hematopoietic gene transfer. In earlier study, we showed that the induction of CD34+ cells having a blood colony forming capacity from CM ESCs is promoted by lentiviral transduction of TAL1 cDNA [Kurita R et al., Stem Cells 24:2014-22,2006]. 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 is not enough 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 from ESCs to HSCs, based on the comparison of gene expression level between human ESCs and HSCs by Digital Differential Display from the Uni-Gene database at the NCBI web site (http://www.ncbi.nlm.nih.gov/UniGene/). Then, we transduced the respective candidate gene in CM ESCs (Cj11), and performed embryoid body (EB) formation assay to induce their differentiation to HSCs for 9 days. We found that lentiviral transduction of LYL1, a basic helix-loop-helix transcription factor, in EBs derived from Cj11, one of CM ESC lines, markedly increased the number of cells positive for CD34, a marker for hematopoietic stem/progenitors. The lymphoblastic leukemia 1 (LYL1) was originally identified as the factor of a chromosomal translocation, resulting in T cell acute lymphoblastic leukemia [Mellentin JD et al., Cell 58:77-83.1989]. These class II bHLH transcription factors regulate gene expression by binding to target gene sequences as heterodimers with E-proteins, in association with Gata1 and Gata2 [Goldfarb AN et al., Blood 85:465-71.1995][Hofmann T et al., Oncogene 13:617-24.1996][Hsu HL et al., Proc Natl Acad Sci USA 91:5947-51.1994]. The Lyl1-deficient mice display the reduction of B cells and impaired long-term hematopoietic reconstitution capacity [Capron C et al., Blood 107:4678-4686. 2006]. And, overexpression of Lyl1 in mouse bone marrow cells induced the increase of HSCs, HPCs and lymphocytes in vitro and in vivo [Lukov GL et al., Leuk Res 35:405-12. 2011]. These information indicate that LYL1 plays important roles in hematopoietic differentiation in primate animals including human and common marmoset. To examine whether overexpression of LYL1 in EBs can promote hematopoietic differentiation in vitro we performed colony-forming unit (CFU) assay, and found that LYL1-overexpressing EBs showed the formation of multi-lineage blood cells consisting of erythroid cells, granulocytes and macrophages. Next, we analyzed gene expression level by RT-PCR, and found that the transduction of LYL1 induced the expression of various hematopoietic genes. These results suggested that the overexpression of LYL1 can promote the differentiation of CM ESCs to HSCs in vitro. Furthermore we found that the combined overexpression of TAL1 and LYL1 could enhance the differentiation of CD34+ cells from CM ESCs than the respective overexrpession of TAL1 or LYL1. Collectively, our novel technology to differentiate hematopoietic cells from ESCs by the transduction of specific transcription factors is novel, and might be applicable to expand human hematopoietic stem/progenitor cells in vitro for future regenerative medicine to cure human hematopoietic cell dyscrasias. Disclosures: No relevant conflicts of interest to declare.

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 ◽  
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.

scholarly journals Surface antigen phenotypes of hematopoietic stem cells from embryos and murine embryonic stem cells

Blood ◽  
2009 ◽  
Vol 114 (2) ◽  
pp. 268-278 ◽  
Author(s):  
Shannon L. McKinney-Freeman ◽  
Olaia Naveiras ◽  
Frank Yates ◽  
Sabine Loewer ◽  
Marsha Philitas ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Fetal Liver ◽  
Embryonic Stem ◽  
Hematopoietic Stem ◽  
Murine Embryonic Stem Cells ◽  
Isolation And Characterization

