A guide to molecular and functional investigations of platelets to bridge basic and clinical sciences

Liquid biopsy: paving a new avenue for cancer research

The current constraints associated with cancer diagnosis and molecular profiling, which rely on invasive tissue biopsies or clinical imaging, have spurred the emergence of the liquid biopsy field. Liquid biopsy involves the extraction of circulating tumor cells (CTCs), circulating free or circulating tumor DNA (cfDNA or ctDNA), circulating cell-free RNA (cfRNA), extracellular vesicles (EVs), and tumor-educated platelets (TEPs) from bodily fluid samples. Subsequently, these components undergo molecular characterization to identify biomarkers that are critical for early cancer detection, prognosis, therapeutic assessment, and post-treatment monitoring. These innovative biosources exhibit characteristics analogous to those of the primary tumor from which they originate or interact. This review comprehensively explores the diverse technologies and methodologies employed for processing these biosources, along with their principal clinical applications.

Platelets in liver cancer

Platelets are an important component of blood. In addition to the key role in the process of hemostasis and coagulation, platelets also have an important role in the occurrence and development of a variety of tumors. Primary liver cancer is one of the most common malignant tumors in the world. Because its development process usually follows the hepatitis-cirrhosis-liver cancer sequence, it is often accompanied by platelet changes. Research on platelets and the development of liver cancer has obtained much new evidence that activated platelets can promote the occurrence and development of liver cancer through direct contact or indirect contact. Therapeutic strategies targeting platelets have the potential to reduce the occurrence and progression of tumors. This article summarizes the research on platelets in liver cancer.

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.

Secreted protein TNA: a promising biomarker for understanding the adipose-bone axis and its impact on bone metabolism

BACKGROUND

Osteoporosis (OP) is a systemic bone disease characterized by reduced bone mass and deterioration of bone microstructure, leading to increased bone fragility. Platelets can take up and release cytokines, and a high platelet count has been associated with low bone density. Obesity is strongly associated with OP, and adipose tissue can influence platelet function by secreting adipokines. However, the biological relationship between these factors remains unclear.

METHODS

We conducted differential analysis to identify OP platelet-related plasma proteins. And, making comprehensive analysis, including functional enrichment, protein-protein interaction network analysis, and Friends analysis. The key protein, Tetranectin (TNA/CLEC3B), was identified through screening. Then, we analyzed TNA's potential roles in osteogenic and adipogenic differentiation using multiple RNA-seq data sets and validated its effect on osteoclast differentiation and bone resorption function through in vitro experiments.

RESULTS

Six OP-platelet-related proteins were identified via differential analysis. Then, we screened the key protein TNA, which was found to be highly expressed in adipose tissue. RNA-seq data suggested that TNA may promote early osteoblast differentiation. In vitro experiments showed that knockdown of TNA expression significantly increased the expression of osteoclast markers, thereby promoting osteoclast differentiation and bone resorption.

CONCLUSIONS

We identified TNA as a secreted protein that inhibits osteoclast differentiation and bone resorption. While, it potentially promoted early osteoblast differentiation from bioinformatic results. TNA may play a role in bone metabolism through the adipose-bone axis.

Glycopolymeric Micellar Nanoparticles for Platelet-Mediated Tumor-Targeted Delivery of Docetaxel for Cancer Therapy

The high level of accumulation of therapeutic agents in tumors is crucial for cancer treatment. Compared to the passive tumor-targeting effect, active tumor-targeting delivery systems, primarily mediated by peptides with high production costs and reduced circulation time, are highly desired. Platelet-driven technologies have opened new avenues for targeted drug delivery prevalently through a membrane coating strategy that involves intricate manufacturing procedures or the fucoidan-mediated hitchhiking method with limited platelet affinity. Here, a novel type of amphiphilic glycopolymer self-assembled micellar nanoparticle has been developed to adhere to naturally activated platelets in the blood. The simultaneous integration of fucose and sialic acid segments into glycopolymers enables closer mimicry of the structure of P-selectin glycoprotein ligand-1 (PSGL-1), thereby increasing the affinity for activated platelets. It results in the formation of glycopolymeric micelle-platelet hybrids, facilitating targeted drug delivery to tumors. The selective platelet-assisted cellular uptake of docetaxel (DTX)-loaded glycopolymeric micelles leads to lower IC50 values against 4T1 cells than that of free DTX. The directed tumor-targeting effect of activated platelets has significantly improved the tumor accumulation capacity of the glycopolymeric nanoparticles, with up to 21.0% found in tumors within the initial 0.2 h. Additionally, with acid-responsive drug release and inherent antimetastasis properties, the glycopolymeric nanoparticles ensured potent therapeutic efficacy, prolonged survival time, and reduced cardiotoxicity, presenting a new and unexplored strategy for platelet-directed drug delivery to tumors, showing promising prospects in treating localized tumors and preventing tumor metastasis.

