Influence of Hepatocellular Carcinoma on Platelet Aggregation in Cirrhosis

Hyper-functional platelets are being proposed as a potential therapeutic target in multiple cancers. Whether this can be considered in patients with cirrhosis and hepatocellular carcinoma (HCC) is unknown as their platelet function has not yet been investigated. We evaluated platelet function in cirrhosis patients with HCC. Patients with cirrhosis with and without HCC were prospectively recruited. Platelet aggregation, a marker of platelet function, was assessed by impedance aggregometry with adenosine diphosphate (ADP), arachidonic acid (ASPI), and thrombin (TRAP) stimulation. Plasmatic levels of Von Willebrand factor antigen (VWF) were also determined. One-hundred patients were recruited (50 cirrhotics with and 50 without HCC). Cirrhosis severity by Child class and platelet count were comparable between cirrhotics with and without HCC. Cirrhotics with HCC had higher ADP- (45 vs. 28; p < 0.001), ASPI- (47 vs. 28; p < 0.001), and TRAP- (85 vs. 75; p = 0.01) induced platelet aggregation than cirrhotics without HCC, all indicative of platelet hyper-function. The relatively increased platelet aggregation in patients with HCC was confirmed after adjusting the analysis for platelet count/severity of thrombocytopenia. Levels of VWF were higher in patients with vs. without HCC (348 vs. 267; p = 0.006), particularly in compensated cirrhosis. In patients with cirrhosis, HCC is associated with increased platelet aggregation and higher VWF. The clinical implications of these findings deserve further investigation.

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Platelet function in cats with hyperthyroidism

Journal of Feline Medicine and Surgery ◽

10.1177/1098612x20920585 ◽

2020 ◽

Vol 22 (12) ◽

pp. 1214-1218

Author(s):

Elizabeth C Hiebert ◽

David L Panciera ◽

Katie M Boes ◽

Lara Bartl

Keyword(s):

Platelet Count ◽

Platelet Function ◽

Adenosine Diphosphate ◽

Control Group ◽

Closure Time ◽

Function Analyzer ◽

The Mean ◽

Platelet Function Analyzer ◽

Von Willebrand ◽

Willebrand Factor

Objectives Cats with hyperthyroidism have been reported to develop thromboembolism, with and without echocardiographic abnormalities consistent with hyperthyroidism. The objective of this study was to compare platelet function in cats with hyperthyroidism with euthyroid age-matched cats. We hypothesized that cats with hyperthyroidism have shortened collagen and adenosine diphosphate (C-ADP) closure times as measured with the platelet function analyzer (PFA-100) in comparison with healthy, age-matched controls. Methods Sixteen hyperthyroid and nine euthyroid healthy cats >7 years of age were recruited from the hospital population. Platelet function, measured using the C-ADP closure times by the PFA-100, and platelet count were measured in healthy euthyroid cats and cats with hyperthyroidism. Results Mean ± SD closure times were not significantly different between control (66.3 ± 9.6 s) and hyperthyroid cats (65.9 ± 11.5 s; P = 0.75). The mean ± SD closure times of hyperthyroid cats that either were untreated or received methimazole for ⩽3 weeks (n = 6; mean 68.5 ± 15.4 s) was not different than that of cats treated for >3 weeks (n = 10; mean 64.3 ± 8.9 s; P = 0.57). The mean automated platelet count was higher in the hyperthyroid group than in the control group ( P = 0.023). Conclusions and relevance Platelet function, as measured by closure time under high shear conditions using C-ADP as an agonist, was not affected by hyperthyroidism in this group of cats. Further research is needed to determine if a hypercoagulable state exists in hyperthyroid cats and the potential roles platelets and von Willebrand factor may have.

