Factors Associated with Platelet Activation-Recent Pharmaceutical Approaches

MITOCDNB DECREASES PLATELET ACTIVATION THROUGH ITS SELECTIVE ACTION ON MITOCHONDRIAL THIOREDOXIN REDUCTASE

Platelet inhibition is a fundamental objective to prevent and treat thrombus formation. Platelet activation depends on mitochondrial function. This study aims to identify a new mitochondria-targeting compound with antiplatelet activity at safe concentrations in vitro. Cytotoxicity and viability tests were performed on human platelets from volunteer donors, together with experiments on aggregation, platelet activation, mitochondrial function, mitochondrial respiration, and thioredoxin reductase 2 (TrxR2) enzymatic activity in isolated platelet mitochondria. The compound MitoCDNB, corresponding to the molecule 5-chloro-2,4-dinitrophenylamino linked with triphenylphosphonium cation (TPP+) by a butyl chain and methanesulfonate as the counterion, was evaluated. MitoCDNB demonstrates potent, high mitochondria-selective antiplatelet effects that provide a novel approach to platelet inhibition with potentially minimized systemic risks. Here, we describe the first compound that inhibits platelet activation by decreasing TrxR2 enzymatic activity and collagen-stimulated maximal mitochondrial respiration, preventing aggregation and platelet activation. These results can be used to develop new antiplatelet drugs targeting mitochondria.

Human Disabled-2 regulates thromboxane A2 signaling for efficient hemostasis in thrombocytopenia

Understanding platelet protein functions facilitates better assessment of platelet disorders. Megakaryocyte lineage-restricted human Disabled-2 knock-in (hDAB2-KI) mice are generated to delineate the functions of hDab2, a regulator of platelet function, in the control of bleeding associated with thrombocytopenia. Here we show that hDab2-KI mice with thrombocytopenia display decreased bleeding time when compared to the control mice. hDab2 augments thromboxane A2 (TxA2) mimetic U46619- but not other agonists-stimulated granule secretion, integrin activation, and aggregation at a lower platelet concentration in vitro. Binding of hDab2 to phosphatidic acid (PA) facilitates formation of the PA-hDab2-AKT complex leading to an increase in U46619-stimulated AKT-Ser473 phosphorylation and the first wave of ADP/ATP release. Consistent with these findings, hDab2 expression in platelets from patients with immune thrombocytopenic purpura is positively correlated with U46619-stimulated ATP release, which in turn inversely correlated with their bleeding tendency. hDab2 appears crucial in regulating bleeding severity associated with thrombocytopenia by a functional interplay with ADP/ATP release underlying TxA2 signaling.

Exploring the antimicrobial potential of Leukocyte- and Platelet-Rich Fibrin - an in vitro study

This study investigates the antimicrobial properties of leukocyte- and platelet-rich fibrin (L-PRF) against Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 90028). Infections can hinder wound healing posing challenges. L-PRF's potential for regeneration and antimicrobial action has been studied. Considering the increasing concern about antibiotic resistance, assessing the antimicrobial properties of L-PRF provides valuable insights into its potential as a therapeutic agent in postoperative infections. Twenty volunteers were enrolled in the study, following ethical guidelines, and obtaining informed consent. Blood samples were collected and L-PRF was prepared. Microbial suspensions were prepared, and susceptibility testing was performed using the Kirby-Bauer agar diffusion method. The study revealed significant heterogeneity in the susceptibility to L-PRF. All L-PRF membrane samples exhibited antimicrobial activity against P. aeruginosa, with inhibition zones of 13 mm ± 3.85 SD. Enterococcus faecalis displayed inhibition diameter of 7.25 mm ± 5.15 SD. Candida albicans susceptibility to L-PRF varied among samples, with both inhibitory and non-inhibitory results. Results showed varying degrees of antimicrobial activity, particularly against P. aeruginosa, and highlight the complexity of the L-PRF-microorganism interaction. Further investigations are needed to elucidate the clinical implications and optimize the use of L-PRF.

