Platelet biology and functions: new concepts and clinical perspectives

From reticulated platelets to immature platelet fraction: structure, function, and clinical applications

In comparison to mature platelets, reticulated platelets (RPs) are newly released from the bone marrow and exhibit a larger size, higher reactivity, and a greater quantity of RNA, and can be an agile indicator of platelet turnover. The transcriptome associated with platelet function is significantly upregulated in RPs, which is a possible explanation for RPs intrinsic hyper-reactivity. We presented a comprehensive overview of the detection techniques for RPs. Current methods to quantify RPs in clinical routine are flow cytometry and fully automated hematology analyzers (Sysmex-XE/XN, Abbott, ADVIA, Mindray), which make the detection of RPs simpler, faster and more affordable. The proportion of RPs increased in the circulation has potential diagnostic and prognostic values in multiple clinical settings (risk stratification in cardiovascular diseases, the effect on antiplatelet drugs, differential diagnosis of thrombocytopenia, monitor platelet recovery after bone marrow or stem cell transplantation, and other diseases). There have been several studies focusing on RPs in recent years, particularly in cardiovascular disease and thrombocytopenia. In this review we summarizes the current study with regard to RPs and discuss their likely contribution in clinical routine.

Metabolic crosstalk between platelets and cancer: Mechanisms, functions, and therapeutic potential

Platelets, traditionally regarded as passive mediators of hemostasis, are now recognized as pivotal regulators in the tumor microenvironment, establishing metabolic feedback loops with tumor and immune cells. Tumor-derived signals trigger platelet activation, which induces rapid metabolic reprogramming, particularly glycolysis, to support activation-dependent functions such as granule secretion, morphological changes, and aggregation. Beyond self-regulation, platelets influence the metabolic processes of adjacent cells. Through direct mitochondrial transfer, platelets reprogram tumor and immune cells, promoting oxidative phosphorylation. Additionally, platelet-derived cytokines, granules, and extracellular vesicles drive metabolic alterations in immune cells, fostering suppressive phenotypes that facilitate tumor progression. This review examines three critical aspects: (1) the distinctive metabolic features of platelets, particularly under tumor-induced activation; (2) the metabolic crosstalk between activated platelets and other cellular components; and (3) the therapeutic potential of targeting platelet metabolism to disrupt tumor-promoting networks. By elucidating platelet metabolism, this review highlights its essential role in tumor biology and its therapeutic implications.

Role of Thrombosis in Neurodegenerative Diseases: An Intricate Mechanism of Neurovascular Complications

Thrombosis, the formation of blood clots in arteries or veins, poses a significant health risk by disrupting the blood flow. It can potentially lead to major cardiovascular complications such as acute myocardial infarction or ischemic stroke (arterial thrombosis) and deep vein thrombosis or pulmonary embolism (venous thrombosis). Nevertheless, over the course of several decades, researchers have observed an association between different cardiovascular events and neurodegenerative diseases, which progressively harm and impair parts of the nervous system, particularly the brain. Furthermore, thrombotic complications have been identified in numerous clinical instances of neurodegenerative diseases, particularly Alzheimer's disease, Parkinson's disease, multiple sclerosis, and Huntington's disease. Substantial research indicates that endothelial dysfunction, vascular inflammation, coagulation abnormalities, and platelet hyperactivation are commonly observed in these conditions, collectively contributing to an increased risk of thrombosis. Thrombosis can, in turn, contribute to the onset, pathogenesis, and severity of these neurological disorders. Hence, this concise review comprehensively explores the correlation between cardiovascular diseases and neurodegenerative diseases, elucidating the cellular and molecular mechanisms of thrombosis in these neurodegenerative diseases. Additionally, a detailed discussion is provided on the commonly employed antithrombotic medications in the context of these neuronal diseases.

Recent progress in polysaccharide microsphere-based hemostatic material for intravascular and extravascular hemostasis: A review

Hemorrhage, a common consequence of diseases, surgical procedures, and traffic accidents, poses a significant threat to public health. Effective hemostasis is crucial for patient survival and prognosis, particular in case of internal bleeding. While polysaccharide microsphere-based hemostatic materials have gained clinical acceptance due to their effectiveness, good biocompatibility, and versatility in both intravascular and extravascular hemostasis, they are limited by their single function and insufficient hemostatic properties. Recently, booming developments have been witnessed in microsphere-based biomaterials to achieve a combination therapy for hemostasis. This review first examines the fundamentals of coagulation process, hemostatic mechanisms, and microsphere fabrication techniques. We then discuss the latest investigations in functionalized microsphere-based hemostatic materials for controlling intravascular and extravascular hemorrhage, focusing on design strategies, hemostatic properties, and clinical implementation. Finally, we also propose some limitations and challenges of these hemostatic materials, aiming to provide valuable insights for future research in novel polysaccharide microsphere-based biomaterial.

NebulaPlate: a droplet microfluidic platform to analyze platelet aggregation

The accurate assessment of platelet activity is crucial in clinical practice and scientific research owing to the pivotal role of platelets in the progression of cardiovascular conditions, such as arterial thrombotic diseases. However, conventional platelet activity assessment methods are currently limited by their requirement of substantial blood samples and inadequate high-throughput capabilities, and therapeutic resistance induced by antiplatelet agents impedes treatment efficacy. In this study, we developed a microdroplet-based platelet function detection method, referred to as NebulaPlate, to achieve miniaturized and robust platelet activity assessment, thereby overcoming current challenges. NebulaPlate supports the merging of platelet samples with drugs confined in picoliter microdroplets and leverages an imaging-based analysis to automatically identify platelets, evaluate their aggregation, and determine P-selectin expression within the anchored microdroplets. We experimentally confirmed the feasibility of aggregation assays on NebulaPlate using various representative antiplatelet drugs. Requiring only 0.3 mL whole blood/chip, which corresponds to approximately 100 platelets/reaction, NebulaPlate reduced the consumption of platelet samples in a single assay. This represents a reduction of 10 times compared to that of conventional techniques. Moreover, our experimental results confirmed the validity and reproducibility of platelet function assays performed using NebulaPlate. Our research highlights important developments in the field of platelet activity assessment and provides fresh prospects for future antiplatelet therapies and personalized medicine. Moreover, it introduces new possibilities for research and clinical practice related to arterial thrombotic diseases.

NR4A1 Acts as a Novel Regulator of Platelet Activation and Thrombus Formation

BACKGROUND

Mounting evidence indicates that nuclear receptors play a critical regulatory role in platelet pathophysiology and thrombotic disorders. Although NR4A (the nuclear receptor subfamily 4 group A) plays an important role in cardiovascular pathophysiology, the expression profile and biological function of NR4A member 1 (NR4A1) in platelets have never been reported.

METHODS

We evaluated the functions and the underlying mechanisms of NR4A1 in platelet activation and thrombus formation using platelet-specific NR4A1-deficient mice and NR4A1-specific agonists. Using a hyperlipidemic mouse model and platelets from patients with hypercholesterolemia, we explored the influence of hypercholesterolemia on NR4A1 expression and the effects of NR4A1-specific agonists on platelet hyperreactivity induced by hypercholesterolemia.

RESULTS

NR4A1 was expressed in both human and mouse platelets. Platelet-specific NR4A1 deletion accelerated FeCl3-induced carotid arterial occlusive thrombus formation, enhanced collagen/epinephrine-induced pulmonary thromboembolism, and exacerbated microvascular microthrombi obstruction and infarct expansion in an acute myocardial infarction model. NR4A1-deficient platelets exhibited enhanced agonist-induced aggregation responses, integrin αIIbβ3 activation, dense granule release, α-granule release, platelet spreading, and clot retraction. Consistently, pharmacological activation of NR4A1 by specific agonists decreased platelet activation in both mouse and human platelets. Mechanistically, CAP1 (adenylyl cyclase-associated protein 1) was identified as the direct downstream interacting protein of NR4A1. NR4A1 deletion decreased cAMP levels and phosphorylation of VASP (vasodilator-stimulated phosphoprotein), while NR4A1-specific agonists increased cAMP levels and phosphorylation of VASP in platelets. Importantly, NR4A1 expression in platelets was upregulated in the setting of hypercholesterolemia, which was derived from its upregulation in megakaryocytes in a reactive oxygen species-dependent manner. Platelets from hypercholesterolemic patients and mice exhibited hyperreactivity. However, NR4A1-specific agonists significantly inhibited the activation of hypercholesterolemic platelets to the levels of healthy control platelets.

CONCLUSIONS

We provide the first evidence that nuclear receptor NR4A1 negatively regulates platelet activation and thrombus formation. NR4A1 may serve as a novel therapeutic target for managing thrombosis-based cardiovascular diseases, especially with hypercholesterolemia.