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Platelet Function and the Bleeding Time in Progressive Renal Failure

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647640 ◽

1988 ◽

Vol 60 (01) ◽

pp. 083-087 ◽

Cited By ~ 30

Author(s):

M P Gordge ◽

R W Faint ◽

P B Rylance ◽

G H Neild

Keyword(s):

Renal Failure ◽

Platelet Aggregation ◽

Platelet Function ◽

Bleeding Time ◽

C Reactive Protein ◽

Severe Renal Failure ◽

Reactive Protein ◽

Thromboxane Production ◽

Von Willebrand ◽

Willebrand Factor

SummaryBleeding time and platelet function tests were performed on 31 patients with progressive chronic renal failure (CRF) due to non-immunological (urological) causes, and compared with 22 healthy controls. Patients were classified as mild (plasma creatinine <300 μmol/l), moderate (300-600 μmol/l) or severe renal failure (>600 μmol/l). Bleeding time was rarely prolonged in mild and moderate CRF and mean bleeding time significantly elevated only in severe CRF (p <0.005). Haematocrit was the only index which correlated with bleeding time (r = -0.40). Platelet counts, collagen stimulated thromboxane generation, and platelet aggregation responses to ADP, collagen and ristocetin were all either normal or increased in all three CRF groups, but thromboxane production in clotting blood was reduced. Plasma fibrinogen, C reactive protein and von Willebrand factor (vWF) were elevated in proportion to CRF. We found no evidence that defects in platelet aggregation or platelet interaction with vWF prolong the bleeding time in patients with progressive CRF.

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The aptamer BT200 blocks von Willebrand factor and platelet function in blood of stroke patients

Scientific Reports ◽

10.1038/s41598-021-82747-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Katarina D. Kovacevic ◽

Stefan Greisenegger ◽

Agnes Langer ◽

Georg Gelbenegger ◽

Nina Buchtele ◽

...

Keyword(s):

Platelet Function ◽

Von Willebrand Factor ◽

Stroke Prevention ◽

Adenosine Diphosphate ◽

Target Range ◽

Large Artery ◽

Dependent Manner ◽

Secondary Stroke Prevention ◽

Von Willebrand ◽

Willebrand Factor

AbstractThe effect of conventional anti-platelet agents is limited in secondary stroke prevention, and their effects are blunted under high shear stress in the presence of increased levels of circulating von Willebrand factor (VWF). VWF is critically involved in thrombus formation at sites of stenotic extracranial/intracranial arteries. A third generation anti-VWF aptamer (BT200) has been generated which could be useful for secondary stroke prevention. To characterize the effects of BT200 in blood of patients with large artery atherosclerosis stroke (LAA). Blood samples were obtained from 33 patients with acute stroke or transient ischemic attack to measure inhibition of VWF activity and VWF-dependent platelet function. Patients who received clopidogrel or dual antiplatelet therapy did not differ in VWF dependent platelet function tests from aspirin treated patients. Of 18 patients receiving clopidogrel with or without aspirin, only 3 had a prolonged collagen adenosine diphosphate closure time, and none of the patients had ristocetin induced aggregation in the target range. BT200 concentration-dependently reduced median VWF activity from 178 to < 3%, ristocetin induced platelet aggregation from 40U to < 10U and prolonged collagen adenosine diphosphate closure times from 93 s to > 300 s. Baseline VWF activity correlated (r = 0.86, p < 0.001) with concentrations needed to reduce VWF activity to < 20% of normal, indicating that BT200 acts in a target concentration-dependent manner. Together with a long half-life supporting once weekly administration, the safety and tolerability observed in an ongoing phase I trial, and the existence of a reversal agent, BT200 is an interesting drug candidate.

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Unique Antiplatelet Effects of a Novel S-Nitrosoderivative of a Recombinant Fragment of von Willebrand Factor, AR545C: In Vitro and Ex Vivo Inhibition of Platelet Function

Blood ◽

10.1182/blood.v94.5.1693.417k32_1693_1700 ◽

1999 ◽

Vol 94 (5) ◽

pp. 1693-1700

Author(s):

Aida Inbal ◽

Osnat Gurevitz ◽

Ilia Tamarin ◽

Regina Eskaraev ◽

Angela Chetrit ◽

...