Classic Light Transmission Platelet Aggregometry: Do We Still Need it?

For more than 50 years, light transmission aggregometry has been accepted as the gold standard test for diagnosing inherited platelet disorders in platelet-rich plasma, although there are other functional approaches performed in whole blood. In this article, several advantages and disadvantages of this technique over other laboratory approaches are discussed in the view of recent guidelines, and the necessity of functional assays, such as light transmission aggregometry in the era of molecular genetic testing, is highlighted.

Research progress of ZIC5 for tumor metastasis

The zinc finger protein of the cerebellum (ZIC) family comprises five members (ZIC1-5), homologous with the odd-paired (OPA) gene in Drosophila melanogila. These transcription factors contain five Cys2His zinc finger domains, constituting one of the most abundant transcription factor families in human cells. ZIC proteins significantly contribute to transcriptional regulation and chromatin remodeling. As a member of the ZIC family, ZIC5 is essential for animal growth and development. Numerous studies have investigated the connection between ZIC proteins and cancer as well as tumor metastases in recent years. Many studies have found that within tumor tissues, the transcription and translation processes increase the expression of ZIC5 which is linked to tumor aggressiveness. This review aims to provide an objective summary of the impact of ZIC5 on tumor metastasis and consider the potential application of ZIC5 targets in both tumor therapy and the early detection of cancer.

Revolutionizing Neurocare: Biomimetic Nanodelivery Via Cell Membranes

Brain disorders represent a significant challenge in medical science due to the formidable blood-brain barrier (BBB), which severely limits the penetration of conventional therapeutics, hindering effective treatment strategies. This review delves into the innovative realm of biomimetic nanodelivery systems, including stem cell-derived nanoghosts, tumor cell membrane-coated nanoparticles, and erythrocyte membrane-based carriers, highlighting their potential to circumvent the BBB's restrictions. By mimicking native cell properties, these nanocarriers emerge as a promising solution for enhancing drug delivery to the brain, offering a strategic advantage in overcoming the barrier's selective permeability. The unique benefits of leveraging cell membranes from various sources is evaluated and advanced technologies for fabricating cell membrane-encapsulated nanoparticles capable of masquerading as endogenous cells are examined. This enables the targeted delivery of a broad spectrum of therapeutic agents, ranging from small molecule drugs to proteins, thereby providing an innovative approach to neurocare. Further, the review contrasts the capabilities and limitations of these biomimetic nanocarriers with traditional delivery methods, underlining their potential to enable targeted, sustained, and minimally invasive treatment modalities. This review is concluded with a perspective on the clinical translation of these biomimetic systems, underscoring their transformative impact on the therapeutic landscape for intractable brain diseases.

"Ultrastructural changes of platelets in COVID-19 and chronic viral hepatitis patients "

Platelet-viral interactions are evolving as a new concern. Coagulation disorder is a major consequence of the COVID-19 infection. In chronic hepatitis virus infections, defect in coagulation factors, thrombocytopenia and platelet function abnormalities are common. A SARS-CoV-2 infection on top of chronic viral hepatitis infection can be common in areas where viral hepatitis is endemic. Here, we investigate the platelet ultrastructural changes and estimate the serum platelet factor-4 (PF-4), ferritin, CRP, and D-dimer in COVID-19 patients (n = 60), COVID-19 patients with associated chronic viral hepatitis (n = 20), and healthy subjects (n = 20). Ultrastructural changes were demonstrated in all test groups, denoting platelet activation. In chronic viral hepatitis patients, Platelet ultrastrustural apoptotic changes were also seen. Significantly high levels of PF-4 were confirmed in moderate and severe COVID-19 patients (P.value <0.001), with a cut off value of 17 ng/ml for predicting disease severity. A positive correlation of PF-4 with the level of serum ferritin, CRP, and D-dimer (p value < 0.001) was noted, while negatively correlated with platelet count and platelet granule count (p value < 0.001). In our study, chronic viral hepatitis patients presented mild COVID-19 signs, and their PF-4 level was comparable with the subgroup of mild COVID-19 infection. The platelet's critical role in COVID-19 coagulopathy and chronic viral hepatitis is evidenced by the ultrastructural changes and the high levels of PF4. Moreover, a dual viral infection poses a substantial burden on the platelets, necessitating close monitoring of the patient's coagulation profile.

