scholarly journals Growth-Supporting Activities of Fibronectin on Hematopoietic Stem/Progenitor Cells In Vitro and In Vivo: Structural Requirement for Fibronectin Activities of CS1 and Cell-Binding Domains

Blood ◽  
1998 ◽  
Vol 91 (9) ◽  
pp. 3263-3272 ◽  
Author(s):  
Takafumi Yokota ◽  
Kenji Oritani ◽  
Hideki Mitsui ◽  
Keisuke Aoyama ◽  
Jun Ishikawa ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Progenitor Cells ◽  
Colony Formation ◽  
Cell Binding ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Colony Forming Units

Abstract Fibronectin (FN) is supposed to play important roles in various aspects of hematopoiesis through binding to very late antigen 4 (VLA4) and VLA5. However, effects of FN on hematopoietic stem cells are largely unknown. In an effort to determine if FN had a growth-supporting activity on hematopoietic stem cells, human CD34+/VLA4bright/VLA5dullhematopoietic stem cells and a murine stem cell factor (SCF)-dependent multipotent cell line, EML-C1, were treated with or without FN in a serum and growth-factor–deprived medium, and then subjected to clonogenic assay in the presence of hematopoietic growth factors. The pretreatment of the CD34+ cells with FN gave rise to significantly increased numbers of granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst colony-forming units, and mixed erythroid-myeloid colony-forming units. In addition, the numbers of blast colony-forming units and CFU-GM that developed after culture of EML-C1 cells with SCF and the combination of SCF and interleukin-3, respectively, were augmented by the pretreatment with FN. The augmented colony formation by FN was completely abrogated by the addition of CS1 fragment, but not of GRGDSP peptide, suggesting an essential role of FN-VLA4 interaction in the FN effects. Furthermore, the effects of various FN fragments consisting of RGDS-containing cell-binding domain (CBD), heparin-binding domain (HBD), and/or CS1 portion were tested on clonogenic growth of CD34+ cells. Increased colony formation was induced by CBD-CS1 and CBD-HBD-CS1 fragments, but not with other fragments lacking CBD or CS1 domains, suggesting that both CS1 and CBD of FN were required for the augmentation of clonogenic growth of hematopoietic stem/progenitor cells in vitro. In addition to the in vitro effects, the in vivo administration of CBD-CS1 fragment into mice was found to increase the numbers of hematopoietic progenitor cells in bone marrow and spleen in a dose-dependent manner. Thus, FN may function on hematopoietic stem/progenitor cells as a growth-supporting factor in vitro and in vivo.

scholarly journals Growth-Supporting Activities of Fibronectin on Hematopoietic Stem/Progenitor Cells In Vitro and In Vivo: Structural Requirement for Fibronectin Activities of CS1 and Cell-Binding Domains

Blood ◽  
1998 ◽  
Vol 91 (9) ◽  
pp. 3263-3272 ◽  
Author(s):  
Takafumi Yokota ◽  
Kenji Oritani ◽  
Hideki Mitsui ◽  
Keisuke Aoyama ◽  
Jun Ishikawa ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Progenitor Cells ◽  
Colony Formation ◽  
Cell Binding ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Colony Forming Units

