Platelet Aggregation and Activation under Complex Patterns of Shear Stress

SummaryArterial stenosis results in a complex pattern of blood flow containing an extremely fast flow in the throat of stenosis and a post-stenosis low flow. The fast flow generates high shear stress that has been demonstrated in vitro to activate and aggregate platelets. One potential problem of these in vitro studies is that platelets are invariably exposed to a high shear stress for a period that is significantly longer than they would have experienced in vivo. More importantly, the role of the poststenosis low flow in platelet activation and aggregation has not been determined. By exposing platelets to a shear profile that contains both high and low shear segments, we found that platelets aggregate when they are exposed to a high shear stress of 100 dyn/cm2 for as short as 2.5 s, a period that is significantly shorter than those previously reported (30–120 s). Platelet aggregation under this condition requires a low shear exposure immediately after a high shear pulse, suggesting that post-stenosis low flow enhances platelet aggregation. Furthermore, platelet aggregation under this condition is not activation-dependent because the CD62P expression of sheared platelets is significantly less than that of platelets treated with ADP. Based on these findings, we propose that shear-induced platelet aggregation may be a process of mechanical crosslinking of platelets, requiring minimal platelet activation. This process may function as a protective mechanism to prevent in vivo irreversible platelet activation and aggregation under temporary high shear.

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Duration of exposure to high fluid shear stress is critical in shear-induced platelet activation-aggregation

Thrombosis and Haemostasis ◽

10.1160/th03-03-0145 ◽

2003 ◽

Vol 90 (10) ◽

pp. 672-678 ◽

Cited By ~ 17

Author(s):

Zhang Jian-ning ◽

Angela Bergeron ◽

Qinghua Yu ◽

Carol Sun ◽

Latresha McBride ◽

...

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Platelet Activation ◽

Whole Blood ◽

Fluid Shear Stress ◽

High Shear ◽

Platelet Response ◽

Short Pulses ◽

Hydrodynamic Effects

SummaryPlatelet functions are increasingly measured under flow conditions to account for blood hydrodynamic effects. Typically, these studies involve exposing platelets to high shear stress for periods significantly longer than would occur in vivo. In the current study, we demonstrate that the platelet response to high shear depends on the duration of shear exposure. In response to a 100 dyn/cm2 shear stress for periods less than 10-20 sec, platelets in PRP or washed platelets were aggregated, but minimally activated as demonstrated by P-selectin expression and binding of the activation-dependent αIIbβ3 antibody PAC-1 to sheared platelets. Furthermore, platelet aggregation under such short pulses of high shear was subjected to rapid disaggregation. The disaggregated platelets could be re-aggregated by ADP in a pattern similar to unsheared platelets. In comparison, platelets that are exposed to high shear for longer than 20 sec are activated and aggregated irreversibly. In contrast, platelet activation and aggregation were significantly greater in whole blood with significantly less disaggregation. The enhancement is likely via increased collision frequency of platelet-platelet interaction and duration of platelet-platelet association due to high cell density. It may also be attributed to the ADP release from other cells such as red blood cells because increased platelet aggregation in whole blood was partially inhibited by ADP blockage. These studies demonstrate that platelets have a higher threshold for shear stress than previously believed. In a pathologically relevant timeframe, high shear alone is likely to be insufficient in inducing platelet activation and aggregation, but acts synergistically with other stimuli.

