scholarly journals Targeting miRNA-551b, a "Stemness"-like microRNA, to Eradicate AML (Stem) Cells

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1494-1494
Author(s):  
Tània Martiáñez ◽  
Noortje Van Gils ◽  
David Christian De Leeuw ◽  
Eline Vermue ◽  
Arjo Rutten ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Research Funding ◽  
Leukemic Stem Cells ◽  
Hematopoietic Stem ◽  
Inhibition Of Proliferation ◽  
Novel Target

Abstract Despite high complete remission (CR) rates achieved after chemotherapy, only 30-40% of patients with Acute Myeloid Leukemia (AML) survive five years after diagnosis. The main cause of this treatment failure is insufficient eradication of a subpopulation of chemotherapy-resistant leukemia cells with stem cell properties, named "leukemic stem cells" (LSCs). LSCs use a variety of mechanisms to resist chemotherapy and targeting them is one of the major challenges in AML treatment. Since miRNAs can target multiple genes/pathways simultaneously, their modulation (downregulation or upregulation) may have great potential for the successful elimination of therapy-resistant leukemic (stem) cells (Martiañez Canales et al. Cancers 2017). Here, we show that miRNA-551b, previously identified by us as a stem cell-like miRNA, can be a potential novel target to specifically eradicate AML stem-like cells. Aiming at identification of miRNA-based therapy to specifically eradicate LSCs, while sparing normal Hematopoietic Stem Cells (HSCs), we determined expression of miRNAs in normal HSCs, Leukemic Stem Cells (LSCs) and leukemic progenitors (LP) all derived from the same AML patient's bone marrow. Using this approach, we identified miRNA-551b as being highly expressed in normal HSCs residing both in healthy and AML bone marrows. In AML, high expression of miR551b demonstrated to be associated with an adverse prognosis. Moreover, miRNA-551b was highly expressed in immature AML cases and its expression in a cohort of patients coincided with the expression of stem cell genes (De Leeuw et al. Leukemia 2016). To further elucidate the link between miRNA-551b and AML "stemness" and to test whether downregulation of miRNA-551b affects the survival of AML (stem/progenitor) cells, proliferation and the balance between differentiation and "stemness", we reduced miRNA-551b expression, either by lentiviral transduction of antagomirs or by adding locked nucleotide acid (LNA)-oligonucleotides to AML cell lines and primary AML cells. Downregulation of miRNA-551b in the stem cell-like AML cell line KG1a led to inhibition of cell growth in vitro, which was due to inhibition of proliferation rather than induction of apoptosis. KG1a tumor growth in an in vivo mouse model was also reduced when miRNA-551b was downregulated. In primary AML, miRNA-551b knockdown resulted in a significant decrease in the survival of leukemic progenitors and LSCs, while hematopoietic stem cells (HSCs) and normal progenitors from healthy bone marrows were not affected. These results suggest that a therapeutic approach inhibiting miRNA-551b expression might specifically eradicate leukemic progenitors and LSCs from primary AML, while sparing HSCs. We are currently studying miRNA-551b targets which can be responsible for this specific LSCs elimination. In conclusion, our results suggest that inhibition of miRNA-551b could be a promising approach to eliminate stem cell-like AML cells, thereby decreasing relapse rates and improving AML treatment outcome. Disclosures Ossenkoppele: Pfizer: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Research Funding; Roche: Consultancy, Honoraria; Celgene: Honoraria, Research Funding; Johnson & Johnson: Consultancy, Honoraria, Research Funding; Genmab: Research Funding.

