1
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Neves MA, Ni TT, Mackeigan DT, Shoara AA, Lei X, Slavkovic S, Yu SY, Stratton TW, Gallant RC, Zhang D, Xu XR, Fernandes C, Zhu G, Hu X, Chazot N, Donaldson LW, Johnson PE, Connelly K, Rand M, Wang Y, Ni H. Salvianolic acid B inhibits thrombosis and directly blocks the thrombin catalytic site. Res Pract Thromb Haemost 2024; 8:102443. [PMID: 38993621 PMCID: PMC11238050 DOI: 10.1016/j.rpth.2024.102443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 05/09/2024] [Indexed: 07/13/2024] Open
Abstract
Background Salvianolic acid B (SAB) is a major component of Salvia miltiorrhiza root (Danshen), widely used in East/Southeast Asia for centuries to treat cardiovascular diseases. Danshen depside salt, 85% of which is made up of SAB, is approved in China to treat chronic angina. Although clinical observations suggest that Danshen extracts inhibited arterial and venous thrombosis, the exact mechanism has not been adequately elucidated. Objective To delineate the antithrombotic mechanisms of SAB. Methods We applied platelet aggregation and coagulation assays, perfusion chambers, and intravital microscopy models. The inhibition kinetics and binding affinity of SAB to thrombin are measured by thrombin enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. We used molecular in silico docking models to predict the interactions of SAB with thrombin. Results SAB dose-dependently inhibited platelet activation and aggregation induced by thrombin. SAB also reduced platelet aggregation induced by adenosine diphosphate and collagen. SAB attenuated blood coagulation by modifying fibrin network structures and significantly decreased thrombus formation in mouse cremaster arterioles and perfusion chambers. The direct SAB-thrombin interaction was confirmed by enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. Interestingly, SAB shares key structural similarities with the trisubstituted benzimidazole class of thrombin inhibitors, such as dabigatran. Molecular docking models predicted the binding of SAB to the thrombin active site. Conclusion Our data established SAB as the first herb-derived direct thrombin catalytic site inhibitor, suppressing thrombosis through both thrombin-dependent and thrombin-independent pathways. Purified SAB may be a cost-effective agent for treating arterial and deep vein thrombosis.
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Affiliation(s)
- Miguel A.D. Neves
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Canadian Blood Services Centre for Innovation, Toronto, Ontario, Canada
| | - Tiffany T. Ni
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Daniel T. Mackeigan
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Aron A. Shoara
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Canadian Blood Services Centre for Innovation, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, Canada
| | - Xi Lei
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Sladjana Slavkovic
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Canadian Blood Services Centre for Innovation, Toronto, Ontario, Canada
| | - Si-Yang Yu
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Tyler W. Stratton
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Reid C. Gallant
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Dan Zhang
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Xiaohong Ruby Xu
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Canadian Blood Services Centre for Innovation, Toronto, Ontario, Canada
| | - Cheryl Fernandes
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Guangheng Zhu
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Canadian Blood Services Centre for Innovation, Toronto, Ontario, Canada
| | - Xudong Hu
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Noa Chazot
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
| | - Logan W. Donaldson
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, Canada
| | - Philip E. Johnson
- Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario, Canada
| | - Kim Connelly
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Division of Cardiology, St. Michael’s Hospital, Toronto, Ontario, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Margaret Rand
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Division of Hematology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Yiming Wang
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Canadian Blood Services Centre for Innovation, Toronto, Ontario, Canada
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
- Genetics and Genome Biology Program, Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
- Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Heyu Ni
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Toronto, Ontario, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, Ontario, Canada
- Canadian Blood Services Centre for Innovation, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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2
