Antiplatelet Drug Clopidogrel Research Articles

Clopidogrel Resistance in Ischemic Stroke Patients.

Stroke remained the second leading cause of death globally in 2019. The antiplatelet drug clopidogrel is used to keep blood clots from forming in people who have experienced a stroke. Although most people find clopidogrel to be safe and beneficial, there is inevitably a range in how each patient responds. The review covers about Clopidogrel resistance in stroke patients, their risk factors and the methods to identify it. Clopidogrel resistance is characterized as the drug's inability to prevent the target enzyme from acting. The prognosis of patients with ischemic stroke and the responsiveness to clopidogrel are significantly impacted by the various genetic polymorphism CYP2C19 genotypes. The two primary mutant alleles, CYP2C19 *2 and CYP2C19 *3, have been found to be the most prevalent genotypes. Better mRS scores six months after treatment showed a higher response rate in patients without these CYP2C19 variant alleles. Other factors are drug-drug interaction (proton pump inhibitors), demographics (age, sex, social history), comorbid conditions, etc. Blood samples for testing platelet reactivity were drawn one month after discharge from a peripheral blood sample. Several methods are used to identify the clopidogrel resistance. Some of them are ADP-Induced platelet aggregation, Platelet Reactivity Index VASP, Verify Now Assay, TEG Analyzer, Plasma microRNA-223. Drugs that are not prodrugs and whose metabolism is not dependent upon CYP2C19 can be selected as a superior alternative in case of CR. Ticagrelor is one such effective substitute. Proton pump inhibitors and clopidogrel should only be used concurrently in patients with reliable clinical indications.

Computational drug repositioning of clopidogrel as a novel therapeutic option for focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a glomerular lesion often associated with nephrotic syndrome. It is also associated with a high risk of progression to end-stage kidney disease. Current treatment of FSGS is limited to systemic corticosteroids or calcineurin inhibition, along with inhibitors of the renin-angiotensin-aldosterone system. FSGS is heterogeneous in etiology, and novel therapies targeting specific, dysregulated molecular pathways represent a major unmet medical need. We have generated a network-based molecular model of FSGS pathophysiology using previously established systems biology workflows to allow computational evaluation of compounds for their predicted interference with molecular processes contributing to FSGS. We identified the anti-platelet drug clopidogrel as a therapeutic option to counterbalance dysregulated FSGS pathways. This prediction of our computational screen was validated by testing clopidogrel in the adriamycin FSGS mouse model. Clopidogrel improved key FSGS outcome parameters and significantly reduced urinary albumin to creatinine ratio (P < 0.01) and weight loss (P < 0.01), and ameliorated histopathological damage (P < 0.05). Clopidogrel is used to treat several cardiovascular diseases linked to chronic kidney disease. Clopidogrel's favorable safety profile and its efficacy in the adriamycin mouse FSGS model thus recommend it as an attractive drug repositioning candidate for clinical trial in FSGS.

Influence of a new stimulator of soluble guanylate cyclase on platelet aggregation and vascular endothelial function in experimental ischemic stroke against the background of arterial hypertension