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Novel Platelet Antagonists

Fibrinolytic and Antithrombotic Therapy ◽

10.1093/oso/9780195155648.003.0016 ◽

2006 ◽

Author(s):

Richard C. Becker ◽

Frederick A. Spencer

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Platelet Activation ◽

Adenosine Monophosphate ◽

Stress Conditions ◽

Platelet Glycoprotein ◽

High Shear ◽

High Shear Stress ◽

Surface Receptor ◽

Pharmacologic Agents

The development of pharmacologic agents that inhibit platelet performance could not have proceeded without a fundamental knowledge of normal biology and a clear understanding of the laws that govern cellular events in the circulatory system. The adhesion of platelets to a site of vessel wall injury is mediated by von Willebrand factor (vWF), which binds to the platelet glycoprotein (GP) Ib/IX-V complex receptor (and the GPIIb/IIIa receptor under high shear stress conditions). Monoclonal antibodies to vWF have been developed and tested in animal models, as has aurintricarboxylic acid (Strony et al., 1990), a triphenylmethyl compound that inhibits vWF binding. To date, investigation in humans has not taken place, perhaps because of concerns regarding the potential risk for hemorrhagic complications. Nevertheless, the scientific community remains interested in vWF and its platelet surface receptor as potential pharmacology-directed targets. Although the GPIIb/IIIa receptor antagonists are best known for their ability to inhibit platelet aggregation, under high shear stress conditions vWF can also bind the GPIIb/IIIa receptor, facilitating adhesion. As a result, GPIIb/IIIa antagonists may have an impact on both platelet adhesion and aggregation. As previously discussed, platelet activation is followed by a series of intracellular events that culminate in the release of calcium and substances that augment platelet aggregation and support coagulation protease binding. Thus, pharmacologic agents that inhibit initial surface receptor–mediated activation may also impair platelet aggregation. Several natural prostanoids (prostaglandin [PG] E1 and PGI2) can inhibit platelet activation and aggregation by elevating cyclic adenosine monophosphate (cAMP) levels. Although the mechanism is complex, the primary mode of inhibition is through the activation of adenylate cyclase (with a subsequent rise in cAMP concentrations), which in turn prevents calcium mobilization. The clinical application of PGE1 and PGI2 has been limited by their effect on vascular tone, producing substantial systemic hypotension (Emmons et al., 1967; Terres et al., 1989), and by extensive first-pass metabolism in the lungs (70% of the active compound is rapidly cleared) (Kleiman et al., 1994).

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Known players, new interplay in atherogenesis: Chronic shear stress and carbamylated-LDL induce and modulate expression of atherogenic LR11 in human coronary artery endothelium

Thrombosis and Haemostasis ◽

10.1160/th12-12-0924 ◽

2014 ◽

Vol 111 (02) ◽

pp. 323-332 ◽

Cited By ~ 6

Author(s):

Eva-Theres Gensberger ◽

Susanna Scharrer ◽

Heinz Regele ◽

Klaus Aumayr ◽

Chantal Kopecky ◽

...

Keyword(s):

Shear Stress ◽

Coronary Artery ◽

Ldl Receptor ◽

Low Density ◽

High Shear ◽

High Shear Stress ◽

Human Coronary Artery ◽

Static Conditions

SummaryIn this study we examined whether low-density lipoprotein (LDL) receptor family members represent a link between blood flow characteristics and modified low-density lipoproteins involved in endothelial injury, a pivotal factor in atherogenesis. We demonstrated the expression of pro-atherogenic LDL receptor relative (LR11) for the first time in human coronary artery endothelial cells (HCAEC) in vitro and in vivo. Next, LR11 expression and regulation were explored in HCAEC cultured conventionally or on the inner surface of hollow fiber capillaries under exposure to shear stress for 10 days in the presence or absence of LDL. There was no LR11 expression under static conditions. When exposed to chronic low shear stress (2.5 dynes/cm2) transmembrane and soluble endothelial-LR11 were detected in high levels irrespective of the type of LDL added (carbamylated or native). In contrast, chronic high shear stress (25 dynes/cm2) inhibited the LR11-inducing effect of LDL such that transmembrane and soluble LR11 expression became non-detectable with native LDL. Carbamylated LDL significantly counteracted this atheroprotective effect of high shear stress as shown by lower, yet sustained expression of soluble and transmembrane LR11. Oxidised LDL showed similar effects compared to carbamylated LDL but caused significantly lower LR11 expression under chronic high shear stress. Medium from HCAEC under LR11-inducing conditions enhanced vascular smooth muscle cell migration, which was abrogated by the anti-LR11 antibody. Expression of LR11 depended entirely on p38MAPK phosphorylation. We conclude that coronary endothelial LR11 expression modulated by LDL and chronic shear stress contributes to atherogenesis. LR11 and p38MAPK are potential targets for prevention of atherosclerosis.