Sqstm1 Is Required to Retain Hematopoietic Stem Cell/ Progenitors As a Negative Regulator of Macrophage-Dependent Inflammatory Signaling in the Bone Marrow Osteoblastic Niche

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 350-350
Author(s):  
Kyung-Hee Chang ◽  
Amitava Sengupta ◽  
Ramesh C Nayak ◽  
Angeles Duran ◽  
Sang Jun Lee ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Research Funding ◽  
Negative Regulator ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
P Retention

Abstract In the bone marrow (BM), hematopoietic stem cells and progenitors (HSC/P) reside in specific anatomical niches. Among these niches, a functional osteoblast (Ob)-macrophage (MΦ) niche has been described where Ob and MΦ (so called "osteomacs") are in direct relationship. A connection between innate immunity surveillance and traffic of hematopoietic stem cells/progenitors (HSC/P) has been demonstrated but the regulatory signals that instruct immune regulation from MΦ and Ob on HSC/P circulation are unknown. The adaptor protein sequestosome 1 (Sqstm1), contains a Phox bemp1 (PB1) domain which regulates signal specificities through PB1-PB1 scaffolding and processes of autophagy. Using microenvironment and osteoblast-specific mice deficient in Sqstm1, we discovered that the deficiency of Sqstm1 results in macrophage contact-dependent activation of Ob IKK/NF-κB, in vitro and in vivo repression of Ccl4 (a CCR5 binding chemokine that has been shown to modulate microenvironment Cxcl12-mediated responses of HSC/P), HSC/P egress and deficient BM homing of wild-type HSC/P. Interestingly, while Ccl4 expression is practically undetectable in wild-type or Sqstm1-/- Ob, primary Ob co-cultured with wild-type BM-derived MΦ strongly upregulate Ccl4 expression, which returns to normal levels upon genetic deletion of Ob Sqstm1. We discovered that MΦ can activate an inflammatory pathway in wild-type Ob which include upregulation of activated focal adhesion kinase (p-FAK), IκB kinase (IKK), nuclear factor (NF)-κB and Ccl4 expression through direct cell-to-cell interaction. Sqstm1-/- Ob cocultured with MΦ strongly upregulated p-IKBα and NF-κB activity, downregulated Ccl4 expression and secretion and repressed osteogenesis. Forced expression of Sqstm1, but not of an oligomerization-deficient mutant, in Sqstm1-/- Ob restored normal levels of p-IKBα, NF-κB activity, Ccl4 expression and osteogenic differentiation, indicating that Sqstm1 dependent Ccl4 expression depends on localization to the autophagosome formation site. Finally, Ob Sqstm1 deficiency results in upregulation of Nbr1, a protein containing a PB1 interacting domain. Combined deficiency of Sqstm1 and Nbr1 rescues all in vivo and in vitro phenotypes of Sqstm1 deficiency related to osteogenesis and HSC/P egression in vivo. Together, this data indicated that Sqstm1 oligomerization and functional repression of its PB1 binding partner Nbr1 are required for Ob dependent Ccl4 production and HSC/P retention, resulting in a functional signaling network affecting at least three cell types. A functional ‘MΦ-Ob niche’ is required for HSC/P retention where Ob Sqstm1 is a negative regulator of MΦ dependent Ob NF-κB activation, Ob differentiation and BM HSC/P traffic to circulation. Disclosures Starczynowski: Celgene: Research Funding. Cancelas:Cerus Co: Research Funding; P2D Inc: Employment; Terumo BCT: Research Funding; Haemonetics Inc: Research Funding; MacoPharma LLC: Research Funding; Therapure Inc.: Consultancy, Research Funding; Biomedical Excellence for Safer Transfusion: Research Funding; New Health Sciences Inc: Consultancy.