Background. Correction of endothelial dysfunction during arterial hypertension (AH) is an important measure in preventing cerebrovascular stroke. Drugs activating soluble guanylate cyclase (sGC) and 3’,5’-guanosine monophosphate (cGMP) production independently of nitric oxide (NO) were shown to be therapeutically useful in reducing the risk of stroke. The present work aims to study the antiaggregant and endothelium-protective activity of a new sGC stimulator, an indolinone derivative (2-[2-[(5RS)-5-(hydroxymethyl)-3-methyl-1,3-oxazolidine-2- yliden]-2-cyanoethylidene]-1H-indole-3(2H)-one (codename — GRS) in a model of ischemic stroke with AH. Prior studies have shown that GRS compound inhibits platelet aggregation, lowers blood pressure (BP) in spontaneouslyhypertensive SHR rats, prevents vascular occlusion in models of arterial and venous thrombosis. Antiplatelet drug clopidogrel, a P2Y12 receptor inhibitor, included in the standard of care for secondary prevention of ischemic stroke, was used as the reference drug.Objective. To assess the antiaggregant and endothelium-protective activity of a new indolinone derivative GRS, an sGC stimulator, compared to clopidogrel in a model of ischemic stroke concomitant with high arterial BP in spontaneously-hypertensive SHR rats.Design and methods. Focal brain ischemia/reperfusion was modelled in spontaneously-hypertensive SHR rats (n = 78). GRS in 10 mg/kg dose and clopidogrel in 10 mg/kg dose were administered orally once daily 3 days before modelling ischemia/reperfusion and for 5 days afterwards. Platelet aggregation and functioning of vascular endothelium were monitored.Results. Focal brain ischemia/reperfusion in SHR rats resulted in increased platelet aggregation and the development of endothelial dysfunction and disruption of vasodilatory function of endothelium. GRS compound and clopidogrel in repeated administration have prevented an increase in platelet aggregation (p &lt; 0,05), GRS compound also alleviated endothelial dysfunction (p &lt; 0,05).Conclusions. The indolinone derivative GRS, an sGC stimulator, inhibits increased platelet aggregation and prevents endothelial dysfunction in rats after focal brain ischemia/ reperfusion; the endothelium-protective effects of GRS aren’t related to its antiaggregant activity.

Copper (II) bromide catalysed one pot bromination and amination for the green, cost-effective synthesis of clopidogrel

Copper (II) bromide catalyzed one pot α-bromination and followed by amination of a benzylic ester is reported. The α-bromination of ester by copper (II) bromide generates copper (I) bromide and HBr. The copper (I) bromide is oxidized to copper (II) bromide by N-Methylmorpholine-N-Oxide (NMO) in presence of HBr. The amines undergo nucleophilic substitution reaction with α-brominated ester compound. This methodology was applied for the synthesis of the familiar antiplatelet drug clopidogrel. This green process is an alternate to classical methods for the synthesis of clopidogrel, which requires, generates stochiometric amount of brominating agents and HBr, respectively.

Activated platelets contribute to the progression of hepatocellular carcinoma by altering the tumor environment

AimHepatocellular carcinoma (HCC) is a primary liver cancer that usually develops in a background of chronic liver disease and prolonged inflammation. A major contributor in the complex molecular pathogenesis of HCC is the highly intertwined cross-talk between the tumor and the surrounding stromal cells, such as hepatic stellate cells, endothelial cells, macrophages and other immune cells. These tumor-stroma interactions actively fuel tumor growth and modulate the hepatic microenvironment to benefit tumor invasion and disease progression. Platelets have been reported to interact with different cell types in the tumor microenvironment, including tumor cells, stellate cells and macrophages. Materials and methodsMice were treated with hepatocarcinogenic compound diethylnitrosamine for 25 weeks to induce HCC in the background of fibrosis and inflammation. From week 10, anti-platelet drug Clopidogrel was added to the drinking water and mice were given ad libitum access. Key findingsIn this study, we show that activated platelets promote tumor cell proliferation and contribute to the adverse tumor-stroma cross-talk that fuels tumor progression. We also show that inhibiting platelet activation with the P2Y12-inhibitor Clopidogrel decreases the number of tumors in a chemically induced mouse model for HCC. SignificanceThese results suggest an important role for platelets in the pathogenesis of HCC and that the use of anti-platelet drugs may be therapeutically relevant for patients with liver cancer.

Iridium and bis(4-nitrophenyl)phosphoric acid catalysed amination of diol by hydrogen-borrowing methodology for the synthesis of cyclic amine: Synthesis of clopidogrel

Abstract The borrowing hydrogen method is an environmentally benign process for the synthesis of amines, as H2O is the side product. A new green process for the amination of diol by [Ir] catalyst 15 and bis(4-nitrophenyl)phosphoric acid for the synthesis of cyclic amine is reported. This method was successfully applied for the synthesis of antiplatelet drug clopidogrel.

