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International Journal of Cell Cloning Jul 1990Following experimental platelet destruction in animals, large platelets, which are more hemostatically active, are produced before any change in bone marrow... (Review)
Review
Following experimental platelet destruction in animals, large platelets, which are more hemostatically active, are produced before any change in bone marrow megakaryocyte DNA content. When platelet production is stimulated by administration of i.v. vincristine in rats, megakaryocyte ploidy is increased, but mean platelet volume is unchanged. When platelet production and destruction are both stimulated by chronic hypoxia or administration of anti-platelet serum, mean platelet volume and megakaryocyte DNA content are both increased. Since platelet volume is determined primarily at thrombopoiesis, these results imply that mean platelet volume and megakaryocyte DNA content are under separate hormonal control. Therefore, it has been postulated that changes in mean platelet volume occur following changes in platelet production rate, whereas changes in megakaryocyte ploidy are associated with an increased rate of platelet production. In myocardial infarction, platelets have increased mean volume and reduced bleeding time more than in controls. In addition, men with myocardial infarction have increased megakaryocyte size and increased DNA content when compared to controls. These changes are similar to those observed in rabbits following cholesterol feeding. If megakaryocyte polyploidy and mean platelet volume are under separate hormonal control, this suggests that in myocardial infarction, both hormones are active--one stimulating an increased platelet size, the other stimulating the increased megakaryocyte DNA content. In contrast, patients with lymphoma exhibiting a secondary thrombocytosis have no change in mean platelet volume. However, these subjects also have larger bone marrow megakaryocytes when compared to controls. The relation between megakaryocyte size and ploidy implies that the DNA content of these cells is increased in lymphoma.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Animals; Blood Platelets; Blood Volume; Disease Models, Animal; Humans; Lymphoma; Megakaryocytes; Myocardial Infarction; Platelet Count; Ploidies
PubMed: 2205666
DOI: 10.1002/stem.5530080414 -
International Journal of Molecular... Feb 2023Megakaryocytes (MKs), a kind of functional hematopoietic stem cell, form platelets to maintain platelet balance through cell differentiation and maturation. In recent... (Review)
Review
Megakaryocytes (MKs), a kind of functional hematopoietic stem cell, form platelets to maintain platelet balance through cell differentiation and maturation. In recent years, the incidence of blood diseases such as thrombocytopenia has increased, but these diseases cannot be fundamentally solved. The platelets produced by MKs can treat thrombocytopenia-associated diseases in the body, and myeloid differentiation induced by MKs has the potential to improve myelosuppression and erythroleukemia. Currently, ethnomedicine is extensively used in the clinical treatment of blood diseases, and the recent literature has reported that many phytomedicines can improve the disease status through MK differentiation. This paper reviewed the effects of botanical drugs on megakaryocytic differentiation covering the period 1994-2022, and information was obtained from PubMed, Web of Science and Google Scholar. In conclusions, we summarized the role and molecular mechanism of many typical botanical drugs in promoting megakaryocyte differentiation in vivo, providing evidence as much as possible for botanical drugs treating thrombocytopenia and other related diseases in the future.
Topics: Humans; Megakaryocytes; Platelet Count; Blood Platelets; Thrombocytopenia; Cell Differentiation; Medicine, Traditional
PubMed: 36834579
DOI: 10.3390/ijms24043168 -
Journal of Thrombosis and Haemostasis :... Jan 2021Essentials An easily detectable readout in megakaryocyte cell lines will enhance inflammatory research in these cells. Here, we report the development and...
