In vivo repopulating activity emerges at the onset of hematopoietic specification during embryonic stem cell differentiation.
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ABSTRACT:
SUBMITTER: Pearson S
PROVIDER: S-EPMC4375940 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The generation of hematopoietic stem cells (HSCs) during development is a complex process linked to morphogenic signals. Understanding this process is important for regenerative medicine applications that require in vitro production of HSC. In this study we investigated the effects of canonical Wnt/?-catenin signaling during early embryonic differentiation and hematopoietic specification using an embryonic stem cell system. Our data clearly demonstrates that following early differentiation induction, canonical Wnt signaling induces a strong mesodermal program whilst maintaining a degree of stemness potential. This involved a complex interplay between ?-catenin/TCF/LEF/Brachyury/Nanog. ?-catenin mediated up-regulation of TCF/LEF resulted in enhanced brachyury levels, which in-turn lead to Nanog up-regulation. During differentiation, active canonical Wnt signaling also up-regulated key transcription factors and cell specific markers essential for hematopoietic specification, in particular genes involved in establishing primitive erythropoiesis. This led to a significant increase in primitive erythroid colony formation. ?-catenin signaling also augmented early hematopoietic and multipotent progenitor (MPP) formation. Following culture in a MPP specific cytokine cocktail, activation of ?-catenin suppressed differentiation of the early hematopoietic progenitor population, with cells displaying a higher replating capacity and a propensity to form megakaryocytic erythroid progenitors. This bias towards erythroid lineage commitment was also observed when hematopoietic progenitors were directed to undergo myeloid colony formation. Overall this study underscores the importance of canonical Wnt/?-catenin signaling in mesodermal specification, primitive erythropoiesis and early hematopietic progenitor formation during hematopoietic induction.
| S-EPMC3850021 | biostudies-literature
Project description:Determining the molecular regulators/pathways responsible for the specification of human embryonic stem cells (hESCs) into hematopoietic precursors has far-reaching implications for potential cell therapies and disease modeling. Mouse models lacking SCL/TAL1 (stem cell leukemia/T-cell acute lymphocytic leukemia 1) do not survive beyond early embryogenesis because of complete absence of hematopoiesis, indicating that SCL is a master early hematopoietic regulator. SCL is commonly found rearranged in human leukemias. However, there is barely information on the role of SCL on human embryonic hematopoietic development. Differentiation and sorting assays show that endogenous SCL expression parallels hematopoietic specification of hESCs and that SCL is specifically expressed in hematoendothelial progenitors (CD45(-)CD31(+)CD34(+)) and, to a lesser extent, on CD45(+) hematopoietic cells. Enforced expression of SCL in hESCs accelerates the emergence of hematoendothelial progenitors and robustly promotes subsequent differentiation into primitive (CD34(+)CD45(+)) and total (CD45(+)) blood cells with higher clonogenic potential. Short-hairpin RNA-based silencing of endogenous SCL abrogates hematopoietic specification of hESCs, confirming the early hematopoiesis-promoting effect of SCL. Unfortunately, SCL expression on its own is not sufficient to confer in vivo engraftment to hESC-derived hematopoietic cells, suggesting that additional yet undefined master regulators are required to orchestrate the stepwise hematopoietic developmental process leading to the generation of definitive in vivo functional hematopoiesis from hESCs.
