Platelet Activation Research Articles

Zolmitriptan niosomal transdermal patches: combating migraine via epigenetic and endocannabinoid pathways and reversal of migraine hypercoagulability.

Conventional zolmitriptan (ZOL) has limited oral bioavailability, many adverse effects, and poor membrane penetrability that negatively influences its accessibility to its 5-HT1B/1D receptor binding pocket, located transmemberanous. This work aimed at preparing transdermal ZOL-nanoformulation (niosomes) to surpass these limitations and to explore novel antimigraine mechanisms for ZOL via modulation of the epigenetically-altered chronification genes (RAMP-1, NPTX-2) or microRNAs and affecting the endocannabinoid CB-1/MAPK pathway. The prepared ZOL niosomes (Fsp60/6-1:1) exhibited %EE of 57.28%, PS of 472.3nm, PDI of 0.366, and ZP of -26 mV were cast into patch with content uniformity of 93.12%, maintained endurance after 200-times folding, no interaction between its components (FT-IR), a biphasic release pattern and good stability after storage at 4°C for 6 months. In-vivo ZOL-patch application in rats with nitroglycerin-induced migraine showed significant management of migraine pain symptoms and photophobia assessed behaviorally, decreased brain levels of the trigeminal neuronal activation marker (c-fos), the migraine pain neurotransmitter (CGRP) and the serum levels of different migraine pain markers (substance P, nitric-oxide, and TNF-α). It also significantly decreased RAMP-1, NPTX-2, miR-382-5p, and CB-1/MAPK gene expression reflecting improved efficacy and brain receptors delivery to a much greater extent than conventional ZOL has done. Additionally, this nanoformulation significantly opposed migraine-induced platelet activation and hypercoagulable status in both central and peripheral circulations as evidenced by the significant decrease in adenosine diphosphate, thrombin, factor X, CD41, and Von-Willebrand factor levels assessed peripherally and centrally. TPFsp60/6-1:1 significantly improved ZOL efficacy and accessibility to brain-receptors to a much greater extent than conventional ZOL-solution.KeywordsEndocannabinoid receptors; Epigenetically-altered genes; Hemostatic pathways; Niosomal patch; Transdermal; Zolmitriptan.

The role of protein kinase C and the glycoprotein Ibα cytoplasmic tail in anti-glycoprotein Ibα antibody-induced platelet apoptosis and thrombocytopenia

IntroductionImmune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet counts. ITP patients with anti-platelet glycoprotein (GP) Ibα (a subunit of GPIb-IX-V complex) autoantibodies, which induce Fc-independent signaling and platelet clearance, are refractory to conventional treatment. Protein kinase C (PKC) is activated by the binding of the ligand von Willebrand factor to GPIbα and regulates VWF-GPIbα-induced platelet activation. However, the role of PKC in anti-GPIbα antibody-induced thrombocytopenia remains unknown. Materials and methodsThe anti-GPIbα antibody-induced PKC activation and its underlying mechanisms were first detected by Western blot, and then the effects of PKC inhibitors, PKC knockout, or GPIbα C-terminal removal on anti-GPIbα antibody-induced platelet apoptosis, activation, aggregation, and clearance were investigated by flow cytometry, platelet aggregometry, and platelet posttransfusion, respectively. Meanwhile, platelet retention and co-localization with macrophages in the liver were detected by spinning disc intravital confocal microscopy. ResultsAnti-GPIbα antibody-induced PKC activation depends on GPIbα clustering and phosphoinositide 3-kinase (PI3K) activation and results in Akt phosphorylation. Pharmacologic inhibition or genetic ablation of PKC suppresses anti-GPIbα antibody-induced platelet apoptosis and activation. Moreover, the GPIbα cytoplasmic tail is required for antibody-induced PKC activation, platelet apoptosis, and activation. Inhibition or ablation of PKC and deletion of the GPIbα cytoplasmic tail protect platelets from clearance in vivo. ConclusionsOur study indicates the important role of PKC and the GPIbα cytoplasmic tail in anti-GPIbα antibody-mediated platelet signaling and clearance and suggests a novel therapeutic target for ITP and other thrombocytopenic diseases.