Beclin 1 of megakaryocytic lineage cells is locally dispensable for platelet hemostasis but functions distally in bone homeostasis

The crosstalk between megakaryocytic lineage cells and the skeletal system has just begun to be explored but remains largely elusive. Using conditional gene knockout mouse models, we demonstrated that loss of Beclin 1 (Becn1), a major regulator of mammalian autophagy, exclusively in the megakaryocytic lineage disrupted autophagy in platelets but did not compromise megakaryopoiesis or the formation and function of platelets. Unexpectedly, conditional Becn1 deletion in male mice led to a remarkable increase in bone mass with improved bone quality, in association with a decrease in sex hormone binding globulin (SHBG) and an increase in free testosterone (FT). In vivo Becn1 overexpression in megakaryocytic lineage-specific cells reduced bone mass and quality, along with an increase in SHBG and a decrease in FT. Transplantation of wild-type bone marrow cells into megakaryocytic lineage Becn1-deficient male mice restored bone mass and normalized SHBG and FT. Furthermore, bilateral orchiectomy of Becn1f/f;Pf4-iCre mice, which are crippled with the production of testosterone, resulted in a reduction in bone mass and quality, whereas in vivo overexpression of SHBG, specifically in the liver of Becn1f/f;Pf4-iCre mice, decreased FT and reduced bone mass and quality. In addition, metformin treatment, which induces SHBG expression, reduced FT and normalized bone mass in Becn1f/f;Pf4-iCre mice. We thus concluded that Becn1 of the megakaryocytic lineage is dispensable locally for platelet hemostasis but limits bone mass by increasing SHBG, which in turn reduces the FT of male mice. Our findings highlight a mechanism by which Becn1 from megakaryocytic lineage cells distally balances bone growth.

Platelets and mitochondria: the calcium connection

Calcium signaling has a fundamental importance in maintaining various platelet functions, such as those involved in hemostasis and thrombosis. Agonist-induced mobilization of calcium (Ca2+) from intracellular stores coupled with activation of store-operated calcium entry (SOCE) and non-SOCE or receptor-operated calcium entry (ROCE) regulates platelet degranulation, integrin activation, shape change, generation of thromboxane A2, and aggregation or procoagulant function. Platelet mitochondria also take up a small amount of cytosolic Ca2+ that contributes to bioenergetics, cytosolic Ca2+ buffering, cell signaling and death. Voltage-dependent anion channels (VDAC) in the outer mitochondrial membrane and mitochondrial Ca2+ uniporter complex (MCUC) in the inner mitochondrial membrane (IMM) are pivotal for transporting Ca2+ into the mitochondrial matrix. On the other hand, matrix Ca2+ efflux is dependent on the IMM localized sodium/calcium exchanger (NCLX). Despite the well-established role of cytosolic Ca2+, the participation of mitochondrial Ca2+ homeostasis in platelet physiology remains unknown. This mini-review summarizes the recent developments in the field of mitochondrial Ca2+ transport in platelet physiology.

20-HETE induced platelet activation via a GPR75-independent pathway

BACKGROUND

Arachidonic acid (AA) metabolism is a critical regulator of platelet activation. The cytochrome P450 (CYP450) pathway represents a key metabolic route for AA, yet the precise roles of CYP450 enzymes and their primary product, 20-hydroxyeicosatetraenoic acid (20-HETE), in platelet activation and thrombosis remain incompletely elucidated.

METHODS

We assessed the impact of aspirin on AA-induced platelet aggregation in human platelets. We further explored the influence of 20-HETE on platelet aggregation, granule secretion, and integrin activation. To elucidate the underlying mechanisms of 20-HETE action, we employed the antagonist 20-hydroxyeicosa-6(Z),15(Z)-dienoic acid (20-HEDE) and G protein-coupled receptor 75 (GPR75) knockout mice. Additionally, we evaluated the antiplatelet potential of the CYP450 inhibitor 17-octadecynoic acid (17-ODYA).

RESULTS

Aspirin suppressed platelet aggregation induced by low dose of AA and has no effect on high dose AA-induced aggregation.20-HETE indirectly induced platelet aggregation, granule release, and integrin αIIbβ3 activation in a concentration-dependent manner, independent of GPR75. The effects of 20-HETE were mediated through Gαq-coupled GPCRs. The CYP450 inhibitor 17-ODYA potently suppressed platelet activation and thrombus formation.

CONCLUSIONS

Thromboxane A2 (TXA2) is not indispensable for AA induced platelet activation. Moreover, 20-HETE has been identified as a potent platelet activator that acts through Gαq-coupled GPCRs. Its effects are mediated by downstream metabolites rather than direct interaction with GPR75.

Inhibition of platelet activation process upon tris (2-chloroethyl) phosphate exposure: Role of PFKP-mediated glycolysis and the pentose phosphate pathway

Tris (2-chloroethyl) phosphate (TCEP), recognized as an emerging pollutant, has been frequently detected in human blood. Maintenance of blood homeostasis is indispensable for regulating various physiological states and overall health, yet hematological toxicology of TCEP has not been extensively investigated. Platelets, a vital component of blood, are fundamental in the processes of hemostasis and thrombosis through their activation; thus, this study was designed to elucidate the effects and underlying mechanisms of TCEP on platelet activation. Utilizing an in vivo model, we conducted a proteomic analysis of platelets and found that TCEP exposure inhibited platelet activation. An ex vivo platelet evaluation system was employed to further dissect the processes of platelet activation, revealing that TCEP predominantly suppressed platelet aggregation, degranulation and clot retraction. These processes were highly dependent on energy metabolism, and TCEP was found to decrease ATP levels, primarily by impairing glycolysis and pentose phosphate pathways. Subsequent investigation into the molecular mechanisms revealed that TCEP decreased the activity of phosphofructokinase platelet (PFKP) by enhancing O-linked N-acetylglucosamine (O-GlcNAc) transferase interaction with PFKP. This study is the first to uncover the disruptive effects of TCEP on platelet activation process, providing valuable insights into the assessment of hematologic health risks associated with TCEP-like emerging pollutants exposure.

Systemic immune-inflammation index and long-term mortality in patients with hypertension: a cohort study

OBJECTIVE

The objective of this study was to examine the relationship between systemic inflammation and long-term mortality in patients with hypertension.

METHODS

The study employed a retrospective cohort design. The study population was derived from the National Health and Nutrition Examination Survey (NHANES), and the mortality data for this population was acquired from the National Death Index (NDI) database. Systemic inflammation was quantified by the Systemic Immune Inflammation Index (SII) and the Systemic Inflammatory Response Index (SIRI), which were then categorized into four groups (Q1-Q4, with Q4 representing the highest level of SII or SIRI). Weighted Cox regression models were constructed to investigate the association between mortality and SII and SIRI, with hazard ratios (HRs) subsequently calculated.

RESULTS

A total of 7431 participants were included in the analysis. The highest quantile (Q4) of SII was associated with a higher risk of all-cause mortality (hazard ratio 1.36, 95% CI 1.1-1.69, P  < 0.001). After adjustment for important covariates, the association remained significant (hazard ratio 1.70, 95% CI 1.27-2.30, P  < 0.001). The highest quantile (Q4) of SIRI was also associated with the highest risk of mortality (hazard ratio 2.11, 95% CI 1.64-2.70, P  < 0.001), and this association remained significant after adjustment for important covariates (hazard ratio 1.64, 95% CI 0.61-1.22, P  = 0.001).

CONCLUSION

Both SII and SIRI scores were found to be associated with mortality rates in patients with hypertension. The findings suggest that these scores may serve as complementary biomarkers to the neutrophil-to-lymphocyte ratio (NLR) for assessing mortality risk in patients with hypertension. Further investigation is warranted to elucidate the underlying mechanisms that underpin this association.

Fully Integrated Centrifugal Microfluidics for Rapid Exosome Isolation, Glycan Analysis, and Point-of-Care Diagnosis

Exosomes present in the circulatory system demonstrate considerable promise for the diagnosis and treatment of diseases. Nevertheless, the complex nature of blood samples and the prevalence of highly abundant proteins pose a significant obstacle to prompt and effective isolation and functional evaluation of exosomes from blood. Here, we present a fully integrated lab-on-a-disc equipped with two nanofilters, also termed iExoDisc, which facilitates automated isolation of exosomes from 400 μL blood samples within 45 min. By integrating the plasma separation module, highly abundant protein removal module, and nanopore membrane-based total isolation module, the resulting exosomes exhibited significantly increased purity (∼3-6-fold) compared to conventional ultracentrifugation and polymer precipitation. Additionally, we then successfully performed nontargeted and targeted glycan profiling on exosomes derived from clinical triple-negative breast cancer (TNBC) patients using MALDI-TOF-MS and lectin microarray containing 56 kinds of lectins. The findings from both methodologies indicated that galactosylation and sialylation exhibit potential as diagnostic indicators for TNBC. Finally, by utilizing the exosome-specific glycosylated protein CD63 as a proof-of-concept, we successfully realized the integration of point-of-care on-chip exosome separation and in situ detection with 2 h. Thus, the iExoDisc provides a potential approach to early cancer detection, liquid biopsy, and point-of-care diagnosis.