Antithrombotic therapy in patients with coronary heart disease and atrial fibrillation after direct myocardial revascularization

Aim. To evaluate the clinical efficacy and safety of direct oral anticoagulants versus warfarin as part of antithrombotic therapy (ATT), namely, to study the frequency of bleeding and thromboembolic complications in patients with atrial fibrillation (AF) after direct myocardial revascularization in combination with radiofrequency isolation of pulmonary veins.Material and Methods. A total of 44 patients (36 men) aged 44–77 years (average age of 63.5 ± 7.8 years) with coronary heart disease, indications for direct myocardial revascularization, and AF were included in the study from 2014 to 2016. The observation period was 24 months.Results. Warfarin was one of the components of ATT in 20 patients (48%). However, the target values of international normalized ratio (INR) within the therapeutic range for over 70% of the time were achieved only in seven patients. Two patients who were taking warfarin without achieving target INR values for 24 months suffered from ischemic stroke. One patient taking warfarin (without regular INR control) had gastrointestinal bleeding requiring hospitalization and conservative therapy; ten patients had minor bleedings (nasal and gingival bleeding). All patients, who suffered from thromboembolic and hemorrhagic complications and had inadequate warfarin intake, were recommended to switch to direct oral anticoagulants (DOAC). Thirteen patients (29%) were administered with DOAC: five patients took rivaroxaban 20 mg/day, four patients took dabigatran 300 mg/day, and four patients took apixaban 10 mg/day. DOAC therapy was administered in combination with one of the antiplatelet drugs (aspirin or clopidogrel). In the case of DOAC administration, only minor bleedings were observed: one patient had hemorrhoidal bleeding and four patients had nasal bleedings, which did not require hospitalization, medical intervention, or suspension of anticoagulant therapy. There were no other adverse events in patients taking DOAC.Conclusions. Patients administered with DOAC as a part of antithrombotic therapy after coronary bypass surgery and surgical epicardial radiofrequency isolation of the pulmonary veins had lower incidence rates of thromboembolic and hemorrhagic complications compared with the rates in patients taking warfarin. However, no statistically significant differences were found between the groups due to the small sample size.

Analysis of the Potential Association of Drug-Metabolizing Enzymes CYP2C9*3 and CYP2C19*3 Gene Variations With Type 2 Diabetes: A Case-Control Study.

Cytochrome P450s (CYPs) are drug-metabolizing enzymes catalyzing the metabolism of about 75% of drug in clinical use. CYP2C9 represents 20% CYP proteins in liver cells and is a crucial member of CYPs superfamily. CYP2C19 metabolizes very important drugs such as antiulcer drug omeprazole, the antiplatelet drug clopidogrel and anticonvulsant mephenytoin. Single nucleotide polymorphisms (SNPs) of CYP genes have been associated with unexpected drug reactions and diseases in different populations. We examined the associations of CYP2C9*3 (rs1057910) and CYP2C19*3 (rs4986893) with T2D in Saudi population. We used the allele-specific PCR (AS-PCR) and DNA sequencing in 111 cases and 104 controls for rs1057910, and in 119 cases and 110 controls for rs4986893. It is indicated that the genotype distribution of rs1057910 in cases and controls were not significantly different (P=0.0001). The genotypes of rs1057910 were not associated with type 2 diabetes (T2D) (P>0.05). Whereas the genotype distribution of rs4986893 in cases and controls was significantly different (P=0.049). The AA genotype of rs4986893 may be associated in increased risk to T2D with OR=17.25 (2.06-143.8), RR=6.14(0.96-39.20), P=0.008. The CYP2C9*3 (rs1057910) may not be associated with T2D, while CYP2C19*3 (rs4986893) is probably associated with T2D. These findings need to be validated in follow-up studies with larger sample sizes and different populations.