Abstract Surface antigens on hematopoietic stem cells (HSCs) enable prospective isolation and characterization. Here, we compare the cell-surface phenotype of hematopoietic repopulating cells from murine yolk sac, aorta-gonad-mesonephros, placenta, fetal liver, and bone marrow with that of HSCs derived from the in vitro differentiation of murine embryonic stem cells (ESC-HSCs). Whereas c-Kit marks all HSC populations, CD41, CD45, CD34, and CD150 were developmentally regulated: the earliest embryonic HSCs express CD41 and CD34 and lack CD45 and CD150, whereas more mature HSCs lack CD41 and CD34 and express CD45 and CD150. ESC-HSCs express CD41 and CD150, lack CD34, and are heterogeneous for CD45. Finally, although CD48 was absent from all in vivo HSCs examined, ESC-HSCs were heterogeneous for the expression of this molecule. This unique phenotype signifies a developmentally immature population of cells with features of both primitive and mature HSC. The prospective fractionation of ESC-HSCs will facilitate studies of HSC maturation essential for normal functional engraftment in irradiated adults.

scholarly journals Gfer inhibits Jab1-mediated degradation of p27kip1 to restrict proliferation of hematopoietic stem cells

2011 ◽  
Vol 22 (8) ◽  
pp. 1312-1320 ◽  
Author(s):  
Ellen C. Teng ◽  
Lance R. Todd ◽  
Thomas J. Ribar ◽  
William Lento ◽  
Leah Dimascio ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Adult Stem Cells ◽  
Kinase Inhibitor ◽  
Embryonic Stem ◽  
Mitochondrial Morphology ◽  
In Vitro Proliferation ◽  
Hematopoietic Stem

Growth factor erv1-like (Gfer) is an evolutionarily conserved sulfhydryl oxidase that is enriched in embryonic and adult stem cells and plays an essential prosurvival role in pluripotent embryonic stem cells. Here we show that knockdown (KD) of Gfer in hematopoietic stem cells (HSCs) compromises their in vivo engraftment potential and triggers a hyper-proliferative response that leads to their exhaustion. KD of Gfer in HSCs does not elicit a significant alteration of mitochondrial morphology or loss of cell viability. However, these cells possess significantly reduced levels of the cyclin-dependent kinase inhibitor p27kip1. In contrast, overexpression of Gfer in HSCs results in significantly elevated total and nuclear p27kip1. KD of Gfer results in enhanced binding of p27kip1 to its inhibitor, the COP9 signalosome subunit jun activation-domain binding protein 1 (Jab1), leading to its down-regulation. Conversely, overexpression of Gfer results in its enhanced binding to Jab1 and inhibition of the Jab1-p27kip1 interaction. Furthermore, normalization of p27kip1 in Gfer-KD HSCs rescues their in vitro proliferation deficits. Taken together, our data demonstrate the presence of a novel Gfer-Jab1-p27kip1 pathway in HSCs that functions to restrict abnormal proliferation.

scholarly journals Human Hematopoietic Stem Cells Can Survive In Vitro for Several Months

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
Taro Ishigaki ◽  
Kazuhiro Sudo ◽  
Takashi Hiroyama ◽  
Kenichi Miharada ◽  
Haruhiko Ninomiya ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Cultured Cells ◽  
Es Cells ◽  
Embryonic Stem ◽  
Hematopoietic Stem ◽  
Immunodeficient Mice ◽  
Cell Sample

We previously reported that long-lasting in vitro hematopoiesis could be achieved using the cells differentiated from primate embryonic stem (ES) cells. Thus, we speculated that hematopoietic stem cells differentiated from ES cells could sustain long-lasting in vitro hematopoiesis. To test this hypothesis, we investigated whether human hematopoietic stem cells could similarly sustain long-lasting in vitro hematopoiesis in the same culture system. Although the results varied between experiments, presumably due to differences in the quality of each hematopoietic stem cell sample, long-lasting in vitro hematopoiesis was observed to last up to nine months. Furthermore, an in vivo analysis in which cultured cells were transplanted into immunodeficient mice indicated that even after several months of culture, hematopoietic stem cells were still present in the cultured cells. To the best of our knowledge, this is the first report to show that human hematopoietic stem cells can survive in vitro for several months.

scholarly journals Mettl3 Mediated m6A Modification Is Essential in Fetal Hematopoiesis

