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Blood Advances Jul 2023GATA1 mutations that result in loss of the N-terminal 83 amino acids are a feature of myeloid leukemia in children with Down syndrome, rare familial cases of...
GATA1 mutations that result in loss of the N-terminal 83 amino acids are a feature of myeloid leukemia in children with Down syndrome, rare familial cases of dyserythropoietic anemia, and a subset of cases of Diamond-Blackfan anemia. The Gata1s mouse model, which expresses only the short GATA1 isoform that begins at methionine 84, has been shown to have a defect in hematopoiesis, especially impaired erythropoiesis with expanded megakaryopoiesis, during gestation. However, these mice reportedly did not show any postnatal phenotype. Here, we demonstrate that Gata1s mutant mice display macrocytic anemia and features of aberrant megakaryopoiesis throughout life, culminating in profound splenomegaly and bone marrow fibrosis. These data support the use of this animal model for studies of GATA1 deficiencies.
Topics: Animals; Mice; Cell Lineage; Down Syndrome; Erythropoiesis; Protein Isoforms; Thrombopoiesis
PubMed: 36350717
DOI: 10.1182/bloodadvances.2022008124 -
Blood Cells, Molecules & Diseases Jan 2024Thrombocytopenia is a critical complication after radiation therapy and exposure. Dysfunction of megakaryocyte development and platelet production are key...
Thrombocytopenia is a critical complication after radiation therapy and exposure. Dysfunction of megakaryocyte development and platelet production are key pathophysiological stages in ionizing radiation (IR)-induced thrombocytopenia. Protein kinase C (PKC) plays an important role in regulating megakaryocyte development and platelet production. However, it remains unclear how PKC regulates IR-induced megakaryocyte apoptosis. In this study, we found that pretreatment of PKC pan-inhibitor Go6983 delayed IR-induced megakaryocyte apoptosis, and inhibited IR-induced mitochondrial membrane potential and ROS production in CMK cells. Moreover, suppressing PKC activation inhibited cleaved caspase3 expression and reduced p38 phosphorylation levels, and IR-induced PKC activation might be regulated by p53. In vivo experiments confirmed that Go6983 promoted platelet count recovery after 21 days of 3 Gy total body irradiation. Furthermore, Go6983 reduced megakaryocyte apoptosis, increased the number of megakaryocyte and polyploid formation in bone marrow, and improved the survival rate of 6 Gy total body irradiation. In conclusion, our results provided a potential therapeutic target for IR-induced thrombocytopenia.
Topics: Humans; Megakaryocytes; Protein Kinase C; X-Rays; Thrombocytopenia; Thrombopoiesis; Apoptosis; Blood Platelets
PubMed: 37813040
DOI: 10.1016/j.bcmd.2023.102798 -
Frontiers in Pharmacology 2024Cardiovascular disease is a leading cause of death. The current approach to the prevention of arterial thrombosis in cardiovascular disease is dependent on the use of... (Review)
Review
Cardiovascular disease is a leading cause of death. The current approach to the prevention of arterial thrombosis in cardiovascular disease is dependent on the use of therapies which inhibit the activation of platelets. Predictably these are associated with an increased risk of haemorrhage which causes significant morbidity. The thrombotic potential of an activated platelet is modifiable; being determined before thrombopoiesis. Increased megakaryocyte ploidy is associated with larger and more active platelets carrying an increased risk of thrombosis. The reduction in the ploidy of megakaryocytes is therefore a novel area of therapeutic interest for reducing thrombosis. We propose a new therapeutic approach for the prevention and treatment of thrombosis by targeting the reduction in ploidy of megakaryocytes. We examine the role of a receptor mediated event causing megakaryocytes to increase ploidy, the potential for targeting the molecular mechanisms underpinning megakaryocyte endomitosis and the existence of two separate regulatory pathways to maintain haemostasis by altering the thrombotic potential of platelets as targets for novel therapeutic approaches producing haemostatically competent platelets which are not prothrombotic.
PubMed: 38562457
DOI: 10.3389/fphar.2024.1343896 -
Scandinavian Journal of Clinical and... Apr 2024The Immature Platelet Fraction (IPF) is an indicator of thrombopoiesis which is a useful parameter in thrombocytopenia. It demonstrates compensatory mechanisms in...