Fibronectin (FN) is supposed to play important roles in various aspects of hematopoiesis through binding to very late antigen 4 (VLA4) and VLA5. However, effects of FN on hematopoietic stem cells are largely unknown. In an effort to determine if FN had a growth-supporting activity on hematopoietic stem cells, human CD34+/VLA4bright/VLA5dullhematopoietic stem cells and a murine stem cell factor (SCF)-dependent multipotent cell line, EML-C1, were treated with or without FN in a serum and growth-factor–deprived medium, and then subjected to clonogenic assay in the presence of hematopoietic growth factors. The pretreatment of the CD34+ cells with FN gave rise to significantly increased numbers of granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst colony-forming units, and mixed erythroid-myeloid colony-forming units. In addition, the numbers of blast colony-forming units and CFU-GM that developed after culture of EML-C1 cells with SCF and the combination of SCF and interleukin-3, respectively, were augmented by the pretreatment with FN. The augmented colony formation by FN was completely abrogated by the addition of CS1 fragment, but not of GRGDSP peptide, suggesting an essential role of FN-VLA4 interaction in the FN effects. Furthermore, the effects of various FN fragments consisting of RGDS-containing cell-binding domain (CBD), heparin-binding domain (HBD), and/or CS1 portion were tested on clonogenic growth of CD34+ cells. Increased colony formation was induced by CBD-CS1 and CBD-HBD-CS1 fragments, but not with other fragments lacking CBD or CS1 domains, suggesting that both CS1 and CBD of FN were required for the augmentation of clonogenic growth of hematopoietic stem/progenitor cells in vitro. In addition to the in vitro effects, the in vivo administration of CBD-CS1 fragment into mice was found to increase the numbers of hematopoietic progenitor cells in bone marrow and spleen in a dose-dependent manner. Thus, FN may function on hematopoietic stem/progenitor cells as a growth-supporting factor in vitro and in vivo.

Hematopoietic stem cells with controllable tEpoR transgenes have a competitive advantage in bone marrow transplantation

Blood ◽  
2000 ◽  
Vol 95 (12) ◽  
pp. 3710-3715 ◽  
Author(s):  
Suzanne Kirby ◽  
William Walton ◽  
Oliver Smithies
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Erythropoietin Receptor ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Myeloid Progenitor ◽  
Colony Forming Units

Abstract In a previous study, it was found that a truncated erythropoietin receptor transgene (tEpoR tg) enables multilineage hematopoietic progenitor amplification after treatment with erythropoietin (epo) in vitro and in vivo. This study used competitive bone marrow (BM) repopulation to show that tEpoR tg facilitates transplantation by hematopoietic stem cells (HSC). Individual multilineage colonies, committed myeloid progenitor colonies, and lymphoid colonies (pre-B colony-forming units) were grown from the marrow of animals 6 months after they received a 50/50 mixture of transgene and wild-type BM cells. In epo-treated recipients, the transgene-bearing cells significantly outcompeted the wild-type cells (84%-100% versus 16%-0%, respectively). In recipients treated with phosphate-buffered saline, the repopulation was minimally different from the donor mixture (49%-64% transgene versus 51%-36% wild-type). The epo-induced repopulation advantage is maintained in secondary transplants. In addition, neither accelerated HSC depletion nor uncontrollable proliferation occurred during epo-stimulated serial transplants of transgene-containing BM. Thus, the tEpoR tg functions in a benign fashion in HSC and allows for a significant and controllable repopulation advantage in vivo without excessive HSC depletion relative to wild-type BM.

The Pan-Bcl-2 Family Inhibitor 97C1 Targets Blast Crisis Chronic Myeloid Leukemia Stem Cells but Spares Normal Cord Blood Progenitor Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 516-516 ◽  
Author(s):  
Daniel Goff ◽  
Alice Shih ◽  
Angela Court Recart ◽  
Larisa Balaian ◽  
Ryan Chuang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cord Blood ◽  
Progenitor Cells ◽  
Blast Crisis ◽  
Chemotherapy Resistance ◽  
Chronic Phase ◽  
Hematopoietic Stem ◽  
Cd34 Cells

