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International Journal of Molecular... Jul 2023Zinc (Zn) is released by platelets during a hemostatic response to injury. Extracellular zinc ([Zn]) initiates platelet activation following influx into the platelet...
Zinc (Zn) is released by platelets during a hemostatic response to injury. Extracellular zinc ([Zn]) initiates platelet activation following influx into the platelet cytosol. However, the mechanisms that permit Zn influx are unknown. Fluctuations in intracellular zinc ([Zn]) were measured in fluozin-3-loaded platelets using fluorometry and flow cytometry. Platelet activation was assessed using light transmission aggregometry. The detection of phosphoproteins was performed by Western blotting. [Zn] influx and subsequent platelet activation were abrogated by blocking the sodium/calcium exchanged, TRP channels, and ZIP7. Cation store depletion regulated Zn influx. [Zn] stimulation resulted in the phosphorylation of PKC substates, MLC, and β3 integrin. Platelet activation via GPVI or Zn resulted in ZIP7 phosphorylation in a casein kinase 2-dependent manner and initiated elevations of [Zn] that were sensitive to the inhibition of Orai1, ZIP7, or IPR-mediated pathways. These data indicate that platelets detect and respond to changes in [Zn] via influx into the cytosol through TRP channels and the NCX exchanger. Platelet activation results in the externalization of ZIP7, which further regulates Zn influx. Increases in [Zn] contribute to the activation of cation-dependent enzymes. Sensitivity of Zn influx to thapsigargin indicates a store-operated pathway that we term store-operated Zn entry (SOZE). These mechanisms may affect platelet behavior during thrombosis and hemostasis.
Topics: Cation Transport Proteins; Zinc; Endoplasmic Reticulum; Platelet Activation; Blood Platelets; Cations; Calcium
PubMed: 37511448
DOI: 10.3390/ijms241411689 -
Circulation Research Apr 2024
Topics: Humans; Monocytes; Blood Platelets; Thrombocytopenia; Immune System Phenomena; Immunity
PubMed: 38603477
DOI: 10.1161/CIRCRESAHA.124.324167 -
Seminars in Thrombosis and Hemostasis Jul 2024
Topics: Humans; Blood Platelets
PubMed: 38588703
DOI: 10.1055/s-0044-1785653 -
Science Advances Dec 2023Platelet transfusions are essential for managing bleeding and hemostatic dysfunction and could be expanded as a cell therapy due to the multifunctional role of platelets...
Platelet transfusions are essential for managing bleeding and hemostatic dysfunction and could be expanded as a cell therapy due to the multifunctional role of platelets in various diseases. Creating these cell therapies will require modifying transfusable donor platelets to express therapeutic proteins. However, there are currently no appropriate methods for genetically modifying platelets collected from blood donors. Here, we describe an approach using platelet-optimized lipid nanoparticles containing mRNA (mRNA-LNP) to enable exogenous protein expression in human and rat platelets. Within the library of mRNA-LNP tested, exogenous protein expression did not require nor correlate with platelet activation. Transfected platelets retained hemostatic function and accumulated in regions of vascular damage after transfusion into rats with hemorrhagic shock. We expect this technology will expand the therapeutic potential of platelets.
Topics: Humans; Rats; Animals; RNA, Messenger; Blood Platelets; Blood Donors; Hemostatics
PubMed: 38039367
DOI: 10.1126/sciadv.adi0508 -
Clinics in Perinatology Dec 2023Liberal platelet transfusions are associated with increased morbidity and mortality among preterm neonates, and it is now recognized that platelets are both hemostatic... (Review)
Review
Liberal platelet transfusions are associated with increased morbidity and mortality among preterm neonates, and it is now recognized that platelets are both hemostatic and immune cells. Neonatal and adult platelets are functionally distinct, and adult platelets have the potential to be more immuno-active. Preclinical studies suggest that platelet transfusions (from adult donors) can trigger dysregulated immune responses in neonates, which might mediate the increased morbidity and mortality observed in clinical studies. More research is needed to understand how neonatal and adult platelets differ in their immune functions and the consequences of these differences in the setting of neonatal platelet transfusions.