Deletion of Rac2 inhibits Proliferation of Chronic Myelogenous Leukemia (CML) Stems Cells and Progenitors (HSC/P) In Vivo and Promotes Survival of Scl/p210-BCR-ABL Mice.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3253-3253
Author(s):  
Amitava Sengupta ◽  
Jorden Arnett ◽  
Susan Dunn ◽  
Jose Cancelas
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Chronic Myelogenous Leukemia ◽  
Research Funding ◽  
Myelogenous Leukemia ◽  
Leukemic Stem Cells ◽  
Hematopoietic Stem ◽  
Rac Gtpases ◽  
And Migration

Abstract Abstract 3253 Poster Board III-1 Chronic myelogenous leukemia (CML) is a hematopoietic stem cell (HSC) malignancy induced by p210-BCR-ABL and is characterized by myeloproliferation in the bone marrow (BM) and egress of leukemic stem cells and progenitors (LSC/P) to extramedullary sites. Persistence of BCR-ABL+ HSCs in patients under imatinib suggests that inhibition of ABL-kinase alone is not sufficient to completely eliminate the LSC/P population. Rac GTPases represent integrative molecular switches for p210-BCR-ABL-induced HSC transformation and combined pharmacological and genetic attenuation of Rac GTPases significantly prolong survival in vivo, as reported in a retroviral transduction/transplantation model (Thomas EK & Cancelas JA et al, Cancer Cell 2008). Here, we analyzed the role of Rac2 GTPase in the leukemic maintenance and in the interaction of LSC/P with the leukemic microenvironment in vivo. We used a stem cell leukemia (Scl) promoter-driven, tet-off, Scl-tTA x TRE-BCR-ABL (Scl/p210-BCR-ABL) binary transgenic mouse model (Koschmieder S et al., Blood 2005), where expression of BCR-ABL is restricted to the HSC/P compartment, allowing the study of the intrinsic molecular changes in LSC/P during leukemogenesis. In these mice, Scl-driven expression of BCR-ABL is active in HSC (Lin-/Sca1+/c-kit+; LSK) and progenitors (Lin-/c-kit+/Sca-1-; LK), and CML development is associated with the activation of downstream signaling effectors CrkL, p38-MAPK and JNK. Additionally, Scl/p210-BCR-ABL mice had increased cycling of LSK cells and expansion of circulating and splenic, but not BM, LSC/P, suggesting egress of LSC/Ps from the marrow. These mice share all the characteristics of HSC/P transformation in CML, including increased HSC/P proliferation and survival, severely reduced adhesion to fibronectin, increased migration towards CXCL12, increased cell surface expression of CD44 and decreased expression of L-selectin. Myeloproliferative disease (MPD) in these mice is transplantable into recipient mice, and CML splenocytes have a 10-fold increase in homing to the spleen than towards BM (P<0.05). Leukemic splenocytes are also enriched in endosteal lodging progenitors, compared to the BM-derived progenitors (1.9-fold, P≤0.05). In order to determine the contribution of Rac2 GTPase in the transformation phenotype of leukemic stem cells and progenitors, Scl/p210 mice were intercrossed with Rac2-/- mice. Interestingly loss of Rac2 GTPase alone significantly prolongs survival of the leukemic mice (P≤0.001). Prolonged survival, as observed in Scl/p210 x Rac2-/-, is associated with significantly reduced proliferation of leukemic LK (3-fold, P<0.05) and LSK (6-fold P<0.005) cells, both in BM as well as in spleen, in vivo. Scl/p210 x Rac2-/- mice are also characterized by increased apoptosis (1.7-fold) and lower frequency of LSK cells (2-fold) compared to the Scl/p210 mice in vivo. However, deletion of Rac2 does not significantly reverse the adhesion and migration transformation phenotype of LSC/P. In summary, Rac2 deficiency induces a significant survival of CML mice in a HSC-initiated model of disease through decrease proliferation and survival but does not reverse the transformation phenotype affecting adhesion and migration. This murine model may represent an adequate in vivo system to dissect out the specific signaling pathways involved in p210-BCR-ABL-induced stem cell transformation. Disclosures: Cancelas: CERUS CO: Research Funding; CARIDIAN BCT: Research Funding; HEMERUS INC: Research Funding.