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Antithrombotic Effects of Paeoniflorin from Paeonia suffruticosa by Selective Inhibition on Shear Stress-Induced Platelet Aggregation

International Journal of Molecular Sciences ◽

10.3390/ijms20205040 ◽

2019 ◽

Vol 20 (20) ◽

pp. 5040 ◽

Cited By ~ 4

Author(s):

Thien Ngo ◽

Keunyoung Kim ◽

Yiying Bian ◽

Hakjun Noh ◽

Kyung-Min Lim ◽

...

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Ex Vivo ◽

Antiplatelet Agents ◽

Human Platelets ◽

Platelet Glycoprotein ◽

High Shear ◽

High Shear Stress ◽

Paeonia Suffruticosa ◽

Induced Aggregation

Antiplatelet agents are important in the pharmacotherapeutic regime for many cardiovascular diseases, including thrombotic disorders. However, bleeding, the most serious adverse effect associated with current antiplatelet therapy, has led to many efforts to discover novel anti-platelet drugs without bleeding issues. Of note, shear stress-induced platelet aggregation (SIPA) is a promising target to overcome bleeding since SIPA happens only in pathological conditions. Accordingly, this study was carried out to discover antiplatelet agents selectively targeting SIPA. By screening various herbal extracts, Paeonia suffruticosa and its major bioactive constituent, paeoniflorin, were identified to have significant inhibitory effects against shear-induced aggregation in human platelets. The effects of paeoniflorin on intraplatelet calcium levels, platelet degranulation, and integrin activation in high shear stress conditions were evaluated by a range of in vitro experiments using human platelets. The inhibitory effect of paeoniflorin was determined to be highly selective against SIPA, through modulating von Willebrand Factor (vWF)-platelet glycoprotein Ib (GP Ib) interaction. The effects of paeoniflorin on platelet functions under high shear stress were confirmed in the ex vivo SIPA models in rats, showing the good accordance with the anti-SIPA effects on human platelets. Treatment with paeoniflorin significantly prevented arterial thrombosis in vivo from the dose of 10 mg/kg without prolonging bleeding time or blood clotting time in rats. Collectively, our results demonstrated that paeoniflorin can be a novel anti-platelet agent selectively targeting SIPA with an improved safety profile.

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Numerical Study on Diastolic Left Ventricular Hemodynamics Using Motion Models of Mitral Valve With/Without Edge-to-Edge Repair

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19570 ◽

2010 ◽

Author(s):

Yingying Hu ◽

Liang Shi ◽

Siva Parameswaran ◽

Sergey A. Smirnov ◽

Zhaoming He

Keyword(s):

Shear Stress ◽

Mitral Valve ◽

Left Ventricle ◽

Platelet Activation ◽

Numerical Study ◽

Left Ventricular ◽

High Shear ◽

High Shear Stress ◽

Orifice Area ◽

Motion Models

Edge-to-edge repair (ETER) is a newly developed technique to correct such mitral valve (MV) malfunctions as regurgitation [1,2]. This technique changes MV geometric configuration by suturing the anterior and posterior leaflets at central or commissural edges, and consequently alters MV and left ventricle (LV) dynamics. For instance, stress in the MV elevated due to ETER may cause leaflets tearing near suture. Little has been known about shear stress on the MV and LV walls under MV ETER conditions, where high shear stress might cause platelet activation or hemolysis [3]. When ETER is done at the central leaflet edges, it generates two MV orifices, leads to two deflected jets, and completely changes vortices in the LV. ETER also reduces the orifice area, and increases jet velocity and transmitral pressure [1,2,4]. Flow patterns in the LV and ETER effects on the LV and MV functions have not been understood well.

