-
Journal of Biomechanics Feb 2022Obstruction of blood flow due to thrombosis is a major cause of ischemic stroke, myocardial infarction, and in severe cases, mortality. In particular, in blood wetting...
Obstruction of blood flow due to thrombosis is a major cause of ischemic stroke, myocardial infarction, and in severe cases, mortality. In particular, in blood wetting medical devices, thrombosis is a common reason for failure. The prediction of thrombosis by understanding signaling pathways using computational models, lead to identify the risk of thrombus formation in blood-contacting devices and design improvements. In this study, a mathematical model of thrombus formation and growth is presented. A biochemical model of platelet activation and aggregation is developed to predict thrombus size and shape at the site of vascular injury. Computational fluid dynamics using the finite volume method is employed to compute the velocity and pressure fields which are influenced by the growing thrombi. The passive transport of platelets, agonists, the platelet activation kinetics, their adhesion to the growing thrombi and embolization of platelets are solved by a fully coupled set of convection-diffusion-reaction equations. The thrombogenic surface representing blood-contacting material or injured blood vessel was incorporated into the model as a surface flux boundary condition to initiate thrombus formation. The blood is considered as a Newtonian fluid, while the thrombus is treated as a porous medium. The results are compared with in vitro experiments of a microfluidic chamber at an initial inlet venous shear rate of 200s using a pressure-inlet boundary condition. The thrombus development due to agonist concentrations and change in the shear rate as well as thromboembolism for this benchmark problem is successfully computed. Furthermore, to extend the current model to a physiologically relevant configuration, thrombus formation in a blood tube is simulated. Two different heterogeneous reaction rates for platelet aggregation are used to simulate thrombus growth under a constant inlet flow rate. The findings show that the thrombus shape can be substantially altered by the hemodynamic conditions, increase in the shear rate and due to the combined effects of shear induced platelet activation and the heterogeneous reaction rates. It is also concluded that the model is able to predict thrombus formation in different physiological and pathological hemodynamics.
Topics: Blood Platelets; Humans; Platelet Activation; Platelet Adhesiveness; Platelet Aggregation; Thrombosis
PubMed: 35032838
DOI: 10.1016/j.jbiomech.2021.110915 -
PLoS Computational Biology Jul 2023Hemodynamics is crucial for the activation and aggregation of platelets in response to flow-induced shear. In this paper, a novel image-based computational model...
Hemodynamics is crucial for the activation and aggregation of platelets in response to flow-induced shear. In this paper, a novel image-based computational model simulating blood flow through and around platelet aggregates is presented. The microstructure of aggregates was captured by two different modalities of microscopy images of in vitro whole blood perfusion experiments in microfluidic chambers coated with collagen. One set of images captured the geometry of the aggregate outline, while the other employed platelet labelling to infer the internal density. The platelet aggregates were modelled as a porous medium, the permeability of which was calculated with the Kozeny-Carman equation. The computational model was subsequently applied to study hemodynamics inside and around the platelet aggregates. The blood flow velocity, shear stress and kinetic force exerted on the aggregates were investigated and compared under 800 s-1, 1600 s-1 and 4000 s-1 wall shear rates. The advection-diffusion balance of agonist transport inside the platelet aggregates was also evaluated by local Péclet number. The findings show that the transport of agonists is not only affected by the shear rate but also significantly influenced by the microstructure of the aggregates. Moreover, large kinetic forces were found at the transition zone from shell to core of the aggregates, which could contribute to identifying the boundary between the shell and the core. The shear rate and the rate of elongation flow were investigated as well. The results imply that the emerging shapes of aggregates are highly correlated to the shear rate and the rate of elongation. The framework provides a way to incorporate the internal microstructure of the aggregates into the computational model and yields a better understanding of the hemodynamics and physiology of platelet aggregates, hence laying the foundation for predicting aggregation and deformation under different flow conditions.