In Vitro and In Vivo Evidence That Umbilical Cord Blood (UCB)-Derived CD45-/SSEA-4+/OCT-4+/CD133+/CXCR4+/Lin- Very Small Embryonic/Epiblast Like Stem Cells (VSELs) Do Not Contain Clonogenic Hematopoietic Progenitors but Are Highly Enriched in More Primitive Stem Cells - Novel View On Hierarchy of UCB Stem Cell Compartment.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 35-35 ◽  
Author(s):  
Ewa K. Zuba-Surma ◽  
Izabela Klich ◽  
Marcin Wysoczynski ◽  
Nicholas J Greco ◽  
Mary J. Laughlin ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Cord Blood ◽  
Umbilical Cord ◽  
Umbilical Cord Blood ◽  
Hematopoietic Stem ◽  
Hematopoietic Activity

Abstract Abstract 35 Recently, we identified in umbilical cord blood (UCB) a population of very small embryonic/epiblast-like (VSEL) stem cells (Leukemia 2007;21:297–303) that are i) smaller than erythrocytes, ii) SSEA-4+/Oct-4+/CD133+/CXCR4+/Lin−/CD45−, iii) respond to SDF-1 gradient and iv) possess large nuclei containing primitive euchromatin. We have demonstrated in vitro that UCB-derived VSELs did not reveal hematopoietic activity freshly after isolation, but grow hematopoietic colonies following co-culture/activation over OP-9 cells. To investigate the hierarchy of UCB-derived, CD45 negative VSELs, we employed staining with Aldefluor - detecting aldehyde dehydrogenase (ALDH), the enzyme expressed in primitive hematopoietic cells. Subsequently, we sorted CD45−/CD133+/ALDHhigh and CD45−/CD133+/ALDHlow sub-fractions of VSELs from UCB samples and established that freshly sorted from UCB VSELs in contrast to sorted CD45+/ CD133+/ALDHhigh and CD45+/CD133+/ALDHlow hematopoietic stem cells (HSC) did not grow colonies in vitro. However, when CD45− VSELs were activated/expanded over OP-9 stroma cells, they exhibit hematopoietic potential and grew in routine methylcellulose cultures hematopoietic colonies composed of CD45+ cells. Interestingly, while CD45−/CD133+/ALDHhigh VSELs gave raise to hematopoietic colonies after the first replating, the formation of colonies by CD45−/CD133+/ALDHlow VSELs was somehow delayed, what suggest that they needed more time to acquire hematopoietic commitment. Thus our in vitro data indicate that both populations of CD45− cells may acquire hematopoietic potential; however hematopoietic specification is delayed for CD45−/CD133+/ALDHlow cells, suggesting their more primitive nature. In parallel, real time PCR analysis confirmed that while freshly isolated CD45−/CD133+/ALDHhigh VSELs express more hematopoietic transcripts (e.g., c-myb, 80.2±27.4 fold difference), CD45−/CD133+/ALDHlow exhibit higher levels of pluripotent stem cell markers (e.g., Oct-4, 119.5±15.5 fold difference as compared to total UCB mononuclear cells) (Figure 1 panel A). Next hematopoietic potential of UCB-derived VSELs was tested in vivo after transplantation into NOD/SCID mice (Figure 1 panel B and C). We noticed that both CD45−/CD133+/ALDHhigh and CD45−/CD133+/ALDHlow VSELs, give rise to human lympho-hematopoietic chimerism in lethally irradiated NOD/SCID mice as assayed 4–6 weeks after transplantation. The level of human hematopoietic CD45+ cells in murine peripheral blood (PB), bone marrow (BM) and spleen (SP) were comparable for both transplanted UCB-VSELs fractions - 7.1±2.9% (PB), 23.2±0.2% (SP) and 25.2±1.0% (BM). In conclusion, our data suggest that freshly isolated very small CD45 negative UCB-VSELs are depleted from clonogeneic progenitors, however they are highly enriched for primitive HSC. Based on our in vitro and in vivo data we postulate following hierarchy of hematopoietic stem cells in UCB (from most primitive to more differentiated) i) CD45−/CD133+/ALDHlow, ii) CD45−/CD133+/ALDHhigh , iii) CD45+/CD133+/ALDHlow and iv) CD45−/CD133+/ALDHhigh. We also postulate that as we have already shown for murine BM-derived VSELs, human UCB-derived CD45 negative VSELs correspond to a population of most primitive long term repopulating HSC (LT-HSC). Of note, we also found that currently employed, routine UCB processing strategies may lead up to ∼50% unwanted loss of these small cells that are endowed with such remarkable hematopoietic activity! Disclosures: No relevant conflicts of interest to declare.