Qihuang Zhuyu Formula Modulates Mitochondrial Function to Inhibit Platelet Activation via Endocannabinoid Signaling Mediated by the SIRT1/PPARα Pathway

Ethnopharmacological relevanceDeveloping effective drugs is urgent for preventing platelet activation and atherosclerotic disease. Qihuang Zhuyu Formula (QHZYF) is a curative medical plants formula in clinic while its molecular mechanism remains to be further elucidated. Aim of the studyTo investigate how QHZYF, via the sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor alpha (PPARα) pathway, mediates the endocannabinoid system, regulates mitochondrial function, and inhibits platelet activation, thereby offering novel strategies for the prevention and treatment of cardiovascular diseases. MethodsThe chemical constituents of QHZYF were characterized by ultra-performance liquid chromatography tandem with quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MS). For the in vivo experiments, an atherosclerosis rat model was developed. Platelet activation and endocannabinoid levels were assessed by ELISA, while the expression of PPARα was evaluated by immunofluorescence. Additionally, the expression of endocannabinoid-degrading enzymes was analyzed by Western blotting. In the in vitro studies, the protein-protein interaction between SIRT1 and PPARα was initially investigated using co-immunoprecipitation (Co-IP). Thereafter, platelets were co-cultured with human umbilical vein endothelial cells (HUVECs) stimulated by oxidized low-density lipoprotein (ox-LDL). The mitochondrial function of platelets was examined by flow cytometry. Platelet activation and endocannabinoid levels were quantified using ELISA, and the expression of PPARα and endocannabinoid-degrading enzymes was determined by Western blotting. Subsequently, QHZYF was incorporated into the aforementioned system, and the entire experimental protocol was replicated to explore how QHZYF influences platelet activation through the SIRT1/PPARα pathway-mediated endocannabinoid system. ResultsIn the in vivo experiments, it was observed that QHZYF significantly augmented the levels of SIRT1 and PPARα, concurrently with a decrease in the expression of endocannabinoid-degrading enzymes. This was paralleled by a rise in endogenous cannabinoid levels and a reduction in platelet activation, a process that was found to be regulated by SIRT1. The co-immunoprecipitation (Co-IP) analysis substantiated the cooperative interaction between SIRT1 and PPARα, underscoring their role in mediating the endocannabinoid system, regulating mitochondrial function, and consequently influencing platelet activation. In the in vitro studies, a co-culture system involving platelets and HUVECs stimulated with ox-LDL was employed. It was noted that the SIRT1/PPARα pathway mediates the endocannabinoid system in regulating mitochondrial function, which in turn affects platelet activation. The incorporation of QHZYF-containing serum into this system produced outcomes consistent with those observed in the in vivo experiments. These findings suggest that QHZYF operates by modulating the endocannabinoid system via the SIRT1/PPARα pathway, thereby controlling mitochondrial function and inhibiting platelet activation. ConclusionSIRT1 may mediate endogenous cannabinoid signaling through its interaction with PPARα, regulating mitochondrial function and subsequently influencing platelet activation. QHZYF effectively modulates the endocannabinoid system via the SIRT1/PPARα pathway, thereby inhibiting platelet activation.

Serotonin-functionalized starch-based hemostatic sponges enhance platelet activation in the management of non-compressible hemorrhage

Massive hemorrhage poses a serious threat to human health and even life. Access to rapid and potent hemostatic materials is crucial for lowering mortality rates. Starch-based materials exhibit good biocompatibility and are extensively utilized in hemostatic. However, existing starch-based hemostatic products suffer from limited hemostatic efficacy. Serotonin, an indoleamine naturally occurring in the human body, is recognized for its potent platelet-activating properties. Therefore, this study focused on enhancing the procoagulant activity of starch by incorporating serotonin into the starch backbone via esterification and amidation reactions, yielding a novel serotonin-loaded starch-based hemostatic sponge (SLS sponge). The SLS sponges featured exceptional porosity (≥80 %) and water absorption capacity (≥2000 %), which rapidly initiated the coagulation cascade reaction, promoted the adhesion and aggregation of red blood cells and platelets, and intensified platelet activation. This multifaceted approach synergistically enhanced hemostasis via both active and passive coagulation mechanisms. Notably, the SLS sponges adhered firmly to the wound surfaces without pressure. Compared with gelatin sponges, the SLS sponges significantly reduced blood loss by approximately 40.5 % and shortened the time to achieve hemostasis by approximately 28.9 %. These findings indicate that the newly developed SLS sponges are a promising active hemostatic material, particularly effective in managing non-compressible hemorrhages.

