41BB-based and CD28-based CD123-redirected T-cells ablate human normal hematopoiesis in vivo

BackgroundAcute myeloid leukemia (AML) is a hematopoietic malignancy which is biologically, phenotypically and genetically very heterogeneous. Outcome of patients with AML remains dismal, highlighting the need for improved, less toxic therapies. Chimeric antigen receptor T-cell (CART) immunotherapies for patients with refractory or relapse (R/R) AML are challenging because of the absence of a universal pan-AML target antigen and the shared expression of target antigens with normal hematopoietic stem/progenitor cells (HSPCs), which may lead to life-threating on-target/off-tumor cytotoxicity. CD33-redirected and CD123-redirected CARTs for AML are in advanced preclinical and clinical development, and they exhibit robust antileukemic activity. However, preclinical and clinical controversy exists on whether such CARTs are myeloablative.MethodsWe set out to comparatively characterize in vitro and in vivo the efficacy and safety of 41BB-based and CD28-based CARCD123. We analyzed 97 diagnostic and relapse AML primary samples to investigate whether CD123 is a suitable immunotherapeutic target, and we used several xenograft models and in vitro assays to assess the myeloablative potential of our second-generation CD123 CARTs.ResultsHere, we show that CD123 represents a bona fide target for AML and show that both 41BB-based and CD28-based CD123 CARTs are very efficient in eliminating both AML cell lines and primary cells in vitro and in vivo. However, both 41BB-based and CD28-based CD123 CARTs ablate normal human hematopoiesis and prevent the establishment of de novo hematopoietic reconstitution by targeting both immature and myeloid HSPCs.ConclusionsThis study calls for caution when clinically implementing CD123 CARTs, encouraging its preferential use as a bridge to allo-HSCT in patients with R/R AML.

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Organ-Selective Homing Defines Engraftment Kinetics of Murine Hematopoietic Stem Cells and Is Compromised by Ex Vivo Expansion

Blood ◽

10.1182/blood.v93.5.1557 ◽

1999 ◽

Vol 93 (5) ◽

pp. 1557-1566 ◽

Cited By ~ 113

Author(s):

Stephen J. Szilvassy ◽

Michael J. Bass ◽

Gary Van Zant ◽

Barry Grimes

Keyword(s):

Ex Vivo ◽

Ex Vivo Expansion ◽

Hematopoietic Stem ◽

Murine Bone Marrow ◽

Hematopoietic Reconstitution ◽

Dramatic Decline ◽

Stem And Progenitor Cells ◽

Clonogenic Cells

Abstract Hematopoietic reconstitution of ablated recipients requires that intravenously (IV) transplanted stem and progenitor cells “home” to organs that support their proliferation and differentiation. To examine the possible relationship between homing properties and subsequent engraftment potential, murine bone marrow (BM) cells were labeled with fluorescent PKH26 dye and injected into lethally irradiated hosts. PKH26+ cells homing to marrow or spleen were then isolated by fluorescence-activated cell sorting and assayed for in vitro colony-forming cells (CFCs). Progenitors accumulated rapidly in the spleen, but declined to only 6% of input numbers after 24 hours. Although egress from this organ was accompanied by a simultaneous accumulation of CFCs in the BM (plateauing at 6% to 8% of input after 3 hours), spleen cells remained enriched in donor CFCs compared with marrow during this time. To determine whether this differential homing of clonogenic cells to the marrow and spleen influenced their contribution to short-term or long-term hematopoiesis in vivo, PKH26+ cells were sorted from each organ 3 hours after transplantation and injected into lethally irradiated Ly-5 congenic mice. Cells that had homed initially to the spleen regenerated circulating leukocytes (20% of normal counts) approximately 2 weeks faster than cells that had homed to the marrow, or PKH26-labeled cells that had not been selected by a prior homing step. Both primary (17 weeks) and secondary (10 weeks) recipients of “spleen-homed” cells also contained approximately 50% higher numbers of CFCs per femur than recipients of “BM-homed” cells. To examine whether progenitor homing was altered upon ex vivo expansion, highly enriched Sca-1+c-kit+Lin−cells were cultured for 9 days in serum-free medium containing interleukin (IL)-6, IL-11, granulocyte colony-stimulating factor, stem cell factor, flk-2/flt3 ligand, and thrombopoietin. Expanded cells were then stained with PKH26 and assayed as above. Strikingly, CFCs generated in vitro exhibited a 10-fold reduction in homing capacity compared with fresh progenitors. These studies demonstrate that clonogenic cells with differential homing properties contribute variably to early and late hematopoiesis in vivo. The dramatic decline in the homing capacity of progenitors generated in vitro underscores critical qualitative changes that may compromise their biologic function and potential clinical utility, despite their efficient numerical expansion.