Inhibition of autophagy in platelets as a therapeutic strategy preventing hypoxia induced thrombosis

Hypoxia triggers activation of platelets, leading to thrombosis. If not addressed clinically, it can cause severe complications and fatal consequences. The current treatment regime for thrombosis is often palliative and include long-term administration of anticoagulants, causing over-bleeding risk and other secondary effects as well. This demands a molecular understanding of the process and exploration of an alternative therapeutic avenue. Interestingly, recent studies demonstrate that platelets exhibit functional autophagy. This cellular homeostatic process though well-studied in non-platelet cells, is under-explored in platelets. Herein, we report autophagy activation under physiologically relevant hypoxic condition (10% O2; associated with high altitude) in ex-vivo platelets and in vivo as well. We show that autophagy inhibition using chloroquine (CQ), a repurposed FDA-approved drug, can significantly reduce platelet activation, both in ex-vivo and in-vivo settings. Further, surgical ligation of inferior vena cava (IVC) was performed to induce thrombus formation. Interestingly, CQ pre-treated rats showed reduced clotting ability in surgical animals as well. Importantly, thrombosis inhibitory dose of CQ was considerably lower than the currently used drug-acetazolamide; CQ was also found to be non-toxic to the tissues. Hence, we propose that repurposing of CQ can attenuate hypoxia-induced thrombosis through inhibition of autophagy and can be explored as an effective therapeutic alternative.

Enhanced thrombopoiesis supplies PD-L1 to circulating immune cells via the generation of PD-L1-expressing platelets in patients with lung cancer

BACKGROUND

The increased expression of programmed cell death ligand 1 (PD-L1) on a subset of immune cells in the peripheral blood has been frequently observed in patients with cancer, suggesting a relationship with PD-L1 expression in tumor tissues. In this study, we investigated the mechanisms underlying PD-L1 expression on various types of immune cells in the peripheral blood of patients with cancer.

METHODS

PD-L1 expression on various immune cell populations was analyzed in peripheral blood mononuclear cells of 112 patients with non-small cell lung cancer (NSCLC) using flow cytometry. A mouse model of X-ray-induced acute thrombocytopenia was used to investigate the relationship between thrombopoiesis and PD-L1-expressing platelet generation. The clinical significance of PD-L1-expressing platelets was analyzed in a cohort of patients with stage IV NSCLC who received a combination of anti-programmed cell death 1 (PD-1) therapy and chemotherapy.

RESULTS

All immune cell populations, including monocytes, T cells, B cells, and NK cells, showed higher PD-L1 expression in patients with cancer than in healthy controls. However, this increased frequency of PD-L1-expressing cells was not attributed to the expression of the cells themselves. Instead, it was entirely dependent on the direct interaction of the cells with PD-L1-expressing platelets. Notably, the platelet-dependent acquisition of PD-L1 on circulating immune cells of patients with lung cancer was observed in various other cancer types and was mechanistically associated with a surge in thrombopoiesis, resulting in the increased production of PD-L1-expressing reticulated platelets. Clinically, patients with enhanced thrombopoiesis and concurrently high PD-L1-expressing platelets exhibited a better response to anti-PD-1 therapy.

CONCLUSIONS

These findings highlight the role of tumor-associated thrombopoiesis in generating PD-L1-expressing platelets that may serve as a resource for PD-L1-positive cells in the circulation and act as a predictive biomarker for anti-PD-1/PD-L1 therapy.

Pharmacological effects and mechanism of Ilexsaponin A1 in modulating platelet function

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex pubescens Hook. & Arn. is a traditional Chinese medicine for promoting blood circulation. Ilexsaponin A1 (IsA), a monomer of the compound, exhibits pro-angiogenic, anti-apoptotic and anti-inflammatory activities. Nevertheless, the pharmacological effects and specific mechanisms by which IsA affects platelets remain unknown.

AIM OF THE STUDY

This study aims to investigate the antiplatelet effects of IsA and the underlying molecular mechanisms.

MATERIALS AND METHODS

Platelet aggregation and ATP release were assessed using platelet aggregometry. Flow cytometry was employed to evaluate the exposure of P-selectin, integrin αⅡbβ3 activation and calcium mobilization. Fluorescence microscopy was applied to observe platelet spreading. Clot retraction was imaged by digital camera. Protein phosphorylation regulation of major signaling pathways in platelets was determined by immunoblotting analysis. Doppler flowmetry was used to investigate the in vivo effect of IsA on FeCl3-induced carotid artery injury model. Tail vein transection was used to measure bleeding time.

RESULTS

IsA dose-dependently inhibited platelet aggregation and ATP release induced by collagen, U46619, thrombin and ADP. It also suppressed thrombin-induced P-selectin exposure and PAC-1 binding. Furthermore, IsA inhibited intracellular Ca2+ mobilization and the inward flow of extracellular Ca2+. It also influenced integrin αⅡbβ3 outside-in signaling pathways, including the inhibition of platelet spreading, clot retraction and phosphorylation of outside-in signaling molecules. In addition, IsA suppressed the phosphorylation of Syk-PLCγ2, PI3K-Akt-GSK3β and MAPKs proteins, which are downstream effectors of the collagen and thrombin receptors.

CONCLUSION

IsA inhibited platelet function and thrombus formation. This has potential to be developed into a novel therapeutic agent for the treatment of thrombotic diseases.

Luminescent sensing of conformational integrin activation in living cells

Integrins are major receptors for secreted extracellular matrix, playing crucial roles in physiological and pathological contexts, such as angiogenesis and cancer. Regulation of the transition between inactive and active conformation is key for integrins to fulfill their functions, and pharmacological control of those dynamics may have therapeutic applications. We create and validate a prototypic luminescent β1 integrin activation sensor (β1IAS) by introducing a split luciferase into an activation reporting site between the βI and the hybrid domains. As a recombinant protein in both solution and living cells, β1IAS accurately reports β1 integrin activation in response to (bio)chemical and physical stimuli. A short interfering RNA (siRNA) high-throughput screening on live β1IAS knockin endothelial cells unveils hitherto unknown regulators of β1 integrin activation, such as β1 integrin inhibitors E3 ligase Pja2 and vascular endothelial growth factor B (VEGF-B). This split-luciferase-based strategy provides an in situ label-free measurement of integrin activation and may be applicable to other β integrins and receptors.

Impact of platelet transfusion and bleeding risk stratification in patients with immune thrombocytopenia before procedures

The main treatment goal for immune thrombocytopenia (ITP) is bleeding risk reduction, particularly during procedures. While adjusting platelet thresholds with ITP treatments is recommended, platelet transfusions are commonly used despite controversial benefits. We evaluated the effectiveness of platelet transfusion in reducing post-procedure bleeding risk and identified predictive indicators of bleeding. A nationally representative database was used to develop a model predicting post-procedure bleeding risk in patients with ITP. Machine learning analyses, including random forest feature importance and Shapley additive explanations (SHAP) values, assessed 34 risk factors, including the platelet transfusion amount. The random forest model had an area under the receiver-operating characteristic curve of 93.6%. Key variables influencing bleeding risk included platelet transfusion amount, high-risk procedure, anticoagulant use, anemia, age, ITP treatment, and newly diagnosed ITP, all positively correlated with bleeding risk. Conversely, no antiplatelet or anticoagulant use and moderate- or low-risk procedures were negatively associated with bleeding risk. SHAP plots showed that platelet transfusion amount correlated with high-risk procedures, and bleeding risk increased with age in high-risk procedures. Bleeding risk in patients with ITP is primarily determined by procedural risk and patient condition, rather than platelet transfusion. Minimizing unnecessary platelet transfusions and addressing bleeding risk factors pre-procedure is crucial.

The role of platelets in cancer: from their influence on tumor progression to their potential use in liquid biopsy

Platelets, anucleate blood cells essential for hemostasis, are increasingly recognized for their role in cancer, challenging the traditional notion of their sole involvement in blood coagulation. It has been demonstrated that platelets establish bidirectional communication with tumor cells, contributing to tumor progression and metastasis through diverse molecular mechanisms such as modulation of proliferation, angiogenesis, epithelial-mesenchymal transition, resistance to anoikis, immune evasion, extravasation, chemoresistance, among other processes. Reciprocally, cancer significantly alters platelets in their count and composition, including mRNA, non-coding RNA, proteins, and lipids, product of both internal synthesis and the uptake of tumor-derived molecules. This phenomenon gives rise to tumor-educated platelets (TEPs), which are emerging as promising tools for the development of liquid biopsies. In this review, we provide a detailed overview of the dynamic roles of platelets in tumor development and progression as well as their use in diagnosis and prognosis. We also provide our view on current limitations, challenges and future research areas, including the need to design more efficient strategies for their isolation and analysis, as well as the validation of their sensitivity and specificity through large-scale and rigorous clinical trials. This research will not only enable the evaluation of their clinical viability but could also open new opportunities to enhance diagnostic accuracy and develop personalized treatments in oncology.

Cooperative SIR dynamics as a model for spontaneous blood clot initiation

Blood clotting is an important physiological process to suppress bleeding upon injury, but when it occurs inadvertently, it can cause thrombosis, which can lead to life threatening conditions. Hence, understanding the microscopic mechanistic factors for inadvertent, spontaneous blood clotting, in absence of a vessel breach, can help in predicting and averting such conditions. Here, we present a minimal model - reminiscent of the SIR model - for the initiating stage of spontaneous blood clotting, the collective activation of blood platelets. This model predicts that in the presence of very small initial activation signals, collective activation of the platelet population is possible, but requires a sufficient degree of heterogeneity of platelet sensitivity. To propagate the activation signal and achieve collective activation of the bulk platelet population, it requires the presence of, possibly only few, hyper-sensitive platelets, but also a sufficient proportion of platelets with intermediate, yet higher-than-average sensitivity. A comparison with experimental results demonstrates a qualitative agreement for high platelet signalling activity.

