-
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 -
Physiological Reviews Jan 2012Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites that importantly contribute to vascular and cardiac physiology. The contribution of EETs to vascular... (Review)
Review
Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites that importantly contribute to vascular and cardiac physiology. The contribution of EETs to vascular and cardiac function is further influenced by soluble epoxide hydrolase (sEH) that degrades EETs to diols. Vascular actions of EETs include dilation and angiogenesis. EETs also decrease inflammation and platelet aggregation and in general act to maintain vascular homeostasis. Myocyte contraction and increased coronary blood flow are the two primary EET actions in the heart. EET cell signaling mechanisms are tissue and organ specific and provide significant evidence for the existence of EET receptors. Additionally, pharmacological and genetic manipulations of EETs and sEH have demonstrated a contribution for this metabolic pathway to cardiovascular diseases. Given the impact of EETs to cardiovascular physiology, there is emerging evidence that development of EET-based therapeutics will be beneficial for cardiovascular diseases.
Topics: Animals; Cardiovascular Physiological Phenomena; Epoxide Hydrolases; Epoxy Compounds; Homeostasis; Humans; Neovascularization, Physiologic; Platelet Aggregation; Signal Transduction; Vasodilation
PubMed: 22298653
DOI: 10.1152/physrev.00021.2011 -
Proceedings of the Japan Academy.... 2008Metastasis is the major cause of death from cancer, yet the optimal strategy against it remains uncertain. The pathogenesis of hematogenous metastasis is dynamic and... (Review)
Review
Metastasis is the major cause of death from cancer, yet the optimal strategy against it remains uncertain. The pathogenesis of hematogenous metastasis is dynamic and consists of the following steps: 1) detachment of tumor cells from the primary site, 2) invasion into the host's blood vessels, 3) migration in the host's blood stream, 4) transport along the circulation, 5) arrest in or adhesion to the capillary in a distant organ, 6) extravasation, and 7) proliferation within the foreign tissues. A key to successful hematogenous metastasis is tumor survival in the bloodstream because most circulating tumor cells are rapidly destroyed by the shear forces or are attacked by the immune system. Less than 0.01% of these cells result in metastasis. Tumor cell-induced platelet aggregation has been reported to facilitate hematogenous metastasis by increasing the arrest of tumor cell emboli in the microcirculation. Platelet aggregation is also believed to protect tumor cells from immunological assault in the circulation. We have identified Aggrus as a platelet-aggregating factor expressed on a number of human cancers. Because hematogenous metastasis is reduced when neutralizing antibodies or eliminating carbohydrates attenuates Aggrus function, Aggrus's main contribution to hematogenous metastasis of Aggrus-expressing cells, then, is by promoting platelet aggregation. Aggrus could serve as an ideal target for drug development to block metastasis.
Topics: Humans; Neoplasm Metastasis; Platelet Aggregation
PubMed: 18941298
DOI: 10.2183/pjab.84.189 -
BioMed Research International 2014Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing...
Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro.
Topics: Adenosine Triphosphate; Blood Platelets; Cells, Cultured; Chitin; Chitosan; Humans; Oligosaccharides; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Receptors, Purinergic P2Y12
PubMed: 25247182
DOI: 10.1155/2014/653149 -
Clinical and Applied... 2019Platelet function (PF) plays a pivotal role in both hemostasis and thrombosis, and manual light transmission aggregometry (LTA) is considered the standard of care for...
Platelet function (PF) plays a pivotal role in both hemostasis and thrombosis, and manual light transmission aggregometry (LTA) is considered the standard of care for platelet function testing but is an error-prone and time-consuming procedure. We aimed to test the agreement regarding maximum aggregation (MA), velocity (VEL), and lag-phase (LagP) of platelet aggregation of the automated Sysmex CS-2100 analyzer (Siemens, Germany) against the APACT 4004 (Elitech, France) in samples derived from healthy participants and patients with hemostaseologic disorders. In total, 123 patient-derived samples were investigated, including 42 patients with acetylsalicylic acid and/or clopidogrel intake and 20 patients with other hemostaseologic disorders. Both MA and VEL showed good or excellent intermethod correlation. Agreement between the testing methods was only partially achieved, and values were indicative for a systematic bias to lower measurements below a threshold of 50% MA with the CS-2100 compared to the APACT 4004. All patients with impaired PF in the APACT 4004 were successfully identified with the CS-2100, and reference values for automated LTA are provided. Conclusively, automated LTA with the CS-2100 is a highly standardized and reliable PF testing method and represents a decisive step in the simplification of platelet function testing in clinical routine.
Topics: Blood Coagulation Tests; Female; Humans; Male; Platelet Aggregation; Platelet Function Tests
PubMed: 31773967
DOI: 10.1177/1076029619885184 -
Blood Feb 2012A close homologue to protein disulfide isomerase (PDI) called ERp57 forms disulfide bonds in glycoproteins in the endoplasmic reticulum and is expressed on the platelet...