BACKGROUND
The Immature Platelet Fraction (IPF) is an indicator of thrombopoiesis which is a useful parameter in thrombocytopenia. It demonstrates compensatory mechanisms in production of platelets, but currently not implemented in routine clinical practice. The aim of this study was to establish the reproducibility and stability of IPF, for both percentage (%-IPF) and absolute (A-IPF) measurements. A total of 71 samples, of which 45 for reproducibility and 26 for stability analysis, were assayed for full blood count using the Sysmex XN-10 analyser at room temperature (RT:19-25 °C). For reproducibility analysis, IPF measurements were analysed 11 times by different appraisers using the same sample, while for stability analysis, IPF was measured over fourteen hourly-intervals up to 24 h ( = 21) and then separately extended beyond the point of stability to 72 h ( = 5).
RESULTS
Reproducibility analysis of %-IPF and A-IPF ( = 45) showed very reliable results, with the range of mean CV% values between 1.25-8.90% and 1.70-9.96%, respectively. On the other hand, overall, stability analysis of %-IPF and A-IPF ( = 21) at RT over 24 h showed reliable results, with pooled mean CV% values of 1.32% and 1.43%, respectively, with no significant difference between %-IPF and A-IPF ( = 0.767 and = 0.821). All %-IPF and A-IPF values had exceeded the set acceptance criterion of stability (CV% ≥ 10.0%) before 72 h.
CONCLUSIONS
Overall, %-IPF and A-IPF reproducibility and storage at RT for 24 h predominantly demonstrates the suitability of their usage for testing on the Sysmex XN-series analysers.
Topics: Humans; Reproducibility of Results; Blood Platelets; Platelet Count; Thrombocytopenia; Thrombopoiesis
PubMed: 38420711
DOI: 10.1080/00365513.2024.2321590 -
Thrombosis Research Nov 2023Platelets and their parent cell, the megakaryocyte (MK), are increasingly recognized for their roles during infection and inflammation. The MK residing in the bone...
Platelets and their parent cell, the megakaryocyte (MK), are increasingly recognized for their roles during infection and inflammation. The MK residing in the bone marrow or arising from precursors trafficked to other organs for development go on to form platelets through thrombopoiesis. Infection, by direct and indirect mechanisms, can alter the transcriptional profile of MKs. The altered environment, whether mediated by inflammatory cytokines or other signaling mechanisms results in an altered platelet transcriptome. Platelets released into the circulation, in turn, interact with each other, circulating leukocytes and endothelial cells and contribute to the clearance of pathogens or the potentiation of pathophysiology through such mechanisms as immunothrombosis. In this article we hope to identify key contributions that explore the impact of an altered transcriptomic landscape during severe, systemic response to infection broadly defined as sepsis, and viral infections, including SARS-CoV2. We include current publications that outline the role of MKs from bone-marrow and extra-medullary sites as well as the circulating platelet. The underlying diseases result in thrombotic complications that exacerbate organ dysfunction and mortality. Understanding the impact of platelets on the pathophysiology of disease may drive therapeutic advances to improve the morbidity and mortality of these deadly afflictions.
Topics: Humans; Megakaryocytes; Transcriptome; Endothelial Cells; RNA, Viral; COVID-19; SARS-CoV-2; Blood Platelets; Thrombopoiesis; Sepsis
PubMed: 37258336
DOI: 10.1016/j.thromres.2023.05.015 -
Blood Advances Aug 2023Erythrocytes undergo a well-defined switch from fetal to postnatal circulation, which is mainly reflected by the stage-specific expression of hemoglobin chains....