Increasing the concentration of plasma molecules improves the biological activity of platelet-rich plasma for tissue regeneration

Platelet-rich plasma (PRP) has emerged as a promising therapy in a variety of medical fields. However, it is crucial to go beyond simple platelet concentration and examine the complex molecular composition both inside and outside platelets. The present work studies the effectiveness of a novel type of PRP named 'balanced protein-concentrate plasma' (BPCP). Different growth factor (GF) levels were measured using Enzyme Linked Immunosorbent Assay (ELISA), and in addition to the increase in intra-platelet GFs found in standard PRP (sPRP), BPCP also showed a higher concentration of plasmatic protein. Furthermore, extracellular vesicle (EV) concentration was significantly higher in BPCP. Cell proliferation was higher in cells incubated with lysates derived from BPCP compared to those cultured with sPRP. Regarding cell migration capacity, it was found that the process is platelet-dependent. Finally, the anti-inflammatory effect of BPCP was evaluated by inducing an inflammatory environment in M1-type macrophages. Cytokine levels were measured by ELISA following BPCP administration, showing a significant decrease in pro-inflammatory IL-1β, IL-6 and TNF-α. In summary, although further preclinical and clinical studies are needed in order to determine the therapeutic potential of BPCP, this PRP with unique characteristics demonstrates encouraging in vitro results that could potentially enhance tissue regeneration capacity.

Interplay between platelets and coagulation: from protective haemostasis to pathological arterial thrombosis

Haemostasis refers to the physiological process aimed at repairing vessel injury and preventing bleeding. It involves four interlinked stages culminating in the formation of a platelet-fibrin haemostatic plug that is eventually dissolved once the vessel heals. In contrast, arterial thrombosis is a pathological condition resulting from atheroma exposure, triggering the formation of a platelet-rich thrombus that may obstruct blood flow, leading to the clinical manifestations of ischaemic cardiovascular disease. The following review will provide a comprehensive overview of the finely regulated endogenous antithrombotic mechanisms responsible for maintaining the haemostatic balance and preventing intravascular thrombosis. Thereafter, it will further detail the different stages and mechanisms governing the intricate interplay between the vessel, platelets, and the coagulation cascade in haemostasis, highlighting the most recent advances in platelet biology and function, to further elucidate the differential traits and players contributing to pathological arterial thrombus growth. The review will also delve into the impact of emerging cardiovascular risk factors on tilting the haemostatic balance towards a pro-thrombotic state, thereby increasing the patient's vulnerability to thrombotic events. Finally, it will underscore the importance of early screening for subclinical atherosclerosis through advanced imaging technologies capable of quantifying plaque burden and metabolic activity since they may set the stage for an increased thrombotic risk. Implementing proactive interventions to halt atherosclerosis progression or inducing its regression at early stages is crucial for preserving haemostasis and reducing the likelihood of ischaemic atherothrombotic disease.

Peripheral inflammatory and metabolic markers as potential biomarkers in treatment-resistant schizophrenia: Insights from a Qatari Cohort

Schizophrenia presents significant diagnostic and treatment challenges, particularly in distinguishing between treatment-resistant (TRS) and non-treatment-resistant schizophrenia (NTRS). This cross-sectional study analyzed routine laboratory parameters as potential biomarkers to differentiate TRS, NTRS, and healthy individuals within a Qatari cohort. The study included 31 TRS and 38 NTRS patients diagnosed with schizophrenia, alongside 30 control subjects from the Qatar Biobank. Key measurements included complete blood count, lipid panel, HbA1c, and ferritin levels. Our findings indicated elevated body mass index (BMI) and triglyceride (TG) levels in both patient groups compared to controls. The NTRS group also showed higher HbA1c levels. Variations in inflammatory markers were noted, with the NTRS group exhibiting a higher platelet/lymphocyte ratio (PLR). Multivariate analysis highlighted significant differences in platelet count, mean platelet volume (MPV), TG, HbA1c, BMI, neutrophil/lymphocyte ratio (NLR), monocyte/lymphocyte ratio (MLR), and ferritin among the groups. Linear regression analysis revealed that MLR and clozapine treatment were significantly correlated with the severity of schizophrenia symptoms. The Random Forest model, a supervised machine learning algorithm, efficiently differentiated between cases and controls and between TRS and NTRS, with accuracies of 86.87 % and 88.41 %, respectively. However, removing PANSS scores notably decreased the model's diagnostic effectiveness. These results suggest that accessible peripheral laboratory parameters can serve as useful biomarkers for schizophrenia, potentially aiding in the early identification of TRS, enhancing personalized treatment strategies, and contributing to precision psychiatry. Future longitudinal studies are necessary to confirm these findings and further explore the role of inflammation in schizophrenia pathophysiology and treatment response.

Two-centers machine learning analysis for predicting acid-fast bacilli results in tuberculosis sputum tests

Background

Tuberculosis (TB) is a chronic respiratory infectious disease caused by Mycobacterium tuberculosis, typically diagnosed through sputum smear microscopy for acid-fast bacilli (AFB) to assess the infectivity of TB.

Methods

This study enrolled 769 patients, including 641 patients from the First Affiliated Hospital of Guangxi Medical University as the training group, and 128 patients from Guangxi Hospital of the First Affiliated Hospital of Sun Yat-sen University as the validation group. Among the training cohort, 107 patients were AFB-positive, and 534 were AFB-negative. In the validation cohort, 24 were AFB-positive, and 104 were AFB-negative. Blood samples were collected and analyzed using machine learning (ML) methods to identify key factors for TB diagnosis.

Results

Several ML methods were compared, and support vector machine recursive feature elimination (SVM-RFE) was selected to construct a nomogram diagnostic model. The area under the curve (AUC) of the diagnostic model was 0.721 in the training cohort and 0.758 in the validation cohort. The model demonstrated clinical utility when the threshold was between 38% and 94%, with the NONE line above the ALL line in the decision curve analysis.

Conclusion

We developed a diagnostic model using multiple ML methods to predict AFB results, achieving satisfactory diagnostic performance.

Mean Platelet Volume-to-Platelet Count Ratio (MPR) in Acute Exacerbations of Idiopathic Pulmonary Fibrosis: A Novel Biomarker for ICU Mortality

Background and Objectives: Acute exacerbation of idiopathic pulmonary fibrosis (IPF-AE) often results in severe respiratory distress requiring treatment in the intensive care unit and has a high mortality rate. Identifying prognostic markers and assessing disease severity are crucial for clinicians to gain detailed insights. The mean platelet volume-to-platelet count ratio (MPR) is an inflammatory marker commonly used in malignancies. This study aimed to evaluate MPR and other factors affecting mortality in patients with IPF-AE who were monitored in the intensive care unit (ICU). Materials and Methods: This retrospective study was conducted on patients monitored in the ICU for IPF-AE between 2017 and 2023. Demographic characteristics, vital signs, laboratory and imaging findings, and administered treatments were reviewed. MPR was calculated by dividing the mean platelet volume by the platelet count. The primary endpoint was defined as 1-month in-hospital mortality. Results: A total of 59 patients monitored in the ICU for IPF-AE were included in the study. The mean age of the patients was 62.75 years, and 81.4% of the participants were male. During the 30-day follow-up period, 62.7% of the patients died. The need for invasive mechanical ventilation (IMV) was significantly associated with increased mortality (p < 0.001). The optimal cutoff value for MPR was determined to be 0.033, with a sensitivity of 83.7% and specificity of 63.64%, indicating its predictive value for mortality (AUC: 0.764; 95% CI: 0.635-0.864; p < 0.001). Conclusions: In this study, the need for IMV emerged as a critical parameter in predicting mortality in patients with IPF-AE. Additionally, the use of the MPR as a prognostic biomarker may offer a novel approach in the management of IPF patients. These findings could contribute to the development of strategies aimed at early intervention in IPF patients. Further studies with larger sample sizes are needed to validate these results. This study has demonstrated that MPR is a significant prognostic biomarker for predicting mortality in patients with IPF-AE who are managed in the intensive care unit. The potential use of MPR as a biomarker in clinical decision-making may provide new approaches to the management of IPF patients. Additionally, the need for IMV in IPF-AE emerges as a critical parameter for predicting mortality. These findings may contribute to the development of early intervention strategies for IPF patients. Further studies with larger cohorts are needed to validate these results.