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Platelets, after Exposure to a High Shear Stress, Induce IL-10-Producing, Mature Dendritic Cells In Vitro

The Journal of Immunology ◽

10.4049/jimmunol.172.9.5297 ◽

2004 ◽

Vol 172 (9) ◽

pp. 5297-5303 ◽

Cited By ~ 62

Author(s):

Masao Hagihara ◽

Ayako Higuchi ◽

Noriko Tamura ◽

Yoko Ueda ◽

Kaori Hirabayashi ◽

...

Keyword(s):

Shear Stress ◽

Dendritic Cells ◽

High Shear ◽

High Shear Stress

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The Role of LIM Kinase-1 in the Glycoprotein Ib-IX Complex-Mediated Platelet Activation and Thrombus Formation

Blood ◽

10.1182/blood.v112.11.112.112 ◽

2008 ◽

Vol 112 (11) ◽

pp. 112-112

Author(s):

Aleksandra Stojanovic ◽

Matvey Gorovoy ◽

Tatyana Voyno-Yasenetskaya ◽

Xiaoping Du

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Platelet Activation ◽

Platelet Adhesion ◽

Wild Type ◽

Glycoprotein Ib ◽

Lim Kinase ◽

And Function

Abstract LIM Kinase (LIMK)-1 is a member of the LIMK family of serine-threonine protein kinases that phosphorylates actin-binding protein cofilin and regulates actin cytoskeleton organization. LIMK1 is expressed in many cell types including platelets but the exact role of LIMK1 in platelet function remains unclear. To determine the role of LIMK1 in platelet activation, wild type or LIMK1 knockout mouse platelets were stimulated with platelet agonists. Platelet aggregation and granule secretion were analyzed. Integrin-dependent second wave of platelet aggregation induced by von Willebrand factor (VWF) in the presence of VWF activator botrocetin was abolished in LIMK1 knockout platelets. In contrast, platelet aggregation in response to the agonist peptide of protease-activated receptor-4 (PAR4, thrombin receptor), ADP and collagen was either not affected or enhanced in LIMK1 knockout platelets in comparison with wild type mouse platelets. Thus, LIMK appears to play an important role in platelet activation stimulated by VWF binding to its platelet receptor, glycoprotein Ib-IX complex (GPIb-IX) but had no stimulatory effect on or negatively regulate the GPIb-IX-independent platelet activation pathways mediated by PAR-4, ADP receptors and collagen receptors. To determine whether ligand binding to GPIb-IX stimulates LIMK activation and function, platelets were stimulated with VWF in the presence of either ristocetin or botrocetin, and immunoblotted with antibodies specifically recognizing phosphorylated LIMK1 (Serine 505) or cofilin (Serine 3). VWF induced phosphorylation of LIMK1 and LIMK substrate cofilin. Thus, VWF indeed stimulates LIMK1 activation and function. An important physiological role of GPIb-IX in platelets is to mediate platelet adhesion to subendothelial-bound VWF under shear stress at sites of vascular injury. To determine whether LIMK1 is important in platelet adhesion, we investigated whether LIMK1 knockout affected platelet adhesion to VWF-coated surfaces. LIMK1 knockout platelets are defective in mediating stable platelet adhesion to vWF under shear stress, suggesting that LIMK1 plays an important role in GPIb signaling and GPIb-IX-mediated integrin activation that is required for stable platelet adhesion under shear stress. Importantly, LIMK1 knockout mice showed significant delay in the formation of occlusive thrombus following FeCl3-induced carotid artery injury in comparison with wild type mice, indicating that the role of LIMK1 in GPIb-IX-mediated platelet activation is important in in vivo thrombosis. Together, our study reveals that LIMK1 plays an important role in GPIb-IX-mediated platelet activation and arterial thrombosis in vitro and in vivo.

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