Angiopoietin-2 and D-dimer add prognostic information to clinical risk in pulmonary arterial hypertension

Thrombosis and endothelial injury are pathologic hallmarks of pulmonary arterial hypertension (PAH). We aimed to evaluate whether markers of endothelial dysfunction and coagulation in the blood would provide insight into disease activity, treatment response, and outcomes in PAH. MethodsWe prospectively collected baseline and 3-month follow-up blood samples from treatment-naïve PAH patients (n=22) and those who had a clinical indication to intensify therapy (n=19). In addition, we recruited 12 healthy people and clinically stable PAH patients (n=45) as controls who had two blood samples collected twice within 14 days. We generated platelet-free plasma and measured D-dimer, angiopoietin-2, thrombin time, soluble P-selectin, von Willebrand factor, and vascular endothelial growth factor. We assessed treatment response with Reveal Lite 2 scores (all patients had NT-pro-BNP, 6-minute-walk, and functional class assessment at both visits) and followed clinical outcomes for 3 years. ResultsAngiopoietin-2 levels were elevated and fell with response to effective therapy (drop in Reveal Lite 2 score). At follow-up, persistently elevated angiopoietin-2 levels predicted clinical events and even identified low-risk participants who subsequently had events. D-dimer levels were also elevated in PAH patients but didn’t change in response to therapy. Several other abnormalities in endothelial and platelet activation were identified (including elevated soluble P-selectin, elevated von Willebrand factor, and elevated vascular endothelial growth factor) but these did not change with treatment or predict outcome. ConclusionsAngiopoietin-2 and D-dimer are elevated in PAH patients and may add prognostic information to routine clinical assessment.

Protein disulfide isomerase 1 (PDIA1) regulates platelet-derived extracellular vesicle release

BackgroundProtein disulfide isomerase 1 (PDIA1) and 3 (PDIA3) regulate platelet activation and thrombus formation. However, their role in the formation of platelet-derived extracellular vesicles (pEVs) remains unknown. AimTo characterise the effects of PDIA1 and PDIA3 inhibition on pEV formation in washed murine platelets in response to platelet glycoprotein VI (GPVI) receptor or intracellular calcium signal activation. MethodsWashed platelets were isolated from C57BL/6 mice and activated using convulxin or the calcium ionophore A23187. Then, the resulting pEVs were analysed using nano flow cytometry (FC), platelet aggregation was measured by FC and a 96-well plate-based assay, and intracellular free calcium concentration ([Ca2+]i) was measured by indicator fluorescence. Platelet PDIs were blocked by a classic selective PDIA1 inhibitor (bepristat 2a) and sulphonamides of aziridine-2-carboxylic acid derivatives, novel PDI inhibitors relatively selective for PDIA1 or PDIA3 (C-3389 and C-3399, respectively). Clinically relevant antiplatelet drugs were used for comparison. ResultsConvulxin and A23187 concentration-dependently induced pEV formation. However, unlike convulxin, platelet activation by A23187 did not stimulate their aggregation. Bepristat 2a, C-3389 and C-3399 inhibited convulxin-induced pEV release accompanied by the reduction of [Ca2+]i. In contrast, only bepristat 2a inhibited A23187-induced pEV release, but without effect on [Ca2+]i. Cangrelor and tirofiban, but not acetylsalicylic acid (ASA), inhibited convulxin-induced pEV release, but neither of them inhibited A23187-induced pEV release. ConclusionThe inhibition of PDIA1 represents a novel approach to inhibit pEV formation by a mechanism independent of platelet aggregation and calcium signaling.

The dynamic range of immunoassays for heparin-induced thrombocytopenia

BackgroundFollowing the current guidelines, immunoassays for the diagnosis of heparin-induced thrombocytopenia (HIT) are interpreted dichotomously, with test results categorized as either positive or negative. However, the extent to which test results hold diagnostic significance across the entire dynamic range remains unclear. ObjectivesWe utilized data from the prospective TORADI-HIT study, comprising 1,393 consecutive patients with suspected HIT, to assess the diagnostic significance of two H/PF4 immunoassay test results across their respective dynamic ranges: HemoSil Acustar HIT IgG [CLIA] and Lifecodes PF4 IgG [ELISA]. MethodsHIT diagnosis was determined by a washed-platelet heparin-induced platelet activation assay (HIPA). For each measurement point in the dataset, we computed likelihood ratios (LR), sensitivities, and specificities. To provide post-test probabilities for individual test results, we calculated interval-specific likelihood ratios and integrated it into a web-based calculator. ResultsThe prevalence of HIT was 8.5% (n = 119). A likelihood ratio of ≥ 10 was first achieved at 0.3% of the dynamic range (0.4 U/ml; CLIA) and 16% (0.64 OD; ELISA), respectively. A likelihood ratio of ≥ 100 was present at 9.4% (12 U/ml; CLIA) and 75.0% (3.0 OD; ELISA). The slope of the linear regression line (LR ∼ dynamic range) was 9.5 (CLIA) and 0.9 (ELISA). ConclusionDespite both immunoassays showing an association between results and diagnostic significance, the strength of that association varies by assay. CLIA has a larger increase per measurement unit. Post-test probabilities for individual patients can be estimated using a web-based calculator: https://pcd-research.shinyapps.io/BayesianCalculator/.