CYP2C19 genotype-guided antiplatelet therapy: promises and pitfalls.

Pharmacogenetic variants can alter the mechanism of action (pharmacodynamic gene variants) or kinetic processes such as absorption, distribution, metabolism and elimination (pharmacokinetic gene variants). Many initial successes in precision medicine occurred in the context of genes encoding the cytochromes P450 (CYP enzymes). CYP2C19 activates the antiplatelet drug clopidogrel, and polymorphisms in the CYP2C19 gene are known to alter the outcome for patients taking clopidogrel in the context of cardiovascular disease. CYP2C19 loss-of-function alleles are specifically associated with increased risk for coronary stent thrombosis and major adverse cardiovascular events in patients taking clopidogrel following percutaneous coronary intervention. We explore successes and challenges encountered as the clinical and scientific communities advance CYP2C19 genotyping in the context of routine patient care.

Exploring the effect of khat (Catha edulis) chewing on the pharmacokinetics of the antiplatelet drug clopidogrel in rats using the newly developed LC-MS/MS technique

AbstractClopidogrel (CLOP) is widely used worldwide for cardiovascular complications. CLOP is highly metabolized in the liver to its active metabolite by cytochrome P450 enzymes. Studies have shown that khat, an addictive substance, is a powerful inhibitor of cytochrome P450 enzymes and can influence the metabolism of drugs that are concomitantly used. Therefore, this study was designed to evaluate the effects of khat on the pharmacokinetics of CLOP in rats. In this study, rats were administered either CLOP alone or CLOP combined with khat and their plasma were obtained at different time intervals and analyzed using the newly developed and validated liquid chromatography with tandem mass spectrometry (LC-MS/MS) method using foretinib (FTB) as the internal standard. The corresponding peak area of the analyte versus FTB was used for calculating the peak ratio. The validated LC-MS/MS method resulted in the separation of the well-defined quantifiable peaks of CLOP, FTB, and CLOP metabolite within 7 min. Results showed a significant influence of khat on the peak ratio of CLOP metabolite, which was found to be significantly decreased (P &lt; 0.05) in comparison to CLOP alone, suggesting significant decrease in the conversion of CLOP to its active metabolite due to the inhibition of CYP450 enzymes by khat. Therefore, there might be a need for dose adjustment for regular khat chewers using CLOP.

Antithrombotic therapy after TAVI.

The combination of oral anticoagulation and the antiplatelet drug clopidogrel increases the risk of bleeding after transcatheter aortic valve implantation (TAVI) compared with oral anticoagulation alone, according to the results of the POPular TAVI trial cohort B.

Rhodium-Catalyzed Asymmetric Addition of Arylboronic Acids to Glyoxylates: Access to Optically Active Substituted Mandelic Acid Esters

A rhodium-catalyzed enantioselective addition of glyoxylates to arylboronic acids promoted by a simple chiral sulfinamide-based olefin ligand under mild reaction conditions is described. The reaction provides access to a variety of optically active substituted mandelic acid esters in good yields with up to 83% ee. The catalytic system is also applicable to pyruvate addition. The synthetic utility of this method is highlighted by a formal synthesis of the antiplatelet drug clopidogrel.

One-step colorimetric genotyping of single nucleotide polymorphism using probe-enhanced loop-mediated isothermal amplification (PE-LAMP).