A bio-fabricated tesla valves and ultrasound waves-powered blood plasma viscometer

Introduction: There is clinical evidence that the fresh blood viscosity is an important indicator in the development of vascular disorder and coagulation. However, existing clinical viscosity measurement techniques lack the ability to measure blood viscosity and replicate the in-vivo hemodynamics simultaneously. Methods: Here, we fabricate a novel digital device, called Tesla valves and ultrasound waves-powered blood plasma viscometer (TUBPV) which shows capacities in both viscosity measurement and coagulation monitoring. Results: Based on the Hagen-Poiseuille equation, viscosity analysis can be faithfully performed by a video microscopy. Tesla-like channel ensured unidirectional liquid motion with stable pressure driven that was triggered by the interaction of Tesla valve structure and ultrasound waves. In few seconds the TUBPV can generate an accurate viscosity profile on clinic fresh blood samples from the flow time evaluation. Besides, Tesla-inspired microchannels can be used in the real-time coagulation monitoring. Discussion: These results indicate that the TUBVP can serve as a point-of-care device in the ICU to evaluate the blood's viscosity and the anticoagulation treatment.

The association of the platelet/high-density lipoprotein cholesterol ratio with self-reported stroke and cardiovascular mortality: a population-based observational study

BACKGROUND

Previous studies have shown that the relationship between high-density lipoprotein cholesterol (HDL-C) and stroke is controversial, and the association between the platelet/high-density lipoprotein cholesterol ratio (PHR), a novel marker for inflammation and hypercoagulability states, and stroke has not been established.

METHODS

This study presents an analysis of cross-sectional data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES). Stroke history, HDL-C levels, and platelet counts were obtained during cross-sectional surveys. The PHR was calculated as the ratio of the number of platelets to HDL-C concentration. Weighted logistic regression was used to assess the associations of HDL-C and the PHR with stroke. Nonlinearity of this relationship was determined through restricted cubic splines (RCSs) and two-piecewise linear regression for identifying inflection points. Furthermore, Cox regression was utilized to prospectively analyze the associations of the PHR and HDL-C concentration with cardiovascular disease (CVD) mortality in stroke survivors.

RESULTS

A total of 27,301 eligible participants were included in the study; mean age, 47.28 years and 50.57% were female, among whom 1,040 had a history of stroke. After full adjustment, the odds ratio (OR) of stroke associated with a per standard deviation (SD) increase in the PHR was estimated at 1.13 (95% confidence interval (CI): 1.03 - 1.24, P = 0.01), and the OR of stroke associated with a per SD increase in HDL-C was 0.95 (95% CI: 0.86-1.05, P = 0.30). The RCS indicated a nonlinear relationship for both variables (PPHR = 0.018 and PHDL-C = 0.003), and further piecewise linear regression identified inflection points at PHR = 223.684 and HDL-C = 1.4 mmol/L. Segmental regression indicated that in the PHR ≥ 223.684 segment, the estimated OR of stroke associated with a per-SD increase in the PHR was 1.20 (95% CI: 1.09 - 1.31, P < 0.001), while the association of stroke with HDL-C was not significant before or after the inflection point (P > 0.05). Furthermore, Cox regression and RCS showed that a per-SD increase in the PHR was linearly associated with a greater risk of CVD mortality among stroke survivors (HR: 1.14, 95% CI: 1.06 - 1.22, P < 0.001; nonlinear, P = 0.956), while HDL-C was not significantly associated with CVD mortality.

CONCLUSION

The association between the PHR and stroke incidence exhibited a significant threshold effect, with an inflection point at 223.684. A PHR exceeding 223.684 was positively associated with stroke, while the association between HDL-C and stroke was not significant. Additionally, the PHR was positively and linearly associated with CVD mortality among stroke survivors.