Keyword(s):

Nitric Oxide ◽

Platelet Aggregation ◽

Platelet Function ◽

Von Willebrand Factor ◽

Platelet Adhesion ◽

Ex Vivo ◽

Aggregate Formation ◽

Recombinant Fragment ◽

Von Willebrand ◽

Willebrand Factor

The recombinant fragment of von Willebrand factor (vWF) spanning Ala444 to Asp730 and containing an Arg545Cys mutation (denoted AR545C) has antithrombotic properties that are principally a consequence of its ability to inhibit platelet adhesion to subendothelial matrix. Endothelial-derived nitric oxide (NO) can also inhibit platelet function, both as a consequence of inhibiting adhesion as well as activation and aggregation. Nitric oxide can react with thiol functional groups in the presence of oxygen to form S-nitrosothiols, which are naturally occurring NO derivatives that prolong the biological actions of NO. Because AR545C has a single free cysteine (Cys545), we attempted to synthesize the S-nitroso-derivative of AR545C and to characterize its antiplatelet effects. We successfully synthesized S-nitroso-AR545C and found that it contained 0.96 mol S-NO per mole peptide. S-nitroso-AR545C was approximately 5-fold more potent at inhibiting platelet agglutination than was the unmodified peptide (IC50 = 0.02 ± 0.006 μmol/L v 0.1 ± 0.03 μmol/L, P = .001). In addition and by contrast, S-nitroso-AR545C was a powerful inhibitor of adenosine diphosphate–induced platelet aggregation (IC50 = 0.018 ± 0.002 μmol/L), while AR545C had no effect on aggregation. These effects were confirmed in studies of adhesion to and aggregation on extracellular matrix under conditions of shear stress in a cone-plate viscometer, where 1.5 μmol/L S-nitroso-AR545C inhibited platelet adhesion by 83% and essentially completely inhibited aggregate formation, while the same concentration of AR545C inhibited platelet adhesion by 74% and had significantly lesser effect on aggregate formation on matrix (P ≤ .004 for each parameter by ANOVA). In an ex vivo rabbit model, we also found that S-nitroso-AR545C had a more marked and more durable inhibitory effect on botrocetin-induced platelet aggregation than did AR545C, and these differences were also reflected in the extent and duration of effect on the prolongation of the bleeding time in these animals. These data show that S-nitroso-AR545C has significant and unique antiplatelet effects, inhibiting both adhesion and aggregation, by blocking platelet GPIb receptor through the AR545C moiety and elevating platelet cyclic 3′,5′-guanosine monophosphate through the -SNO moiety. These observations suggest that this NO-modified fragment of vWF may have potential therapeutic benefits as a unique antithrombotic agent.

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Endothelial dysfunction and platelet function disorder in hemostasis in development of hepatic fibrosis in children with autoimmune hepatitis

I P Pavlov Russian Medical Biological Herald ◽

10.23888/pavlovj2018264500-510 ◽

2018 ◽

Vol 26 (4) ◽

pp. 500-510

Author(s):

Ekaterina Yu. Konovalova ◽

Alla E. Lavrova ◽

Marina V. Presnyakova

Keyword(s):