Erythrocytes undergo a well-defined switch from fetal to postnatal circulation, which is mainly reflected by the stage-specific expression of hemoglobin chains. Perinatal alterations in thrombopoiesis are poorly understood. We assessed the ontogenesis of platelet phenotype and function from early prematurity to adulthood. We recruited 64 subjects comprising 7 extremely preterm (27-31 weeks gestational age), 25 moderately preterm (32-36 weeks), 10 term neonates, 8 infants (<2 years), 5 children (2-13 years), and 9 adults (>13 years). Blood was withdrawn at up to 3 different time points in neonates (t1: 0-2, t2: 3-7, and t3: 8-14 days after birth). We found that the expression levels of the major surface receptors for fibrinogen, collagen, vWF, fibronectin, and laminin were reduced but correlated with decreased platelet size, indicating a normal surface density. Although CD62P and CD63 surface exposure upon stimulation with TRAP-6, ADP, or U46619 was unaltered or only slightly reduced in neonates, GPIIb/IIIa inside-out and outside-in activation was blunted but showed a continuous increase until adulthood, correlating with the expression of the GPIIb/IIIa regulating tetraspanin CD151. Platelet subpopulation analysis using automated clustering revealed that neonates presented with a CD63+/PAC-1- pattern, followed by a continuous increase in CD63+/PAC-1+ platelets until adulthood. Our findings revealed that the number of platelet-monocyte and platelet-neutrophil aggregates, but not platelet-lymphocyte aggregates, is increased in neonates and that neonatal aggregate formation depends in part on CD62P activation. Our PLatelets In Neonatal Infants Study (PLINIUS) provides several lines of evidence that the platelet phenotype and function evolve continuously from neonates to adulthood.
Topics: Humans; Pregnancy; Female; Infant, Newborn; Blood Platelets; Platelet Activation; Platelet Glycoprotein GPIIb-IIIa Complex; Infant, Premature; 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
PubMed: 37042931
DOI: 10.1182/bloodadvances.2023009824 -
Journal of Veterinary Internal Medicine 2024The immature platelet fraction (IPF), a parameter obtained by the Sysmex XN-1000V analyzer, is used in humans to differentiate between central (CEN) and peripheral (PER)...
BACKGROUND
The immature platelet fraction (IPF), a parameter obtained by the Sysmex XN-1000V analyzer, is used in humans to differentiate between central (CEN) and peripheral (PER) thrombocytopenia (TP) but has not been evaluated in small animals.
OBJECTIVES
Compare IPF between healthy, clinical non-TP and TP dogs and cats, study IPF in different causes of TP in dogs and cats and, establish IPF reference intervals (RIs), and study the effect of age and sex on IPF in healthy dogs and cats.
ANIMALS
A total of 3281 dogs and 726 cats.
METHODS
Retrospective review of medical records. Animals were classified as nonthrombocytopenic (healthy group and group of clinical patients without TP [NTP]) or TP. These latter animals were subclassified as pseudothrombocytopenia (PSE), CEN and PER, based on evaluation of platelet clumps, estimated platelet count in blood smears and final diagnosis. Blood samples were evaluated using a Sysmex XN-1000V with a specific platelet channel (PLT-F).
RESULTS
The IPF was significantly different between each subtype of TP in both species. Immature platelet fractions <6.9% in dogs or 13.6% in cats, once PSE has been eliminated by review of blood smears, are indicative of CEN. Reference intervals for IPF were 0.5%-8% in healthy dogs and 1%-40.3% in healthy cats.
CONCLUSIONS AND CLINICAL IMPORTANCE
We determined that IPF can differentiate between CEN and PER in dogs and cats, guiding additional testing and avoiding more invasive procedures (bone marrow sampling). A blood smear always should be evaluated to rule out platelet clumping.
Topics: Animals; Dogs; Cats; Dog Diseases; Thrombocytopenia; Cat Diseases; Retrospective Studies; Female; Male; Diagnosis, Differential; Platelet Count; Blood Platelets; Reference Values
PubMed: 38619127
DOI: 10.1111/jvim.17074 -
Seminars in Thrombosis and Hemostasis Jun 2024By integrating findings from comprehensive reviews, meta-analyses, and cutting-edge genetic studies, this article illuminates the significance of stress-induced...