Integrating Phenotypic and Chemoproteomic Approaches to Identify Covalent Targets of Dietary Electrophiles in Platelets

A large variety of dietary phytochemicals has been shown to improve thrombosis and stroke outcomes in preclinical studies. Many of these compounds feature electrophilic functionalities that potentially undergo covalent addition to the sulfhydryl side chain of cysteine residues within proteins. However, the impact of such covalent modifications on the platelet activity and function remains unclear. This study explores the irreversible engagement of 23 electrophilic phytochemicals with platelets, unveiling the unique antiplatelet selectivity of sulforaphane (SFN). SFN impairs platelet responses to adenosine diphosphate (ADP) and a thromboxane A2 receptor agonist while not affecting thrombin and collagen-related peptide activation. It also substantially reduces platelet thrombus formation under arterial flow conditions. Using an alkyne-integrated probe, protein disulfide isomerase A6 (PDIA6) was identified as a rapid kinetic responder to SFN. Mechanistic profiling studies revealed SFN's nuanced modulation of PDIA6 activity and substrate specificity. In an electrolytic injury model of thrombosis, SFN enhanced the thrombolytic activity of recombinant tissue plasminogen activator (rtPA) without increasing blood loss. Our results serve as a catalyst for further investigations into the preventive and therapeutic mechanisms of dietary antiplatelets, aiming to enhance the clot-busting power of rtPA, currently the only approved therapeutic for stroke recanalization that has significant limitations.

The Physiological Inorganic Polymers Biosilica and Polyphosphate as Key Drivers for Biomedical Materials in Regenerative Nanomedicine

There is a need for novel nanomaterials with properties not yet exploited in regenerative nanomedicine. Based on lessons learned from the oldest metazoan phylum, sponges, it has been recognized that two previously ignored or insufficiently recognized principles play an essential role in tissue regeneration, including biomineral formation/repair and wound healing. Firstly, the dependence on enzymes as a driving force and secondly, the availability of metabolic energy. The discovery of enzymatic synthesis and regenerative activity of amorphous biosilica that builds the mineral skeleton of siliceous sponges formed the basis for the development of successful strategies for the treatment of osteochondral impairments in humans. In addition, the elucidation of the functional significance of a second regeneratively active inorganic material, namely inorganic polyphosphate (polyP) and its amorphous nanoparticles, present from sponges to humans, has pushed forward the development of innovative materials for both soft (skin, cartilage) and hard tissue (bone) repair. This energy-rich molecule exhibits a property not shown by any other biopolymer: the delivery of metabolic energy, even extracellularly, necessary for the ATP-dependent tissue regeneration. This review summarizes the latest developments in nanobiomaterials based on these two evolutionarily old, regeneratively active materials, amorphous silica and amorphous polyP, highlighting their specific, partly unique properties and mode of action, and discussing their possible applications in human therapy. The results of initial proof-of-concept studies on patients demonstrating complete healing of chronic wounds are outlined.

The role of platelets in non-alcoholic fatty liver disease: From pathophysiology to therapeutics

Platelets are one of the key mediators in thrombosis as well as in the progression of many diseases. An increase in platelet activation and a decrease in platelet count is associated with a plethora of liver diseases. In non-alcoholic fatty liver disease (NAFLD), platelets are highly activated and participate in the disease progression by enhancing the pro-thrombotic and pro-inflammatory state. Some altered platelet parameters such as mean platelet volume, plateletcrits, and platelet distribution width, aspartate transaminase to platelet ratio index, liver stiffness to platelet ratio and red cell distribution width to platelet ratio were found to be associated with NAFLD disease. Further, platelet contributes to the progression of cardiovascular complications in NAFLD is gaining the researcher's attention. An elevated mean platelet volume is known to enhance the risk of stroke, atherosclerosis, thrombosis, and myocardial infarction in NAFLD. Evidence also suggested that modulation in platelet function using aspirin, ticlopidine, and cilostazol help in controlling the NAFLD progression. Future research should focus on antiplatelet therapy as a treatment strategy that can control platelet activation in NAFLD as well as its cardiovascular risk. In the present review, we have detailed the role of platelets in NAFLD and its cardiovascular complications. We further aimed to highlight the growing need for antiplatelet therapy in NAFLD.

How can we use proteomics to learn more about platelets?