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Eltringham-Smith LJ, Meixner SC, Pryzdial ELG, Sheffield WP. Correction of haemorrhagic shock-associated coagulopathy and impaired haemostasis by plasma, prothrombin complex concentrates or an activated protein C-targeted DNA aptamer in mice. Sci Rep 2023; 13:3811. [PMID: 36882463 PMCID: PMC9992365 DOI: 10.1038/s41598-023-30794-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 03/01/2023] [Indexed: 03/09/2023] Open
Abstract
Even with extensive transfusion support, trauma-induced bleeding often leads to death. Early intervention may improve outcomes, yet which blood products, factor concentrates, or other drugs constitute optimal treatment is unclear. Patients with acute traumatic coagulopathy (ATC), arising from trauma and haemorrhagic shock, have the worst prognosis. Here, multiple interventions were compared in a mouse model of ATC. After the trauma of tissue excision, anaesthetized mice were bled to 35 mm Hg mean arterial pressure, maintained under shock for 60 min, and resuscitated with fluids equal in volume to the shed blood. Resuscitated mice were subjected to liver laceration to test haemostasis and blood loss was quantified. Saline-treated mice lost two- to three-fold more blood than sham-treated animals and were coagulopathic by prothrombin time elevation post- versus pre-procedure. Murine fresh-frozen plasma (mFFP), anti-activated protein C aptamer HS02-52G, or prothrombin complex concentrates eliminated the bleeding diathesis and coagulopathy; fibrinogen, plasminogen activator inhibitor-1, or tranexamic acid ameliorated bleeding or coagulopathy, but not both. HS02-52G and mFFP also eliminated the changes in plasma aPC and tissue plasminogen activator levels observed in saline-treated mice, as judged via microtiter plate biomarker assays. Procoagulant interventions, especially inhibiting aPC, could be beneficial in human ATC.
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Affiliation(s)
| | - Scott C Meixner
- Medical Affairs and Innovation, Canadian Blood Services, Vancouver, BC, Canada
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Edward L G Pryzdial
- Medical Affairs and Innovation, Canadian Blood Services, Vancouver, BC, Canada
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - William P Sheffield
- Medical Affairs and Innovation, Canadian Blood Services, Hamilton, ON, Canada.
- Department of Pathology and Molecular Medicine, McMaster University, HSC 4N66, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
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Ask A, Eltringham-Smith L, Bhakta V, Donkor DA, Pryzdial EL, Sheffield WP. Spotlight on animal models of acute traumatic coagulopathy: An update. Transfus Apher Sci 2022; 61:103412. [DOI: 10.1016/j.transci.2022.103412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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4
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MacKeigan DT, Ni T, Shen C, Stratton TW, Ma W, Zhu G, Bhoria P, Ni H. Updated Understanding of Platelets in Thrombosis and Hemostasis: The Roles of Integrin PSI Domains and their Potential as Therapeutic Targets. Cardiovasc Hematol Disord Drug Targets 2021; 20:260-273. [PMID: 33001021 DOI: 10.2174/1871529x20666201001144541] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/20/2020] [Accepted: 07/26/2020] [Indexed: 11/22/2022]
Abstract
Platelets are small blood cells known primarily for their ability to adhere and aggregate at injured vessels to arrest bleeding. However, when triggered under pathological conditions, the same adaptive mechanism of platelet adhesion and aggregation may cause thrombosis, a primary cause of heart attack and stroke. Over recent decades, research has made considerable progress in uncovering the intricate and dynamic interactions that regulate these processes. Integrins are heterodimeric cell surface receptors expressed on all metazoan cells that facilitate cell adhesion, movement, and signaling, to drive biological and pathological processes such as thrombosis and hemostasis. Recently, our group discovered that the plexin-semaphorin-integrin (PSI) domains of the integrin β subunits exert endogenous thiol isomerase activity derived from their two highly conserved CXXC active site motifs. Given the importance of redox reactions in integrin activation and its location in the knee region, this PSI domain activity may be critically involved in facilitating the interconversions between integrin conformations. Our monoclonal antibodies against the β3 PSI domain inhibited its thiol isomerase activity and proportionally attenuated fibrinogen binding and platelet aggregation. Notably, these antibodies inhibited thrombosis without significantly impairing hemostasis or causing platelet clearance. In this review, we will update mechanisms of thrombosis and hemostasis, including platelet versatilities and immune-mediated thrombocytopenia, discuss critical contributions of the newly discovered PSI domain thiol isomerase activity, and its potential as a novel target for anti-thrombotic therapies and beyond.