Association of Premature Ventricular Contraction (PVC) with hematological parameters: a data mining approach

Premature ventricular contraction (PVC) is characterized by early repolarization of the myocardium originating from Purkinje fibers. PVC may occur in individuals who are otherwise healthy. However, it may be associated with some pathological conditions. In this research the association between hematological factors and PVC was studied. In this study, 9,035 participants were enrolled in the Mashhad stroke and heart atherosclerotic disorder (MASHAD) cohort study. The association of hematological factors with PVC was evaluated using different machine learning (ML) algorithms, including logistic regression (LR), C5.0, and boosting decision tree (DT). The dataset was divided into training and test, and each model's performance was appraised on the test dataset. All data analyses used SPSS version 26 and SPSS Modeler 10. The results show that the Boosting DT was the most effective algorithm. Boosting DT had an accuracy of 98.13% and 96.92% for males and females respectively. According to the models, RDW and PLT were the most significant hematological factors for both males and females. WBC, PDW, and HCT for males and RBC, MCV, and MXD for females were also important. Some hematological factors associated with PVC were found using ML models. Further studies are needed to confirm these results in other populations, considering the novelty of the exploration of the relationship between hematological parameters and PVC.

Nicotine's impact on platelet function: insights into hemostasis mechanisms

Introduction

Traditional Miao and Dai Chinese medicines have used nicotine-rich leaf tobacco to treat traumatic injuries by promoting hemostasis. While nicotine is known to enhance platelet aggregation, its effects on other platelet functions and underlying mechanisms remain unclear.

Methods and Results

This study aimed to thoroughly investigate nicotine's effects on human platelets and its pharmacological mechanisms, using thromboelastography to assess nicotine's impact on platelet function during coagulation. This study aimed to investigate the functional effects of nicotine on human platelets and elucidate its pharmacological mechanisms. The impact of nicotine on platelet function during the coagulation process was assessed using thromboelastography. Further studies showed that nicotine fully activates washed platelets, promoting aggregation, granule release, adhesion, spreading, and plaque retraction. Concurrently, nicotine was found to enhance the intracellular concentration of calcium ions in platelets ([Ca2+]i). To explore the underlying mechanisms, molecular docking software was employed to identify the platelet membrane receptors PAR1 and PAR4, which exhibited the highest docking scores with nicotine. Intervention with two receptor inhibitors demonstrated that only the PAR4 inhibitor could reverse the stimulatory effects of nicotine on platelet granule release. Through the examination of alterations in the downstream signaling pathways of PAR4 receptors, it was determined that nicotine promo-facilitates the phosphorylation of PI3K, AKT, and ERK1/2 proteins, subsequently contributing to the activation of αIIbβ3 receptors in platelets. Conversely, the application of PAR4 inhibitors was found to reverse these effects.

Discussion

In conclusion, nicotine activates αIIbβ3 receptors and significantly enhances platelet function by promoting the phosphorylation of the platelet PAR4 receptor signaling pathway. These findings suggest the potential utility of nicotine as a hemostatic agent.

Lymphatic platelet thrombosis limits bone repair by precluding lymphatic transporting DAMPs

In the musculoskeletal system, lymphatic vessels (LVs), which are interdigitated with blood vessels, travel and form an extensive transport network. Blood vessels in bone regulate osteogenesis and hematopoiesis, however, whether LVs in bone affect fracture healing is unclear. Here, we investigate the lymphatic draining function at the tibial fracture sites using near-infrared indocyanine green lymphatic imaging (NIR-ICG) and discover that lymphatic drainage insufficiency (LDI) starts on day one and persists for up to two weeks following the fracture in male mice. Sufficient lymphatic drainage facilitates fracture healing in male mice. Furthermore, we identify that lymphatic platelet thrombosis (LPT) blocks the draining lymphoid sinus and LVs, causes LDI, and inhibits fracture healing in male mice, which can be rescued by a blood thinner. Moreover, unblocked lymphatic drainage decreases neutrophils and increases M2-type macrophages of the hematoma niche to support osteoblast (OB) survival and bone marrow-derived mesenchymal stem cell (BMSC) proliferation via transporting damage-associated molecular patterns (DAMPs) in male rats. Lymphatic platelet thrombolysis also benefits senile fracture healing in female mice. These findings demonstrate that LPT limits bone regeneration by impeding lymphatic transporting DAMPs. Together, these findings represent a way forward in the treatment of bone repair.

Aptamer BT200 is protective against myocardial ischemia-reperfusion injury in mice

BACKGROUND

Myocardial ischemia-reperfusion (MI/R) injury tends to affect cardiac function and leads to poor patient prognosis, and there is still no effectively targeted drug to develop anti-von Willebrand factor (VWF) aptamer in acute coronary heart disease. However, the newly anti-VWF aptamer BT200 is applied not only for stroke and hemophilia but also for antithrombolism function in clinical development. The role of BT200 in acute myocardial injury during MI/R is still unknown.

OBJECTIVES

To investigate the cardioprotective effect of aptamer BT200 in a mouse model of MI/R.

METHODS

C57BL/6 mice were subjected to 30-minute ischemia and 24-hour reperfusion to establish MI/R model. Mice were treated with intravenous injection of cy3-labeled BT200 and were observed by an in vivo imaging system at different time points. Then, mice were sampled and evaluated by echocardiography, Evans triphenyltetrazolium chloride staining, histopathologic, western blotting, and real-time quantitative polymerase chain reaction assays to detect cardiac injury and inflammation response after 24-hour reperfusion.

RESULTS

BT200 aptamer can enter and infiltrate into the ischemic myocardium after 24-hour reperfusion. BT200 was shown to inhibit VWF A1 activity and prolong bleeding time in MI/R mice. Moreover, BT200-treated mice had a significant reduction in infarct size and an improvement in cardiac function post-MI/R. BT200 treatment can also alleviate MI/R-induced microvascular obstruction, inflammation response, and cardiomyocyte apoptosis.

CONCLUSION

Pharmacologic targeting of VWF with BT200 alleviates acute MI/R injury in a murine model and may be a novel therapy strategy for acute myocardial infarction.

Polyphenol Treatment of Peripheral Blood Mononuclear Cells from Individuals of Different Ages

Human peripheral blood mononuclear cells (PBMCs) have been largely utilized to assess the cytotoxic, immunomodulatory, and anti-inflammatory properties of both synthetic and natural compounds. Within the latter category, polyphenols from dietary sources have been extensively analyzed. PBMCs represent a feasible in vitro model to study polyphenol hallmarks and activity according to quantitative and qualitative differences in immune responses in individuals of different age. In this chapter, we propose a method for PBMC treatment with polyphenols and analysis designed on age-dependent qualitative and quantitative variability in immune cell performance.

Carbon dioxide alleviates platelet storage lesions via stimulating fatty acid metabolism and reducing platelet glucose consumption

Background

The timely administration of platelet transfusions is critical for patient survival, and the clinical demand for platelet transfusions has been steadily increasing. However, platelet storage lesions (PSLs) that develop during in vitro preservation exacerbate these shortages. The PSL is significantly influenced by various factors, including temperature, gas composition, and buffering systems. Strategies to mitigate PSLs and improve platelet storage have been actively explored in recent years.

Objectives

This study aimed to investigate whether elevated carbon dioxide (CO2) levels improve platelet quality and functionality during storage.

Methods

Platelet concentrates from 28 donors were stored under control or 3% CO2 conditions at 22 ± 2 °C for up to 7 days. Platelet quality was evaluated through scanning electron microscopy, adhesion, aggregation, clot contraction, activation, apoptosis assays, blood gas, adenosine triphosphate, metabolomics analyses, and in vivo thrombosis and survival tests.

Results

Our findings indicate that increasing the CO2 concentration in the storage environment mitigates PSLs and improves platelet quality.

Conclusion

Our study highlights the potential benefits of utilizing a high CO2 storage environment to improve platelet preservation, offering a promising method to address clinical platelet shortages.

Physical-Matched Nanoplatelets Boost Heterogeneous Thrombi Targeting Through Self-Adaptive Deformation for Thrombolysis and Endothelial Repairing

The heterogeneity of thrombi in terms of composition, structure, and blood rheology parameters presents a challenge for effective thrombus-targeting drug delivery. To address this, a self-adaptive nano-delivery system, termed D-PLT, is developed. It consists of platelet membrane-cloaked deformable mesoporous organic silicon dioxide nanocomposite, enabling it to respond to the challenge of the heterogeneity of thrombi in arteries and veins. The system exhibits progressive targeting, with the ability to target arterial and venous thrombosis and damaged blood vessels. D-PLT physically matches the pore structure of the thrombus by undergoing varied deformation, leading to advanced targeting and enrichment of arterial and venous thrombus. When co-loaded with the thrombolytic drug urokinase (UK) and the endothelium-protecting agent atorvastatin calcium (AT), the system improves rapid vascular opening of arterial and venous thrombosis in 90 min and provides up to 7 days of durable thrombolysis and recovery from endothelial dysfunction in vivo. This self-adaptive delivery system offers a promising strategy to overcome thrombus heterogeneity.