Association between perioperative platelet distribution width changes and postoperative acute kidney injury in patients with renal insufficiency: a retrospective study

BackgroundAcute kidney injury (AKI) is a major complication following cardiac surgery with a high incidence in those with existing kidney dysfunction. Platelet distribution width (PDW) reflects variability in platelet size and serves as an indicator of platelet activation. Recent investigations linked PDW changes to kidney pathology, suggesting its utility in identifying individuals at risk for AKI, thus necessitating exploration of its predictive value.MethodsPatients with preoperative renal dysfunction [15 ≤ estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m2] who underwent cardiac surgery from January 2018 to December 2021 were retrospectively enrolled. PDW values were measured preoperatively and again upon admission to the ICU immediately after cardiac surgery, with the change in PDW (dPDW) defined as the difference between these two measurements. The primary outcome was postoperative AKI, defined base on the Kidney Disease: Improving Global Outcomes (KDIGO) definition and staging criteria. Multivariate regression models were performed to identify the association between dPDW and AKI and its potential trend. Restricted cubic spline analysis assessed non-linear associations between dPDW and AKI. The Youden index identified an optimal dPDW cut-off for AKI prediction. Subgroup analysis was performed to elucidate the consistency of these associations across the various subgroups.ResultsAKI occurred in 53.10% (513/966) of patients, accompanied by significant PDW increases in cases of AKI (P < 0.001). After adjusting confounders, dPDW was identified as a significant risk factor for AKI [odds ratio (OR) = 1.09, 95% confidence interval (CI): (1.02 ~ 1.16), P = 0.012]. Patients in the highest dPDW quartile (Q4) had a 195% higher AKI risk compared to those in the lowest quartile (Q1) (OR = 2.95, 95% CI:1.78 ∼ 4.90, P < 0.001). Trend analysis indicates that the risk of AKI increased with higher dPDW quartiles (P for trend < 0.001). Youden index showed that dRDW = 1.1 was identified as the optimal diagnostic cut-off value for AKI. Subgroup analyses and interaction tests showed a robust association between dPDW and AKI in all subgroups (P for interaction > 0.05).ConclusionsThis study underscored perioperative PDW changes as a significant predictor of postoperative AKI in patients with renal insufficiency, highlighting its potential in refining risk stratification and management strategies.Clinical trial numberNot applicable for this observational retrospective study.

Antibacterial chitosan/organic rectorite nanocomposite-conjugated gelatin/β-cyclodextrin hydrogels with improved hemostasis performance for wound repair

Bacterial infections and severe bleeding continue to pose significant challenges in wound repair. There is an urgent need for innovative, nature-inspired hydrogel dressings with antibacterial and hemostatic properties. A Ge-β-CD-CS-OREC conjugate hydrogel was developed by grafting β-CD and CS-OREC nanocomposites into a Ge matrix using EDC/NHS crosslinking, as confirmed by FT-IR and EDX analyses. Compared to single Ge-β-CD cross-linked hydrogels, the addition of CS-OREC enhanced the hydrogel's properties, including increased pore size (60 ± 14 μm), improved wettability (WCA = 28.82 ± 0.6°), enhanced tensile strength (41.3 ± 3.56 KPa), and strong tissue adhesion. Furthermore, this hydrogel demonstrated excellent cytocompatibility when co-cultured with keratinocytes (Kcs) and vascular endothelial cells (VECs). The incorporation of CS chains into OREC interlayers allowed the hydrogel to specifically target bacteria and increase membrane permeability in Pseudomonas aeruginosa (PA), Klebsiella pneumoniae (KP), and Staphylococcus aureus (SA), effectively reducing the bacterial load in infected wounds by 50.24–73.92 % compared to controls in vivo. Further, the hydrogel exhibited superior hemostatic efficiency (78 ± 10 s) over commercial gauze and other gels by enhancing platelet activation and coagulation factor secretion. The hydrogel accelerated tissue regeneration by promoting epithelial maturation and blood vessel regeneration, indicating its clinical potential as promising wound dressing.