scholarly journals Selective activation of STAT5 unveils its role in stem cell self-renewal in normal and leukemic hematopoiesis

2005 ◽  
Vol 202 (1) ◽  
pp. 169-179 ◽  
Author(s):  
Yuko Kato ◽  
Atsushi Iwama ◽  
Yuko Tadokoro ◽  
Kazuya Shimoda ◽  
Mayu Minoguchi ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Leukemic Stem Cells ◽  
Myeloproliferative Disease ◽  
Self Renewal ◽  
Hematopoietic Stem

Although the concept of a leukemic stem cell system has recently been well accepted, its nature and the underlying molecular mechanisms remain obscure. Constitutive activation of signal transducers and activators of transcription 3 (STAT3) and STAT5 is frequently detected in various hematopoietic tumors. To evaluate their role in normal and leukemic stem cells, we took advantage of constitutively active STAT mutants to activate STAT signaling selectively in hematopoietic stem cells (HSCs). Activation of STAT5 in CD34–c-Kit+Sca-1+ lineage marker– (CD34–KSL) HSCs led to a drastic expansion of multipotential progenitors and promoted HSC self-renewal ex vivo. In sharp contrast, STAT3 was demonstrated to be dispensable for the HSC maintenance in vivo, and its activation facilitated lineage commitment of HSCs in vitro. In a mouse model of myeloproliferative disease (MPD), sustained STAT5 activation in CD34–KSL HSCs but not in CD34+KSL multipotential progenitors induced fatal MPD, indicating that the capacity of STAT5 to promote self-renewal of hematopoietic stem cells is crucial to MPD development. Our findings collectively establish a specific role for STAT5 in self-renewal of normal as well as leukemic stem cells.

TGF-β signaling–deficient hematopoietic stem cells have normal self-renewal and regenerative ability in vivo despite increased proliferative capacity in vitro

Blood ◽  
2003 ◽  
Vol 102 (9) ◽  
pp. 3129-3135 ◽  
Author(s):  
Jonas Larsson ◽  
Ulrika Blank ◽  
Hildur Helgadottir ◽  
Jon Mar Björnsson ◽  
Mats Ehinger ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Negative Regulator ◽  
Type I ◽  
Hematopoietic Stem ◽  
Knock Out

Abstract Studies in vitro implicate transforming growth factor β (TGF-β) as a key regulator of hematopoiesis with potent inhibitory effects on progenitor and stem cell proliferation. In vivo studies have been hampered by early lethality of knock-out mice for TGF-β isoforms and the receptors. To directly assess the role of TGF-β signaling for hematopoiesis and hematopoietic stem cell (HSC) function in vivo, we generated a conditional knock-out model in which a disruption of the TGF-β type I receptor (TβRI) gene was induced in adult mice. HSCs from induced mice showed increased proliferation recruitment when cultured as single cells under low stimulatory conditions in vitro, consistent with an inhibitory role of TGF-β in HSC proliferation. However, induced TβRI null mice show normal in vivo hematopoiesis with normal numbers and differentiation ability of hematopoietic progenitor cells. Furthermore HSCs from TβRI null mice exhibit a normal cell cycle distribution and do not differ in their ability long term to repopulate primary and secondary recipient mice following bone marrow transplantation. These findings challenge the classical view that TGF-β is an essential negative regulator of hematopoietic stem cells under physiologic conditions in vivo.