Topics: Blood Platelets; Hemodynamics; Blood Flow Velocity; Microfluidics; Platelet Aggregation; Stress, Mechanical
PubMed: 37428797
DOI: 10.1371/journal.pcbi.1010965 -
Environmental Health and Preventive... Dec 2017Although ethanol is known to inhibit platelet aggregation, the effects of another variant of alcohol, methanol, have not been reported. The purpose of this study was to...
BACKGROUND
Although ethanol is known to inhibit platelet aggregation, the effects of another variant of alcohol, methanol, have not been reported. The purpose of this study was to determine whether methanol and its metabolite, formic acid, affect Ca entry into and subsequent aggregation of platelets in vitro.
METHODS
Ca entry into and aggregation of human platelets were measured by spectrofluorometry using Fura-2/AM as an indicator and the light transmission method, respectively.
RESULTS
Thrombin-induced platelet aggregation was significantly augmented by methanol at pharmacological concentrations (0.5-2%) in a concentration-dependent manner. Methanol at 2% significantly attenuated thapsigargin-induced platelet aggregation, which was not significantly affected by lower concentrations (0.5 and 1%) of methanol. Methanol (0.5-2%) did not significantly affect platelet aggregation induced by 1-oleoyl-2-acetyl-sn-glycerol (OAG), or Ca entry into platelets induced by thrombin, thapsigargin, or OAG. Platelet aggregation induced by thrombin, thapsigargin, or OAG was significantly inhibited by formic acid at toxic concentrations (0.01% or higher). Ca entry into platelets induced by thrombin or thapsigargin was also significantly inhibited by formic acid at 0.01% or higher, while that induced by OAG was not affected by formic acid at 0.005 and 0.01% and augmented by that at 0.02%.
CONCLUSIONS
Methanol at pharmacological doses has diverse effects on platelet aggregation, depending on the aggregation stimuli, without affecting Ca entry into platelets. Formic acid at toxic concentrations has an inhibitory action on platelets aggregation, which was partly explained by the reduction of Ca entry into platelets.
Topics: Blood Platelets; Calcium; Calcium Signaling; Diglycerides; Formates; Hemostatics; Humans; Methanol; Platelet Aggregation; Thapsigargin; Thrombin
PubMed: 29246106
DOI: 10.1186/s12199-017-0687-7 -
Journal of Thrombosis and Haemostasis :... Jul 2021Coagulopathic bleeding is a major cause of mortality after trauma, and platelet dysfunction contributes to this problem. The causes of platelet dysfunction are... (Observational Study)
Observational Study
BACKGROUND
Coagulopathic bleeding is a major cause of mortality after trauma, and platelet dysfunction contributes to this problem. The causes of platelet dysfunction are relatively unknown, but a great deal can be learned from the plasma environment about the possible pathways involved.
OBJECTIVE
Describe the changes in plasma proteomic profile associated with platelet dysfunction after trauma.
METHODS
Citrated blood was collected from severely injured trauma patients at the time of their arrival to the Emergency Department. Samples were collected from 110 patients, and a subset of twenty-four patients was identified by a preserved (n = 12) or severely impaired (n = 12) platelet aggregation response to five different agonists. Untargeted proteomics was performed by nanoflow liquid chromatography tandem mass spectrometry. Protein abundance levels for each patient were normalized to total protein concentration to control for hemodilution by crystalloid fluid infusion prior to blood draw.
RESULTS
Patients with platelet dysfunction were more severely injured but otherwise demographically similar to those with retained platelet function. Of 232 proteins detected, twelve were significantly different between groups. These proteins fall into several broad categories related to platelet function, including microvascular obstruction with platelet activation, immune activation, and protease activation.
CONCLUSIONS
This observational study provides a description of the change in proteomic profile associated with platelet dysfunction after trauma and identifies twelve proteins with the most profound changes. The pathways involving these proteins are salient targets for immediate investigation to better understand platelet dysfunction after trauma and identify targets for intervention.