Platelet antiaggregant activity of Hypericum perforatum extracts

BackgroundIn addition to its potential use as an antidepressant, different studies have shown that Hypericum perforatum (HP) can have antibacterial, antioxidant, and antiviral properties. Despite this potential, most of the therapeutic bioactivities attributed to HP need further scientific support. In a previous study we found an inhibitory effect of HP in platelet activation markers. So, in the present work we investigate the effect of HP in another aspect of platelet function, platelet aggregation. MethodsFirst, the effect of different concentrations of the total alcoholic extract of HP on platelet aggregation was studied in 9 healthy donors by aggregometry methods using collagen as agonist. After that, to obtain dose-effect curves, 3 experiments were carried out independently in a single individual using collagen, adenosine diphosphate and epinephrine as agonists. ResultsOur results reveal a marked inter-individual variability and a significant dose-dependent decrease of aggregation responses induced by collagen in the presence of HP extracts (mean of minimum inhibition: 8% at a dose of 0.068 mg es/ml and mean of maximum inhibition: 43% at a dose of 0.456 mg es/ml). With the results obtained it was possible to obtained a IC50 value of 0.34 mg es/ml. ConclusionsWe can conclude that HP has a dose-dependent inhibitory effect on platelet function (activation and aggregation responses), therefore, our results suggest that HP may be recognized as an herbal medicine with anti-platelet properties.

Enhanced platelet sensitization is accompanied by increased expression of the transporter MRP4 and elevated plasma S1P levels in mild COVID-19 convalescents

Viral infections can lead to platelet activation and hemostatic complications. However, the extent to which platelet reactivity remains altered after convalescence, contributing to long-term health impairments as observed after COVID-19 is not yet fully understood. Therefore, we conducted a cohort study (DRKS00025217) to determine platelet function in individuals convalesced from mild COVID-19. Assays were performed ex vivo with blood from convalescents at 2–15 weeks and 6–10 months after convalescence, focusing on platelet aggregation, activation markers, and thrombin formation. In addition, two other potentially relevant factors for platelet function were examined: the immunomodulatory mediator sphingosine-1-phosphate (S1P) and the platelet expression of the transporter MRP4 (ABCC4). Our findings indicate that robust platelet functions, including platelet aggregation determined by light transmission aggregometry, and thrombin formation, were not altered in convalescents compared to matched control individuals. However, an elevation in subtle platelet activation markers, such as P-selectin surface expression and activation of glycoprotein IIb/IIIa, was observed 2–15 weeks after convalescence. This was accompanied by an increased expression of MRP4 in platelets and significantly elevated levels of S1P in platelet-poor plasma. Our findings suggest increased platelet sensitization and a pro-inflammatory state even after convalescence from mild COVID-19, pointing toward MRP4 and S1P as associated factors.

Functional Foods in Preventing Human Blood Platelet Hyperactivity-Mediated Diseases-An Updated Review.

A systematic search of the PUBMED database from 2000 to 2023 was conducted using the selected keywords: "functional foods", "polyphenols", "fatty acids", "herbs", fruits and vegetables", "cardioprotective agents", "plant", "platelet aggregation", "platelet activation", "clinical and non-clinical trial", "randomized", and "controlled". Potent natural antiplatelet factors have been described, including omega-3 fatty acids, polyphenols, and other phytochemicals. Antiplatelet bioactive compounds in food that can prevent platelet hyperactivity and thus may prevent several platelet-mediated diseases, including cardiovascular disease. This narrative review describes the work during 2000-2023 in developing functional foods from natural sources with antiplatelet effects.

Novel Calcitonin Gene-Related Peptide (CGRP) Interfering Migraine Therapies and Stroke-A Review.

Migraine and stroke are neurological disorders with significant global prevalence and impact. Recent advances in migraine therapy have focused on the calcitonin gene-related peptide (CGRP) pathway. This review examines the shared pathomechanisms between migraine and stroke, with emphasis on the role of CGRP. We analyze the current literature on CGRP's functions in cerebrovascular regulation, edema formation, neuroinflammation, and neuroprotection. CGRP acts as a potent vasodilator and plays a crucial role in trigeminovascular activation during migraine attacks. In stroke, CGRP has demonstrated neuroprotective effects by improving collateral circulation and reducing ischemia-reperfusion injury. Concerns have been raised about the potential impact of CGRP inhibitors on stroke risk and outcomes. Studies in animals suggest that CGRP receptor antagonists may worsen cerebral ischemia by impairing collateral flow. We discuss the implications of these findings for the use of CGRP-targeting therapies in migraine patients, especially those at increased risk of stroke. Additionally, we explore the complex interplay between CGRP, endothelial function, and platelet activity in both conditions. This review highlights the need for further research to elucidate the long-term cerebrovascular safety of CGRP pathway inhibitors and to identify potential subgroups of migraine patients who may be at higher risk of adverse cerebrovascular events with these novel therapies.

Hyperexpression of PTAFR and PF4 as Possible Platelet Risk Biomarkers in Patients With COVID-19.