Proteomics tools provide a powerful means to identify, detect, and quantify protein-related details in studies of platelet phenotype and function. Here, we consider how historical and recent advances in proteomics approaches have informed our understanding of platelet biology, and, how proteomics tools can be used going forward to advance studies of platelets. It is now apparent that the platelet proteome is comprised of thousands of different proteins, where specific changes in platelet protein systems can accompany alterations in platelet function in health and disease. Going forward, many challenges remain in how to best carry out, validate and interpret platelet proteomics experiments. Future studies of platelet protein post-translational modifications such as glycosylation, or studies that take advantage of single cell proteomics and top-down proteomics methods all represent areas of interest to profiling and more richly understanding platelets in human wellness and disease.

High Autophagy Patterns in Swelling Platelets During Apheresis Platelet Storage

Platelets undergo remarkable morphological changes during storage. Platelets change into different sizes and densities and differ in their biochemistry and functions. However, the correlation between structural heterogeneity and platelet autophagy is largely unknown. The aim of this study was to investigate the autophagy process in vitro, such as routine storage of platelets, and explore the role of reactive oxygen species (ROS) involved in the regulation of platelet autophagy. The ROS and autophagy levels of platelet concentrates from apheresis platelets were evaluated through flow cytometry. The expression levels of autophagy-associated proteins (LC3I, LC3II, Beclin1, Parkin, and PINK1) were measured via Western blot. All biomarkers were dynamically monitored for seven days. Moreover, the morphological characteristics of platelet morphology during storage were analyzed through transmission electron microscopy (TEM). Flow cytometry showed that the levels of total cell ROS and mitochondria ROS increased in the stored platelets. Together with the increase in mitochondrial ROS, the autophagy signal LC3 in the platelets was strongly amplified. The number of swollen platelets (large platelets) considerably increased, and that of autophagy signal LC3 was remarkably higher than that of the normal platelets. Western blot revealed that the expression levels of Beclin1 and LC3 II/LC3 I ratio were enhanced, whereas those of Parkin and PINK1 almost did not change during the seven days of storage. The existence of autophagosomes or autophagolysosomes in the platelets at the middle stage of platelet storage was observed via TEM. Our data demonstrated that the subpopulation of large (swollen) platelets exhibited different autophagy patterns. Furthermore, increased platelet autophagy was associated with mitochondrial ROS. These preliminary results suggest that swelling platelets have a higher autophagy pattern than normal platelets during storage.

Blood-based bioenergetics: a liquid biopsy of mitochondrial dysfunction in disease

Mitochondria operate as hubs of cellular metabolism that execute important regulatory functions. Damaged/dysfunctional mitochondria are recognized as major pathogenic contributors to many common human diseases. Assessment of mitochondrial function relies upon invasive tissue biopsies; peripheral blood cells, specifically platelets, have emerged as an ideal candidate for mitochondrial function assessment. Accessibility and documented pathology-related dysfunction have prompted investigation into the role of platelets in disease, the contribution of platelet mitochondria to pathophysiology, and the capacity of platelets to reflect systemic mitochondrial health. Platelet mitochondrial bioenergetics are being investigated in neurodegenerative and cardiopulmonary diseases, infection, diabetes, and other (patho)physiological states such as aging and pregnancy. Early findings support the use of platelets as a biomarker for mitochondrial functional health.

Insights into platelet pharmacology from a cryo-EM structure of the ABCC4 transporter

Structural determination of the ABCC4 transporter is a major first step in providing crucial molecular insights into the transport of platelet substrates into granules, as well as drug transport from platelets. The findings provide a framework for understanding platelet interactions and potential design of specific platelet antagonists.

Real-time intelligent classification of COVID-19 and thrombosis via massive image-based analysis of platelet aggregates

Microvascular thrombosis is a typical symptom of COVID-19 and shows similarities to thrombosis. Using a microfluidic imaging flow cytometer, we measured the blood of 181 COVID-19 samples and 101 non-COVID-19 thrombosis samples, resulting in a total of 6.3 million bright-field images. We trained a convolutional neural network to distinguish single platelets, platelet aggregates, and white blood cells and performed classical image analysis for each subpopulation individually. Based on derived single-cell features for each population, we trained machine learning models for classification between COVID-19 and non-COVID-19 thrombosis, resulting in a patient testing accuracy of 75%. This result indicates that platelet formation differs between COVID-19 and non-COVID-19 thrombosis. All analysis steps were optimized for efficiency and implemented in an easy-to-use plugin for the image viewer napari, allowing the entire analysis to be performed within seconds on mid-range computers, which could be used for real-time diagnosis.