Platelets camouflaged nanovehicle improved bladder cancer immunotherapy by triggering pyroptosis

The regulation of immunosuppressive microenvironments in tumors through targeted drug delivery shows promise for immunochemotherapy in bladder cancer. Drawing inspiration from stealth tactics, a nano-vehicle camouflaged with platelets (PLTs) was developed to enable precise delivery and trigger pyroptosis for tumor immunotherapy. Methods: Erdafitinib (Erda) was nano-sized and encapsulated in PLTs to construct nano-Erda@PLT. Characterization of the PLTs camouflaged nano-vehicle was conducted using Zetasizer, SEM, and confocal laser scanning microscopy. The excellent targeted delivery property of the PLTs nano-vehicle was investigated through intravital imaging, three-dimensional microspheres, and SEM. Validation of pyroptosis in bladder cancer cells via the caspase-3/GSDME pathway was performed using western blot, immunofluorescence, and ELISA tests. Immunotherapy by nano-Erda@PLT treatment in vivo was confirmed using H&E, immunohistochemical, and flow cytometry. Lastly, the side effects of nano-Erda@PLT were assessed. Results: Proteomic analysis revealed that the activation of p-selectin on platelets facilitated the identification of nano-Erda@PLT targeted therapies. Nanoscale of Erda released in response to adenosine diphosphate, facilitated intratumoral permeation. This could contribute to an upregulation of the key proteins of pyroptosis, caspase-3 and GSDME, in bladder cancer cells due to nano-Erda@PLT accumulation. Additionally, the burst release of numerous inflammatory factors may enhance the system's adaptive immune response. In a bladder cancer animal model, this treatment was found to regulate the immunosuppressive microenvironment, resulting in effective tumor immunotherapy and the induction of a long-lasting, robust immune memory. Conclusion: PLTs-camouflaged nano-vehicles enable nano-Erda-mediated tumor immunotherapy through the induction of pyroptosis. These findings introduce a novel approach in exploring nanomaterial-mediated pyroptosis for cancer immunotherapy.

Platelets isolation and ectonucleotidase assay: Revealing functional aspects of the communication between the vasculature and the immune system

Platelets are enucleated fragments of cells with a diversity of internal granules. They are responsible for functions related to hemostasis, coagulation, and inflammation. The activation of these processes depends on a cascade coordinated by cytokines, chemokines, and components of purinergic signaling, such as ATP, ADP, and adenosine. Platelets express distinct components of the purinergic system: P2X1, P2Y1, PY12, and P2Y14 receptors; and the ectonucleotidases NTPDase, NPP, and 5NTE (ecto-5'-nucleotidase). Except for P2Y14, which has not yet exhibited a known function, all other components relate to the biological processes mentioned before. Platelets are known to display specific responses to microorganisms, being capable of recognizing pathogen-associated molecular patterns (PAMPs), engulfing certain classes of viruses, and participating in NETosis. Platelet function dysregulation implicates various pathophysiological processes, including cardiovascular diseases (CVDs) and infections. In COVID-19 patients, platelets exhibit altered purinergic signaling and increased activation, contributing to inflammation. Excessive platelet activation can lead to complications from thrombosis, which can affect the circulation of vital organs. Therefore, controlling the activation is necessary to end the inflammatory process and restore homeostasis. Ectonucleotidases, capable of hydrolyzing ATP, ADP, and AMP, are of fundamental importance in activating platelets, promising pharmacological targets for clinical use as cardiovascular protective drugs. In this review, we revisit platelet biology, the purinergic receptors and ectonucleotidases on their surface, and their importance in platelet activity. Additionally, we describe methods for isolating platelets in humans and murine, as well as the main techniques for detecting the activity of ectonucleotidases in platelets. Considering the multitude of functions revealed by platelets and their potential use as potent bioreactors able to secrete and present molecules involved in the communication of the vasculature with the immune system, it is crucial to deeply understand platelet biology and purinergic signaling participation to contribute to the developing of therapeutic strategies in diseases of the cardiovascular, inflammatory, and immune systems.

Beyond Blood Clotting: The Many Roles of Platelet-Derived Extracellular Vesicles

Platelet-derived extracellular vesicles (pEVs) are emerging as pivotal players in numerous physiological and pathological processes, extending beyond their traditional roles in hemostasis and thrombosis. As one of the most abundant vesicle types in human blood, pEVs transport a diverse array of bioactive molecules, including growth factors, cytokines, and clotting factors, facilitating crucial intercellular communication, immune regulation, and tissue healing. The unique ability of pEVs to traverse tissue barriers and their biocompatibility position them as promising candidates for targeted drug delivery and regenerative medicine applications. Recent studies have underscored their involvement in cancer progression, viral infections, wound healing, osteoarthritis, sepsis, cardiovascular diseases, rheumatoid arthritis, and atherothrombosis. For instance, pEVs promote tumor progression and metastasis, enhance tissue repair, and contribute to thrombo-inflammation in diseases such as COVID-19. Despite their potential, challenges remain, including the need for standardized isolation techniques and a comprehensive understanding of their mechanisms of action. Current research efforts are focused on leveraging pEVs for innovative anti-cancer treatments, advanced drug delivery systems, regenerative therapies, and as biomarkers for disease diagnosis and monitoring. This review highlights the necessity of overcoming technical hurdles, refining isolation methods, and establishing standardized protocols to fully unlock the therapeutic potential of pEVs. By understanding the diverse functions and applications of pEVs, we can advance their use in clinical settings, ultimately revolutionizing treatment strategies across various medical fields and improving patient outcomes.