Topics: Blood Platelet Disorders; Humans; Platelet Activation; Platelet Aggregation; Platelet Function Tests; Proteomics; Wounds and Injuries
PubMed: 33774904
DOI: 10.1111/jth.15316 -
British Journal of Haematology Nov 2023Abnormalities of platelet function were reported in patients with severe COVID-19 (severe-C), but few data are available in patients with mild COVID-19 (mild-C) and...
Abnormalities of platelet function were reported in patients with severe COVID-19 (severe-C), but few data are available in patients with mild COVID-19 (mild-C) and after COVID-19 recovery. The aim of this study was to investigate platelet parameters in mild-C patients (n = 51), with no evidence of pneumonia, and severe-C patients (n = 49), during the acute phase and after recovery, compared to 43 healthy controls. Both mild-C and severe-C patients displayed increased circulating activated platelets, low δ-granule content (ADP, serotonin), impaired platelet activation by collagen (light transmission aggregometry) and impaired platelet thrombus formation on collagen-coated surfaces under controlled flow conditions (300/s shear rate). The observed abnormalities were more marked in severe-C patients than in mild-C patients. Overall, 61% (30/49) of mild-C and 73% (33/45) of severe-C patients displayed at least one abnormal platelet parameter. In a subgroup of just 13 patients who showed no persisting signs/symptoms of COVID-19 and were re-evaluated at least 1 month after recovery, 11 of the 13 subjects exhibited normalization of platelet parameters. In conclusion, mild abnormalities of platelet parameters were present not only in severe-C but also, albeit to a lesser extent, in mild-C patients during the acute phase of COVID-19 and normalized in most tested patients after clinical recovery.
Topics: Humans; Blood Platelets; Platelet Aggregation; COVID-19; Platelet Activation; Collagen
PubMed: 37615207
DOI: 10.1111/bjh.19062 -
Molecules (Basel, Switzerland) May 2021The valorization of food industry by-products as sources of bioactive compounds is at the forefront of research in functional foods and nutraceuticals. This study...
The valorization of food industry by-products as sources of bioactive compounds is at the forefront of research in functional foods and nutraceuticals. This study focuses on bioactives of apple cider by-products (ACBPs) with putative cardio-protective properties. Total lipids (TLs) were extracted from ACBPs of apple varieties that are low (ACBP1), medium (ACBP2), and high (ACBP3) in tannins and were further separated into polar lipids (PLs) and neutral lipids (NLs). The functionality of these lipid extracts and of their HPLC-derived lipid fractions/PL subclasses were assessed in vitro against human platelet aggregation induced by the thrombotic and inflammatory platelet agonists platelet-activating factor (PAF) and adenosine diphosphate (ADP). The fatty acid profile of PLs and their most bioactive lipid fractions were evaluated by GC-MS analysis. The PL extracts exhibited higher specificity against the PAF-induced platelet aggregation compared to their anti-ADP effects, while TL and NL showed lower bioactivities in all ACBPs. HPLC analysis unveiled that the most bioactive PL from all ACBPs were those in PL fraction 3 containing phosphatidylcholines (PCs). PLs from all ACBPs and their PC bioactives were rich in polyunsaturated fatty acids (PUFAs) and especially in the essential omega-6 (n-6) linoleic acid (LA) and omega-3 (n-3) alpha linolenic acid (ALA), with favorably low values of the n-6/n-3 PUFA ratio, thus providing a rationale for their higher anti-inflammatory bioactivities. Within this study, highly bioactive PL compounds with strong anti-inflammatory and anti-platelet properties were identified in ACBPs, which can be potentially utilized for producing cardio-protective functional foods and/or nutraceuticals.