Non-traumatic Acute Subdural Hematoma in a Patient With Scleroderma Complicated by Pulmonary Arterial Hypertension: A Case Report

Non-traumatic acute subdural hematoma (SDH) in patients with scleroderma is infrequently described in literature reviewing the neurologic disorders in scleroderma. We report a case of a patient with scleroderma complicated by severe pulmonary arterial hypertension (PAH), and a history of pulmonary embolism on warfarin who developed an SDH, requiring hemicraniectomy after initiating therapy with IV epoprostenol. The proposed mechanisms for SDH development and management strategy are discussed.

Precision antiplatelet therapy

A State of the Art lecture titled "Personalizing Antiplatelet Therapy Based on Platelet Turnover and Metabolic Phenotype" was presented by Bianca Rocca at the International Society on Thrombosis and Haemostasis (ISTH) Congress in 2022. Increased variability in drug response may be associated with serious, mechanism-based and off-target side effects, especially in the case of drugs that do not routinely undergo therapeutic drug monitoring, such as antiplatelet drugs or direct oral anticoagulants. Precision pharmacology can be defined as the identification of a drug regimen that maximizes the benefit/risk balance at the level of an individual patient. Key tools for identifying relevant sources of variability and developing precision drug dosing are represented by genetic, biochemical, and pharmacological biomarkers recognized as a valid surrogate or strong predictor of major clinical complications. Pharmacodynamic, pharmacokinetic, and/or disease-related biomarkers are central to identifying the right population to be targeted, characterizing the sources of variability in drug response, guiding precision treatments that maximize benefits and minimize risks, and designing precision dosing trials. Another valuable tool for guiding precision pharmacology is represented by in silico pharmacokinetic/pharmacodynamic models and simulations instructed by real-world data of validated biomarkers. This review critically analyzes the tools for precision dosing and exemplifies conditions in which precision dosing can considerably optimize the efficacy and safety of antiplatelet drugs, namely aspirin and P2Y12 receptor blockers, used alone and in combination. Finally, we summarize relevant new data on this topic presented during the 2022 ISTH Congress.

The Role of Platelets in Hypoglycemia-Induced Cardiovascular Disease: A Review of the Literature

Cardiovascular diseases (CVDs) are the leading cause of death globally as well as the leading cause of mortality and morbidity in type 2 diabetes (T2D) patients. Results from large interventional studies have suggested hyperglycemia and poor glycemic control to be largely responsible for the development of CVDs. However, the association between hypoglycemia and cardiovascular events is also a key pathophysiological factor in the development of CVDs. Hypoglycemia is especially prevalent in T2D patients treated with oral sulfonylurea agents or exogenous insulin, increasing the susceptibility of this population to cardiovascular events. The adverse cardiovascular risk of hypoglycemia can persist even after the blood glucose levels have been normalized. Hypoglycemia may lead to vascular disease through mechanisms such as enhanced coagulation, oxidative stress, vascular inflammation, endothelial dysfunction, and platelet activation. In the following review, we summarize the evidence for the role of hypoglycemia in platelet activation and the subsequent effects this may have on the development of CVD. In addition, we review current evidence for the effectiveness of therapies in reducing the risk of CVDs.

Platelet-derived TLT-1 promotes tumor progression by suppressing CD8+ T cells

Current understanding of tumor immunosuppressive mechanisms forms the basis for modern day immunotherapies. Immunoregulatory role of platelets in cancer remains largely elusive. Platelets from non-small cell lung cancer (NSCLC) patients revealed a distinct activation phenotype. TREM-like transcript 1 (TLT-1), a platelet protein, was increased along with enhanced extracellular release from NSCLC platelets. The increased platelet TLT-1 was also evident in humanized mice with patient-derived tumors. In immunocompetent mice with syngeneic tumors, TLT-1 binding to T cells, in vivo, led to suppression of CD8 T cells, promoting tumor growth. We identified direct interaction between TLT-1 and CD3ε on T cells, implicating the NF-κB pathway in CD8 T cell suppression. Anti-TLT-1 antibody rescued patients' T cells from platelet-induced suppression ex vivo and reduced tumors in mice in vivo. Clinically, higher TLT-1 correlated with reduced survival of NSCLC patients. Our findings thus identify TLT-1 as a platelet-derived immunosuppressor that suppresses CD8 T cells and demonstrate its therapeutic and prognostic significance in cancer.