Abstract Abstract 516 Introduction: Several studies have demonstrated the role of leukemia stem cells (LSC) in the development and maintenance of human chronic myeloid leukemia (CML). These cells, which first develop in chronic phase CML (CP CML) with acquisition of the BCR-ABL fusion protein, are often quiescent and can be highly resistant to apoptosis induced by drugs and radiotherapy that target rapidly dividing cells. Data has also shown that CML LSC become increasingly resistant to BCR-ABL inhibition with progression to blast crisis CML (BC CML). Bcl-2 family proteins are key regulators of apoptosis and have been shown by numerous studies to regulate cancer resistance to chemotherapy. This family of proteins has also been implicated in the development of BC CML, however most studies have focused on CML cell lines and their expression of Bcl-2 family proteins in vitro. Thus, there is relatively little data on expression of Bcl-2 family proteins in primary CML LSC and on the role of these proteins in regulating chemotherapy resistance in CML LSC in vivo. As Bcl-2 family proteins are known regulators of chemotherapy resistance we hypothesized that human BC CML LSC may overexpress these proteins compared to normal hematopoietic stem cells. We analyzed Bcl-2 family mRNA and protein expression in CP CML and BC CML LSC and compared this expression to normal cord blood stem and progenitor cells. We also analyzed whether these cells were sensitive to chemotherapy treatment in vitro. Finally, we tested whether a high potency pan-Bcl-2 inhibitor, 97C1, could effectively kill CML LSC in vitro and in vivo. Methods: Bcl-2 and Mcl-1 protein expression was measured in primary CP CML, BC CML, and normal cord blood cells using intracellular FACS. We also measured Bcl-2, Mcl-1, Bcl-X, and Bfl-1 mRNA expression in FACS sorted CD34+CD38+lin− cells (LSC) from these samples. For all drug studies we used either serially transplanted CD34+ cells derived from primary BC CML patient samples or primary CD34+ normal cord blood cells. In vitro drug responses were tested by culturing CD34+ cells either alone or in co-culture with a mouse bone marrow stromal cell line (SL/M2). Effects on colony formation and replating were also tested by culturing sorted CD34+CD38+lin− cells in methylcellulose in the presence and absence of drug. For in vivo testing of 97C1 we transplanted neonatal RAG2-/-yc-/- mice with CD34+ cells from 3 different BC CML and cord blood samples. Transplanted mice were screened for peripheral blood engraftment at 6–8 weeks post-transplant and engrafted mice were then treated for 2 weeks with 97C1 by IP injection. Following the treatment period the mice were sacrificed and hemotapoietic organs were analyzed for human engraftment by FACS. Results: BC CML progenitors expressed higher levels of Bcl-2 and Mcl-1 protein compared to normal cord blood and chronic phase CML cells. mRNA expression of Mcl-1, Bcl-X, and Bfl-1 was also increased in BC CML progenitors compared to CP CML progenitors. While BC CML LSC cultured in vitro were resistant to etoposide and dasatinib-induced cell death, 97C1 treatment led to a dose-dependent increase in cell death along with a dose-dependent decrease in the frequency of CD34+CD38+lin− cells compared to vehicle treated controls. While cord blood progenitor cells were also sensitive to 97C1 treatment they had an IC50 around 10 times higher than that for the BC CML cells (100nM versus 10nM). Importantly, 97C1 treatment did not inhibit cord blood colony formation or colony replating in vitro. Mice transplanted with BC CML LSC developed CML in 6–8 weeks post-transplant with diffuse myeloid sarcomas and engraftment of human CD34+CD38+lin− cells in the peripheral blood, liver, spleen, and bone marrow. In vivo treatment with 97C1 led to a significant reduction in both total human engraftment and engraftment of CD34+CD38+lin− cells in all hematopoietic organs analyzed. Conclusion: Our results demonstrate that BC CML LSC are resistant to conventional chemotherapy but are sensitive to 97C1 in vitro and in vivo. Broad-spectrum inhibition of Bcl-2 family proteins may help to eliminate CML LSC while sparing normal hematopoietic stem and progenitor cells. Disclosures: Jamieson: CoronadoBiosciences: Research Funding; CIRM: Research Funding.

Interleukin-27 directly induces differentiation in hematopoietic stem cells

Blood ◽  
2008 ◽  
Vol 111 (4) ◽  
pp. 1903-1912 ◽  
Author(s):  
Jun Seita ◽  
Masayuki Asakawa ◽  
Jun Ooehara ◽  
Shin-ichiro Takayanagi ◽  
Yohei Morita ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Extramedullary Hematopoiesis ◽  
Multiple Roles ◽  
Hematopoietic Stem ◽  
Human Cd34 ◽  
Cd34 Cells ◽  
Common Signal