Platelet signaling in immune landscape: comprehensive mechanism and clinical therapy

Platelets are essential for blood clotting and maintaining normal hemostasis. In pathological conditions, platelets are increasingly recognized as crucial regulatory factors in various immune-mediated inflammatory diseases. Resting platelets are induced by various factors such as immune complexes through Fc receptors, platelet-targeting autoantibodies and other platelet-activating stimuli. Platelet activation in immunological processes involves the release of immune activation stimuli, antigen presentation and interaction with immune cells. Platelets participate in both the innate immune system (neutrophils, monocytes/macrophages, dendritic cells (DCs) and Natural Killer (NK) cells and the adaptive immune system (T and B cells). Clinical therapeutic strategies include targeting platelet activation, platelet-immune cell interaction and platelet-endothelial cell interaction, which display positive development prospects. Understanding the mechanisms of platelets in immunity is important, and developing targeted modulations of these mechanisms will pave the way for promising therapeutic strategies.

Combination of age-adjusted d-dimer, platelet distribution width and other factors predict preoperative deep venous thrombosis in elderly patients with femoral neck fracture

PURPOSE

This retrospective cohort study aimed to identify factors associated with preoperative deep venous thrombosis (DVT) in elderly patients with femoral neck fractures, and to investigate whether combining these factors could improve the ability to predict DVT.

METHOD

Medical records and laboratory test results were reviewed patients presenting with a femoral neck fracture and receiving routine chemoprophylaxis for DVT between January 2020 and December 2023 in a tertiary referral, university-affiliated hospital. Preoperative DVT was confirmed by Doppler ultrasound or CT venography. Demographic, injury, comorbidity, and laboratory variables were analyzed using univariate and multivariate approaches. The performance of combined predictive factors was evaluated using receiver operating characteristic (ROC) curve analysis.

RESULTS

Among the 499 patients included, 47 (9.4%) were diagnosed with a preoperative DVT. In the univariate analysis, five variables were found to be statistically significant, including alcohol consumption (P = 0.017), history of renal disease (P < 0.001), elevated D-dimer level (both traditional and age-adjusted cut-off used) (P = 0.007 or < 0.003), increased platelet distribution width (PDW) (P < 0.001) and reduced albumin in continuous or categorical variable (P = 0.027, P = 0.002). Multivariate analysis confirmed all except alcohol consumption as independent predictors (all P < 0.05). ROC curve analysis showed that combining these four significant variables with age improved the ability to predict preoperative DVT, with an area under the curve of 0.749 (95% CI: 0.676-0.822, P < 0.001), sensitivity of 0.617, and specificity of 0.757.

CONCLUSION

This study identified several factors associated with preoperative DVT, and combining them demonstrated improved performance in predicting DVT, which can facilitate risk assessment, stratification and improved management in clinical practice.

Effect of aspirin on platelet-rich plasma of diabetes mellitus with lower extremity atherosclerosis

Aim: Platelet-rich plasma (PRP), enriched with multiple growth factors, is a promising adjunctive therapy for diabetic foot ulcers (DFUs). As a classic anti-platelet drug for diabetic patients, the effects of aspirin on the content of growth factors in PRP remains unclear.Methods: Our study enrolled diabetic patients who were currently taking or not taking aspirin as the research subjects, with healthy volunteers as the control. PRP from these individuals was activated with glucose calcium and thrombin. Growth factors levels in PRP activated supernatant (PRP-AS) and wound healing ability of platelet gel (PG) in the full-thickness skin defect diabetic mouse model were compared.Results: We found the level of growth factors in PRP-AS derived from two groups of diabetic patients were not statistically different, whereas both lower than that from healthy volunteers. Similarly, we found better wound healing ability of PG from healthy volunteers than those from diabetic patients, but no difference between the two groups of diabetic patients in the mouse model.Discussion: Aspirin does not interfere with autologous PRP therapy when using calcium gluconate and thrombin as agonists. However considering the content of growth factors, PRP from healthy volunteers is a preferable option for promoting DFU repair.

The use of platelets as a clinical tool in oncology: opportunities and challenges

Platelets are small circulating anucleated cells mainly involved in thrombosis and hemostasis processes. Moreover, platelets play an active role in tumorigenesis and cancer progression, stimulating angiogenesis and vascular remodelling, and protecting circulating cancer cells from shear forces and immune surveillance. Several reports indicate that platelet number in the blood circulation of cancer patients is associated with prognosis and response to treatment. However, the mechanisms of platelets "education" by cancer cells and the crosstalk between platelets and tumor are still unclear, and the role of "tumor educated platelets" (TEPs) is achieving growing interest in cancer research. TEPs are a biological source of cancer-derived biomarkers, especially RNAs that are protected by platelets membrane from circulating RNases, and could serve as a non-invasive tool for tumor detection, molecular profiling and evolution during therapy in clinical practice. Moreover, short platelet lifespan offers the possibility to get a snapshot assessment of cancer molecular profile, providing a real-time tool. We review and discuss the potential and the clinical utility, in terms of cancer diagnosis and monitoring, of platelet count together with other morphological parameters and of the more recent and innovative TEP profiling.

Predicting the risk of pulmonary embolism in patients with tuberculosis using machine learning algorithms

BACKGROUND

This study aimed to develop predictive models with robust generalization capabilities for assessing the risk of pulmonary embolism in patients with tuberculosis using machine learning algorithms.

METHODS

Data were collected from two centers and categorized into development and validation cohorts. Using the development cohort, candidate variables were selected via the Recursive Feature Elimination (RFE) method. Five machine learning algorithms, logistic regression (LR), random forest (RF), extreme gradient boosting (XGBoost), light gradient boosting machine (LightGBM), and support vector machine (SVM), were utilized to construct the predictive models. Model performance was evaluated through nested cross-validation and area under the curve (AUC) metrics, supplemented by interpretations using Shapley Additive explanations (SHAP) and line charts of AUC values. Models were subjected to external validation using an independent validation group, facilitating the early identification and management of pulmonary embolism risks in tuberculosis patients.

RESULTS

Data from 694 patients were used for model development, and 236 patients from the validation group met the enrollment criteria. The optimal subset of variables identified included D-dimer, smoking status, dyspnea, age, sex, diabetes, platelet count, cough, fibrinogen, hemoglobin, hemoptysis, hypertension, chronic obstructive pulmonary disease (COPD), and chest pain. The RF model outperformed others, achieving an AUC of 0.839 (95% CI 0.780-0.899) and maintaining the highest average performance in external fivefold cross-validation (AUC: 0.906 ± 0.041).

CONCLUSIONS

The RF model demonstrates high and consistent effectiveness in predicting pulmonary embolism risk in tuberculosis patients.

Pathological roles of mitochondrial dysfunction in endothelial cells during the cerebral no-reflow phenomenon: A review

Emergency intravascular interventional therapy is the most effective approach to rapidly restore blood flow and manage occlusion of major blood vessels during the initial phase of acute ischemic stroke. Nevertheless, several patients continue to experience ineffective reperfusion or cerebral no-reflow phenomenon, that is, hypoperfusion of cerebral blood supply after treatment. This is primarily attributed to downstream microcirculation disturbance. As integral components of the cerebral microvascular structure, endothelial cells (ECs) attach importance to regulating microcirculatory blood flow. Unlike neurons and microglia, ECs harbor a relatively low abundance of mitochondria, acting as key sensors of environmental and cellular stress in regulating the viability, structural integrity, and function of ECs rather than generating energy. Mitochondria dysfunction including increased mitochondrial reactive oxygen species levels and disturbed mitochondrial dynamics causes endothelial injury, further causing microcirculation disturbance involved in the cerebral no-reflow phenomenon. Therefore, this review aims to discuss the role of mitochondrial changes in regulating the role of ECs and cerebral microcirculation blood flow during I/R injury. The outcomes of the review will provide promising potential therapeutic targets for future prevention and effective improvement of the cerebral no-reflow phenomenon.

Platelets accelerate lipid peroxidation and induce pathogenic neutrophil extracellular trap release

Neutrophil extracellular traps (NETs), an important host defense mechanism, are assembled after the release of decondensed chromatin and other nuclear components by a process termed NETosis. However, excessive NET release destroys surrounding tissues, leading to conditions such as sepsis where platelets are implicated in the pathogenic switch of NETosis. Here, we show that platelets trigger iron accumulation and promote lipid peroxide production in neutrophils co-stimulated with lipopolysaccharide and platelets in vitro, resulting in the induction of NETosis. We also screened for compounds that inhibit lipid peroxidation, identified 8-methyl-N-geranyl-6-nonamide (capsaicin), and assessed its potential in suppressing platelet-mediated pathogenic NETosis. Capsaicin inhibited lipopolysaccharide/platelet-induced cellular lipid peroxidation and suppressed NETosis in vitro. Furthermore, capsaicin attenuated NETosis in a mouse model of lipopolysaccharide-induced lung inflammation. Our findings provide an original therapeutic strategy to target lipid peroxidation and pave the way for drug development for a wide range of NETosis-related diseases.