Essentials An easily detectable readout in megakaryocyte cell lines will enhance inflammatory research in these cells. Here, we report the development and characterization of a novel megakaryocyte NF-κB-reporter cell line (Meg-01R). Multiple inflammatory molecules modulate NF-κB activity in Meg-01R cells. Meg-01R cells respond to small molecule inhibitors such as IMD0354 and C87 that are known to inhibit NF-κB activity upon stimulation with TNFα. ABSTRACT: Background Because of the difficulties in acquiring large numbers of megakaryocytes, the impact of inflammatory responses on these cells and their ability to produce fully functional platelets under various pathological conditions has not been investigated in detail. Objectives The primary objective of this study is to develop and functionally characterize a novel megakaryocyte nuclear factor κB (NF-κB) reporter cell line to determine the effects of various inflammatory molecules on megakaryocytes and their signalling pathways. Methods A Meg-01-NF-κB-GFP-Luc (Meg-01R) cell line was developed by inserting a reporter NF-κB-GFP-Luc cassette into normal Meg-01 cells to produce luciferase following activation of NF-κB to enable easy detection of pro-inflammatory and reparative signalling. Results and conclusions Meg-01 and Meg-01R cells have comparable characteristics, including the expression of both GPIbα and integrin β . Meg-01R cells responded to various inflammatory molecules as measured by NF-κB-dependent bioluminescence. For example, inflammatory molecules such as tumor necrosis factor-α and Pam3CSK4 increased NF-κB activity, whereas an antimicrobial peptide, LL37, reduced its activity. Meg-01R cells were also found to be sensitive to inhibitors (IMD0354 and C87) of inflammatory pathways. Notably, Meg-01R cells were able to respond to lipopolysaccharide (LPS; non-ultrapure), although it was not able to react to ultrapure LPS because of the lack of sufficient TLR4 molecules on their surface. For the first time, we report the development and characterization of a novel megakaryocyte NF-κB reporter cell line (Meg-01R) as a robust tool to study the inflammatory responses/signalling of megakaryocytes upon stimulation with a broad range of inflammatory molecules that can affect NF-κB activity.
Topics: Cell Line; Humans; Lipopolysaccharides; Megakaryocytes; NF-kappa B; Signal Transduction
PubMed: 33037735
DOI: 10.1111/jth.15118 -
Blood Mar 2016The classical model of hematopoiesis has long held that hematopoietic stem cells (HSCs) sit at the apex of a developmental hierarchy in which HSCs undergo long-term... (Review)
Review
The classical model of hematopoiesis has long held that hematopoietic stem cells (HSCs) sit at the apex of a developmental hierarchy in which HSCs undergo long-term self-renewal while giving rise to cells of all the blood lineages. In this model, self-renewing HSCs progressively lose the capacity for self-renewal as they transit into short-term self-renewing and multipotent progenitor states, with the first major lineage commitment occurring in multipotent progenitors, thus giving rise to progenitors that initiate the myeloid and lymphoid branches of hematopoiesis. Subsequently, within the myeloid lineage, bipotent megakaryocyte-erythrocyte and granulocyte-macrophage progenitors give rise to unipotent progenitors that ultimately give rise to all mature progeny. However, over the past several years, this developmental scheme has been challenged, with the origin of megakaryocyte precursors being one of the most debated subjects. Recent studies have suggested that megakaryocytes can be generated from multiple pathways and that some differentiation pathways do not require transit through a requisite multipotent or bipotent megakaryocyte-erythrocyte progenitor stage. Indeed, some investigators have argued that HSCs contain a subset of cells with biased megakaryocyte potential, with megakaryocytes directly arising from HSCs under steady-state and stress conditions. In this review, we discuss the evidence supporting these nonclassical megakaryocytic differentiation pathways and consider their relative strengths and weaknesses as well as the technical limitations and potential pitfalls in interpreting these studies. Ultimately, such pitfalls will need to be overcome to provide a comprehensive and definitive understanding of megakaryopoiesis.
Topics: Animals; Cell Differentiation; Humans; Lymphoid Progenitor Cells; Lymphopoiesis; Megakaryocyte-Erythroid Progenitor Cells; Megakaryocytes; Myelopoiesis; Thrombopoiesis
PubMed: 26787736
DOI: 10.1182/blood-2015-07-607945 -
Scientific Reports Apr 2023Hematopoiesis is the process by which blood cells are generated. During embryonic development, these cells migrate through different organs until they reach the bone...
Hematopoiesis is the process by which blood cells are generated. During embryonic development, these cells migrate through different organs until they reach the bone marrow, their definitive place in adulthood. Around E10.5, the fetal liver starts budding from the gut, where first hematopoietic cells arrive and expand. Hematopoietic cell migration occurs through cytokine stimulation, receptor expression, and glycosylation patterns on the cell surface. In addition, carbohydrates can modulate different cell activation states. For this reason, we aimed to characterize and quantify fetal megakaryocytic cells in mouse fetal liver according to their glycan residues at different gestational ages through lectins. Mouse fetuses between E11.5 and E18.5 were formalin-fixed and, paraffin-embedded, for immunofluorescence analysis using confocal microscopy. The results showed that the following sugar residues were expressed in proliferating and differentiating megakaryocytes in the fetal liver at different gestational ages: α-mannose, α-glucose, galactose, GlcNAc, and two types of complex oligosaccharides. Megakaryocytes also showed three proliferation waves during liver development at E12.5, E14.5, and E18.5. Additionally, the lectins that exhibited high and specific pattern intensities at liver capsules and vessels were shown to be a less time-consuming and robust alternative alternative to conventional antibodies for displaying liver structures such as capsules and vessels, as well as for megakaryocyte differentiation in the fetal liver.