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3825-3825 ◽  
Author(s):  
Yimeng Gao ◽  
Radovan Vasic ◽  
Toma Tebaldi ◽  
Yuanbin Song ◽  
Rhea Teng ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Regulation Of Gene Expression ◽  
Embryonic Stem ◽  
Rna Modification ◽  
Hematopoietic Stem ◽  
Human Cd34

Abstract N6-methyladenosine (m6A) is the most abundant RNA modification, with key roles in RNA metabolism and regulation of gene expression. Recent studies have elucidated a role for m6A in normal hematopoiesis and myeloid malignancies. Constitutive deletion of the m6A methyltransferase Mettl3 in zebrafish enforces endothelial identity during the endothelial-to-hematopoietic transition, thus precluding normal developmental emergence of HSPCs. Studies conducted in human CD34+ cells, as well as human and murine AML cell lines have suggested that loss of METTL3 results in resolution of differentiation blockade, and impaired engraftment in murine transplantation assays. However, the effects of METTL3 deletion on hematopoietic stem cells in the context of an intact hematopoietic hierarchy in vivo have not yet been extensively characterized. To study the effects of Mettl3 deletion on the hematopoietic system in vivo, we generated Vav-Cre METTL3-/- (VCM3-/-) mice. Deletion of Mettl3 resulted in embryonic lethality, evidenced by skewing of Mendelian ratios at birth. Occasional stillborn VCM3-/- pups were smaller than wildtype littermates, and exhibited pallor, pancytopenia, and dramatically reduced marrow cellularity. To study the effects of Mettl3 deletion on embryonic hematopoiesis, we isolated fetal liver (FL) at embryonic day 14.5 for analysis. At E14.5, expected Mendelian ratios were preserved. Western blot and qPCR confirmed loss of Mettl3 expression in VCM3-/- mice. Reduction of total m6A levels in VCM3-/- mice was confirmed by ELISA. Flow cytometry for hematopoietic markers demonstrated a significant increase in the total number and frequency of Lin-Sca+c-Kit+ (LSK) cells in E14.5 VCM3-/- FL, with an increase in the frequency of HPC-1 (CD48+CD150-) and HPC-2 (CD48+CD150+) cells. To determine the function of VCM3-/- FL cells, we performed colony forming and transplantation assays. VCM3-/- FL cells demonstrated reduced colony forming ability in methylcellulose culture, and colonies that did arise were morphologically abnormal. VCM3-/- FL cells were also deficient in hematopoietic rescue assays, with all lethally irradiated recipient mice dying by day 14 post-transplant. Transplantation of CFSE labeled cells confirmed that absence of Mettl3 -/- hematopoiesis was not attributable to a homing defect. Competitive transplantation of VCM3-/- FL with Pep3b bone marrow similarly resulted in almost total loss of peripheral blood and bone marrow VCM3-/- engraftment, whereas mice transplanted with VCM3+/+ FL maintained chimerism at 8 weeks. Interestingly, VCM3-/- FL cells and FL LSK cells displayed no differences in apoptotic rate or cell cycle. To determine the mechanism underlying the observed phenotypes, we first performed RNA sequencing of VCM3+/+ and VCM3-/- FL LSK. Mettl3 deletion resulted in the increased expression of 701 transcripts, and reduced expression of 1395 transcripts. Gene ontology (GO) analysis revealed that upregulated genes were enriched for mitochondrial function, ribosome and ribonucleoprotein complex proteins and downregulated genes for cell adhesion and developmental processes. M6A RNA modification affects mRNA stability and translation. To determine the effect of m6A depletion on the hematopoieitic stem and progenitor cell proteome we are in the process of validating changes in protein levels of select genes essential in hematopoiesis. Previously, studies have demonstrated that deletion of METTL3 in human CD34+ hematopoietic cells and AML cell lines promote myeloid differentiation. Interestingly, we see a similar depletion of myeloid progenitors in VCM3-/- FL, with an increased percentage of mature myeloid CD11b+ cells. However, these results also coincide with an increased fraction of LSK HSPCs at E14.5. Interestingly, this resembles the METTL3 knockout phenotype in embryonic stem cells, which results in a reinforced naïve pluripotent state with impaired differentiation. Our ongoing studies seek to determine the role of m6A in FL HSC maintenance and differentiation. Disclosures No relevant conflicts of interest to declare.