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Synergy of NUP98-HOXA10 Fusion Gene and NrasG12D Mutation Preserves the Stemness of Hematopoietic Stem Cells on Culture Condition

Cells ◽

10.3390/cells8090951 ◽

2019 ◽

Vol 8 (9) ◽

pp. 951 ◽

Cited By ~ 2

Author(s):

Yong Dong ◽

Chengxiang Xia ◽

Qitong Weng ◽

Tongjie Wang ◽

Fangxiao Hu ◽

...

Keyword(s):

Stem Cells ◽

Hematopoietic Stem Cells ◽

Pluripotent Stem Cells ◽

Culture Condition ◽

Fusion Gene ◽

Nras Mutation ◽

Hematopoietic Stem ◽

Bona Fide

Natural hematopoietic stem cells (HSC) are susceptible and tend to lose stemness, differentiate, or die on culture condition in vitro, which adds technical challenge for maintaining bona fide HSC-like cells, if ever generated, in protocol screening from pluripotent stem cells. It remains largely unknown whether gene-editing of endogenous genes can genetically empower HSC to endure the culture stress and preserve stemness. In this study, we revealed that both NUP98-HOXA10HD fusion and endogenous Nras mutation modifications (NrasG12D) promoted the engraftment competitiveness of HSC. Furthermore, the synergy of these two genetic modifications endowed HSC with super competitiveness in vivo. Strikingly, single NAV-HSC successfully maintained its stemness and showed robust multi-lineage engraftments after undergoing the in vitro culture. Mechanistically, NUP98-HOXA10HD fusion and NrasG12D mutation distinctly altered multiple pathways involving the cell cycle, cell division, and DNA replication, and distinctly regulated stemness-related genes including Hoxa9, Prdm16, Hoxb4, Trim27, and Smarcc1 in the context of HSC. Thus, we develop a super-sensitive transgenic model reporting the existence of HSC at the single cell level on culture condition, which could be beneficial for protocol screening of bona fide HSC regeneration from pluripotent stem cells in vitro.

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Recombinant mammalian DNA methyltransferase activity on model transcriptional gene silencing short RNA–DNA heteroduplex substrates

Biochemical Journal ◽

10.1042/bj20100579 ◽

2010 ◽

Vol 432 (2) ◽

pp. 323-332 ◽

Cited By ~ 16

Author(s):

Jason P. Ross ◽

Isao Suetake ◽

Shoji Tajima ◽

Peter L. Molloy

Keyword(s):

Gene Silencing ◽

Dna Methyltransferase ◽

De Novo ◽

Double Helix ◽

In Vitro Assays ◽

Enzyme Analysis ◽

Transcriptional Gene Silencing ◽

Restriction Enzyme Analysis

The biochemical mechanism of short RNA-induced TGS (transcriptional gene silencing) in mammals is unknown. Two competing models exist; one suggesting that the short RNA interacts with a nascent transcribed RNA strand (RNA–RNA model) and the other implying that short RNA forms a heteroduplex with DNA from the unwound double helix, an R-loop structure (RNA–DNA model). Likewise, the requirement for DNA methylation to enact TGS is still controversial. In vitro assays using purified recombinant murine Dnmt (DNA methyltransferase) 1-dN (where dN indicates an N-terminal truncation), 3a and 3b enzymes and annealed oligonucleotides were designed to question whether Dnmts methylate DNA in a RNA–DNA heteroduplex context and whether a RNA–DNA heteroduplex R-loop is a good substrate for Dnmts. Specifically, model synthetic oligonucleotides were used to examine methylation of single-stranded oligonucleotides, annealed oligonucleotide duplexes, RNA–DNA heteroduplexes, DNA bubbles and R-loops. Dnmt methylation activity on the model substrates was quantified with initial velocity assays, novel ARORA (annealed RNA and DNA oligonucleotide-based methylation-sensitive restriction enzyme analysis), tBS (tagged-bisulfite sequencing) and the quantitative PCR-based method MethylQuant. We found that RNA–DNA heteroduplexes and R-loops are poor substrates for methylation by both the maintenance (Dnmt1) and de novo (Dnmt3a and Dnmt3b) Dnmts. These results suggest the proposed RNA/DNA model of TGS in mammals is unlikely. Analysis of tagged-bisulfite genomic sequencing led to the unexpected observation that Dnmt1-dN can methylate cytosines in a non-CpG context in DNA bubbles. This may have relevance in DNA replication and silencing of transcriptionally active loci in vivo.