A close homologue to protein disulfide isomerase (PDI) called ERp57 forms disulfide bonds in glycoproteins in the endoplasmic reticulum and is expressed on the platelet surface. We generated 2 rabbit Abs to ERp57. One Ab strongly inhibited ERp57 in a functional assay and strongly inhibited platelet aggregation. There was minimal cross-reactivity of this Ab with PDI by Western blot or in the functional assay. This Ab substantially inhibited activation of the αIIbβ3 fibrinogen receptor and P-selectin expression. Furthermore, adding ERp57 to platelets potentiated aggregation. In contrast, adding a catalytically inactive ERp57 inhibited platelet aggregation. When infused into mice the inactive ERp57 prolonged the tail bleeding times. We generated 2 IgG2a mAbs that reacted with ERp57 by immunoblot. One of these Abs inhibited both ERp57 activity and platelet aggregation. The other Ab did not inhibit ERp57 activity or platelet aggregation. The inhibitory Ab inhibited activation of αIIbβ3 and P-selectin expression, prolonged tail bleeding times, and inhibited FeCl(3)-induced thrombosis in mice. Finally, we found that a commonly used mAb to PDI also inhibited ERp57 activity. We conclude that a glycoprotein-specific member of the PDI family, ERp57, is required for platelet aggregation, hemostasis, and thrombosis.
Topics: Animals; Cysteine; Hemostasis; Humans; Male; Mice; Mice, Inbred C57BL; Mutagenesis, Site-Directed; Mutant Proteins; Platelet Aggregation; Protein Disulfide-Isomerases; Rabbits; Serine; Thrombosis
PubMed: 22207737
DOI: 10.1182/blood-2011-06-360685 -
Journal of Healthcare Engineering 2017Platelet hyperactivity plays an important role in arterial thrombosis and atherosclerosis. The present study was aimed to investigate the effects of different extracts...
Platelet hyperactivity plays an important role in arterial thrombosis and atherosclerosis. The present study was aimed to investigate the effects of different extracts of propolis and components of flavonoids on platelet aggregation. Platelet-rich plasma was prepared and incubated in vitro with different concentrations of the tested extracts and components of flavonoids. Platelets aggregation was induced by different agonists including adenosine diphosphate (ADP, 10 M), thrombin receptor activator peptide (TRAP, 50 M), and collagen (5 g/mL). At 25 mg/L to 300 mg/mL, the water extract propolis (WEP) inhibited three agonists-induced platelet aggregations in a dose-dependent manner. The flavonoids isolated from the propolis also showed markedly inhibited platelet aggregation induced by collagen, ADP, and TRAP, respectively. The components including caffeic acid phenethyl ester (CAPE), galangin, apigenin, quercetin, kaempferol, ferulic acid, rutin, chrysin, pinostrobin, and pinocembrin and their abilities of inhibiting platelet aggregation were studied. It was concluded that propolis had an antiplatelet action in which flavonoids were mainly implicated.
Topics: Coronary Artery Disease; Humans; Phytotherapy; Platelet Aggregation; Platelet Aggregation Inhibitors; Propolis; Trees
PubMed: 29129989
DOI: 10.1155/2017/3050895 -
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 -
Biological & Pharmaceutical Bulletin 2013Hydrogen sulfide (H2S), a gasotransmitter, plays a variety of roles in the mammalian body including the cardiovascular system. Given evidence that H2S donors including...
Hydrogen sulfide (H2S), a gasotransmitter, plays a variety of roles in the mammalian body including the cardiovascular system. Given evidence that H2S donors including NaHS inhibit human platelet aggregation, we examined and characterized the effects of NaHS on rabbit platelet aggregation and cytosolic Ca(2+) mobilization. Rabbit platelet aggregation was determined in platelet-rich plasma (PRP) and washed platelets. Intracellular Ca(2+) levels were monitored in Fura2-loaded washed platelets. NaHS prevented rabbit platelet aggregation induced by collagen or ADP, and the effective concentration range of NaHS was 0.1-0.3 mM in PRP and 1-3 mM in washed platelets. In washed platelets, NaHS attenuated cytosolic Ca(2+) mobilization induced by collagen or ADP and also reduced platelet aggregation induced by ionomycin, a Ca(2+) ionophore. The anti-platelet effect of NaHS was blocked by an adenylyl cyclase inhibitor and enhanced by a phosphodiesterase inhibitor. H2S thus suppresses rabbit platelet aggregation by interfering with both upstream and downstream signals of cytosolic Ca(2+) mobilization in a cAMP-dependent manner.
Topics: Adenosine Diphosphate; Animals; Calcium; Collagen; Hydrogen Sulfide; L-Lactate Dehydrogenase; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Rabbits
PubMed: 23902972
DOI: 10.1248/bpb.b13-00018 -
Thrombosis Research 2007Von Willebrand factor (VWF) is a large multimeric glycoprotein produced in endothelial cells and megakaryocytes and present in subendothelial matrix, blood plasma and... (Review)
Review
Von Willebrand factor (VWF) is a large multimeric glycoprotein produced in endothelial cells and megakaryocytes and present in subendothelial matrix, blood plasma and platelets. VWF mediates adhesion and aggregation of platelets at sites of vascular injury, processes that are critical for both haemostasis and thrombosis. Thrombus formation involves complex events that are influenced by different environmental conditions. Progress in understanding the structure and function of VWF and the mechanisms that underlie its interactions with platelets has led to important insight into the differentiation between normal haemostasis and pathological arterial thrombosis. The conventional view of signalling-induced platelet aggregation has recently been extended to include activation-independent aggregation. A novel mechanism has been demonstrated for initiating thrombus formation under high haemodynamic forces that involves alpha(IIb)beta(3)-independent platelet aggregation at the interface between immobilised and soluble VWF. This VWF-mediated process may be a key determinant of platelet accumulation in stenotic arteries leading to acute thrombotic occlusion.
Topics: Humans; Platelet Adhesiveness; Platelet Aggregation; Thrombosis; von Willebrand Factor
PubMed: 17493665
DOI: 10.1016/j.thromres.2007.03.011