| S-EPMC3392972 | biostudies-literature
Project description:Although Hematopoietic Stem Cell Transplantation (HSCT) routinely treats hematologic disease, many patients experience adverse outcomes. Understanding the molecular regulation of HSC engraftment is paramount to improving HSCT regimens. Here, we executed a large-scale transplant-based functional screen for novel regulators of HSC repopulation.. Of >50 gene candidates tested, 18 were required for in vivo hematopoietic repopulation and two were detrimental to repopulation, as their loss enhanced this activity. Each Hit was validated in a second screen. Eleven Hits have never before been implicated in HSC biology. We further show that one novel Hit, Foxa3, is required for optimal engraftment as Foxa3-/- bone marrow is defective in both primary and secondary hematopoietic reconstitution. We also present evidence that Foxa3 is a novel pioneer factor in HSC. Each gene identified in our screen is a window into the cellular mechanisms that control hematopoietic reconstitution. Thus, this work represents a resource to the community to better understand these processes 3 FOXA3 KO samples are compared to 3 wt samples
2015-07-01 | E-GEOD-63830 | biostudies-arrayexpress
Project description:Although Hematopoietic Stem Cell Transplantation (HSCT) routinely treats hematologic disease, many patients experience adverse outcomes. Understanding the molecular regulation of HSC engraftment is paramount to improving HSCT regimens. Here, we executed a large-scale transplant-based functional screen for novel regulators of HSC repopulation.. Of >50 gene candidates tested, 18 were required for in vivo hematopoietic repopulation and two were detrimental to repopulation, as their loss enhanced this activity. Each Hit was validated in a second screen. Eleven Hits have never before been implicated in HSC biology. We further show that one novel Hit, Foxa3, is required for optimal engraftment as Foxa3-/- bone marrow is defective in both primary and secondary hematopoietic reconstitution. We also present evidence that Foxa3 is a novel pioneer factor in HSC. Each gene identified in our screen is a window into the cellular mechanisms that control hematopoietic reconstitution. Thus, this work represents a resource to the community to better understand these processes
2015-07-01 | GSE63830 | GEO
Project description:Human hematopoietic stem cells are defined by their ability to repopulate multiple hematopoietic lineages in the bone marrow of transplanted recipients and therefore are functionally distinct from hematopoietic progenitors detected in vitro. Although factors capable of regulating progenitors are well established, in vivo regulators of hematopoietic repopulating function are unknown. By using a member of the vertebrate Wnt family, Wnt-5A, the proliferation and differentiation of progenitors cocultured on stromal cells transduced with Wnt-5A or treated with Wnt-5A conditioned medium (CM) was unaffected. However, i.p. injection of Wnt-5A CM into mice engrafted with human repopulating cells increased multilineage reconstitution by >3-fold compared with controls. Furthermore, in vivo treatment of human repopulating cells with Wnt-5A CM produced a greater proportion of phenotypically primitive hematopoietic progeny that could be isolated and shown to possess enhanced progenitor function independent of continued Wnt-5A treatment. Our study demonstrates that Wnt-5A augments primitive hematopoietic development in vivo and represents an in vivo regulator of hematopoietic stem cell function in the human. Based on these findings, we suggest a potential role for activation of Wnt signaling in managing patients exhibiting poor hematopoietic recovery shortly after stem cell transplantation.
| S-EPMC152308 | biostudies-literature
Project description:Hematopoietic stem cell (HSC) function is regulated by activation of receptor tyrosine kinases (RTKs). Receptor protein tyrosine phosphatases (PTPs) counterbalance RTK signaling; however, the functions of receptor PTPs in HSCs remain incompletely understood. We found that a receptor PTP, PTP?, was substantially overexpressed in mouse and human HSCs compared with more mature hematopoietic cells. Competitive transplantation of bone marrow cells from PTP?-deficient mice revealed that the loss of PTP? substantially increased long-term HSC-repopulating capacity compared with BM cells from control mice. While HSCs from PTP?-deficient mice had no apparent alterations in cell-cycle status, apoptosis, or homing capacity, these HSCs exhibited increased levels of activated RAC1, a RhoGTPase that regulates HSC engraftment capacity. shRNA-mediated silencing of PTP? also increased activated RAC1 levels in wild-type HSCs. Functionally, PTP?-deficient BM cells displayed increased cobblestone area-forming cell (CAFC) capacity and augmented transendothelial migration capacity, which was abrogated by RAC inhibition. Specific selection of human cord blood CD34?CD38?CD45RA?lin? PTP?? cells substantially increased the repopulating capacity of human HSCs compared with CD34?CD38?CD45RA?lin? cells and CD34?CD38?CD45RA?lin?PTP?? cells. Our results demonstrate that PTP? regulates HSC functional capacity via RAC1 inhibition and suggest that selecting for PTP?-negative human HSCs may be an effective strategy for enriching human HSCs for transplantation.