Topics: Pregnancy; Female; Mice; Animals; Megakaryocytes; Lectins; Capsules; Hematopoiesis; Carbohydrates; Liver
PubMed: 37185919
DOI: 10.1038/s41598-023-32863-3 -
Blood Apr 1980
Review
Topics: Animals; Blood Platelets; Cell Membrane; Hematopoiesis; Humans; Lung; Megakaryocytes; Rats
PubMed: 6986921
DOI: No ID Found -
International Journal of Cell Cloning Jul 1990The DNA content of normal megakaryocytes usually ranges from 8N to 64N, with 16N as the modal DNA content. The frequency of cells at each DNA content can be altered by... (Review)
Review
The DNA content of normal megakaryocytes usually ranges from 8N to 64N, with 16N as the modal DNA content. The frequency of cells at each DNA content can be altered by experimental induction of thrombocytopenia, thrombocytosis or marrow ablation, and in various disease states; however, the mechanisms and regulation involved in the process of polyploidization remain obscure. This discussion will focus on genetic and physiologic variations in megakaryocyte DNA content distributions. The genetic variations are those we have observed among mouse strains, with the most pronounced present in several C3H substrains in which the modal megakaryocyte DNA content is 32N, rather than 16N. The physiologic variation reported here is a shift to the right in megakaryocyte DNA content distributions during late pregnancy in the rat.
Topics: Animals; DNA; Female; Megakaryocytes; Mice; Polyploidy; Pregnancy; Rats; Species Specificity
PubMed: 2205663
DOI: 10.1002/stem.5530080410 -
Experimental Hematology Jan 2000Polyploidy, the state of having greater than the diploid content of DNA, has been recognized in a variety cells. Among these cell types, the megakaryocytes are... (Review)
Review
OBJECTIVE
Polyploidy, the state of having greater than the diploid content of DNA, has been recognized in a variety cells. Among these cell types, the megakaryocytes are classified as obligate polyploid cells, developing a polyploid DNA content regularly during the normal life cycle of the organism, while other cells may become polyploid only in response to certain stimuli. The objective of this review is to briefly describe the different cell cycle alterations that may lead to high ploidy, while focusing on the megakaryocyte and the importance of high ploidy to platelet level and function.
MATERIALS AND METHODS
Relevant articles appearing in scientific journals and books published in the United States and in Europe during the years 1910-1999 were used as resources for this review. We selected fundamental studies related to cell cycle regulation as well as studies relevant to the regulation of the endomitotic cell cycle in megakaryocytes. Also surveyed were publications describing the relevance of high ploidy to high platelet count and to platelet reactivity, in normal situations and in a disease state.
RESULTS
Different cells may achieve polyploidy through different alterations in the cell cycle machinery.
CONCLUSIONS
While upregulation of cyclin D3 further augments ploidy in polyploidizing megakaryocytes in vivo, future investigation should aim to explore how normal megakaryocytes may initiate the processes of skipping late anaphase and cytokinesis associated with high ploidy. In humans, under normal conditions, megakaryocyte ploidy correlates with platelet volume, and large platelets are highly reactive. This may not apply, however, to the disease state.
Topics: Animals; Blood Platelets; Cardiovascular Diseases; Cell Cycle; DNA; Diploidy; Humans; Leukemia; Megakaryocytes; Mitosis; Myeloproliferative Disorders; Polyploidy
PubMed: 10658672
DOI: 10.1016/s0301-472x(99)00124-1 -
The EMBO Journal May 2024Understanding the regulatory mechanisms facilitating hematopoietic stem cell (HSC) specification during embryogenesis is important for the generation of HSCs in vitro....