GSDME-mediated pyroptosis contributes to chemotherapy-induced platelet hyperactivity and thrombotic potential

ABSTRACT

Thrombotic complications due to platelet hyperreactivity are a major cause of death in patients undergoing chemotherapy. However, the underlying mechanisms are not fully understood. Herein, using human platelets and platelets from mice lacking gasdermin E (GSDME), we show that GSDME is functionally expressed in anucleate platelets, and that GSDME-mediated pyroptosis, a newly identified form of cell death in mammalian nucleated cells, contributes to platelet hyperactivity in cisplatin-based chemotherapy. Cisplatin or etoposide activates caspase-3 to cleave GSDME, thereby releasing the N-terminal fragment of GSDME (GSDME-N) toward the platelet plasma membrane, subsequently forming membrane pores and facilitating platelet granule release. This eventually promotes platelet hyperactivity and thrombotic potential. We identified flotillin-2, a scaffold protein, as a GSDME-N interactor that recruits GSDME-N to the platelet membrane. Loss of GSDME protects mice from cisplatin-induced platelet hyperactivity. Our results provide evidence that targeting GSDME-mediated pyroptosis could reduce thrombotic potential in chemotherapy.

TRAP-Induced Platelet Reactivity Is Inhibited by Omega-3 Fatty Acid-Derived Prostaglandin E3 (PGE3)

Background: Prostaglandins are naturally occurring local mediators that can participate in the modulation of the cardiovascular system through their interaction with Gs/Gi-coupled receptors in different tissues and cells, including platelets. Thrombin is one of the most important factors that regulates platelet reactivity and coagulation. Clinical trials have consistently shown that omega-3 fatty acid supplementation lowers the risk for cardiovascular mortality and morbidity. Since omega-3 fatty acids are the main precursors of PGE3 in vivo, it would be relevant to investigate the effects of PGE3 on Thrombin Receptor Activating Peptide (TRAP-6)-induced platelet reactivity to determine the receptors and possible mechanisms of action of these compounds. Methods: We have measured platelet aggregation, P-selectin expression, and vasodilator-stimulated phosphoprotein (VASP) phosphorylation to evaluate platelet reactivity induced by TRAP-6 to determine the effects of PGE3 on platelet function. Results: We assessed the ability of DG-041, a selective prostanoid EP3 receptor antagonist, and of ONO-AE3-208, a selective prostanoid EP4 receptor antagonist, to modify the effects of PGE3. PGE3 inhibited TRAP-6-induced platelet aggregation and activation. This inhibition was enhanced in the presence of a Gi-coupled EP3 receptor antagonist and abolished in the presence of a Gs-coupled EP4 receptor antagonist. The effects of PGE3 were directly related to changes in cAMP, assessed by VASP phosphorylation. Conclusions: The general effects of PGE3 on human platelet reactivity are the consequence of a balance between activatory and inhibitory effects at receptors that have contrary effects on adenylate cyclase. These results indicate a potential mechanism by which omega-3 fatty acids underlie cardioprotective effects.

Impaired hemostatic and immune functions of platelets after acute thrombocytopenia

BACKGROUND

Platelets are pivotal in maintaining vascular integrity, hemostasis, and immune modulation, with newly generated, immature platelets being the most responsive in fulfilling these tasks. Therefore, the immature platelet fraction provides insights into thrombopoiesis dynamics and clinical prognostication. However, it is currently unclear how immature platelet functions change in settings of acute thrombocytopenia.

OBJECTIVES

We aimed to investigate the functional consequences of acute thrombocytopenia on newly generated immature platelets in various mouse models and human subjects.

METHODS

To examine platelet functionality after acute thrombocytopenia, we depleted either megakaryocytes using a platelet factor 4-specific inducible diphtheria toxin receptor transgenic mouse model or platelets via antibody-mediated depletion in mice, and collected blood from acute myeloid leukemia (AML) patients before and after consolidation or induction chemotherapy. Chemotherapy treatment was further repeated in an animal model. We assessed surface receptor expression of activation markers (CD62P, active GPIIb/IIIa, CD40L, CD63, CD107a) and toll-like receptors (TLR2, TLR4, TLR9) on immature and mature platelets following activation. Additionally, we investigated procoagulant platelet formation and platelet-leukocyte interactions in mouse models and patients with AML.

RESULTS

In murine models, acute thrombocytopenia led to impaired hemostatic function and altered surface receptor expression in newly generated immature platelets. Similarly, AML patients during regeneration post chemotherapy exhibited reduced platelet activation and procoagulant function, alongside altered receptor expression and diminished platelet-leukocyte interactions.

CONCLUSION

After acute thrombocytopenia platelet-mediated hemostasis and immune modulation by newly generated platelets are impaired, underscoring the clinical relevance of understanding platelet function alterations in (post)thrombocytopenic conditions for therapeutic optimization.

High-Dimensional Single-Cell Mass Cytometry Demonstrates Differential Platelet Functional Phenotypes in Infants With Congenital Heart Disease

BACKGROUND

Congenital heart disease (CHD) is a group of complex heart defects associated with hematologic abnormalities, including increased risk of thrombotic and bleeding events. Past studies have observed evidence of platelet hyperreactivity, while other studies showed decreased platelet activation in patients with CHD. The goal of this study was to develop a mass spectrometry approach to characterize single platelets in infants with CHD and identify potential etiology for such discrepant results.

METHODS

We enrolled 19 infants with CHD along with 21 non-CHD controls at Yale New Haven Children's Heart Center. A single-cell high-dimensional mass cytometry method was developed to quantitatively interrogate platelet surface markers in whole blood. Additionally, plasma cytokine analysis was performed through a multiplexed panel of 52 vascular and inflammatory markers to assess for platelet releasates.

RESULTS

We found that infants with CHD had significant differences in platelet activation and functional markers by mass cytometry compared with non-CHD controls. Based on cell surface markers, we classified the platelets into 8 subpopulations (P0 to P7). Distinct subpopulations of platelets (P1, P4, and P5) exhibiting decreased aggregatory phenotype but altered secretory phenotypes were also identified and found to be more abundant in the blood of infants with CHD. Electron microscopy identified increased proportion of hypogranular platelets in CHD. Moreover, cytokine analysis demonstrated an overall increase in plasma cytokines and biomarkers in CHD, including IL (interleukin)-6, IL-8, IL-27, RANTES (regulated upon activation, normal T cell expressed and secreted), and VWF (von Willebrand factor), which are expressed in platelet granules and can be released upon activation.

CONCLUSIONS

We developed a robust mass cytometry approach to identify platelet phenotypic heterogeneity. Infants with CHD had alterations in distinct subpopulations of platelets with overall reduced aggregatory phenotype and secretory dysfunction. These findings suggest that platelets in infants with CHD may be exhausted due to persistent stimulation and may explain both bleeding and thrombotic vascular complications associated with CHD.

Modified Sijunzi Granules Exhibit Hemostatic Effect by Activating Akt and Erk Signal Pathways via Regulating 5-HT and Its Receptors Levels

OBJECTIVE

To investigate the hemostatic effect of modified Sijunzi Granules (MSG) in primary immune thrombocytopenia (ITP) zebrafish model and explore the potential mechanism.

METHODS

AB strain wild type zebrafish were treated with simvastatin (6 µmol/L) for 24 h to establish the hemorrhage model (model control group). The zebrafish were treated with MSG at different doses (55.6, 167, and 500 µg/mL), respectively. The hemostatic effect was assessed by examining the intestinal bleeding and hemostatic rate. 5-Hydroxytryptamine (5-HT) content was determined using enzyme-linked immunosorbent assay (ELISA) assay. The expressions of 5-HT2aR, 5-HT2bR, and SERT genes were detected by quantitative real-time polymerase chain reaction(PCR). The protein expressions of protein kinase B (Akt), p-Akt, extracellular regulated protein kinases (Erk), and p-Erk were examined using Western blot analysis.

RESULTS

The intestinal bleeding rate was 37%, 40%, and 80% in the 55.6, 167, and 500 µg/mL dose of MSG, respectively, in which 55.6 and 167 µg/mL MSG dose groups were associated with significantly decreased intestinal bleeding rate when compared with the model control group (70%, P<0.05). Significantly higher hemostatic rates were also observed in the 55.6 (54%) and 167 (52%) µg/mL MSG dose groups (P<0.05). MSG increased the 5-HT content and mRNA expression levels of 5-HT2aR, 5-HT2bR, and SERT (P<0.05). In addition, caspase3/7 activity was inhibited (P<0.05). Significant increase in p-Akt and p-Erk was also detected after treatment with MSG (P<0.05).

CONCLUSIONS

MSG could reduce the incidence and severity of intestinal bleeding in zebrafish by activating MAPK/Erk and PI3K/Akt signal pathways through regulating the levels of 5-HT and its receptors, which may provide evidence for the treatment of ITP.

Potential Player of Platelet in the Pathogenesis of Cardiotoxicity: Molecular Insight and Future Perspective

Cancer patients may encounter the onset of cardiovascular disease due to tumor advancement or chemotherapy, commonly known as "cardiotoxicity." In this respect, the conventional chemotherapy treatment protocol involves a mixture of different medications. These medications can be detrimental to cardiac tissue, consequently exposing the patient to the possibility of irreversible cardiac injury. The enhancement of oxidative stress and inflammation is an important mechanism of chemotherapeutic agents for developing cardiotoxicity. Regarding their dual pro- and anti-inflammatory functions, platelets can significantly influence the progression or suppression of cardiotoxicity. Therefore, the expression of platelet activatory markers can serve as valuable prognostic indicators for cardiotoxicity. The primary objective of this study is to examine the significance of platelets in cardiotoxicity and explore potential strategies that could effectively target malignant cells while minimizing their cytotoxic impact, such as cardiotoxicity and thrombosis.