Topics: Anti-Inflammatory Agents; Blood Donors; Chromatography, High Pressure Liquid; Fruit; Fruit and Vegetable Juices; Functional Food; Gas Chromatography-Mass Spectrometry; Humans; Linoleic Acid; Malus; Phosphatidylcholines; Phytochemicals; Platelet Activation; Platelet Aggregation; alpha-Linolenic Acid
PubMed: 34066136
DOI: 10.3390/molecules26102869 -
Journal of Thrombosis and Haemostasis :... Apr 2020Succinate is a Krebs cycle intermediate whose formation is enhanced under metabolic stress, and for which a selective sensor GPR91 has been identified on various cell...
BACKGROUND
Succinate is a Krebs cycle intermediate whose formation is enhanced under metabolic stress, and for which a selective sensor GPR91 has been identified on various cell types including platelets. Platelet-derived eicosanoids play pivotal roles in platelet activation/aggregation, which is key to thrombus formation and progression of atherothrombosis.
OBJECTIVES
This study aims to decipher the molecular mechanism(s) and potential involvement of eicosanoids in succinate enhanced platelet activation/aggregation.
METHODS
We used liquid chromatography-mass spectrometry (LC-MS)/MS-based lipid mediator profiling to identify eicosanoids regulated by succinate. We ran light transmittance aggregometry and flow cytometry to assess platelet aggregation, P-selectin expression, and platelet-polymorphonuclear leukocyte (PMN) adherence. Various pharmacological tools were used to assess the contributions of GPR91 signalling and eicosanoids in platelet aggregation.
RESULTS
Succinate and two types of synthetic non-metabolite GPR91 agonists-cis-epoxysuccinate (cES) and Cmpd131-potentiated platelet aggregation, which was partially blocked by a selective GPR91 antagonist XT1. GPR91 activation increased production of 12-hydroxy-eicosatetraenoic acid (12-HETE), thromboxane (TX) A , and 12-hydroxy-heptadecatrienoic acid (12-HHT) in human platelets, associated with phosphorylation of cytosolic phospholipase A (cPLA ), suggesting increased availability of free arachidonic acid. Blocking 12-HETE and TXA synthesis, or antagonism of the TXA receptor, significantly reduced platelet aggregation enhanced by GPR91 signalling. Moreover, platelet-PMN suspensions challenged with succinate exhibited enhanced transcellular biosynthesis of leukotriene C (LTC ), a powerful proinflammatory vascular spasmogen.
CONCLUSION
Succinate signals through GPR91 to promote biosynthesis of eicosanoids, which contribute to platelet aggregation/activation and potentially vascular inflammation. Hence, GPR91 may be a suitable target for pharmacological intervention in atherothrombotic conditions.
Topics: Blood Platelets; Humans; Leukotriene C4; Platelet Activation; Platelet Aggregation; Thromboxane A2
PubMed: 31930602
DOI: 10.1111/jth.14734 -
Acta Pharmaceutica (Zagreb, Croatia) Dec 2019Flavonoids are natural polyphenolic compounds present in a wide spectrum of plants that have a beneficial effect on human health. In the context of cardiovascular...
Flavonoids are natural polyphenolic compounds present in a wide spectrum of plants that have a beneficial effect on human health. In the context of cardiovascular diseases related to plaque and thrombus formation, flavonoids exhibit an anti-aggregatory effect. Previously, it has been reported that all tested flavonoids exhibit an antiaggregatory effect on platelet aggregation when measured by impedance aggregometry on whole blood, in the test of aggregation induced by adenosine diphosphate (ADP). As not all flavonoids have the same targets within signaling pathways, an assumption of a common non-specific mechanism related to lipophilicity is to be considered. To test this hypothesis, reverse-phase thin layer chromatography was used to assess the lipophilicity of flavonoids; impedance aggregometry was used for testing of platelet aggregation and flow cytometry to monitor the influence of flavonoids on platelet activation. Lipophilicity analysis showed a highly negative correlation of logP and MINaAC for groups of flavones and flavanones. As determined by flow cytometry, the exposition of receptors necessary for the promotion of platelet activation and primary clot formation was diminished, i.e., lowered expression of the activated form of integrin αIIbβ3 was observed in the presence of flavanone. Platelet membrane stabilization by flavonoids as a mechanism of antiaggregatory effect has been supported by impedance aggregometry experiments when specific inhibitors of platelet aggregation signaling pathways (U73122, indomethacin, verapamil) were used in the presence of a weak (ADP) and a strong (TRAP-6) agonist of aggregation. While individual flavonoids can have specific targets within aggregation signaling pathways, all flavonoids share a common non-specific mechanism of platelet aggregation inhibition related to their lipophilicity and membrane stabilization that, to some extent, contributes to their antiaggregatory effect.