Platelet Count ◽

Platelet Aggregation ◽

Endothelial Dysfunction ◽

Autoimmune Hepatitis ◽

Hepatic Fibrosis ◽

Von Willebrand Factor ◽

Metavir Score ◽

Aggregation Activity ◽

Von Willebrand ◽

Willebrand Factor

The purpose is: To assess the clinical relevance of the endothelial condition and platelet aggregation in the development of hepatic fibrosis in children with autoimmune hepatitis. Materials and Methods. 35 patients aged from 3 to 17 years old were studied, including 19 girls - (54%) and 16 boys - (46%). The 1st group consisted of 17 children with the degree of fibrosis F 0-2 acc. to the METAVIR score; the 2nd group consisted of 18 patients with the degree of fibrosis F 3-4 (METAVIR) acc. to the METAVIR score based on the indirect elastometry data in children of the 2nd group hepatic cirrhosis was diagnosed; the control group consisted of 15 children with health group I or II. The endothelium state and the platelet aggregation activity were assessed in all the patients. To test statistical hypotheses, the Mann-Whitney U test, the Spearman correlation coefficient and the Fisher criterion were used. The critical value of the significance level is assumed to be 0.05. Quantitative data are presented as: median and the first; third quartile of Me (Q1; Q3). Results. In children with autoimmune hepatitis some signs of the various-degree fibrosis formation were revealed in the ¾ of the examined. Patients of the 2nd group have a more aggressive course as compared to the 1st group: in the disease debut there were mainly expressed asthenoneurotic complaints (p = 0.021), manifestations of the jaundice syndrome (p = 0.014), more frequently hepatic-cell insufficiency (p = 0.045) is diagnosed and followed by complications of the disease (hypersplenism (p = 0.014), varicose veins of the esophagus (p = 0.003)). All children with autoimmune hepatitis have the endothelial dysfunction, the enhancing platelet aggregation activity. The degree of fibrosis correlates with the concentration of endothelin-1 (r = 0.4, p = 0.004), the von Willebrand factor (vWF) activity (r = 0.5, p <0.001), the platelet count (r = -0.5, p = 0.003). The determination of the endothelin-1 concentration, the von Willebrand factor activity and the platelet count may be used to assess the hepatopathy severity in children with autoimmune hepatitis. Conclusion. In children with autoimmune hepatitis the endothelial dysfunction and platelet disorders are revealed in the hemostasis system correlating with the severity of the pathological process.

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Multiplate® Platelet Aggregation Findings Are Dependent on Platelet Count but Can Be Corrected by Use of a Ratio

Applied Sciences ◽

10.3390/app10227971 ◽

2020 ◽

Vol 10 (22) ◽

pp. 7971

Author(s):

Mohamed Soliman ◽

Matthias Hartmann

Keyword(s):

Platelet Count ◽

Platelet Aggregation ◽

Platelet Function ◽

Platelet Rich Plasma ◽

Platelet Aggregation Inhibitors ◽

Impedance Aggregometry ◽

Aggregation Inhibitors ◽

Thrombotic Complications ◽

Highly Correlated ◽

Bedside Method

Impedance aggregometry (Multiplate®) detects the effects of platelet aggregation inhibitors and can predict thrombotic complications after coronary and cerebrovascular stent interventions. The bedside method uses whole blood samples not corrected for platelet count. It is claimed but not proved that the findings are unrelated to platelet count in the physiological range. We therefore investigated in the experimental study: (1) whether impedance aggregometry findings and platelet count are correlated and (2) whether the aggregation/platelet count ratio expresses platelet function independent of platelet count. Following ethics committee approval, platelet-rich plasma from healthy probands was diluted with platelet-poor plasma to obtain different platelet counts. Thereafter, platelet count was measured and samples were subjected to impedance aggregometry using thrombin receptor activating peptide (TRAP) for platelet activation. In all probands, impedance aggregometry findings and platelet count were highly correlated (r = 0.88 to 0.94; p < 0.05). The combination of all experiments revealed the proportionality between impedance aggregometry findings and platelet count (n = 31, r = 0.78, p = 0.0001). In contrast, the ratio of impedance aggregometry findings and platelet count was not significantly correlated with platelet count (r = 0.017; p = 0.3) and thus constitutes a specific measure for platelet function. In conclusion, impedance aggregometry findings subsequent to the activation with TRAP are dependent on both platelet function and platelet count. Normalization of impedance aggregometry findings for platelet count can be achieved by a ratio resulting in more specific results.

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Reduced platelet function in subarachnoid hemorrhage

Journal of Neurosurgery ◽

10.3171/jns.1986.64.6.0907 ◽

1986 ◽

Vol 64 (6) ◽

pp. 907-910 ◽

Cited By ~ 10

Author(s):

Sotirios A. Tsementzis ◽

Jaswinder S. Gill ◽

Edward R. Hitchcock ◽

Jennifer A. Hartley ◽

Surinder K. Gill ◽

...