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Xenotransplantation of Primary CD34+CD38- Hematopoietic Stem Cells Results in an In Vivo Model of Idiopathic Myelofibrosis.

Blood ◽

10.1182/blood.v108.11.666.666 ◽

2006 ◽

Vol 108 (11) ◽

pp. 666-666

Author(s):

Noriyuki Saito ◽

Fumihiko Ishikawa ◽

Kazuya Shimoda ◽

Shuro Yoshida ◽

Yoriko Saito ◽

...

Keyword(s):

Stem Cells ◽

In Vivo Model ◽

Idiopathic Myelofibrosis ◽

Hematopoietic Stem ◽

Hematopoietic Reconstitution ◽

Cd34 Cells ◽

Normal Human ◽

Myelomonocytic Cells ◽

Xenotransplantation Model

Abstract Idiopathic myelofibrosis (IMF) is characterized by clonal proliferation of abnormal myelomonocytic cells and megakaryocytes. These abnormal cells secrete various cytokines resulting in reactive fibrosis and increased collagen content in the bone marrow (BM), and lead to extramedullary hematopoiesis and the appearance of CD34+ cells in the peripheral blood (PB). Although IMF is thought to originate at the level of hematopoietic stem cell (HSC), this has not been demonstrated directly in primary human IMF. To demonstrate the involvement of HSCs in the pathogenesis of IMF and to establish an in vivo model of IMF, we used the newborn NOD/SCID/IL2rg-null xenotransplantation model. We purified PB CD34+ cells from six IMF patients, transplanted 1–10 x10e4 cells intravenously into newborn NOD/SCID/IL2rg-null recipients and analyzed PB and BM human CD45+ hematopoietic cell chimerism, degree of suppression of murine hematopoiesis, presence of hallmark BM fibrosis and plasma TGF-b1 levels in the recipients at 6 months post-transplantation. Primary IMF PB CD34+ cells from five out of six patients engrafted in twelve out of twelve recipients. BM of all engrafted recipients demonstrated fibrotic changes associated with increased proliferation of murine fibroblasts, the presence of human megakaryocytes and elevated plasma TGF-b1 levels, recapitulating the clinical features of IMF. Three distinct patterns of human hematopoietic reconstitution were observed among the engrafted recipients: Predominantly malignant myelomonocytic engraftment in the PB and BM (n=4), Reconstitution of both normal human hematopoiesis (with mature B and T cells, myeloid cells and platelets) and malignant myelomonocytic cells (n=6) and Development of acute leukemia (n=2). Fibrotic change was seen even in the BM of recipients that showed normal human hematopoietic reconstitution, showing that in IMF, there is co-existence of both normal and malignant hematopoietic stem/progenitor cells in the PB CD34+ fraction. Furthermore, when 5–10 x 10e3 sorted PB CD34+CD38– cells from three patients were transplanted into six newborn NOD/SCID/IL2rg-null recipients, reconstitution with human myelomonocytic cells associated with BM fibrosis was demonstrated in all recipients, with compatible level of PB and BM chimerism with those transplanted with PB CD34+ cells. These findings demonstrate that the IMF-initiating cells are contained within the HSC fraction. The newborn NOD/SCID/IL2rg-null xenotransplantation model provides an in vivo model of primary human IMF that may lead to better understanding of the mechanisms of IMF pathogenesis including the identification of IMF stem cells and may be useful for development of novel therapeutic agents for IMF.

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The Role of Nucleophosmin In Hematopoietic Stem Cells and the Pathogenesis of Myelodysplastic Syndrome

Blood ◽

10.1182/blood.v116.21.95.95 ◽

2010 ◽

Vol 116 (21) ◽

pp. 95-95 ◽

Cited By ~ 1

Author(s):