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Affiliation(s)
- Daniel T MacKeigan
- Department of Physiology, University of Toronto, Toronto, ON M5S, Canada
| | - Tiffany Ni
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Chuanbin Shen
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Tyler W Stratton
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Wenjing Ma
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Guangheng Zhu
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Preeti Bhoria
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Heyu Ni
- Department of Physiology, University of Toronto, Toronto, ON M5S, Canada
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5
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Eramanis LM, Woodward A, Courtman N, Hughes D, Padula A, Winkel KD, Boller M. Coagulation factor activity patterns of venom-induced consumption coagulopathy in naturally occurring tiger snake (Notechis scutatus) envenomed dogs treated with antivenom. Toxicon 2020; 181:36-44. [PMID: 32330462 DOI: 10.1016/j.toxicon.2020.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/17/2020] [Accepted: 03/31/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Venom-induced consumption coagulopathy (VICC) from tiger snake (Notechis scutatus) envenomation results in a dose-dependent coagulopathy that is detectable on coagulometry. However, individual coagulation factor activities in dogs with tiger snake envenomation have not been determined. This study aimed to characterise VICC and the time course of recovery in tiger snake envenomed dogs and to investigate an association between tiger snake venom (TSV) concentrations and factor activity. METHODS This was a prospective, observational, cohort study. The study cohort was 11 dogs of any age, breed, sex, body weight >10 kg, confirmed serum TSV on ELISA and treated with antivenom. Blood was collected at enrolment before antivenom administration, then at 3, 12 and 24 h after antivenom administration. Tiger snake venom concentrations were detected with a sandwich ELISA. Fibrinogen was measured using a modified Clauss method, and coagulation factors (F) II, V, VII, VIII and X were measured with factor-deficient human plasma using a modified prothrombin (PT) and activated partial thromboplastin (aPTT) method. Linear mixed models, with multiple imputations of censored observations, were used to determine the effect of time and TSV concentration on the coagulation times and factor activity. This cohort was compared to 20 healthy controls. RESULTS At enrolment, there were severe deficiencies in fibrinogen, FV and FVIII, with predicted recovery by 10.86, 11.75 and 13.14 h after antivenom, respectively. There were modest deficiencies in FX and FII, with predicted recovery by 20.57 and 32.49 h after antivenom, respectively. No changes were detected in FVII. Prothrombin time and aPTT were markedly prolonged with predicted recovery of aPTT by 12.58 h. Higher serum TSV concentrations were associated with greater deficiencies in FII, FV and FVIII, and greater prolongations in coagulation times. The median (range) serum TSV concentration was 57 (6-2295) ng/mL. CONCLUSIONS In tiger snake envenomed dogs, we detected a profound, TSV-concentration-related consumption of select coagulation factors, that rapidly recovered toward normal. These findings allowed further insight into tiger snake VICC in dogs.
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Affiliation(s)
- Louis Mark Eramanis
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, VIC, 3030, Australia.
| | - Andrew Woodward
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, VIC, 3030, Australia
| | - Natalie Courtman
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, VIC, 3030, Australia
| | - Dez Hughes
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, VIC, 3030, Australia
| | - Andrew Padula
- Australian Venom Research Unit, Department of Pharmacology and Therapeutics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Kenneth D Winkel
- Melbourne School of Population and Global Health, University of Melbourne, 207-221 Bouverie St., Parkville, VIC, 3010, Australia.
| | - Manuel Boller
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, VIC, 3030, Australia; Translational Research and Animal Clinical Trial Study Group (TRACTS), Faculty of Veterinary and Agricultural Sciences, University of Melbourne, 250 Princes Highway, Werribee, VIC, 3030, Australia.