scholarly journals Hematopoietic Stem Cells Fail to Regenerate In Vivo Following Inflammatory Stress

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1472-1472
Author(s):  
Ruzhica Bogeska ◽  
Paul Kaschutnig ◽  
Stella Paffenholz ◽  
Julia Maassen ◽  
Jan-Philipp Mallm ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Research Funding ◽  
Post Transplantation ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Fold Reduction

Abstract An often-cited defining property of hematopoietic stem cells (HSCs) is their extensive or unlimited in vivo self-renewal capacity. We have recently described a novel mouse disease model forFanconi anemia, in which serial challenge with pro-inflammatory agonists that mimic infection, such aspolyinosinic:polycytidylic acid (pI:C), results in HSC attrition followed by a highly penetrant severe aplastic anemia, closely recapitulating the disease in patients (Walter et al., 2015, Nature). In order to explore the broader implications of these findings in the context of HSC self-renewal, we conducted apI:Cdose escalation regimen using standard C57BL6 mice. A single injection withpI:Cprovoked transient peripheral blood (PB)cytopenias, with the recovery of mature blood cell numbers correlating with HSCs being forced into active cell cycle. Injection with 1-3 rounds ofpI:C(1-3 x 8 injections) led to no discernable sustained impact on blood production as, at 5 weeks post-treatment, PB frequencies were in the normal range, as were the absolute numbers of HSCs and all progenitor compartments in the bone marrow (BM), as determined by flowcytometry. However, in vitro analysis of the proliferation and differentiation potential of 411 individual sorted long-term (LT)-HSCs 5 weeks after 3 rounds of pI:C challenge, revealed a decrease in the frequency of LT-HSCs able to generate progeny in vitro (1.6-fold reduction, p<0.05), and a 2-fold reduction in the total number of progeny produced per HSC, which was even more pronounced inmultilineage potential clones (2.6-fold decrease, p<0.0001) compared touni- or bi-lineage clones. In line with this data, competitive repopulation assays demonstrated a progressive depletion of functional HSC numbers with increasing rounds ofpI:C treatment, with a 1.8, 3.4 and 15.3-fold decrease in donorchimerism across all lineages at 6 months post-transplantation (p<0.01) following 1, 2 or 3 rounds ofpI:C treatment, respectively. Notably, robust engraftment (up to 65% donorchimerism, 6 months post-transplantation, p<0.01) was achieved when mice exposed to 3 rounds ofpI:C treatment were used as a recipient for non-treated BM cells in the absence of any irradiation conditioning, while engraftment was always <1% when non-treated controls were used as recipients. This excludes the possibility that the observed progressive depletion of functional HSCs was the result of artifacts associated with a compromised niche or the non-physiologic stress imposed on donor cells during transplantation. In order to test the kinetics of HSC recovery following HSC challenge, BM was harvested from mice at either 5, 10 or 20 weeks after treatment with 3 rounds of pI:C, and both competitive and limiting dilution transplantation assays (Table 1) were used to quantify HSC frequencies. Surprisingly, both assays demonstrated that HSCs failed to regenerate at all following pI:Cchallenge, directly contradicting the canonical view that HSCs possess extensive self-renewal capacity in vivo. The physiologic relevance of this observation was illustrated when we measured the hematologic parameters of aged mice that had been exposed to chronicpI:C treatment in early to mid-life. Although these mice had normal PB counts at 4 weeks post-treatment, at 2 years of age, peripheral bloodcytopenias and bone marrow aplasia became evident (Table 2), recapitulating clinically relevant features of non-malignant aged human hematopoiesis that are never seen in standard laboratory mice. Together, these data suggest that functional HSCs can be progressively and irreversibly depleted in response to environmental agonists, such as infection and inflammation, which force HSCs to reconstitute mature blood cells consumed by such stimuli. This model has clear implications relating to the role of adult stem cells in tissue maintenance and regeneration during ageing, and how stress agonists that are absent in most laboratory animal models, but would be ubiquitous in the wild, are likely key mediators of age-associated disease pathologies. Disclosures Frenette: PHD Biosciences: Research Funding; Pfizer: Consultancy; GSK: Research Funding.