Keisuke Ito ◽

Paolo Sportoletti ◽

John G Clohessy ◽

Grisendi Silvia ◽

Pier Paolo Pandolfi

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Myelodysplastic Syndrome ◽

Cell Biology ◽

De Novo ◽

Stem Cell Biology ◽

Hematopoietic Stem

Abstract Abstract 95 Myelodysplastic syndrome (MDS) is an incurable stem cell disorder characterized by ineffective hematopoiesis and an increased risk of leukemia transformation. Nucleophosmin (NPM) is directly implicated in primitive hematopoiesis, the pathogenesis of hematopoietic malignancies and more recently of MDS. However, little is known regarding the molecular role and function of NPM in MDS pathogenesis and in stem cell biology. Here we present data demonstrating that NPM plays a critical role in the maintenance of hematopoietic stem cells (HSCs) and the transformation of MDS into leukemia. NPM is located on chromosome 5q and is frequently lost in therapy-related and de novo MDS. We have previously shown that Npm1 acts as a haploinsufficient tumor suppressor in the hematopoietic compartment and Npm1+/− mice develop a hematologic syndrome with features of human MDS, including increased susceptibility to leukemogenesis. As HSCs have been demonstrated to be the target of the primary neoplastic event in MDS, a functional analysis of the HSC compartment is essential to understand the molecular mechanisms in MDS pathogenesis. However, the role of NPM in adult hematopoiesis remains largely unknown as Npm1-deficiency leads to embryonic lethality. To investigate NPM function in adult hematopoiesis, we have generated conditional knockout mice of Npm1, using the Cre-loxP system. Analysis of Npm1 conditional mutants crossed with Mx1-Cre transgenic mice reveals that Npm1 plays a crucial role in adult hematopoiesis and ablation of Npm1 in adult HSCs leads to aberrant cycling and followed by apoptosis. Analysis of cell cycle status revealed that HSCs are impaired in their ability to maintain quiescence after Npm1-deletion and are rapidly depleted in vivo as well as in vitro. Competitive reconstitution assay revealed that Npm1 acts cell-autonomously to maintain HSCs. Conditional inactivation of Npm1 leads to an MDS phenotype including a profoundly impaired ability to differentiate into cells of the erythroid lineage, megakaryocyte dyspoiesis and centrosome amplification. Furthermore, Npm1 loss evokes a p53-dependent response and Npm1-deleted HSCs undergo apoptosis in vivo and in vitro. Strikingly, transfer of the Npm1 mutation into a p53-null background rescued the apoptosis of Npm1-ablated HSCs and resulted in accelerated transformation to an aggressive and lethal form of acute myeloid leukemia. Our findings highlight the crucial role of NPM in stem cell biology and identify a new mechanism by which MDS can progress to leukemia. This has important therapeutic implications for de novo MDS as well as therapy-related MDS, which is known to rapidly evolve to leukemia with frequent loss or mutation of TRP53. Disclosures: No relevant conflicts of interest to declare.

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DNMT3A Mutation Leads to Hematopoietic Dysregulation.

Blood ◽

10.1182/blood.v120.21.2382.2382 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2382-2382

Author(s):

Jie Xu ◽

Wei-na Zhang ◽

Tao Zhen ◽

Yang Li ◽

Jing-yi Shi ◽

...

Keyword(s):

Transcriptional Activation ◽

Dna Methyltransferase ◽

De Novo ◽

Conflicts Of Interest ◽

Epigenetic Modification ◽

Hematopoietic Cells ◽

In Vitro Assays ◽

Clinical Samples ◽

Hematopoietic Stem

Abstract Abstract 2382 Epigenetic modification process is required for the development of hematopoietic cells. DNA methyltransferase DNMT3A, responsible for de novo DNA methylation, was newly reported to have a high frequency of mutations in hematopoietic malignancies. Conditional knock-out of DNMT3A promoted self-renewal activity of murine hematopoietic stem cells (HSCs). However, the role of mutated DNMT3A in hematopoiesis and its regulative mechanism of epigenetic network mostly remain unknown. Here we showed that the Arg882His (R882H) hotspot locus on DNMT3A impaired the normal function of this enzyme and resulted in an abnormal increase of primitive hematopoietic cells. In both controlled in vivo and in vitro assays, we found that the cells transfected by R882H mutant promoted cell proliferation, while decreased the differentiation of myeloid lineage compared to those with wild type. Analysis of bone marrow (BM) cells from mice transduced by R882H reveals an expansion of Lin−Sca-1+C-kit+ populations and a reduction of mature myeloid cells. Meanwhile, a cluster of upregulated genes and downregulated lineage-specific differentiation genes associated with hematopoiesis were discovered in mice BM cells with R882H mutation. We further evaluated the association of mutated DNMT3A and HOXB4 which was previously detected to be highly expressed in clinical samples carrying R882 mutation. Compared with wildtype DNMT3A, R882H mutation disrupted the repression of HOXB4 by largely recruiting tri-methylated histone 3 lysine 4 (H3K4). Taken together, our results showed that R882H mutation disturbed HSC activity through H3K4 tri-methylation, and transcriptional activation of HSC-related genes. Disclosures: No relevant conflicts of interest to declare.