Comprehensive analysis of L-PRF exudate components and their impact on whole blood platelets

OBJECTIVE

This study assessed the cellular composition and effects of leukocyte-platelet-rich fibrin (L-PRF) exudate on whole blood platelets from healthy volunteers. Key objectives included evaluating leukocyte subpopulations, platelet activation markers, platelet-leukocyte interactions and quantifying inflammatory cytokines within the L-PRF exudate.

MATERIALS AND METHODS

L-PRF was obtained from 20 healthy donors. Flow cytometry methodologies were used to assess intracellular calcium kinetics and activated GPIIbIIIa, and P-selectin expression. Leukocyte subpopulations and platelet-leukocyte interactions were characterized using monoclonal antibodies. Inflammatory cytokines (IL-8, IL-1β, IL-6, IL-10, TNF, IL-12p70) within L-PRF exudate were quantified using a cytometric bead array.

RESULTS

The expression of activated GPIIbIIIa, and P-selectin exhibited a significant increase (p < 0.001) when L-PRF exudate was added to platelets of whole blood. Regarding intracellular Ca2+ mobilization, the L-PRF exudate elicited significant responses (p < 0.001). L-PRF exudate contained different leukocytes populations, being TCD4 + the most representative of T cells. It was possible to stablish a profile of cytokines produced by the L-PRF exudate, with human IL-8 cytokine exhibiting the highest average (16.90 pg/mL).

CONCLUSIONS

Despite the study limitations, the research yielded important insights: 1- L-PRF exudate can stimulate platelet activation, essential in healing, tissue inflammation and remodeling. 2-The presence of leukocyte subpopulations within L-PRF exudate reflexes its complexity and potential to enhance immune responses. 3-The analysis of inflammatory cytokines within L-PRF exudate revealed its immunomodulatory potential. These findings are valuable evidences for understanding the potential role of L-PRF exudate in regenerative dentistry and medicine, offering innovative therapeutic strategies.

CLINICAL RELEVANCE

This research highlights crucial aspects that could significantly influence the clinical use of L-PRF exudate in the oral cavity. The findings support the application of L-PRF exudate in both surgical and regenerative dentistry, facilitating the development of innovative therapeutic strategies to enhance patient outcomes.

Molecular Insights into the Relationship Between Platelet Activation and Endothelial Dysfunction: Molecular Approaches and Clinical Practice

Platelets are one of the coagulation cells. When platelet activation occurs, many mediators are released and affect endothelial cells (ECs) and lead to endothelial dysfunction (ED). ED plays an important role in the pathogenesis of many diseases, including cardiovascular disease (CVD). Platelet are of important factors in ED. The release of mediators by platelets causes the stimulation of inflammatory pathways, oxidative stress, and apoptosis, which ultimately result in ED.On the other hand, platelet activation in CVD patients can be associated with a bad prognosis. Platelet activation can increase the level of markers such as p-selectin in the serum. Also, in this study, we have discussed the role of platelet as a diagnostic factor, as well as its use as a treatment option. In addition, we discussed some of the molecular pathways that are used to target platelet activation.

Vascular Alterations Following COVID-19 Infection: A Comprehensive Literature Review

SARS-CoV-2, the causative agent of the ongoing COVID-19 pandemic, has revealed a broader impact beyond the respiratory system, predominantly affecting the vascular system with various adverse manifestations. The infection induces endothelial dysfunction and immune system dysregulation, creating an inflammatory and hypercoagulable state. It affects both microvasculature and macrovasculature, leading to thromboembolic events, cardiovascular manifestations, impaired arterial stiffness, cerebrovascular complications, and nephropathy, as well as retinopathy-frequently observed in cases of severe illness. Evidence suggests that SARS-CoV-2 infection may result in persistent effects on the vascular system, identified as long-term COVID-19. This is characterized by prolonged inflammation, endotheliopathy, and an increased risk of vascular complications. Various imaging modalities, histopathological studies, and diagnostic tools such as video capillaroscopy and magnetic resonance imaging have been employed to visualize vascular alterations. This review aims to comprehensively summarize the evidence concerning short and long-term vascular alterations following COVID-19 infection, investigating their impact on patients' prognosis, and providing an overview of preventive strategies to mitigate associated vascular complications.