Topics: Infant, Newborn; Adult; Humans; Platelet Transfusion; Hemostatics; Hemostasis; Blood Platelets
PubMed: 37866848
DOI: 10.1016/j.clp.2023.07.002 -
Cell Reports Nov 2023Platelets are anucleate blood cells that contain mitochondria and regulate blood clotting in response to injury. Mitochondria contain their own gene expression machinery...
Platelets are anucleate blood cells that contain mitochondria and regulate blood clotting in response to injury. Mitochondria contain their own gene expression machinery that relies on nuclear-encoded factors for the biogenesis of the oxidative phosphorylation system to produce energy required for thrombosis. The autonomy of the mitochondrial gene expression machinery from the nucleus is unclear, and platelets provide a valuable model to understand its importance in anucleate cells. Here, we conditionally delete Elac2, Ptcd1, or Mtif3 in platelets, which are essential for mitochondrial gene expression at the level of RNA processing, stability, or translation, respectively. Loss of ELAC2, PTCD1, or MTIF3 leads to increased megakaryocyte ploidy, elevated circulating levels of reticulated platelets, thrombocytopenia, and consequent extended bleeding time. Impaired mitochondrial gene expression reduces agonist-induced platelet activation. Transcriptomic and proteomic analyses show that mitochondrial gene expression is required for fibrinolysis, hemostasis, and blood coagulation in response to injury.
Topics: Humans; Genes, Mitochondrial; Proteomics; Hemostasis; Blood Coagulation; Blood Platelets; Megakaryocytes; Thrombosis; Gene Expression; Mitochondrial Proteins
PubMed: 37889747
DOI: 10.1016/j.celrep.2023.113312 -
British Journal of Pharmacology Feb 2024Sepsis is a complicated pathological condition in response to severe infection. It is characterized by a strong systemic inflammatory response, where multiple components... (Review)
Review
Sepsis is a complicated pathological condition in response to severe infection. It is characterized by a strong systemic inflammatory response, where multiple components of the immune system are involved. Currently, there is no treatment for sepsis. Blood platelets are known for their role in haemostasis, but they also participate in inflammation through cell-cell interaction and the secretion of inflammatory mediators. Interestingly, an increase in platelet activation, secretion, and aggregation with other immune cells (such as monocytes, T-lymphocytes and neutrophils) has been detected in septic patients. Therefore, antiplatelet therapy in terms of P2Y antagonists has been evaluated as a possible treatment for sepis. It was found that blocking P2Y receptors decreased platelet marker expression and limited attachment to immune cells in some studies, but not in others. This review addresses the role of platelets in sepsis and discusses whether antagonizing P2Y signalling pathways can alter the disease outcome. Challenges in studying P2Y antagonists in sepsis also are discussed. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.
Topics: Humans; Blood Platelets; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Immunity; Sepsis; Receptors, Purinergic P2Y12; Platelet Aggregation
PubMed: 37525937
DOI: 10.1111/bph.16207 -
Platelets Dec 2023When platelet concentrates (PCs) were first introduced in the 1960s as a blood component therapy, they were stored in the cold. As platelet transfusion became more... (Review)
Review
When platelet concentrates (PCs) were first introduced in the 1960s as a blood component therapy, they were stored in the cold. As platelet transfusion became more important for the treatment of chemotherapy-induced thrombocytopenia, research into ways to increase supply intensified. During the late 1960s/early 1970s, it was demonstrated through radioactive labeling of platelets that room temperature platelets (RTP) had superior post-transfusion recovery and survival compared with cold-stored platelets (CSP). This led to a universal switch to room temperature storage, despite CSP demonstrating superior hemostatic effectiveness upon being transfused. There has been a global resurgence in studies into CSP over the last two decades, with an increase in the use of PC to treat acute bleeding within hospital and pre-hospital care. CSP demonstrate many benefits over RTP, including longer shelf life, decreased bacterial risk and easier logistics for transport, making PC accessible in areas where they have not previously been, such as the battlefield. In addition, CSP are reported to have greater hemostatic function than RTP and are thus potentially better for the treatment of bleeding. This review describes the history of CSP, the functional and metabolic assays used to assess the platelet storage lesion in PC and the current research, benefits and limitations of CSP. We also discuss whether the application of new technology for studying mitochondrial and glycolytic function in PC could provide enhanced understanding of platelet metabolism during storage and thus contribute to the continued improvements in the manufacturing and storage of PC.