Interleukin (IL)-27, one of the most recently discovered IL-6 family cytokines, activates both the signal transducer and activator of transcription (STAT)1 and STAT3, and plays multiple roles in pro- and anti-inflammatory immune responses. IL-27 acts on various types of cells including T, B, and macrophage through the common signal-transducing receptor gp130 and its specific receptor WSX-1, but the effect of IL-27 on hematopoietic stem cells (HSCs) remains unknown. Here, we show that IL-27 together with stem cell factor (SCF) directly acts on HSCs and supports their early differentiation in vitro and in vivo. CD34−/lowc-Kit+Sca-1+lineage marker− (CD34−KSL) cells, a population highly enriched in mouse HSCs, were found to express both IL-27 receptor subunits. In vitro cultures of CD34−KSL cells with IL-27 and SCF resulted in an expansion of progenitors including short-term repopulating cells, while some of their long-term repopulating activity also was maintained. To examine its in vivo effect, transgenic mice expressing IL-27 were generated. These mice exhibited enhanced myelopoiesis and impaired B lymphopoiesis in the bone marrow with extramedullary hematopoiesis in the spleen. Moreover, IL-27 similarly acted on human CD34+ cells. These results suggest that IL-27 is one of the limited cytokines that play a role in HSC regulation.

Extracellular nucleotides are potent stimulators of human hematopoietic stem cells in vitro and in vivo

Blood ◽  
2004 ◽  
Vol 104 (6) ◽  
pp. 1662-1670 ◽  
Author(s):  
Roberto M. Lemoli ◽  
Davide Ferrari ◽  
Miriam Fogli ◽  
Lara Rossi ◽  
Cinzia Pizzirani ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Severe Combined Immunodeficiency ◽  
Extracellular Nucleotides ◽  
Hematopoietic Stem ◽  
Nonobese Diabetic ◽  
Cd34 Cells ◽  
Wide Range

Abstract Although extracellular nucleotides support a wide range of biologic responses of mature blood cells, little is known about their effect on blood cell progenitor cells. In this study, we assessed whether receptors for extracellular nucleotides (P2 receptors [P2Rs]) are expressed on human hematopoietic stem cells (HSCs), and whether activation by their natural ligands, adenosine triphosphate (ATP) and uridine triphosphate (UTP), induces HSC proliferation in vitro and in vivo. Our results demonstrated that CD34+ HSCs express functional P2XRs and P2YRs of several subtypes. Furthermore, stimulation of CD34+ cells with extracellular nucleotides caused a fast release of Ca2+ from intracellular stores and an increase in ion fluxes across the plasma membrane. Functionally, ATP and, to a higher extent, UTP acted as potent early acting growth factors for HSCs, in vitro, because they strongly enhanced the stimulatory activity of several cytokines on clonogenic CD34+ and lineage-negative CD34- progenitors and expanded more primitive CD34+-derived long-term culture-initiating cells. Furthermore, xenogenic transplantation studies showed that short-term preincubation with UTP significantly expanded the number of marrow-repopulating HSCs in nonobese diabetic/severe combined immunodeficiency mice. Our data suggest that extracellular nucleotides may provide a novel and powerful tool to modulate HSC functions. (Blood. 2004;104:1662-1670)

scholarly journals Etoposide-Initiated MLL Rearrangements Detected at High Frequency in Human Primitive Hematopoietic Stem Cells with In Vitro and In Vivo Long-Term Repopulating Potential.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 98-98 ◽  
Author(s):  
Jolanta Libura ◽  
Marueen Ward ◽  
Grzegorz Przybylski ◽  
Christine Richardson
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Scid Mouse ◽  
P Value ◽  
Hematopoietic Stem ◽  
Cd34 Cells