Platelet-membrane camouflaged cerium nanoparticle-embedded gelatin methacryloyl hydrogel for accelerated diabetic wound healing

Impaired angiogenesis and excessive inflammation are major factors contributing to delayed wound healing in diabetic patients. This study presents the development of a novel multifunctional hydrogel, Pltm@CNPs/Gel, which incorporates platelet membrane camouflaged cerium nanoparticles into a gelatin methacryloyl matrix. The Pltm@CNPs/Gel nanocomposite hydrogel was characterized and tested for its effects on platelet activation, coagulation, cell viability, anti-oxidation, and anti-inflammation in vitro. Moreover, we evaluated the wound healing potential of the hydrogel in a diabetic rat model. Our findings demonstrate that the Pltm@CNPs/Gel hydrogel possesses anti-oxidative and anti-inflammatory properties. Furthermore, it accelerates diabetic wound healing by promoting neovascularization, cell proliferation, and collagen fiber organization. This study highlights the potential of the Pltm@CNPs/Gel hydrogel as a therapeutic option for diabetic wound healing and its promising applications as a diabetic wound dressing candidate.

A literature perspective on the pharmacological applications of yohimbine

Introduction: Phytochemicals have garnered much attention because they are useful in managing several human diseases. Yohimbine is one such phytochemical with significant pharmacological potential and could be exploited for research by medicinal chemists. It is an indole alkaloid obtained from various natural/synthetic sources.Aims and Results: The research on yohimbine started early, and its use as a stimulant and aphrodisiac by humans has been reported for a long time. The pharmacological activity of yohimbine is mediated by the combined action of the central and peripheral nervous systems. It selectively blocks the pre and postsynaptic α₂-adrenergic receptors and has a moderate affinity for α1 and α2 subtypes. Yohimbine also binds to other behaviourally relevant monoaminergic receptors in the following order: α-2 NE > 5HT-1A>, 5HT-1B > 1-D > D3 > D2 receptors.Conclusion: The current review highlights some significant findings that contribute to developing yohimbine-based drugs. It also highlights the therapeutic potential of yohimbine against selected human diseases. However, further research is recommended on the pharmacokinetics, molecular mechanisms, and drug safety requirements using well-designed randomized clinical trials to produce yohimbine as a pharmaceutical agent for human use.Key MessagesYohimbine is a natural indole alkaloid with significant pharmacological potential.Humans have used it as a stimulant and aphrodisiac from a relatively early time.It blocks the pre- and postsynaptic α2-adrenergic receptors that could be exploited for managing erectile dysfunction, myocardial dysfunction, inflammatory disorders, and cancer.

Platelets and platelet extracellular vesicles in drug delivery therapy: A review of the current status and future prospects

Platelets are blood cells that are primarily produced by the shedding of megakaryocytes in the bone marrow. Platelets participate in a variety of physiological and pathological processes in vivo, including hemostasis, thrombosis, immune-inflammation, tumor progression, and metastasis. Platelets have been widely used for targeted drug delivery therapies for treating various inflammatory and tumor-related diseases. Compared to other drug-loaded treatments, drug-loaded platelets have better targeting, superior biocompatibility, and lower immunogenicity. Drug-loaded platelet therapies include platelet membrane coating, platelet engineering, and biomimetic platelets. Recent studies have indicated that platelet extracellular vesicles (PEVs) may have more advantages compared with traditional drug-loaded platelets. PEVs are the most abundant vesicles in the blood and exhibit many of the functional characteristics of platelets. Notably, PEVs have excellent biological efficacy, which facilitates the therapeutic benefits of targeted drug delivery. This article provides a summary of platelet and PEVs biology and discusses their relationships with diseases. In addition, we describe the preparation, drug-loaded methods, and specific advantages of platelets and PEVs targeted drug delivery therapies for treating inflammation and tumors. We summarize the hot spots analysis of scientific articles on PEVs and provide a research trend, which aims to give a unique insight into the development of PEVs research focus.