Relative Hypercoagulopathy of the SARS-CoV-2 Beta and Delta Variants when Compared to the Less Severe Omicron Variants Is Related to TEG Parameters, the Extent of Fibrin Amyloid Microclots, and the Severity of Clinical Illness

Earlier variants of SARS-CoV-2 have been associated with plasma hypercoagulability (as judged by thromboelastography) and an extensive formation of fibrin amyloid microclots, which are considered to contribute to the pathology of the coronavirus 2019 disease (COVID-19). The newer Omicron variants appear to be far more transmissible, but less virulent, even when taking immunity acquired from previous infections or vaccination into account. We here show that while the clotting parameters associated with Omicron variants are significantly raised over those of healthy, matched controls, they are only raised to levels significantly lower than those seen with more severe variants such as beta and delta. We also observed that individuals infected with omicron variants manifested less extensive microclot formation in platelet-poor plasma compared with those harboring the more virulent variants. The measurement of clotting effects between the different variants acts as a kind of "internal control" that demonstrates the relationship between the extent of coagulopathies and the virulence of the variant of interest. This adds to the evidence that microclots may play an important role in reflecting the severity of symptoms observed in COVID-19.

Platelets as a Gauge of Liver Disease Kinetics?

A multitude of laboratory and clinical interferences influence the utility of platelet-based diagnostic indices, including immature platelet fraction, in longitudinal monitoring and prognostication of patients with chronic liver disease (CLD). The complex yet highly regulated molecular basis of platelet production and clearance kinetics becomes dysregulated in liver pathogenesis. These underlying molecular mechanisms, including premature platelet clearance and bone marrow suppression in parallel with the progressive (e.g., treatment-naïve) or regressive (e.g., on-treatment and off-treatment) disease courses, involved in CLDs, may further confound the changes in platelet-liver correlations over time. Platelet count and function are commonly and secondarily altered in vivo in CLDs. However, the precise characterization of platelet functions during cirrhosis, including in vitro platelet aggregation, has proven challenging due to interferences such as thrombocytopenia. A flow cytometric approach may help monitor the unstably rebalanced hyper- and hypoaggregable states in patients with cirrhosis at risk of hyperaggregable, prothrombotic, or bleeding events. Studies have attempted to stratify patients with cirrhosis by substages and prognosis through the use of novel indices such as the ratio of in vitro endogenous platelet aggregation to platelet count. This review attempts to highlight clinical and laboratory precautions in the context of platelet-assisted CLD monitoring.

Baseline platelet count may predict short-term functional outcome of cerebral infarction

BACKGROUND AND AIMS

Platelets play an important role in homeostasis however, they have also been associated with increased mortality after myocardial infarction. In the present study, we investigated whether platelet count is associated with differences in the short-term prognosis at the time of hospital discharge and early neurological deterioration in ischemic stroke patients.

METHODS

Patients with ischemic stroke were enrolled from among 661 cerebrovascular disease patients admitted between January 2018 and December 2020. Patients who received hyperacute treatment, had a pre-onset modified Rankin scale (mRS) ≥ 3, transient ischemic attack, or active malignant disease were excluded. The platelet count was divided into quartiles (Q1-4) according to the number of patients, and the relationship between platelet count and prognosis was assessed using multivariable analysis.

RESULTS

In total, 385 patients were included in the study. Regarding the functional outcome by platelet count, there was a significant increase in mRS ≥ 3 at discharge in the Q4 (range: 243-1327 × 109/L, p = 0.013, ORs: 1.674, 95%CI: 1.253-6.681) group compared to the Q3 (range: 205-242 × 109/L) group even after adjusting for factors with P < 0.2 in univariate analysis. Furthermore, the frequency of neurological deterioration (NIHSS ≥ 4) within 1 week was significantly lower in the Q3 group than in the Q1 (range; 19-173 × 109/L) and Q4 groups even after adjustment (Q1; p = 0.020 ORs: 6.634, 95%CI: 1.352-32.557, Q4; p = 0.007 ORs: 8.765, 95%CI: 1.827-42.035).

CONCLUSION

Platelet count at onset may affect the prognosis of cerebral infarction and early neurological deterioration. This study may help clarify the pathogenesis of cerebral infarction to improve prognosis.