SARS-CoV-2 infection presents different severity levels that suggest the influence of genetic factors on the clinical outcome of the disease. In cases of severe COVID-19, the presence of elevated coagulation markers, increased platelet activation and aggregation and the risk of thrombotic complications are described. Given the participation of these cells in several serious viral infections and their negative role when associated with a prothrombotic response, it is important to understand the mechanistic role of SARS-CoV-2 in platelet physiology. This study evaluated the hyperexpression of platelet-activating factor receptor (PTAFR) and platelet factor 4 (PF4) in unvaccinated and hospitalized patients with COVID-19. The study included 43 COVID-19 patients stratified according to WHO guidelines. Subsequently, the expression of the PTAFR and PF4 genes were evaluated using the real-time quantitative PCR and their possible correlation with the severity of the disease and clinical variables including hospitalization, outcome, sex, age and laboratory parameters (platelet count, INR and D-dimer). The analysis demonstrated a significant (p<0.05) hyperexpression of these genes COVID-19 patients (n=43) compared to healthy controls. Expression of these genes in patients was not statistically significant (p>0.05) different between patients stratified according to clinical variables. The expression of PTAFR and PF4 suggests an important molecular pathway in the pathophysiology of the disease and may be valuable platelet biomarkers to indicate increased risk in patients with COVID-19 who require hospital care, contributing to personalized intervention strategies and improving their clinical management.

Monitoring Cell Activation and Extracellular Vesicle Generation in Platelet Concentrates for Transfusion.

Platelets play a crucial role in blood transfusions, and understanding the changes that occur during their storage is important for maintaining the quality of preparations. In this study, we examined key alternating factors, with a particular focus on platelet activation and the release of extracellular vesicles. Additionally, we compared two detection methods-imaging flow cytometry (IFC) and nanoparticle tracking analysis (NTA)-for their effectiveness in detecting particles. Platelet concentrates were prepared by pooling buffy coats from five blood group-compatible donors in an additive solution. Samples were analysed after one, three, and seven days of storage for residual white blood cells (WBCs), glucose levels, platelet activation, and extracellular vesicle concentrations. Over the storage period, the total platelet concentration decreased slightly, while the residual WBC count remained stable. Glucose levels declined, whereas platelet activation and extracellular vesicle concentration increased, with a positive correlation between the two. The particle size remained relatively unchanged throughout the storage period. Ultimately, despite controlled processing and storage conditions, platelet activation, and the release of extracellular vesicles still occurred, which may have implications for transfusion recipients. Although an optimised method is still needed, IFC has proved to be specific and potentially appropriate for detecting extracellular vesicles in transfusion preparations.

CS585, a novel prostacyclin receptor agonist, demonstrates sustained efficacy in vivo in the prevention of thrombosis

Abstract Background Uncontrolled platelet activity resulting from cardiovascular disease can lead to occlusive thrombi, culminating in myocardial infarction or stroke. Despite major advances in anti-platelet therapeutics, many patients remain at risk. Although prostacyclin (IP) receptor agonists are currently used for the treatment of pulmonary arterial hypertension (PAH), activation of the IP receptor has been shown to decrease platelet reactivity. However, engaging the IP receptor as a therapeutic target was previously considered unviable due to the lack of a sustained effect of current IP agonists in the blood. The development of an IP agonist with sustained effects in the blood would represent a novel prevention strategy in targeting platelet hyperreactivity and thrombosis. Purpose Assess the stability profile of CS585, an IV and orally bioavailable IP agonist, compared to FDA-approved IP agonists iloprost and selexipag, with regards to sustained activity in vivo in the blood in limiting platelet activation and thrombosis. Methods Using ex vivo and in vivo mouse models, we assessed the timeframe of effect of CS585, iloprost and selexipag in blood. Blood was drawn from wild-type mice 24 hours following a single IV dose of CS585, iloprost or selexipag. Platelet adhesion and blood clotting were measured using perfusion flow chamber at arterial shear and total thrombus activation system (T-TAS), respectively. In vivo, platelets and fibrin were labelled 24 hours post IV or oral administration of CS585, iloprost or selexipag, and accumulation at the site of injury was measured using the cremaster arteriole injury thrombosis assay. Results Blood drawn from mice administered CS585 was observed to show a decrease in platelet adhesion and clot formation in the perfusion flow chamber and T-TAS assays. The effects of iloprost and selexipag are no longer observed at 24 hours post-administration. Administration of CS585 resulted in sustained inhibition of platelet accumulation and fibrin formation in the laser-induced cremaster arteriole thrombosis assay up to 18 hours post-administration. In mice administered iloprost, a decrease in thrombus formation was observed 10 minutes post-administration, but thrombus size returned to vehicle levels by 4 hours. Selexipag-dosed mice demonstrated inhibition of thrombus formation up to 4 hours, but effects were no longer observed at 18 hours. Conclusions CS585, a novel IP agonist, inhibits platelet activation and clot formation up to 24 hours post-administration. In both in vivo and ex vivo models, we demonstrate the sustained effects of CS585. In contrast, current FDA-approved IP agonists do not possess an effect profile sufficient to target the IP receptor in blood. By overcoming the sustainability challenge facing IP agonists, CS585 represents a novel approach to anti-platelet treatment of thrombotic diseases, which could include thrombosis, VTE, secondary prevention after MI and stroke, and PAH.