Keyword(s):

Platelet Count ◽

Subarachnoid Hemorrhage ◽

Platelet Aggregation ◽

Platelet Function ◽

Maximum Rate ◽

Adenosine Diphosphate ◽

Platelet Adhesiveness ◽

Content Type ◽

Aneurysmal Rupture ◽

Fine Print

✓ The hypothesis that abnormalities of platelet function may relate to the occurrence or recurrence of subarachnoid hemorrhage (SAH) has been examined. Seventy patients with SAH and 65 control individuals were studied. The adenosine diphosphate (ADP) threshold for secondary platelet aggregation was significantly higher in the SAH group than in the controls. In tests using 4.0 µg/ml ADP, the percent platelet aggregation (at 2 minutes) and the maximum rate of platelet aggregation (over 20 seconds) were significantly lower in the SAH patients. There was no difference in total platelet count between the two groups. Platelet adhesiveness was lower in the SAH patients when compared to controls. Circulating microaggregates did not differ between the two groups. The results indicate that reduced platelet function does relate to SAH and may either contribute to aneurysmal rupture in cases of SAH or be a consequence of it.

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The MICELI (MICrofluidic, ELectrical, Impedance): Prototyping a Point-of-Care Impedance Platelet Aggregometer

International Journal of Molecular Sciences ◽

10.3390/ijms21041174 ◽

2020 ◽

Vol 21 (4) ◽

pp. 1174 ◽

Cited By ~ 1

Author(s):

Yana Roka-Moiia ◽

Silvia Bozzi ◽

Chiara Ferrari ◽

Gabriele Mantica ◽

Annalisa Dimasi ◽

...

Keyword(s):

Platelet Count ◽

Platelet Aggregation ◽

Platelet Function ◽

Electrical Impedance ◽

Platelet Rich Plasma ◽

Point Of Care ◽

Calcium Ionophore ◽

Performance Comparison ◽

Operational Performance ◽

Impedance Aggregometry

As key cellular elements of hemostasis, platelets represent a primary target for thrombosis and bleeding management. Currently, therapeutic manipulations of platelet function (antithrombotic drugs) and count (platelet transfusion) are performed with limited or no real-time monitoring of the desired outcome at the point-of-care. To address the need, we have designed and fabricated an easy-to-use, accurate, and portable impedance aggregometer called “MICELI” (MICrofluidic, ELectrical, Impedance). It improves on current platelet aggregation technology by decreasing footprint, assay complexity, and time to obtain results. The current study aimed to optimize the MICELI protocol; validate sensitivity to aggregation agonists and key blood parameters, i.e., platelet count and hematocrit; and verify the MICELI operational performance as compared to commercial impedance aggregometry. We demonstrated that the MICELI aggregometer could detect platelet aggregation in 250 μL of whole blood or platelet-rich plasma, stimulated by ADP, TRAP-6, collagen, epinephrine, and calcium ionophore. Using hirudin as blood anticoagulant allowed higher aggregation values. Aggregation values obtained by the MICELI strongly correlated with platelet count and were not affected by hematocrit. The operational performance comparison of the MICELI and the Multiplate® Analyzer demonstrated strong correlation and similar interdonor distribution of aggregation values obtained between these devices. With the proven reliability of the data obtained by the MICELI aggregometer, it can be further translated into a point-of-care diagnostic device aimed at monitoring platelet function in order to guide pharmacological hemostasis management and platelet transfusions.

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Loss of high-molecular-weight von Willebrand factor multimers mainly affects platelet aggregation in patients with aortic stenosis

Thrombosis and Haemostasis ◽

10.1160/th09-06-0391 ◽

2010 ◽

Vol 103 (02) ◽

pp. 408-414 ◽

Cited By ~ 37

Author(s):

Roza Badr Eslam ◽

Alexandra Schneller ◽

Alexandra Kaider ◽

Daniela Koren ◽

Beate Eichelberger ◽

...

Keyword(s):

