Platelet biology: the role of shear

Background/AimsAlthough epigallocatechin-3-gallate (EGCG), which is found in high contents in the dried leaves of green tea, has been reported to have an anti-platelet effect, synergistic effects of EGCG in addition to current anti-platelet medications remains to be elucidated.MethodsBlood samples were obtained from 40 participants who took aspirin (ASA, n = 10), clopidogrel (CPD, n = 10), ticagrelor (TCG, n = 10) and no anti-platelet medication (Control, n = 10). Ex vivo platelet aggregation and adhesion under various stimulators were analyzed by multiple electrode aggregometry (MEA) and Impact-R systems. PAC-1 and P-selectin expressions in human platelets were analyzed by flow cytometry.ResultsIn MEA analysis, adenosine diphosphate (ADP) and thrombin receptor activating peptide (TRAP)-induced platelet aggregations were lower in the CPD and the TCG groups; arachidonic acid (AA)-induced platelet aggregation was lower in the ASA group, whereas collagen (COL)-induced platelet aggregations were comparable among four groups. EGCG significantly reduced ADP- and COL-induced platelet aggregation in dose-dependent manner (ADP, p = 0.04; COL, p < 0.01). There were no additional suppressions of platelet aggregation stimulated by AA in the ASA group, and by ADP in the CPD and TCG groups. Moreover, EGCG suppressed shear stress-induced platelet adhesion on Impact-R, and had no effect on P-selectin and PAC-1 expressions.ConclusionsEx vivo treatment of EGCG inhibited platelet adhesion and aggregation without changes in P-selectin and PAC-1 expression. There was no additional suppressions in platelet aggregation stimulated by AA in the ASA group and ADP in the CPD and TCG groups.

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“…Thrombus formation is also associated with shear stress [ 29 ]. Shear stress can potentiate the effects of agonists for platelet aggregation.…”

Section: Discussionmentioning

confidence: 99%

Anti-platelet effects of epigallocatechin-3-gallate in addition to the concomitant aspirin, clopidogrel or ticagrelor treatment

Joo

Park

Hong

et al. 2018

Korean J Intern Med

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“…4D ). As the expression of P-selectin on the activated platelet surface is lower than that of the fibrinogen receptor, αIIbβ3 ( 34 ), the fluorescence intensity of the former was weak, compared with that of the latter, which made analysis difficult ( Fig. 4A ).…”

Section: Resultsmentioning

confidence: 99%

Effects of different shear rates on the attachment and detachment of platelet thrombi

Shi

Yang

Huang

et al. 2016

Molecular Medicine Reports

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Thrombosis and hemostasis take place in flowing blood, which generates shear forces. The effect of different shear rates, particularly pathological forces, on platelet thrombus formation remains to be fully elucidated. The present study observed the morphological characteristics and hierarchical structure of thrombi on the collagen surface at a wide range of wall shear rates (WSRs) and examined the underlying mechanisms. Calcein AM-labeled whole blood was perfused over a collagen-coated surface at different shear rates set by a Bioflux 200 microfluidic device and the thrombi formed were assessed for area coverage, the height and the hierarchical structure defined by the extent of platelet activation and packing density. The factors that affect thrombus formation were also investigated. Platelet thrombus formation varied under different WSRs, for example, dispersed platelet adhesion mixed with erythrocytes was observed at 125–250 s−1, extensive and thin platelet thrombi were observed at 500–1,500 s−1, and sporadic, thick thrombi were observed at pathological WSRs of 2,500–5,000 s−1, which showed a tendency to be shed. With increasing WSRs, the height of the thrombi showed an increasing linear trend, whereas the total fluorescence intensity and area of the thrombi exhibited a parabolic curve-like change, with a turning point at a WSR of 2,500 s−1. The number of thrombi, the average fluorescence intensity and the area per thrombus showed similar trends, with an initial upwards incline followed by a decline. The thrombi formed at higher WSRs had a thicker shell, which led to a more densely packed core. Platelet thrombus formation under shear-flow was regulated by the adhesive strength, which was mediated by receptor-ligand interaction, the platelet deposition induced by shear rates and the detachment by the dynamic force of flow. This resulted in a balance between thrombus attachment, including adhesion and aggregation, and detachment. Collectively, compared with physiological low WSRs, pathological high WSRs caused thicker and more easily shed thrombi with more condensed cores, which was regulated by an attachment-detachment balance. These results provide novel insights into the properties of thrombus formation on collagen at different WSRs, and offers possible explanations for certain clinical physiopathological phenomena, including physical hemostasis and pathological thrombosis.

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“…The platelet concentration in the circulating blood is ~150×10 9 /L to 350×10 9 /L with an average life span of 7–10 days; after this period, platelets are removed by reticuloendothelial cells from the liver and spleen. 81 , 82 …”

Section: Platelets As Drug Delivery Systemsmentioning

confidence: 99%

Recent advancements in erythrocytes, platelets, and albumin as delivery systems

Xu¹,

Wang

Wang³

et al. 2016

OTT

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In the past few years, nanomaterial-based drug delivery systems have been applied to enhance the efficacy of therapeutics and to alleviate negative effects through the controlled delivery of targeting and releasing agents. However, few drug carriers can achieve high targeting efficacy, even when targeting modalities and surface markers are introduced. Immunological problems have also limited their wide applications. Biological drug delivery systems, such as erythrocytes, platelets, and albumin, have been extensively investigated because of their unique properties. In this review, erythrocytes, platelets, and albumin are described as efficient drug delivery systems. Their properties, applications, advantages, and limitations in disease treatment are explained. This review confirms that these systems can be used to facilitate a specific, biocompatible, and smart drug delivery.

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Platelet biology: the role of shear

Cited by 12 publications

References 76 publications

Anti-platelet effects of epigallocatechin-3-gallate in addition to the concomitant aspirin, clopidogrel or ticagrelor treatment

Anti-platelet effects of epigallocatechin-3-gallate in addition to the concomitant aspirin, clopidogrel or ticagrelor treatment

Effects of different shear rates on the attachment and detachment of platelet thrombi

Recent advancements in erythrocytes, platelets, and albumin as delivery systems

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Platelet biology: the role of shear

Cited by 12 publications

References 76 publications

Anti-platelet effects of epigallocatechin-3-gallate in addition to the concomitant aspirin, clopidogrel or ticagrelor treatment

Anti-platelet effects of epigallocatechin-3-gallate in addition to the concomitant aspirin, clopidogrel or ticagrelor treatment

Effects of different shear rates on the attachment and detachment of platelet thrombi

Recent advancements in erythrocytes, platelets, and&nbsp;albumin as delivery systems

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Recent advancements in erythrocytes, platelets, and albumin as delivery systems