Direct IL-6 inhibition prevents arterial thrombosis by reducing collagen-mediated platelets activation

Abstract Introduction Interleukin 6 (IL-6) has a pivotal role in atherothrombosis. Yet, targeting IL-6 to prevent atherothrombotic events still requires validation of efficacy and safety. The recent phase 2 RESCUE trial reported that direct inhibition of IL-6 ligand by the monoclonal antibody (mAb) Ziltivekimab is safe in patients with elevated cardiovascular risk. Purpose This project investigated the effects of direct IL-6 inhibition on arterial thrombosis, and assessed the underlying cellular mechanisms. Methods Three month old C56Bl/6 male mice received very-low dose LPS i.p. for 4 weeks. During the last week they were randomized to receive in addition either anti-mouse IL-6 mAb 200 μg i.p. every other day or IgG1 isotype control. Then thrombosis of left common carotid artery (LCCA) was induced by laser injury under anesthesia. Platelets of treated mice were isolated and stimulated with either adenosine di-phosphate (ADP), collagen-related peptide (CRP) or thrombin receptor activating peptide (TRAP). Platelets activation was measured by flow-cytometry, as expression of P-selectin and JON/A.The effect of direct IL-6 inhibition was confirmed in patients with stable coronary artery disease (sCAD) by ex-vivo incubation of isolated platelets with either anti-human IL-6 mAb 1.5 μg/mL or IgG1 isotype control. Platelet activation was measured by flow-cytometry, as expression of P-selectin. Results Mice treated with anti-IL6 antibody displayed a significantly longer time-to-occlusion after the LCCA (Figure 1), without any significant difference in coagulation parameters. After stimulation with CRP, platelets were significantly activated in control mice, but not in mice treated with anti-IL6 mAb. Similarly, activation of isolated platelets from patients with sCAD was significantly reduced (Figure 2) by the ex-vivo treatment with anti-IL6 mAb. Conclusion The direct inhibition of IL-6 reduces platelets reactivity to collagen, thereby blunting arterial thrombosis upon endothelial damage. These results provide a potential mechanism to explain the reduction of cardiovascular risk associated to direct IL-6 inhibition. Conclusion The direct inhibition of IL-6 reduces platelets reactivity to collagen, thereby blunting arterial thrombosis upon endothelial damage. These results provide a potential mechanism to explain the reduction of cardiovascular risk associated to direct IL-6 inhibition.Figure 1Figure 2

The implantation of a left ventricular assist device causes changes in the aortic miRNome and proteome - an integrative analysis

Abstract Background Left ventricular assist devices (LVAD) have been widely used and accepted to treat patients with end-stage heart failure. LVAD non-physiological blood flow velocity, wall shear stress distribution, vorticity current intensity, and vorticity flow generation affect the pathophysiology of vascular changes in aortic tissue. Purpose In this study, we performed multi-omics-based analysis of the aorta to identify molecular markers that could clarify vascular remodeling during LVAD support. Methods Aortic specimens from 48 patients (pair matched samples N=96) were excised during implantation and explantation of LVAD. Small RNA-Seq screening using Next Generation Sequencing and proteomic profile using Data-Independent Acquisition mass spectroscopy were conducted. Experimental and computational approaches, proteomics and transcriptomics data, were integrated and bioinformatics analyses were performed. Results The principal component analysis of miRNome and permutational multivariate analysis of variance of proteomic profile clearly segregated samples before and after LVAD support. We identified a total of 113 differently expressed (DE) miRNAs (61 up-regulated; Padj&amp;lt;0.05 and log2 fold change&amp;gt;|0.5|) after long-term LVAD support. Proteomic analysis identified in total 93 protein significantly changed (47 increased; Padj&amp;lt;0.05 and log2 fold change&amp;gt;|0.5|). Correlation analysis identified strong association between 270 proteins and 66 DE-miRNAs (Padj&amp;lt;0.05 and correlation coefficient&amp;gt;|0.7|). Gene Set Enrichment Analysis revealed, that predicted target genes of DE-miRNAs were mainly engaged in axon guidance, regulation of actin cytoskeleton, endocytosis, and MAP signaling pathway (Padj&amp;lt;0.05). DE-proteins participated mainly in ECM-receptor interaction, focal adhesion, and platelet activation (Padj&amp;lt;0.05). Conclusion Our study presents a network-based method of integrating microRNAs and proteome data and reveals molecular signatures that reflects aortic vascular remodeling due to LVAD treatment.PCA of miRNA DESeq2PCA of protemic profile

Neutrophil-Mimetic Upconversion Photosynthetic Nanosystem Derived from Microalgae for Targeted Treatment of Thromboembolic Stroke.