Platelet Aggregation ◽

Aortic Stenosis ◽

Valve Replacement ◽

Platelet Function ◽

Von Willebrand Factor ◽

Severe Aortic Stenosis ◽

High Shear ◽

Acquired Von Willebrand Syndrome ◽

Von Willebrand ◽

Willebrand Factor

SummarySevere aortic stenosis is associated with a haemostatic abnormality that resembles acquired von Willebrand syndrome type 2. It is assumed that high shear conditions render large von Willebrand factor (VWF) multimers accessible to cleavage by ADAMTS-13. However, whether loss of these large multimers affects platelet function by impairing adhesion, aggregate formation, or both has not been evaluated in clinical studies. We prospectively enrolled 47 patients with severe aortic stenosis, and studied them prior to aortic valve surgery and at a median of six months after valve replacement. We investigated levels of large VWF multimers, platelet function under high shear conditions, and residual response to suboptimal concentrations of ADP to express P-selectin. As expected, there was a significant reduction of VWF large multimers before surgery that resolved thereafter in most patients (p<0.0001). The closure time of the ADP cartridge of the PFA-100 was also corrected in most patients after the operation (p<0.0001). We used the cone and plate(let) analyser Impact-R to differentiate between adhesion and aggregation. Both adhesion (p=0.03) and ADP-inducible platelet aggregation (p=0.002) improved considerably after valve replacement. Consequently, ADP-inducible expression of P-selectin was higher after valve replacement (p=0.001). We conclude that reduced levels of large VWF multimers associated with aortic stenosis lead to impairment of both adhesion and, especially, ADP-inducible platelet aggregation.

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Unique Antiplatelet Effects of a Novel S-Nitrosoderivative of a Recombinant Fragment of von Willebrand Factor, AR545C: In Vitro and Ex Vivo Inhibition of Platelet Function

Blood ◽

10.1182/blood.v94.5.1693 ◽

1999 ◽

Vol 94 (5) ◽

pp. 1693-1700 ◽

Cited By ~ 9

Author(s):

Aida Inbal ◽

Osnat Gurevitz ◽

Ilia Tamarin ◽

Regina Eskaraev ◽

Angela Chetrit ◽

...

Keyword(s):

Nitric Oxide ◽

Platelet Aggregation ◽

Platelet Function ◽

Von Willebrand Factor ◽

Platelet Adhesion ◽

Ex Vivo ◽

Aggregate Formation ◽

Recombinant Fragment ◽

Von Willebrand ◽

Willebrand Factor

Abstract The recombinant fragment of von Willebrand factor (vWF) spanning Ala444 to Asp730 and containing an Arg545Cys mutation (denoted AR545C) has antithrombotic properties that are principally a consequence of its ability to inhibit platelet adhesion to subendothelial matrix. Endothelial-derived nitric oxide (NO) can also inhibit platelet function, both as a consequence of inhibiting adhesion as well as activation and aggregation. Nitric oxide can react with thiol functional groups in the presence of oxygen to form S-nitrosothiols, which are naturally occurring NO derivatives that prolong the biological actions of NO. Because AR545C has a single free cysteine (Cys545), we attempted to synthesize the S-nitroso-derivative of AR545C and to characterize its antiplatelet effects. We successfully synthesized S-nitroso-AR545C and found that it contained 0.96 mol S-NO per mole peptide. S-nitroso-AR545C was approximately 5-fold more potent at inhibiting platelet agglutination than was the unmodified peptide (IC50 = 0.02 ± 0.006 μmol/L v 0.1 ± 0.03 μmol/L, P = .001). In addition and by contrast, S-nitroso-AR545C was a powerful inhibitor of adenosine diphosphate–induced platelet aggregation (IC50 = 0.018 ± 0.002 μmol/L), while AR545C had no effect on aggregation. These effects were confirmed in studies of adhesion to and aggregation on extracellular matrix under conditions of shear stress in a cone-plate viscometer, where 1.5 μmol/L S-nitroso-AR545C inhibited platelet adhesion by 83% and essentially completely inhibited aggregate formation, while the same concentration of AR545C inhibited platelet adhesion by 74% and had significantly lesser effect on aggregate formation on matrix (P ≤ .004 for each parameter by ANOVA). In an ex vivo rabbit model, we also found that S-nitroso-AR545C had a more marked and more durable inhibitory effect on botrocetin-induced platelet aggregation than did AR545C, and these differences were also reflected in the extent and duration of effect on the prolongation of the bleeding time in these animals. These data show that S-nitroso-AR545C has significant and unique antiplatelet effects, inhibiting both adhesion and aggregation, by blocking platelet GPIb receptor through the AR545C moiety and elevating platelet cyclic 3′,5′-guanosine monophosphate through the -SNO moiety. These observations suggest that this NO-modified fragment of vWF may have potential therapeutic benefits as a unique antithrombotic agent.

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