Abstract Rearrangements involving the MLL gene locus at chromosome band 11q23 are observed in therapy-related acute myeloid leukemia and myelodysplastic syndromes following treatment with topoisomerase II (topoII) inhibitors including etoposide. We have shown that one hour of etoposide exposure (20–50 μM) stimulates stable MLL rearrangements in primary human CD34+ cells and that the spectrum of repair products within MLL gene is broader than so far described (Libura et al, Blood, 2005). Clinical data suggest that MLL-associated malignant leukemias originate within primitive hematopietic stem cells capable of differentiation into all hematopoietic lineages and repopulation of myelo-ablated hosts. These cells can be analyzed using the in vivo NOD-SCID mouse model as well as the in vitro long-term culture initiating cell (LTC-IC) assay. We adopted our in vitro CD34+ cell culture model to investigate the impact of etoposide exposure on the most primitive hematopoietic stem cells using parallel assays for LTC-IC and NOD-SCID Repopulating Cells (SRC). Following etoposide exposure (20–50 μM for 1 hour), and 48–96 hours recovery in vitro, untreated control and etoposide-treated CD34+ cells were either seeded in LTC-IC with a supportive feeder layer (Stem Cell Technologies, Inc.), or injected into NOD-SCID mice (0.1–1.5x106 cells per mouse). After 12 weeks, both LTC-IC cultures and bone marrow cells from NOD-SCID mice were seeded in methylcellulose media supplemented with growth factors that promote only human cell colony formation. An increased number of colonies in etoposide-treated samples was obtained from LTC-IC cultures in 3 out of 5 experiments (p value<0.05). This increase in colony number was more dramatic in etoposide-treated samples from NOD-SCID bone marrow (57 versus 0, 8 versus 0). These data demonstrate that etoposide exposure can significantly alter the potential of early hematopoietic stem cells to survive and proliferate both in vitro and in vivo. Injection of as few as 3x105 CD34+ cells into a NOD-SCID mouse was sufficient to obtain methylcellulose colonies, suggesting that this method can be used for the analysis of cells obtained from a single patient sample. Mutation analysis of human methylcellulose colonies derived from both LTC-IC and NOD-SCID was performed by inverse PCR and ligation-mediated PCR followed by sequencing. This analysis revealed that rearrangements originating within the MLL breakpoint cluster region (bcr) were present in 12 out of 29 colonies from etoposide-treated samples versus 5 out of 39 colonies from control samples (p value <0.01), demonstrating that etoposide exposure promotes stable rearrangements within a hematopoietic stem cell compartment with significant proliferative potential. Eight of the 17 events were sequenced, and showed 6 MLL tandem duplications within intron 8, one complex translocation between MLL and chr.15 and tandem duplication, and one event with foreign sequence of unknown origin. Our data are the first report of the spectrum and frequency of MLL rearrangements following topo II inhibitor exposure in a cell population thought to be the target for recombinogenic events leading to therapy-related leukemias.

Enhanced Engraftment and Maintenance of CXCR4 Expressing CD34+ Cells In Vivo Is Related to Microenvironmental Interactions, Rather Than Direct Receptor Signaling to Hematopoietic Stem Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2306-2306 ◽  
Author(s):  
Naomi J. Anderson ◽  
Ravi Bhatia
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Progenitor Cell ◽  
Hematopoietic Cell ◽  
Hematopoietic Stem ◽  
Cell Engraftment ◽  
Cd34 Cells