Topics: Blood Platelets; Estrenes; Flavonoids; Humans; Indomethacin; Platelet Aggregation; Pyrrolidinones; Signal Transduction; Verapamil
PubMed: 31639087
DOI: 10.2478/acph-2019-0040 -
Inflammation Feb 2016The cardioprotective mechanisms of colchicine in patients with stable ischemic heart disease remain uncertain. We tested varying concentrations of colchicine on platelet...
The cardioprotective mechanisms of colchicine in patients with stable ischemic heart disease remain uncertain. We tested varying concentrations of colchicine on platelet activity in vitro and a clinically relevant 1.8-mg oral loading dose administered over 1 h in 10 healthy subjects. Data are shown as median [interquartile range]. Colchicine addition in vitro decreased light transmission platelet aggregation only at supratherapeutic concentrations but decreased monocyte- (MPA) and neutrophil-platelet aggregation (NPA) at therapeutic concentrations. Administration of 1.8 mg colchicine to healthy subjects had no significant effect on light transmission platelet aggregation but decreased the extent of MPA (28 % [22-57] to 22 % [19-31], p = 0.05) and NPA (19 % [16-59] to 15 % [11-30], p = 0.01), platelet surface expression of PAC-1 (370 mean fluorescence intensity (MFI) [328-555] to 333 MFI [232-407], p = 0.02) and P-selectin (351 MFI [269-492] to 279 [226-364], p = 0.03), and platelet adhesion to collagen (10.2 % [2.5-32.6] to 2.0 % [0.2-9.5], p = 0.09) 2 h post-administration. Thus, in clinically relevant concentrations, colchicine decreases expression of surface markers of platelet activity and inhibits leukocyte-platelet aggregation but does not inhibit homotypic platelet aggregation.
Topics: Adult; Blood Platelets; Cardiotonic Agents; Cell Adhesion; Colchicine; Female; Healthy Volunteers; Humans; Inflammation; Male; Monocytes; Myocardial Ischemia; Neutrophils; Pilot Projects; Platelet Activation; Platelet Aggregation; Prospective Studies; Young Adult
PubMed: 26318864
DOI: 10.1007/s10753-015-0237-7 -
Purinergic Signalling Dec 2015The involvement of purinergic signalling in the physiology of erythrocytes, platelets and leukocytes was recognised early. The release of ATP and the expression of... (Review)
Review
The involvement of purinergic signalling in the physiology of erythrocytes, platelets and leukocytes was recognised early. The release of ATP and the expression of purinoceptors and ectonucleotidases on erythrocytes in health and disease are reviewed. The release of ATP and ADP from platelets and the expression and roles of P1, P2Y(1), P2Y(12) and P2X1 receptors on platelets are described. P2Y(1) and P2X(1) receptors mediate changes in platelet shape, while P2Y(12) receptors mediate platelet aggregation. The changes in the role of purinergic signalling in a variety of disease conditions are considered. The successful use of P2Y(12) receptor antagonists, such as clopidogrel and ticagrelor, for the treatment of thrombosis, myocardial infarction and stroke is discussed.
Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Blood Cells; Blood Platelets; Humans; Platelet Aggregation; Receptors, Purinergic; Signal Transduction
PubMed: 26260710
DOI: 10.1007/s11302-015-9462-7