By integrating findings from comprehensive reviews, meta-analyses, and cutting-edge genetic studies, this article illuminates the significance of stress-induced hypercoagulability in clinical medicine. In particular, the findings from numerous prospective cohort studies indicate that stress and hemostatic factors of a hypercoagulable state are associated with increased incident risk and poor prognosis for atherosclerotic cardiovascular disease and venous thromboembolism. Mendelian randomization studies suggest that these associations are partially causal. The review synthesizes extensive research on the link between acute and chronic stress and hypercoagulability, outlining a potential pathway from stress to thrombosis risk. Consistent with the allostatic load concept, acute stress-induced hypercoagulability, initially adaptive, can turn maladaptive under chronic stress or excessive acute stress, leading to arterial or venous thrombotic events. Individuals with predisposing factors, including atherosclerosis, thrombophilia, or immobilization, may exhibit an increased risk of thrombotic disease during stress. Contextual sociodemographic characteristics, the stress experience, and coping resources additionally modulate the extent of stress-induced hypercoagulability. Research into the neuroendocrine, cellular, and molecular bases reveals how stress influences platelet activation coagulation and fibrinolysis. The activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, along with vagal withdrawal, and the effects of catecholamines, cortisol, and vasopressin, are the central mechanisms involved. Hemoconcentration, inflammation, endothelial dysfunction, and thrombopoiesis additionally contribute to stress-induced hypercoagulability. Further research is needed to prove a causal link between chronic stress and hypercoagulability. This includes exploring its implications for the prevention and management of thrombotic diseases in stressed individuals, with a focus on developing effective psychosocial and pharmacological interventions.
PubMed: 38914118
DOI: 10.1055/s-0044-1787660 -
Cells Oct 2023Platelets are generated by specialized cells called megakaryocytes (MKs). However, MK's origin and platelet release mode have remained incompletely understood. Here, we...
Platelets are generated by specialized cells called megakaryocytes (MKs). However, MK's origin and platelet release mode have remained incompletely understood. Here, we established direct visualization of embryonic thrombopoiesis in vivo by combining multiphoton intravital microscopy (MP-IVM) with a fluorescence switch reporter mouse model under control of the platelet factor 4 promoter (). Using this microscopy tool, we discovered that fetal liver MKs provide higher thrombopoietic activity than yolk sac MKs. Mechanistically, fetal platelets were released from MKs either by membrane buds or the formation of proplatelets, with the former constituting the key process. In E14.5 c-Myb-deficient embryos that lack definitive hematopoiesis, MK and platelet numbers were similar to wild-type embryos, indicating the independence of embryonic thrombopoiesis from definitive hematopoiesis at this stage of development. In summary, our novel MP-IVM protocol allows the characterization of thrombopoiesis with high spatio-temporal resolution in the mouse embryo and has identified membrane budding as the main mechanism of fetal platelet production.
Topics: Mice; Animals; Thrombopoiesis; Microscopy; Blood Platelets; Megakaryocytes; Platelet Count
PubMed: 37830625
DOI: 10.3390/cells12192411 -
ELife May 2024Erythropoiesis and megakaryopoiesis are stringently regulated by signaling pathways. However, the precise molecular mechanisms through which signaling pathways regulate...
Erythropoiesis and megakaryopoiesis are stringently regulated by signaling pathways. However, the precise molecular mechanisms through which signaling pathways regulate key transcription factors controlling erythropoiesis and megakaryopoiesis remain partially understood. Herein, we identified heat shock cognate B (HSCB), which is well known for its iron-sulfur cluster delivery function, as an indispensable protein for friend of GATA 1 (FOG1) nuclear translocation during erythropoiesis of K562 human erythroleukemia cells and cord-blood-derived human CD34+CD90+hematopoietic stem cells (HSCs), as well as during megakaryopoiesis of the CD34+CD90+HSCs. Mechanistically, HSCB could be phosphorylated by phosphoinositol-3-kinase (PI3K) to bind with and mediate the proteasomal degradation of transforming acidic coiled-coil containing protein 3 (TACC3), which otherwise detained FOG1 in the cytoplasm, thereby facilitating FOG1 nuclear translocation. Given that PI3K is activated during both erythropoiesis and megakaryopoiesis, and that FOG1 is a key transcription factor for these processes, our findings elucidate an important, previously unrecognized iron-sulfur cluster delivery independent function of HSCB in erythropoiesis and megakaryopoiesis.
Topics: Erythropoiesis; Humans; Transcription Factors; Phosphatidylinositol 3-Kinases; K562 Cells; Thrombopoiesis; Signal Transduction; Nuclear Proteins; Cell Nucleus; Protein Transport; Hematopoietic Stem Cells; HSC70 Heat-Shock Proteins; Active Transport, Cell Nucleus
PubMed: 38757931
DOI: 10.7554/eLife.95815