Decrease in platelet count in patients with AKI and its association with major adverse kidney events

INTRODUCTION

A reduction in platelet count in critically ill patients is a marker of severity of the clinical condition. However, whether this association holds true in acute kidney injury (AKI) is unknown. We analyzed the association between platelet reduction in patients with AKI and major adverse kidney events (MAKE).

METHODS

In this retrospective cohort, we included AKI patients at the Hospital Civil of Guadalajara, in Jalisco, Mexico. Patients were divided according to whether their platelet count fell >21% during the first 10 days. Our objectives were to analyze the associations between a platelet reduction >21% and MAKE at 10 days (MAKE10) or at 30-90 days (MAKE30-90) and death.

RESULTS

From 2017 to 2023, 400 AKI patients were included, 134 of whom had a > 21% reduction in platelet count. The mean age was 54 years, 60% were male, and 44% had sepsis. The mean baseline platelet count was 194 x 103 cells/µL, and 65% of the KDIGO3 patients met these criteria. Those who underwent hemodialysis (HD) had lower platelet counts. After multiple adjustments, a platelet reduction >21% was associated with MAKE10 (OR 4.2, CI 2.1-8.5) but not with MAKE30-90. The mortality risk increased 3-fold (OR 2.9, CI 1.1-7.7, p = 0.02) with a greater decrease in the platelets (<90 x 103 cells/µL). As the platelets decreased, the incidence of MAKE was more likely to increase. These associations lost significance when accounting for starting HD.

CONCLUSION

In our retrospective cohort of patients with AKI, a > 21% reduction in platelet count was associated with MAKE. Our results are useful for generating hypotheses and motivating us to continue studying this association with a more robust design.

Innovative utilization of cell membrane-coated nanoparticles in precision cancer therapy

Cell membrane-coated nanoparticles (CMNPs) have recently emerged as a promising platform for cancer therapy. By encapsulating therapeutic agents within a cell membrane-derived coating, these nanoparticles combine the advantages of synthetic nanoparticles and natural cell membranes. This review provides a comprehensive overview of the recent advancements in utilizing CMNPs as effective drug delivery vehicles for cancer therapy. The synthesis and fabrication methods of CMNPs are comprehensively discussed. Various techniques, such as extrusion, sonication, and self-assembly, are employed to coat synthetic nanoparticles with cell membranes derived from different cell types. The cell membrane coating enables biocompatibility, reducing the risk of an immune response and enhancing the stability of the nanoparticles in the bloodstream. Moreover, functionalization strategies for CMNPs, primarily chemical modification, genetic engineering, and external stimuli, are highlighted. The presence of specific cell surface markers on the coated membrane allows targeted drug delivery to cancer cells and maximizes therapeutic efficacy. Preclinical studies utilizing CMNPs for cancer therapy demonstrated the successful delivery of various therapeutic agents, such as chemotherapeutic drugs, nucleic acids, and immunotherapeutic agents, using CMNPs. Furthermore, the article explores the future directions and challenges of this technology while offering insights into its clinical potential.

The longevity-associated BPIFB4 gene guarantees vascular homeostasis and immune protection through platelets

Beyond their activity in hemostasis and thrombosis, recent advances attribute platelets a pro-youthful role capable to attenuate immune senescence and age-related neuroinflammation. Previous studies from our group associated a polymorphic haplotype variant in the BPIFB4 gene (LAV-BPIFB4) with exceptional longevity. Transfer of the LAV-BPIFB4 in preclinical models has proved strategic to cope with frailty conditions, aging-related events, e.g., cardiovascular ones, and immune dysfunction mainly through a favorable conditioning of the immune system. However, whether platelets participate in LAV-BPIFB4 therapeutic action is currently unknown. Herein, we discovered that platelets were instrumental in boosting the favorable health outcomes of the systemic AAV-LAV-BPIFB4 gene transfer in vivo, as the α-CD42b platelet depletion completely abolished the vascular protective action of LAV-BPIFB4 and suppressed its pro-resolutive CD206 + anti-/CD86 + pro-inflammatory Ly6C + monocyte skewing to LPS stimulation. Of note, this is associated with a huge drop in the protective levels of BPIFB4 in the plasma of AAV-LAV-BPIFB4-injected C57BL/6 mice, indicating that plasma circulating platelets may be a reservoir of the BPIFB4 protein. Indeed, we noticed that BPIFB4 was released by human platelets, a process that is amplified in LAV-allele carrier donors. Accordingly, lentivirus-mediated overexpression of human LAV-BPIFB4 isoform, but not WT-BPIFB4 isoform was able in leading differentiated megakaryocytes to release more platelet-like-particles enriched for BPIFB4. In addition, in vitro, the M2 macrophage polarization increased when releasate from platelets, and even more from LAV pre-stimulated once, was added in monocyte cell culture. Our data suggest that platelet release of BPIFB4 and of yet-to-be-determined unidentified factors mediates the therapeutic efficacy of LAV-BPIFB4 treatment.

Development of a super-hydrophilic anaerobic tube for the optimization of platelet-rich fibrin

Horizontal platelet-rich fibrin (H-PRF) contains a variety of bioactive growth factors and cytokines that play a key role in the process of tissue healing and regeneration. The blood collection tubes used to produce Solid-PRF (plasmatrix (PM) tubes) have previously been shown to have a great impact on the morphology, strength and composition of the final H-PRF clot. Therefore, modification to PM tubes is an important step toward the future optimization of PRF. To this end, we innovatively modified the inner wall surface of the PM tubes with plasma and adjusted the gas environment inside the PM tubes to prepare super-hydrophilic anaerobic plasmatrix tubes (SHAP tubes). It was made anaerobic for the preparation of H-PRF with the aim of improving mechanical strength and bioactivity. The findings demonstrated that an anaerobic environment stimulated platelet activation within the PRF tubes. After compression, the prepared H-PRF membrane formed a fibrous cross-linked network with high fracture strength, ideal degradation characteristics, in addition to a significant increase in size. Thereafter, the H-PRF membranes prepared by the SHAP tubes significantly promoted collagen synthesis of gingival fibroblast and the mineralization of osteoblasts while maintaining excellent biocompatibility, and advantageous antibacterial properties. In conclusion, the newly modified PRF tubes had better platelet activation properties leading to better mechanical strength, a longer degradation period, and better regenerative properties in oral cell types including gingival fibroblast and alveolar osteoblasts. It also improves the success rate of H-PRF preparation in patients with coagulation dysfunction and expands the clinical application scenario.

An automated method for thrombocyte counting in capillary microsamples

INTRODUCTION

We aimed to develop an automated, low-volume method for thrombocyte counting in capillary blood using the Sysmex predilution (PD) mode.

METHODS

Microsamples were prepared by resuspension of 50 μL blood in 300 μL DCL CellPack. Thrombocyte counting was done in the impedance (PLT-I) and fluorescence (PLT-F) channels. The imprecision and bias was evaluated in >394 microsamples from adult blood. Preanalytical factors (skin-piercing, storage, and transportation in our pneumatic tube system) was assessed, and studies on pediatric microsamples were made for comparison. The improvement in analytical quality and turnaround time was examined.

RESULTS

For PLT-F, the imprecision was 1.1%-3.7%, and the bias was 10.1% (95% CI: 8.8-11.3). After skin-piercing, the bias was 8.1% (95% CI: 5.6-10.6) and the imprecision 1.9% (95% CI: 1.3-2.5). Thrombocyte counts kept stable after 4 h at room temperature (94.8% [95% CI: 93.2-96.4]) and after pneumatic tube transportation [6.7% (95% CI: 4.8-8.6)]. The bias of the PD mode for pediatric microsamples was 13.0% (95% CI: -8.4-34.4) in the PLT-F channel. The automated method had a considerably lower imprecision than the existing manual thrombocyte counting method and reduced turnaround times.

CONCLUSION

The automated microsample method offers a low-volume alternative for measurement of thrombocytes. The method appears useful also in pediatric samples.

Progress Analysis of Personalized Antiplatelet Therapy in Patients with Coronary Heart Disease Undergoing Interventional Therapy

Coronary atherosclerosis (or coronary heart disease [CHD]) is a common cardiovascular disease that seriously damages human health. Percutaneous coronary stent implantation represents the primary treatment option for severe CHD in clinical practice; meanwhile, dual antiplatelet therapy (DAPT) is widely used to reduce the risk of postoperative thrombosis. Although the mechanisms of action of the two most commonly used antiplatelet drugs, aspirin and clopidogrel, remain unclear, clinical studies have shown that some patients are susceptible to stent thrombosis-antiplatelet resistance (high on-treatment platelet reactivity [HTPR])-despite using these drugs. Therefore, screening for HTPR and formulating personalized antiplatelet therapies is necessary. Ticagrelor, indobufen, and rivaroxaban are the most common and safe antiplatelet drugs used in clinical practice, with broad application prospects. This review summarizes the mechanisms of action of existing antiplatelet drugs, reasons for personalized treatment, screening of antiplatelet reactions, and development of novel antiplatelet drugs.