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6
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Prothrombin, alone or in complex concentrates or plasma, reduces bleeding in a mouse model of blood exchange-induced coagulopathy. Sci Rep 2019; 9:13029. [PMID: 31506556 PMCID: PMC6736877 DOI: 10.1038/s41598-019-49552-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 08/27/2019] [Indexed: 11/29/2022] Open
Abstract
Prothrombin complex concentrates (PCC) are fractionated plasma protein drugs that reverse warfarin anticoagulation. PCC may control more general bleeding. We sought to identify the dominant procoagulant factor in PCC in vivo. We tested PCC or coagulation factor (F) treatment in CD1 mice made coagulopathic by exchange of whole blood for washed red cells. Anesthetized mice were transfused with murine fresh-frozen plasma (mFFP), PCC, mixtures of human vitamin K-dependent proteins (VKDP) (prothrombin, FVII, FIX, or FX), or purified single human VKDP, immediately prior to tail transection (TT), liver laceration (LL), or intravascular laser injury (ILI). Plasma donor mice were treated with vehicle or control antisense oligonucleotide (ASO-CON) or ASO specific for prothrombin (FII) (ASO-FII) to yield mFFP or ASO-CON mFFP or ASO-FII mFFP. Blood losses were determined spectrophotometrically (TT) or gravimetrically (LL). Thrombus formation was quantified by intravital microscopy of laser-injured arterioles. PCC or four factor- (4F-) VKDP or prothrombin significantly reduced bleeding from TT or LL. Omission of prothrombin from 4F-VKDP significantly reduced its ability to limit bleeding. Mice transfused with ASO-FII mFFP demonstrated inferior haemostasis versus those transfused with ASO-FII following TT, LL, or ILI. Prothrombin is the dominant procoagulant component of PCC and could limit bleeding in trauma.
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MacLennan S. Focus on fresh frozen plasma - facilitating optimal management of bleeding through collaboration between clinicians and transfusion specialists on component specifications. Presse Med 2016; 45:e299-302. [PMID: 27476020 DOI: 10.1016/j.lpm.2016.06.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND A symposium on plasma for direct clinical use was held in September 2015 by the European directorate for the quality of medicines and healthcare (EDQM) in order to consider changes to the Council of Europe guide to the preparation, use and quality assurance of blood components monographs on plasma components. METHODS The programme reviewed use of plasma in various settings, novel components, adverse reactions, manufacturing and quality monitoring issues. RESULTS The main requirement identified was that plasma should be made available to support early transfusion in the trauma/massive haemorrhage setting. Further guidance on component manufacturing and reviewing of quality monitoring requirements will also be addressed. CONCLUSION A working group has been established to review component monographs and other advice in the guide relating to plasma components, with the aim of providing optimal components to support clinical management of patients requiring plasma.