Insights into the Role of Neutrophils and Neutrophil Extracellular Traps in Causing Cardiovascular Complications in Patients with COVID-19: A Systematic Review

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic caused by the SARS-CoV-2 virus has resulted in significant mortality and burdening of healthcare resources. While initially noted as a pulmonary pathology, subsequent studies later identified cardiovascular involvement with high mortalities reported in specific cohorts of patients. While cardiovascular comorbidities were identified early on, the exact manifestation and etiopathology of the infection remained elusive. This systematic review aims to investigate the role of inflammatory pathways, highlighting several culprits including neutrophil extracellular traps (NETs) which have since been extensively investigated.

METHOD

A search was conducted using three databases (MEDLINE; MEDLINE In-Process & Other Non-Indexed Citations and EMBASE). Data from randomized controlled trials (RCT), prospective series, meta-analyses, and unmatched observational studies were considered for the processing of the algorithm and treatment of inflammatory response during SARS-CoV-2 infection. Studies without the SARS-CoV-2 Infection period and case reports were excluded.

RESULTS

A total of 47 studies were included in this study. The role of the acute inflammatory response in the propagation of the systemic inflammatory sequelae of the disease plays a major part in determining outcomes. Some of the mechanisms of activation of these pathways have been highlighted in previous studies and are highlighted.

CONCLUSION

NETs play a pivotal role in the pathogenesis of the inflammatory response. Despite moving into the endemic phase of the disease in most countries, COVID-19 remains an entity that has not been fully understood with long-term effects remaining uncertain and requiring ongoing monitoring and research.

Comparative Efficacy and Safety of P2Y12 Inhibitor Monotherapy and Dual Antiplatelet Therapy in Patients with and without Diabetes Mellitus Undergoing Percutaneous Coronary Intervention

Increasing evidence has shown P2Y12 inhibitor monotherapy is a feasible alternative treatment for patients after percutaneous coronary intervention (PCI) with stent implantation in the modern era. However, patients with diabetes mellitus (DM) have a higher risk of ischemic events and more complex coronary artery disease. The purpose of this study is to evaluate the efficacy and safety of this novel approach among patients with DM and those without DM. We conducted a systematic review and meta-analysis of randomized controlled trials that compared P2Y12 inhibitor monotherapy with 12 months of dual antiplatelet therapy (DAPT) in patients who underwent PCI with stent implantation. PubMed, Embase, Cochrane library database, ClinicalTrials.gov, and three other websites were searched for our data from the earliest report to January 2022. The primary efficacy outcome was major adverse cardiovascular and cerebrovascular events (MACCE): a composite of all-cause mortality, myocardial infarction, stent thrombosis, and stroke. The primary safety outcome was major or minor bleeding events. The secondary endpoint was net adverse clinical events (NACE) which are defined as a composite of major bleeding and adverse cardiac and cerebrovascular events. A total of four randomized controlled trials with 29,136 patients were included in our meta-analysis. The quantitative analysis showed a significant reduction in major or minor bleeding events in patients treated with P2Y12 inhibitor monotherapy compared to standard DAPT (OR: 0.68, 95% CI: 0.46-0.99, p = 0.04) without increasing the risk of MACCE (OR: 0.96, 95% CI: 0.85-1.09, p = 0.50). The number of NACE was significantly lower in the patients treated with P2Y12 inhibitor monotherapy (OR: 0.84, 95% CI: 0.72-0.97, p = 0.019). In DM patients, P2Y12 inhibitor monotherapy was associated with a lower risk of MACCE compared to standard DAPT (OR: 0.85, 95% CI: 0.74-0.98, p = 0.02). Furthermore, P2Y12 inhibitor monotherapy was accompanied by a favorable reduction in major or minor bleeding events (OR: 0.80, 95% CI: 0.64-1.05, p = 0.107). In non-DM patients, P2Y12 inhibitor monotherapy showed a significant reduction in major or minor bleeding events (OR: 0.58, 95% CI: 0.38-0.88, p = 0.01), but without increasing the risk of MACCE (OR: 0.99, 95% CI: 0.82-1.19, p = 0.89). Based on these findings, P2Y12 inhibitor monotherapy could significantly decrease bleeding events without increasing the risk of stent thrombosis or myocardial infarction in the general population. The benefit of reducing bleeding events was much more significant in non-DM patients than in DM patients. Surprisingly, P2Y12 inhibitor monotherapy could lower the risk of MACCE in DM patients. Our study supports that P2Y12 inhibitor monotherapy is a promising alternative choice of medical treatment for patients with DM undergoing PCI with stent implantation in the modern era.