Understanding the regulatory mechanisms facilitating hematopoietic stem cell (HSC) specification during embryogenesis is important for the generation of HSCs in vitro. Megakaryocyte emerged from the yolk sac and produce platelets, which are involved in multiple biological processes, such as preventing hemorrhage. However, whether megakaryocytes regulate HSC development in the embryonic aorta-gonad-mesonephros (AGM) region is unclear. Here, we use platelet factor 4 (PF4)-Cre;Rosa-tdTomato cells to report presence of megakaryocytes in the HSC developmental niche. Further, we use the PF4-Cre;Rosa-DTA (DTA) depletion model to reveal that megakaryocytes control HSC specification in the mouse embryos. Megakaryocyte deficiency blocks the generation and maturation of pre-HSCs and alters HSC activity at the AGM. Furthermore, megakaryocytes promote endothelial-to-hematopoietic transition in a OP9-DL1 coculture system. Single-cell RNA-sequencing identifies megakaryocytes positive for the cell surface marker CD226 as the subpopulation with highest potential in promoting the hemogenic fate of endothelial cells by secreting TNFSF14. In line, TNFSF14 treatment rescues hematopoietic cell function in megakaryocyte-depleted cocultures. Taken together, megakaryocytes promote production and maturation of pre-HSCs, acting as a critical microenvironmental control factor during embryonic hematopoiesis.
Topics: Animals; Megakaryocytes; Mice; Hematopoietic Stem Cells; Cell Differentiation; Hematopoiesis; Mesonephros; Endothelial Cells; Coculture Techniques
PubMed: 38580775
DOI: 10.1038/s44318-024-00079-4 -
Cell Death & Disease Oct 2016A better understanding of the mechanisms involved in megakaryocyte maturation will facilitate the generation of platelets in vitro and their clinical applications. A...
A better understanding of the mechanisms involved in megakaryocyte maturation will facilitate the generation of platelets in vitro and their clinical applications. A microRNA, miR-125b, has been suggested to have important roles in the self-renewal of megakaryocyte-erythroid progenitors and in platelet generation. However, miR-125b is also critical for hematopoietic stem cell self-renewal. Thus, the function of miR-125b and the complex signaling pathways regulating megakaryopoiesis remain to be elucidated. In this study, an attentive examination of the endogenous expression of miR-125b during megakaryocyte differentiation was performed. Accordingly, the differentiation of hematopoietic stem cells requires the downregulation of miR-125b, whereas megakaryocyte determination and maturation synchronize with miR-125b accumulation. The overexpression of miR-125b improves megakaryocytic differentiation of K562 and UT-7 cells. Furthermore, stage-specific overexpression of miR-125b in primary cells demonstrates that miR-125b mediates an enhancement of megakaryocytic differentiation after megakaryocyte determination, the stage at which megakaryocytes are negative for the expression of the hematopoietic progenitor marker CD34. The identification of miR-125b targets during megakaryopoiesis was focused on negative regulators of cell cycle because the transition of the G1/S phase has been associated with megakaryocyte polyploidization. Real-time PCR, western blot and luciferase reporter assay reveal that p19 is a direct target of miR-125b. P19 knockdown using small interfering RNA (siRNA) in megakaryocyte-induced K562 cells, UT-7 cells and CD61 promegakaryocytes results in S-phase progression and increased polyploidy, as well as improved megakaryocyte differentiation, similarly to the effects of miR-125b overexpression. P19 overexpression reverses these effects, as indicated by reduced expression of megakaryocyte markers, G1-phase arrest and polyploidy decrease. P19 knockdown in miR-125b downregulated cells or p19 overexpression in miR-125b upregulated cells rescued the effect of miR-125b. Taken together, these findings suggest that miR-125b expression positively regulates megakaryocyte development since the initial phases of megakaryocyte determination, and p19 is one of the key mediators of miR-125b activity during the onset of megakaryocyte polyploidization.
Topics: Base Sequence; Blood Platelets; Cell Differentiation; Colony-Forming Units Assay; Cyclin-Dependent Kinase Inhibitor p19; Down-Regulation; Fetal Blood; G1 Phase; Gene Knockdown Techniques; Hematopoietic Stem Cells; Humans; K562 Cells; Leukocytes, Mononuclear; Megakaryocytes; MicroRNAs; Polyploidy; Tetradecanoylphorbol Acetate; Up-Regulation
PubMed: 27763644
DOI: 10.1038/cddis.2016.288