Single nucleotide polymorphism (SNP) is the most abundant molecular marker associated with many physiologic and pathologic phenotypes. An isothermal, accurate and cost-effective SNP detection could make a great difference in point-of-care testing (POCT) or on-site diagnosis. However, there are two challenges, the expensive instrument and labor-intensive process, faced by the development of on-site SNP detection. We reported a novel SNP typing method based on the probe-enhanced loop-mediated isothermal amplification (PE-LAMP), which combines the oligonucleotide probe with a conventional LAMP to realize the SNP discrimination by analyzing the great discrepancy in amplification efficiency.Methods: We firstly constructed the genotyping method by combining the hybridization of the specific probe with the powerful amplification of LAMP. Then we validated the method by genotyping the SNP rs3741219 and we sought to realize one-step visualized typing. Finally, we applied the method to pharmacogenomic testing by genotyping CYP2C19*2 and MDR1 C3435T.Results: The PE-LAMP was successfully constructed to detect SNP and the sensitivity of our method is as low as 1000 copies of target DNA, which is sufficient to routine diagnosis. The high specificity in detecting mutant in the presence of excess wild-type allele could be achieved. It has shown good performance in helping predict the individual response of antiplatelet drug Clopidogrel through typing simply treated saliva samples.Conclusions: The proposed method is one-step, colorimetric, specific and sensitive enough to detect crudely treated samples, showing great potential in the pharmacogenomic study and POCT use.

293. Preclinical assessment of new generation antiplatelet therapies to prevent preeclampsia

Key pathophysiological steps in preeclampsia include 1) placental oxidative stress, 2) elevated sFlt1 and 3) endothelial dysfunction. While the antiplatelet drug aspirin has shown potential to prevent preeclampsia, its effectiveness remains limited. New generation antiplatelet drugs (Clopidogrel, Prasugrel and Ticagrelor) have distinct properties beyond antiplatelet actions (inflammation and endothelial dysfunction), thus may be more effective to prevent preeclampsia. We examined whether new generation antiplatelet drugs are better than aspirin at countering various pathophysiological steps in models of preeclampsia. Methods Primary human cytotrophoblast, placental explants and endothelial cells (HUVEC and uterine microvascular (UtMVs)) were treated with increasing doses of Clopidogrel, Prasugrel, Ticagrelor or Aspirin (0–100 μM). Endothelial dysfunction was induced and antiplatelet agents were added. Functional assays measured the adherence of primary human monocytes to stimulated endothelial cells. Media and cell lysates were collected to assess 1) ROS production, 2) antioxidant response element signaling pathways, 3) production of vasoactive mediators, 4) production of sFlt1, PlGF and pro-inflammatory mediators and 4) markers of endothelial dysfunction. Results New generation antiplatelet agents induced nuclear Nrf2 translocation (antioxidant transcription factor), increased antioxidant gene expression (HO-1, NQO1 and GCLC). Consistently reactive oxygen species (ROS) production was reduced with new generation antiplatelet treatment. Furthermore the new generation antiplatelets potently reduced sFlt1 secretion from preeclamptic placental explants, and importantly they also increased PlGF mRNA expression. Antiplatelet agents rescued endothelial dysfunction, mitigating monocyte-endothelial adhesion, and reduced VCAM1 and ET-1 expression (both mRNA and protein) and enhanced eNOS activity. Aspirin however had no beneficial effects in our in vitro/ex vivo models of preeclampsia. Conclusions In contrast to aspirin, new generation antiplatelets potently upregulate antioxidant defences, reduce ROS formation, decrease sFlt1 secretion, enhance activity of vasoactive mediators and counter endothelial dysfunction in human models of preeclampsia. Given they are classified as category B/C drugs, they represent exciting candidate therapies to prevent preeclampsia.

Combination Therapy with DETA/NO and Clopidogrel Inhibits Metastasis in Murine Mammary Gland Cancer Models via Improved Vasoprotection