Topics: Humans; Blood Preservation; Blood Platelets; Cold Temperature; Platelet Transfusion; Hemorrhage; Energy Metabolism
PubMed: 36922733
DOI: 10.1080/09537104.2023.2188969 -
Blood Advances Oct 2023Complement activation in the diseases paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS) results in cytolysis and fatal thrombotic...
Complement activation in the diseases paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS) results in cytolysis and fatal thrombotic events, which are largely refractory to anticoagulation and/or antiplatelet therapy. Anticomplement therapy, however, efficiently prevents thrombotic events in PNH and aHUS, but the underlying mechanisms remain unresolved. We show that complement-mediated hemolysis in whole blood induces platelet activation similarly to activation by adenosine 5'-diphosphate (ADP). Blockage of C3 or C5 abolished platelet activation. We found that human platelets failed to respond functionally to the anaphylatoxins C3a and C5a. Instead, complement activation did lead to prothrombotic cell activation in the whole blood when membrane attack complex (MAC)-mediated cytolysis occurred. Consequently, we demonstrate that ADP receptor antagonists efficiently inhibited platelet activation, although full complement activation, which causes hemolysis, occurred. By using an established model of mismatched erythrocyte transfusions in rats, we crossvalidated these findings in vivo using the complement inhibitor OmCI and cobra venom factor. Consumptive complement activation in this animal model only led to a thrombotic phenotype when MAC-mediated cytolysis occurred. In conclusion, complement activation only induces substantial prothrombotic cell activation if terminal pathway activation culminates in MAC-mediated release of intracellular ADP. These results explain why anticomplement therapy efficiently prevents thromboembolisms without interfering negatively with hemostasis.
Topics: Humans; Rats; Animals; Complement Membrane Attack Complex; Hemolysis; Erythrocytes; Complement Activation; Blood Platelets; Hemoglobinuria, Paroxysmal; Atypical Hemolytic Uremic Syndrome
PubMed: 37428869
DOI: 10.1182/bloodadvances.2023010817 -
Arteriosclerosis, Thrombosis, and... Oct 2023Platelet adhesion and activation is fundamental to the formation of a hemostatic response to limit loss of blood and instigate wound repair to seal a site of vascular... (Review)
Review
Platelet adhesion and activation is fundamental to the formation of a hemostatic response to limit loss of blood and instigate wound repair to seal a site of vascular injury. The process of platelet aggregate formation is supported by the coagulation system driving injury-proximal formation of thrombin, which converts fibrinogen to insoluble fibrin. This highly coordinated series of molecular and membranous events must be routinely achieved in flowing blood, at vascular fluid shear rates that place significant strain on molecular and cellular interactions. Platelets have long been recognized to be able to slow down and adhere to sites of vascular injury and then activate and recruit more platelets that forge and strengthen adhesive ties with the vascular wall under these conditions. It has been a major challenge for the Platelet Research Community to construct experimental conditions that allow precise definition of the molecular steps occurring under flow. This brief review will discuss work to date from our group, as well as others that has furthered our understanding of platelet function in flowing blood.
Topics: Humans; Vascular System Injuries; Blood Platelets; Hemostasis; Blood Coagulation; Platelet Adhesiveness; Hemostatics
PubMed: 37615110
DOI: 10.1161/ATVBAHA.123.317048