In vitro generation of HSC-like cells from murine ESCs/iPSCs by enforced expression of LIM-homeobox transcription factor Lhx2

Blood ◽  
2011 ◽  
Vol 117 (14) ◽  
pp. 3748-3758 ◽  
Author(s):  
Kenji Kitajima ◽  
Ken-ichi Minehata ◽  
Kenji Sakimura ◽  
Toru Nakano ◽  
Takahiko Hara
Keyword(s):  
Stem Cells ◽  
Transcription Factor ◽  
Ectopic Expression ◽  
Hematopoietic Cells ◽  
Embryonic Stem ◽  
Hematopoietic Stem ◽  
Homeobox Transcription Factor ◽  
Induced Pluripotent

Abstract Identification of genes involved in in vitro differentiation induction of embryonic stem cells (ESCs) into hematopoietic stem cells (HSCs) has been challenged during last decade. To date, a homeobox transcription factor Hoxb4 has been only demonstrated to possess such an effect in mice. Here, we show that HSC-like cells were efficiently induced from mouse ESCs by enforced expression of Lhx2, a LIM-homeobox transcription factor. Transduction of Lhx2 into ESC-derived mesodermal cells resulted in robust differentiation of c-Kit+/Sca-1+/Lineage− (KSL) cells in vitro. The KSL cell induction frequency was superior to the case of Hoxb4. Furthermore, transplantation of Lhx2-transduced hematopoietic cells into lethally irradiated mice resulted in multilineage repopulation of hematopoietic cells over 4 months. Transduction of Lhx2 into induced pluripotent stem cells (iPSCs) was also effective in generating KSL cells in vitro, as well as HSC-like activities in vivo. These results demonstrate that ectopic expression of Lhx2 confers an in vivo engrafting capacity to ESC/iPSC-derived hematopoietic cells and in vivo behavior of iPSC-derived hematopoietic cells is almost identical to that of ESC-derived cells.

TET Family Oncogene Fus Is Essential for the Maintenance of Self-Renewing Hematopoietic Stem Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2529-2529
Author(s):  
Takeaki Sugawara ◽  
Hideyuki Oguro ◽  
Atsushi Iwama
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Transcriptional Repression ◽  
Cell Activation ◽  
B Lymphocyte ◽  
Rna Binding ◽  
Conflicts Of Interest ◽  
Hematopoietic Stem

Abstract Abstract 2529 Poster Board II-506 A Proto-oncogene FUS (fusion derived from malignant liposarcoma), also known as TLS (translocated in liposarcoma), was originally identified in chromosomal translocation of human soft tissue sarcoma. FUS is also known to be fused with an ETS family transcription factor ERG in human myeloid leukemia with t(16;21) which is associated with poor prognosis. Based on its protein structure, DNA- and RNA-binding activity and involvement in many human cancers as the fusion with various transcription factors, FUS is now grouped with EWS and TAFII68 into TET (FET) oncogene family. Multiple functions have been postulated for FUS, including non-coding-RNA-mediated transcriptional repression, posttranscriptional RNA processing and the maintenance of genomic integrity. Fus-deficient (Fus−/−) mice showed a non-cell-autonomous defect in B lymphocyte development, defective B cell activation and increased sensitivity to radiation in previous studies. However, its physiological function in hematopoiesis remains unknown. In this study we performed detailed analyses of Fus−/− hematopoietic stem cells (HSCs). Fus−/− fetal livers at embryonic day 14.5 exhibited a mild reduction in numbers of hematopoietic stem and progenitor cells compared with the wild type. Disruption of Fus, however, did not grossly affect proliferation or differentiation of hematopoietic progenitors. Of note, Fus−/− HSCs had significantly reduced repopulating activity of hematopoiesis in competitive repopulation assays, and did not repopulate hematopoiesis at all in tertiary recipients. Moreover, Fus−/− HSCs were highly sensitive to radiation both in vitro and in vivo and showed a drastic reduction in numbers in recipient mice after sublethal irradiation. All these findings implicate Fus in the maintenance and radioprotection of HSCs. Studies of chromosome stability, telomere length, apoptosis and levels of reactive oxigen species (ROS) appeared not accountable for the apparent defect of Fus−/− HSCs. However, gene expression profiling identified changes in expression of several genes in Fus−/− HSCs, and dysregulated expression of some of these genes might be responsible for the defective function of Fus−/− HSCs. Disclosures: No relevant conflicts of interest to declare.