Thromboembolic stroke constitutes the majority of brain strokes, resulting in elevated mortality and morbidity rates, as well as significant societal and economic burdens. Although intravenous thrombolysis serves as the standard clinical treatment, its narrow therapeutic window and the inflammatory response induced by tissue plasminogen activator (tPA) administration limit its efficacy. In the initial stages of stroke, the abrupt cessation of blood flow leads to an energy metabolism disorder, marked by a substantial decrease in adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH) levels, causing irreversible damage to neural cells. In this study, we introduce a neutrophil-mimetic, microalgae-derived upconversion photosynthetic nanosystem designed for targeted treatment of thromboembolic stroke. This system features upconversion nanoparticles coated with a thylakoid membrane and wrapped in an activated neutrophil membrane, further decorated with ROS-responsive thrombolytic tPA on its surface. The neutrophil-mimetic design facilitates high targeting specificity and accumulation at the thrombus site after intravenous administration. Upon exposure to elevated levels of reactive oxygen species (ROS) at the thrombus location, the nanosystem promptly demonstrated potent thrombolytic efficacy through the surface-modified tPA. Furthermore, near-infrared II (NIR-II) laser irradiation activated the generation of ATP and NADPH, which inhibited inflammatory cell infiltration, platelet activation, oxidative stress, and neuronal injury. This constructed nanoplatform not only showcases exceptional targeting efficiency at the stroke site and controllable release of the thrombolytic agent but also facilitates ATP/NADPH-mediated thrombolytic, anti-inflammatory, antioxidative stress, and neuroprotective effects. Additionally, it offers valuable insights into the potential therapeutic applications of microalgae-based derivatives in managing thromboembolic stroke.

Effects of rivaroxaban on vascular endothelial function and circulating endothelial progenitor cells: a randomized controlled trial

Abstract Background Combination of low dose rivaroxaban with aspirin was shown to reduce major adverse cardiovascular events when compared to aspirin monotherapy in COMPASS trial. The beneficial effect of rivaroxaban beyond factor Xa inhibition remains unknown. Purpose This randomized controlled trial explored the effects of rivaroxaban on vascular endothelial function and circulating endothelial progenitor cells in patients with stable atherosclerotic disease. Methods An investigator-initiated, investigator-blinded, single-center randomized clinical trial was conducted from May 2021 to August 2023. 142 patients were randomized in 1:1 ratio to receive rivaroxaban 2.5mg twice daily plus aspirin 100mg once daily (Treatment Group) or aspirin 100mg once daily (Control Group) and had follow-up for 3 months. The primary outcome was change of flow mediated dilation (FMD) from baseline to 3-month follow-up. Key secondary outcomes included change of circulating endothelial progenitor cells (CD45+/34+/133+, CD45+/34+/KDR+), platelet activation marker (CD41+/62p+), inflammatory marker (CD14+/11b+) and thrombo-inflammatory maker (CD14+/42b+) measured by flow cytometry, as well as platelet function (aspirin reaction unit, ARU) measured by blood biochemistry. Intention-to-treat analysis was performed with analysis of covariance (ANCOVA) and P &amp;lt; 0.05 was considered statistically significant. Results Overall, 142 patients were enrolled in the study. One patient was excluded from analysis due to protocol deviation. Among the remaining 141 patients (78.8% male and mean age 69±9 years), there were 71 in Treatment Group and 70 in Control Group. The recruited patients had a high prevalence of cardiovascular comorbidities including 76.6% with hypertension, 50.4% with hyperlipidemia, 45.4% with diabetes, and 92.2% with percutaneous coronary intervention. At 3 months, Treatment Group had greater FMD improvements (+2.18±5.66% vs +1.57±5.07%, P=0.03), and more reduction in platelet activation marker (-0.33±13.55% vs +5.78±21.60%, P=0.01). There was no significant change in circulating endothelial progenitor cells, inflammatory marker, thrombo-inflammatory maker, and platelet function. Minor bleeding occurred in 2 patients (2.82%) in Treatment Group and none in Control Group (P&amp;gt;0.05). Conclusion In patients with stable atherosclerotic disease, addition of rivaroxaban to aspirin was well tolerated, and it improved vascular endothelial function and reduced platelet activation.