Strategies to Protect Hematopoietic Stem Cells from Culture-Induced Stress Conditions

2020 ◽  
Vol 15 ◽  
Author(s):  
Fatima Aerts-Kaya
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Ex Vivo ◽  
Stress Conditions ◽  
Stress Factors ◽  
Hematopoietic Stem ◽  
Induced Stress

: In contrast to their almost unlimited potential for expansion in vivo and despite years of dedicated research and optimization of expansion protocols, the expansion of Hematopoietic Stem Cells (HSCs) in vitro remains remarkably limited. Increased understanding of the mechanisms that are involved in maintenance, expansion and differentiation of HSCs will enable the development of better protocols for expansion of HSCs. This will allow procurement of HSCs with long-term engraftment potential and a better understanding of the effects of the external influences in and on the hematopoietic niche that may affect HSC function. During collection and culture of HSCs, the cells are exposed to suboptimal conditions that may induce different levels of stress and ultimately affect their self-renewal, differentiation and long-term engraftment potential. Some of these stress factors include normoxia, oxidative stress, extra-physiologic oxygen shock/stress (EPHOSS), endoplasmic reticulum (ER) stress, replicative stress, and stress related to DNA damage. Coping with these stress factors may help reduce the negative effects of cell culture on HSC potential, provide a better understanding of the true impact of certain treatments in the absence of confounding stress factors. This may facilitate the development of better ex vivo expansion protocols of HSCs with long-term engraftment potential without induction of stem cell exhaustion by cellular senescence or loss of cell viability. This review summarizes some of available strategies that may be used to protect HSCs from culture-induced stress conditions.

Endothelial stroma programs hematopoietic stem cells to differentiate into regulatory dendritic cells through IL-10

Blood ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 1189-1197 ◽  
Author(s):  
Hua Tang ◽  
Zhenhong Guo ◽  
Minghui Zhang ◽  
Jianli Wang ◽  
Guoyou Chen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Regulatory Function ◽  
Hematopoietic Stem ◽  
Regulatory Dendritic Cells

Abstract Regulatory dendritic cells (DCs) have been reported recently, but their origin is poorly understood. Our previous study demonstrated that splenic stroma can drive mature DCs to proliferate and differentiate into regulatory DCs, and their natural counterpart with similar regulatory function in normal spleens has been identified. Considering that the spleen microenvironment supports hematopoiesis and that hematopoietic stem cells (HSCs) are found in spleens of adult mice, we wondered whether splenic microenvironment could differentiate HSCs into regulatory DCs. In this report, we demonstrate that endothelial splenic stroma induce HSCs to differentiate into a distinct regulatory DC subset with high expression of CD11b but low expression of Ia. CD11bhiIalo DCs secreting high levels of TGF-β, IL-10, and NO can suppress T-cell proliferation both in vitro and in vivo. Furthermore, CD11bhiIalo DCs have the ability to potently suppress allo-DTH in vivo, indicating their preventive or therapeutic perspectives for some immunologic disorders. The inhibitory function of CD11bhiIalo DCs is mediated through NO but not through induction of regulatory T (Treg) cells or T-cell anergy. IL-10, which is secreted by endothelial splenic stroma, plays a critical role in the differentiation of the regulatory CD11bhiIalo DCs from HSCs. These results suggest that splenic microenvironment may physiologically induce regulatory DC differentiation in situ.

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

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 951 ◽  
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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