Abstract Interaction of the chemokine receptor CXCR4 with its ligand SDF-1α (SDF) has been reported to play an important role in engraftment of hematopoietic stem cells (HSC) in the bone marrow (BM). However a critical requirement for CXCR4 in HSC engraftment is still controversial. It also remains unclear whether the effects that CXCR4 has on hematopoietic cell engraftment are related to enhanced homing of HSC to the bone marrow cavity, increased retention in marrow microenvironment or direct and indirect effects of CXCR4 stimulation on stem and progenitor cell proliferation, self-renewal and survival. To address these questions we have overexpressed CXCR4 in human cord blood CD34+ cells by transduction with an MSCV retroviral vector containing CXCR4 and eGFP (MIG-CXCR4). CXCR4 overexpressing cells were compared with control cells transduced with vectors expressing eGFP alone (MIG). CD34+eGFP+ cells were selected after transduction by flow cytometry sorting. We confirmed that CD34+ cells transduced with the MIG-CXCR4 vector demonstrated increased CXCR4 expression compared with MIG vector transduced controls (mean channel fluorescence for CXCR4 was 340±77.8 for MIG-CXCR4 transduced CD34+ cells compared with 142±37.1 for MIG transduced cells, n=8). MIG-CXCR4 transduced CD34+ cells demonstrated significantly enhanced chemotaxis to SDF in transwell migration assays (36±2% migration for MIG-CXCR4 vs. 20±4% migration for MIG transduced CD34+ cells to 100nM SDF-1, n=4, p=0.05). CD34+ cells transduced with MIG-CXCR4 demonstrated a 1.52±0.4 fold increase in expansion of total cell number compared with controls after 1 week of in vitro culture with growth factors (GF) [SCF (50ng/ml), TPO (100ng/ml), FL (100ng/ml), SDF (60ng/ml), n=3]. However, enhanced cellular expansion was not sustained on further GF culture. To evaluate the effect of CXCR4 overexpression on in vivo engraftment, CD34+ cells transduced with MIG-CXCR4 and MIG vectors were injected intravenously into sublethally irradiated NOD/SCID mice and human hematopoietic cell engraftment was evaluated after 6–8 weeks. MIG-CXCR4 transduced cells demonstrated significantly higher levels of engraftment with human CD45+ cells compared with MIG transduced cells (8±4.8% vs. 0.22±0.07% CD45+ cells in bone marrow, 1.3±0.9% vs. 0.2±0.09% CD45+ cells in spleen, and 1.8±1.0% vs. 0.3±0.25% CD45+ cells in peripheral blood for MIG-CXCR4 vs. MIG transduced cells, respectively, n=5). In addition, markedly higher levels of CD34+ cell engraftment was observed in the bone marrow of animals receiving MIG-CXCR4 vs. MIG transduced cells (1.7±1.0% vs. 0.06±0.03% CD34+ cells respectively, n=5). Consistent with this, the human CFC frequency in bone marrow of mice receiving MIG-CXCR4 transduced CD34+ cells was increased compared to mice receiving MIG transduced cells (31±0.5 CFC/100,000 cells vs. 5±3.2 CFC/100,000 cells, n=2,3, respectively). In conclusion, our results indicate that ectopic expression of CXCR4 in CD34+ cells results in enhanced engraftment of human hematopoietic cells and increased maintenance of hematopoietic stem and progenitor cells in the NOD/SCID mouse model. The effects of CXCR4 overexpression are considerably more prominent in vivo than in direct in vitro assays. It therefore appears that altered stem and progenitor cell homing and microenvironmental interaction, rather than direct signaling to HSC, may be responsible for enhanced CD34+ cell engraftment and maintenance following CXCR4 receptor overexpression.

Hematopoietic stem cells with controllable tEpoR transgenes have a competitive advantage in bone marrow transplantation

Blood ◽  
2000 ◽  
Vol 95 (12) ◽  
pp. 3710-3715 ◽  
Author(s):  
Suzanne Kirby ◽  
William Walton ◽  
Oliver Smithies
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Erythropoietin Receptor ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Myeloid Progenitor ◽  
Colony Forming Units

In a previous study, it was found that a truncated erythropoietin receptor transgene (tEpoR tg) enables multilineage hematopoietic progenitor amplification after treatment with erythropoietin (epo) in vitro and in vivo. This study used competitive bone marrow (BM) repopulation to show that tEpoR tg facilitates transplantation by hematopoietic stem cells (HSC). Individual multilineage colonies, committed myeloid progenitor colonies, and lymphoid colonies (pre-B colony-forming units) were grown from the marrow of animals 6 months after they received a 50/50 mixture of transgene and wild-type BM cells. In epo-treated recipients, the transgene-bearing cells significantly outcompeted the wild-type cells (84%-100% versus 16%-0%, respectively). In recipients treated with phosphate-buffered saline, the repopulation was minimally different from the donor mixture (49%-64% transgene versus 51%-36% wild-type). The epo-induced repopulation advantage is maintained in secondary transplants. In addition, neither accelerated HSC depletion nor uncontrollable proliferation occurred during epo-stimulated serial transplants of transgene-containing BM. Thus, the tEpoR tg functions in a benign fashion in HSC and allows for a significant and controllable repopulation advantage in vivo without excessive HSC depletion relative to wild-type BM.

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.

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