Stromal Cell Regulation of Murine Hematopoietic Stem Cells.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1566-1566
Author(s):  
Stefan Wohrer ◽  
Keegan Rowe ◽  
Heidi Mader ◽  
Claudia Benz ◽  
Michael R Copley ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Stromal Cell ◽  
Cultured Cells ◽  
Conflicts Of Interest ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Daughter Cells

Abstract Abstract 1566 Recent advances in purifying murine hematopoietic stem cells (HSCs) to near homogeneity (>20%) have made it possible to analyze their in vivo clonal growth, self-renewal and differentiation properties over prolonged periods and the effects of various manipulations on these key functional parameters. However, conditions that allow genetically unaltered HSCs to maintain their original functional properties over equivalent periods of prolonged proliferation in vitro have not yet been identified. Since initial studies showed that the UG26 stromal cell could support murine HSC maintenance for limited periods, we first asked whether the addition of cytokines that also maintain HSCs for short periods might synergize with UG26 cells to enable HSC expansion to occur. Limiting dilution transplants that used a 6-month read-out of reconstituted blood elements (>1%) showed that the addition of 100 ng/ml Steel Factor (SF) and 20 ng/ml IL-11 to cultures containing UG26 cells and single purified (50%) HSCs (EPCR+CD150+CD48-, ESLAM cells) consistently stimulated a 3–5 fold HSC expansion after 7 days (3 expts). Furthermore, the effect of the UG26 cells could be replaced by UG26 conditioned medium (CM) and, in the presence of the CM+SF/IL-11 cocktail, the HSCs showed sustained longterm in vivo lympho-myeloid reconstituting activity in both primary and secondary recipients. Under these conditions, every ESLAM cell isolated proliferated several times within 7 days, but individual analysis of paired daughter cells showed that most first divisions (13/42) were, nevertheless, asymmetrical in terms of the numbers and types of different lineages produced by each of the 2 daughter cells for at least 4 months, although occasional evidence of symmetry was obtained (2/42 divisions). Interestingly, these first divisions showed a biphasic curve with 75% of the cells dividing before and 25% after 48 hours - the late dividers being more highly enriched for HSCs (95% vs 20%). We next asked whether TGF-β might be an important factor in UG26 CM, since UG26 cells exert a strong cell cycle inhibitory effect, and produce abundant TGF-beta. Accordingly, we next analyzed the effect of adding a neutralizing anti-TGF-β antibody or replacing the CM with TGF-β in the same type of single HSC cultures by tracking the survival and division kinetics of the cells as well as measuring the repopulating activity of their in vitro progeny present after 7 days. Strikingly, the addition of anti-TGF-β to the CM+SF/IL-11 supplemented HSC cultures eliminated the late wave of first cell divisions and caused an accompanying loss of myeloid reconstituting ability in recipients transplanted with the cultured cells. Conversely, replacement of the CM with TGF-β restored a biphasic division kinetics curve to cultures supplemented with SF/IL-11 but no CM. However, this did not protect against the early 50% loss of cells by apoptosis. These findings provide evidence of a new role of TGF-β in preserving the integrity of HSC functionality in vitro, but suggest a requirement for other types of factors released by certain stromal cells to achieve sustained symmetrical HSC self-renewal in vitro. Disclosures: No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document