Vascular endothelial dysfunction and platelet activation play a key role in tumor metastasis, and therefore, both of these processes are considered important therapeutic targets in cancer. The aim of our studies was to analyze antimetastatic activity of combination therapy using nitric oxide donor DETA/NO and antiplatelet drug clopidogrel. Nitric oxide acts as a vasoprotective mediator, while clopidogrel inhibits ADP-mediated platelet aggregation. 4T1-luc2-tdTomato cell line transplanted intravenously (i.v.) and 4T1 cell line transplanted orthotopically were used as metastatic mammary gland cancer models. Moreover, antiaggregation action of compounds was tested ex vivo on the blood samples taken from breast cancer patients. We have shown that in selected dosage regimes, DETA/NO combined with clopidogrel significantly reduced lung metastatic foci formation in an i.v. model, and such inhibition was transiently observed also in an orthotopic model. The antimetastatic effect was correlated with a significant increase of prostacyclin (PGI2) metabolite and reduction of endothelin-1, sE-selectin, sI-CAM, and TGF-β plasma levels as well as decreased V-CAM expression on the endothelium. Combination therapy decreased fibrinogen binding to the resting platelets at the early stage of tumor progression (day 14). However, at the later stages (days 21 and 28), the markers of platelet activation were detected (increased JON/A antibody bound, P-selectin level, binding of fibrinogen, and vWf). Decreased aggregation as well as a lower release of TGF-β were detected in platelets incubated ex vivo with compounds tested from metastatic breast cancer patients. Although combination therapy increases E-cadherin, the increase of N-cadherin and α-SMA in tumor tissue was also observed. The results showed that at the early stages of tumor progression, combined therapy with DETA/NO and clopidogrel improves vasoprotective and antiplatelet activity. However, in advanced tumors, some adverse effects toward platelet activation can be observed.

Adherence to Platelet Inhibitor Therapy Following Percutaneous Coronary Intervention

The antiplatelet drugs clopidogrel, prasugrel, and ticagrelor (Brilinta) are prescribed following percutaneous coronary intervention (PCI). In this

Clopidogrel Carboxylic Acid Glucuronidation is Mediated Mainly by UGT2B7, UGT2B4, and UGT2B17: Implications for Pharmacogenetics and Drug-Drug Interactions .

The antiplatelet drug clopidogrel is metabolized to an acyl-β-d-glucuronide, which causes time-dependent inactivation of CYP2C8. Our aim was to characterize the UDP-glucuronosyltransferase (UGT) enzymes that are responsible for the formation of clopidogrel acyl-β-d-glucuronide. Kinetic analyses and targeted inhibition experiments were performed using pooled human liver and intestine microsomes (HLMs and HIMs, respectively) and selected human recombinant UGTs based on preliminary screening. The effects of relevant UGT polymorphisms on the pharmacokinetics of clopidogrel were evaluated in 106 healthy volunteers. UGT2B7 and UGT2B17 exhibited the greatest level of clopidogrel carboxylic acid glucuronidation activities, with a CLint,u of 2.42 and 2.82 µl⋅min-1⋅mg-1, respectively. Of other enzymes displaying activity (UGT1A3, UGT1A9, UGT1A10-H, and UGT2B4), UGT2B4 (CLint,u 0.51 µl⋅min-1⋅mg-1) was estimated to contribute significantly to the hepatic clearance. Nonselective UGT2B inhibitors strongly inhibited clopidogrel acyl-β-d-glucuronide formation in HLMs and HIMs. The UGT2B17 inhibitor imatinib and the UGT2B7 and UGT1A9 inhibitor mefenamic acid inhibited clopidogrel carboxylic acid glucuronidation in HIMs and HLMs, respectively. Incubation of clopidogrel carboxylic acid in HLMs with UDPGA and NADPH resulted in strong inhibition of CYP2C8 activity. In healthy volunteers, the UGT2B17*2 deletion allele was associated with a 10% decrease per copy in the plasma clopidogrel acyl-β-d-glucuronide to clopidogrel carboxylic acid area under the plasma concentration-time curve from 0 to 4 hours (AUC0-4) ratio (P < 0.05). To conclude, clopidogrel carboxylic acid is metabolized mainly by UGT2B7 and UGT2B4 in the liver and by UGT2B17 in the small intestinal wall. The formation of clopidogrel acyl-β-d-glucuronide is impaired in carriers of the UGT2B17 deletion. These findings may have implications regarding the intracellular mechanisms leading to CYP2C8 inactivation by clopidogrel.