| S-EPMC4382260 | biostudies-literature
Project description:BackgroundKupffer cells (KCs) originate from yolk-sac progenitors before birth. Throughout adulthood, they self-maintain independently from the input of circulating monocytes (MOs) at a steady state and are replenished within 2 weeks after having been depleted, but the origin of repopulating KCs in adults remains unclear. The current paradigm dictates that repopulating KCs originate from preexisting KCs or monocytes, but there remains a lack of fate-mapping evidence.MethodsWe first traced the fate of preexisting KCs and that of monocytic cells with tissue-resident macrophage-specific and monocytic cell-specific fate-mapping mouse models, respectively. Secondly, we performed genetic lineage tracing to determine the type of progenitor cells involved in response to KC-depletion in mice. Finally, we traced the fate of hematopoietic stem cells (HSCs) in an HSC-specific fate-mapping mouse model, in the context of chronic liver inflammation induced by repeated carbon tetrachloride treatment.ResultsBy using fate-mapping mouse models, we found no evidence that repopulating KCs originate from preexisting KCs or MOs and found that in response to KC-depletion, HSCs proliferated in the bone marrow, mobilized into the blood, adoptively transferred into the liver and differentiated into KCs. Then, in the chronic liver inflammation context, we confirmed that repopulating KCs originated directly from HSCs.ConclusionTaken together, these findings provided in vivo fate-mapping evidence that repopulating KCs originate directly from HSCs, which presents a completely novel understanding of the cellular origin of repopulating KCs and shedding light on the divergent roles of KCs in liver homeostasis and diseases.
| S-EPMC10712046 | biostudies-literature
Project description:The bromodomain and extra terminal (BET) protein family member BRD4 is a transcriptional regulator, critical for cell cycle progression and cellular viability. Here, we show that BRD4 plays an important role in embryonic stem cell (ESC) regulation. During differentiation of ESCs, BRD4 expression is upregulated and its gene promoter becomes demethylated. Disruption of BRD4 expression in ESCs did not induce spontaneous differentiation but severely diminished hematoendothelial potential. Although BRD4 regulates c-Myc expression, our data show that the role of BRD4 in hematopoietic commitment is not exclusively mediated by c-Myc. Our results indicate that BRD4 is epigenetically regulated during hematopoietic differentiation ESCs in the context of a still unknown signaling pathway.
| S-EPMC4121367 | biostudies-literature
Project description:Growth factors are important regulators during organ development. For many vertebrates (but not humans) it is known how they contribute to the formation and expansion of PDX1-positive cells during pancreas organogenesis. Here, the effects of the fibroblast growth factors FGF2, FGF7, FGF10, and epidermal growth factor (EGF) on pancreas development in humans were assessed by using human pluripotent stem cells (hPSCs). During this, FGF2 was identified as a potent anti-pancreatic factor whereas FGF7, FGF10, and EGF increased the cell mass while retaining PDX1-positivity. FGF2 increased the expression of the anti-pancreatic factor sonic hedgehog (SHH) while suppressing PDX1 in a dose-dependent manner. Differentiating cells secreted SHH to the medium and we interrogated the cells' secretome during differentiation to globally examine the composition of secreted signaling factors. Members of the TGF-beta-, Wnt-, and FGF-pathways were detected. FGF17 showed a suppressive anti-pancreatic effect comparable to FGF2. By inhibition of specific branches of FGF-receptor signaling, we allocated the SHH-induction by FGF2 to MEK/ERK-signaling and the anti-pancreatic effect of FGF2 to the receptor variant FGFR1c or 3c. Altogether, we report findings on the paracrine activity of differentiating hPSCs during generation of pancreatic progenitors. These observations suggest a different role for FGF2 in humans compared to animal models of pancreas organogenesis.
| S-EPMC7565644 | biostudies-literature
Project description:Retroviral vector-mediated gene therapy has been successfully used to correct genetic diseases. However, a number of studies have shown a subsequent risk of cancer development or aberrant clonal growths due to vector insertion near or within proto-oncogenes. Recent advances in the sequencing technology enable high-throughput clonality analysis via vector integration site (VIS) sequencing, which is particularly useful for studying complex polyclonal hematopoietic progenitor/stem cell (HPSC) repopulation. However, clonal repopulation analysis using the current methods is typically semiquantitative. Here, we present a novel system and standards for accurate clonality analysis using 454 pyrosequencing. We developed a bidirectional VIS PCR method to improve VIS detection by concurrently analyzing both the 5' and the 3' vector-host junctions and optimized the conditions for the quantitative VIS sequencing. The assay was validated by quantifying the relative frequencies of hundreds of repopulating HPSC clones in a nonhuman primate. The reliability and sensitivity of the assay were assessed using clone-specific real-time PCR. The majority of tested clones showed a strong correlation between the two methods. This assay permits high-throughput and sensitive assessment of clonal populations and hence will be useful for a broad range of gene therapy, stem cell, and cancer research applications.
| S-EPMC2977897 | biostudies-literature