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8
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Xu XR, Zhang D, Oswald BE, Carrim N, Wang X, Hou Y, Zhang Q, Lavalle C, McKeown T, Marshall AH, Ni H. Platelets are versatile cells: New discoveries in hemostasis, thrombosis, immune responses, tumor metastasis and beyond. Crit Rev Clin Lab Sci 2016; 53:409-30. [PMID: 27282765 DOI: 10.1080/10408363.2016.1200008] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Platelets are small anucleate blood cells generated from megakaryocytes in the bone marrow and cleared in the reticuloendothelial system. At the site of vascular injury, platelet adhesion, activation and aggregation constitute the first wave of hemostasis. Blood coagulation, which is initiated by the intrinsic or extrinsic coagulation cascades, is the second wave of hemostasis. Activated platelets can also provide negatively-charged surfaces that harbor coagulation factors and markedly potentiate cell-based thrombin generation. Recently, deposition of plasma fibronectin, and likely other plasma proteins, onto the injured vessel wall has been identified as a new "protein wave of hemostasis" that may occur even earlier than the first wave of hemostasis, platelet accumulation. Although no experimental evidence currently exists, it is conceivable that platelets may also contribute to this protein wave of hemostasis by releasing their granule fibronectin and other proteins that may facilitate fibronectin self- and non-self-assembly on the vessel wall. Thus, platelets may contribute to all three waves of hemostasis and are central players in this critical physiological process to prevent bleeding. Low platelet counts in blood caused by enhanced platelet clearance and/or impaired platelet production are usually associated with hemorrhage. Auto- and allo-immune thrombocytopenias such as idiopathic thrombocytopenic purpura and fetal and neonatal alloimmune thrombocytopenia may cause life-threatening bleeding such as intracranial hemorrhage. When triggered under pathological conditions such as rupture of an atherosclerotic plaque, excessive platelet activation and aggregation may result in thrombosis and vessel occlusion. This may lead to myocardial infarction or ischemic stroke, the major causes of mortality and morbidity worldwide. Platelets are also involved in deep vein thrombosis and thromboembolism, another leading cause of mortality. Although fibrinogen has been documented for more than half a century as essential for platelet aggregation, recent studies demonstrated that fibrinogen-independent platelet aggregation occurs in both gene deficient animals and human patients under physiological and pathological conditions (non-anti-coagulated blood). This indicates that other unidentified platelet ligands may play important roles in thrombosis and might be novel antithrombotic targets. In addition to their critical roles in hemostasis and thrombosis, emerging evidence indicates that platelets are versatile cells involved in many other pathophysiological processes such as innate and adaptive immune responses, atherosclerosis, angiogenesis, lymphatic vessel development, liver regeneration and tumor metastasis. This review summarizes the current knowledge of platelet biology, highlights recent advances in the understanding of platelet production and clearance, molecular and cellular events of thrombosis and hemostasis, and introduces the emerging roles of platelets in the immune system, vascular biology and tumorigenesis. The clinical implications of these basic science and translational research findings will also be discussed.
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Affiliation(s)
- Xiaohong Ruby Xu
- a Department of Laboratory Medicine and Pathobiology , University of Toronto , Toronto , ON , Canada .,b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,c Department of Medicine , Guangzhou University of Chinese Medicine , Guangzhou , Guangdong , P.R. China
| | - Dan Zhang
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,c Department of Medicine , Guangzhou University of Chinese Medicine , Guangzhou , Guangdong , P.R. China
| | - Brigitta Elaine Oswald
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,d Canadian Blood Services , Toronto , ON , Canada .,e Department of Physiology , University of Toronto , Toronto , ON , Canada
| | - Naadiya Carrim
- a Department of Laboratory Medicine and Pathobiology , University of Toronto , Toronto , ON , Canada .,b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,d Canadian Blood Services , Toronto , ON , Canada
| | - Xiaozhong Wang
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,f The Second Affiliated Hospital of Nanchang University , Nanchang , Jiangxi , P.R. China
| | - Yan Hou
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,g Jilin Provincial Center for Disease Prevention and Control , Changchun , Jilin , P.R. China
| | - Qing Zhang
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,h State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University , Guangzhou , Guangdong , P.R. China , and
| | - Christopher Lavalle
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,e Department of Physiology , University of Toronto , Toronto , ON , Canada
| | - Thomas McKeown
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada
| | - Alexandra H Marshall
- b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada
| | - Heyu Ni
- a Department of Laboratory Medicine and Pathobiology , University of Toronto , Toronto , ON , Canada .,b Department of Laboratory Medicine , Keenan Research Centre for Biomedical Science, St. Michael's Hospital, and Toronto Platelet Immunobiology Group, Li Ka Shing Knowledge Institute , Toronto , ON , Canada .,d Canadian Blood Services , Toronto , ON , Canada .,e Department of Physiology , University of Toronto , Toronto , ON , Canada .,i Department of Medicine , University of Toronto , Toronto , ON , Canada
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