Influence of a low dosage of clopidogrel on platelet function in cats as measured by the platelet function analyser PFA-100 and the multiplate analyser

The antiplatelet drug clopidogrel is widely used for prophylaxis of arterial thromboses in cats in a standard dosage of 18.75mg per cat once daily. The aim of the study was to verify if a reduced daily dose of 10mg clopidogrel per cat has a similar antiplatelet effect as the standard dosage. Platelet function was measured with the platelet function analyser PFA-100® and a novel impedance aggregometer.Suitability of the platelet function analyser was tested in citrated blood samples of 59 healthy cats and reference ranges were established. In addition, agonist concentrations for impedance aggregometry were optimised. In the main experiment two groups of 6 healthy cats received clopidogrel either in a dosage of 10 or 18.75mg per cat over a period of seven days. Analyses were performed on days 1, 2, 3, 5, and 7.In comparison to baseline both clopidogrel dosages showed an inhibitory effect on results of the platelet function analyser and velocity of ADP-induced platelet aggregation. Values at all times were different from baseline, with the exception of day 1 in cats receiving 10mg clopidogrel where the closure time of the platelet function analysis and part of ADP-induced aggregation did not show a significant difference. Significant differences were not found between the two doses.In conclusion, our study indicates that 10mg clopidogrel per day may be as effective as 18.75mg although the latter may be advantageous as an initial loading dosage to achieve effective levels more rapidly.

In Vitro Effects of Pantoprazole on Platelet Aggregation in Blood Samples From Clopidogrel and Aspirin-treated Patients.

Platelet inhibition during treatment with the antiplatelet drug clopidogrel is prone to great interindividual variability and is believed to be affected by several factors such as genetics and drug-drug interactions. Proton pump inhibitors have been shown to interfere with the liver metabolism of clopidogrel. However, there are limited data on any direct effects proton pump inhibitors may have on clopidogrel. The aim of the study was to evaluate whether the in vitro addition of pantoprazole affects platelet aggregation in blood samples from clopidogrel and aspirin-treated patients. Blood samples were drawn from 66 patients on clopidogrel and aspirin who underwent coronary angiography. Platelet aggregation was analyzed using the bed-side Plateletworks assay before and after the addition of 2 different amounts of pantoprazole. The addition of 2.5 μL (4 mg/mL) pantoprazole, final concentration 0.01 mg/mL, was followed by a significant reduction (26%, P ≤ 0.001) of platelet aggregation, which was further reduced (39%, P ≤ 0.001) when a higher dose, 10 μL (4 mg/mL), final concentration 0.04 mg/mL, was added. In conclusion, platelet aggregation was significantly decreased by in vitro addition of pantoprazole. To explore the clinical relevance of this, future studies are needed.

Activated platelets inhibit hepatocellular carcinoma cell differentiation and promote tumor progression via platelet-tumor cell binding.

Lack of differentiation in hepatocellular carcinoma (HCC) is associated with increased circulating platelet size. We measured platelet activation and plasma adenosine diphosphate (ADP) levels in HCC patients based on differentiation status. Local platelet accumulation and platelet-hepatoma cell binding were measured using immunohistochemistry (IHC) or flow cytometry. Using a xenograft assay in NON/SCID mice, we tested the effects of the anti-platelet drug clopidogrel on platelet activation, platelet infiltration, platelet-tumor cell binding and tumor cell differentiation. HCC patients with poor differentiation status displayed elevated platelet activation and higher ADP levels. Platelets accumulated within poorly differentiated tissues and localized at hepatoma cell membranes. Platelet-tumor cell binding was existed in carcinoma tissues, largely mediated by P-selectin on platelets. NOD/SCID mice with xenograft tumors also exhibited increased platelet activation and platelet-tumor cell binding. Clopidogrel therapy triggered hepatoma cell differentiation by attenuating platelet activation and platelet-tumor cell binding. TCF4 knockdown promoted HepG-2 cell differentiation and inhibited tumor formation, and TCF4 could be the potential downstream target for clopidogrel therapy.