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De novo disease-associated mutations in KIF1A dominant negatively inhibit axonal transport of synaptic vesicle precursors

10.1101/2021.07.22.453457 ◽

2021 ◽

Author(s):

Yuzu Anazawa ◽

Tomoki Kita ◽

Kumiko Hayashi ◽

Shinsuke Niwa

Keyword(s):

Synaptic Vesicle ◽

Axonal Transport ◽

De Novo ◽

Molecular Motor ◽

Model Systems ◽

In Vitro Assays ◽

In Vivo Model ◽

Wild Type

KIF1A is a kinesin superfamily molecular motor that transports synaptic vesicle precursors in axons. Mutations in Kif1a lead to a group of neuronal diseases called KIF1A-associated neuronal disorder (KAND). KIF1A forms a homodimer and KAND mutations are mostly de novo and autosomal dominant; however, it is not known whether the function of wild-type KIF1A is inhibited by disease-associated KIF1A. No reliable in vivo model systems to analyze the molecular and cellular biology of KAND have been developed; therefore, here, we established Caenorhabditis elegans models for KAND using CRISPR/cas9 technology and analyzed defects in axonal transport. In the C. elegans models, heterozygotes and homozygotes exhibited reduced axonal transport phenotypes. In addition, we developed in vitro assays to analyze the motility of single heterodimers composed of wild-type KIF1A and disease-associated KIF1A. Disease-associated KIF1A significantly inhibited the motility of wild-type KIF1A when heterodimers were formed. These data indicate the molecular mechanism underlying the dominant nature of de novo KAND mutations.

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Aorta-associated CD34+ hematopoietic cells in the early human embryo

Blood ◽

10.1182/blood.v87.1.67.67 ◽

1996 ◽

Vol 87 (1) ◽

pp. 67-72 ◽

Cited By ~ 290

Author(s):

M Tavian ◽

L Coulombel ◽

D Luton ◽

HS Clemente ◽

F Dieterlen-Lievre ◽

...

Keyword(s):

Stem Cells ◽

Human Embryo ◽

Hematopoietic Cells ◽

Yolk Sac ◽

Blood System ◽

In Vitro Assays ◽

Avian Embryo ◽

Hematopoietic Stem

Abstract Hematopoiesis is established from circulating blood stem cells that seed the embryonic rudiments of blood-forming tissues, a basic notion in developmental hematology. However, the assumption that these stem cells originate from the extraembryonic mesoderm, where primitive hematopoiesis is initiated by intrinsic precursors, has been reconsidered after analysis of blood cell development in avian embryo chimeras: yolk-sac-derived stem cells do not contribute significantly to the definitive blood system, whose first forerunners develop independently along the ventral aspect of the embryonic aorta. Recently, the homologous intraembryonic tissues of the mouse have been submitted to sensitive in vivo and in vitro assays, which showed that they also harbor multipotential hematopoietic stem cells. We have now identified a dense population of hematogenous cells, marked by the surface expression of the CD34 glycoprotein, associated with the ventral endothelium of the aorta in the 5-week human embryo. Therefore, we extend to the human species the growing evidence that intraembryonic hematopoietic cells developing independently of the yolk sac might be the real stem of the whole blood system.

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The hemogenic endothelium: a critical source for the generation of PSC-derived hematopoietic stem and progenitor cells

Cellular and Molecular Life Sciences ◽

10.1007/s00018-021-03777-y ◽

2021 ◽

Author(s):

Lucas Lange ◽

Michael Morgan ◽

Axel Schambach

Keyword(s):

Stem Cells ◽

De Novo ◽

Cell Types ◽

Hemogenic Endothelium ◽

Hematopoietic Stem ◽

Autologous Cell ◽

Stem And Progenitor Cells ◽

Bona Fide

AbstractIn vitro generation of hematopoietic cells and especially hematopoietic stem cells (HSCs) from human pluripotent stem cells (PSCs) are subject to intensive research in recent decades, as these cells hold great potential for regenerative medicine and autologous cell replacement therapies. Despite many attempts, in vitro, de novo generation of bona fide HSCs remains challenging, and we are still far away from their clinical use, due to insufficient functionality and quantity of the produced HSCs. The challenges of generating PSC-derived HSCs are already apparent in early stages of hemato-endothelial specification with the limitation of recapitulating complex, dynamic processes of embryonic hematopoietic ontogeny in vitro. Further, these current shortcomings imply the incompleteness of our understanding of human ontogenetic processes from embryonic mesoderm over an intermediate, specialized hemogenic endothelium (HE) to their immediate progeny, the HSCs. In this review, we examine the recent investigations of hemato-endothelial ontogeny and recently reported progress for the conversion of PSCs and other promising somatic cell types towards HSCs with the focus on the crucial and inevitable role of the HE to achieve the long-standing goal—to generate therapeutically applicable PSC-derived HSCs in vitro.

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

Blood ◽

10.1182/blood.v118.21.1290.1290 ◽

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.

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