Chemical and Microbiological Changes of Expired Platelet Concentrate

Background

Platelets are a commonly used blood component to prevent or treat bleeding in patients with thrombocytopenia or platelet dysfunction. They are stored at room temperature (22-24°C) for five days unless specific measures are taken to extend the shelf life to seven days or more. After five days, this study evaluated platelet units' biochemical changes and bacterial growth.

Study Design and Methods

Platelet concentrate was collected from 30 random donors: 8 females and 22 males. The collected samples were then placed on an agitator at room temperature and tested for their pH, protein content, and glucose levels using Roche Combur 100 Test® Strips. The Haemonetics eBDS™ System was used for bacterial detection. The measurements were taken on day five as the control and then repeated on days 7, 9, and 11 to observe any changes. On days 5 and 7, all parameters remained unchanged. However, glucose levels significantly changed (p=<0.0001) on days 9 and 11. Regarding pH, a significant change was observed on day 9 (p=0.033) and day 11 (p=0.0002).

Results

There were no significant changes in all parameters on days 5 and 7. However, glucose was substantially changed (p=<0.0001) on days 9 and 11. For pH, there was a significant change in pH on day 9 (p=0.033) and day 11 (p=0.0002).

Discussions

Our study found that platelet concentrate extension is possible for up to seven days. However, further studies are needed to evaluate platelet function during expiry time and to assess the stability of platelet morphology and function.

Impact of systematic variations in hematocrit and platelet count on thrombelastometry tissue factor activated assay parameters

BACKGROUND

Thromboelastogram testing is increasingly being used to manage patients with massive bleeding. An earlier study found that the test results were influenced by the hematocrit (Hct) and platelet (PLT) concentrations. This study sought to determine if these factors confounded the results of a different manufacturer's thromboelastography testing.

METHODS

Using freshly collected whole blood from volunteers and stored red blood cells (RBC) and plasma, the whole blood was manipulated to achieve different Hct values and PLT concentrations. Each reconstituted whole blood sample was tested in triplicate on the ROTEM Delta device and the ExTEM results were recorded.

RESULTS

Many of the ExTEM results varied according to the Hct and PLT concentration. In particular, the ExTEM clot formation time (CFT) was abnormally long when the Hct was 45% and the PLT concentration was ≤75 × 109/L, normalizing only when the PLT count was ≥100 × 109/L. CFT samples with Hct 25% and 35% were also abnormal with low PLT concentrations but normalized at lower PLT concentrations compared to the Hct 45% samples. The ExTEM angle also demonstrated abnormal results when the Hct was 45% and the PLT concentration was ≤50 × 109/L. The ExTEM A10 and maximum clot firmness (MCF) tests tended to also be abnormal when the Hct was between 25% and 45% and the platelet concentrations were below 75 × 109/L.

CONCLUSION

While thromboelastogram testing is gaining popularity for managing bleeding patients, clinicians should be aware of these confounding factors when making transfusion decisions based on their results.

Predicting the Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer Using Soluble Immune Checkpoints

Introduction: Personalizing neoadjuvant therapy for locally advanced rectal cancer (LARC) requires identifying biomarkers that predict treatment response. This study evaluates soluble immune checkpoints (sICPs) as predictive markers for neoadjuvant treatment response in LARC patients located in the middle and lower rectum. Materials and Methods: This prospective study included patients diagnosed with clinical stage T3 or T4 rectal cancer (RC) based on pelvic magnetic resonance imaging, with or without pelvic lymph node involvement. The modified Ryan scoring system was used to assess the response to neoadjuvant chemoradiotherapy (nCRT). Blood samples were collected from all RC patients before initiating nCRT. Various sICPs (sCD25, 4-1BB, B7.2, free active TGF-β1, CTLA-4, PD-L1, PD-1, Tim-3, LAG-3, galectin-9), along with age, gender, stage, blood cell counts, and biochemical variables, were recorded and compared based on tumor regression grade (TRG). Results: Among 38 participants, lymphocyte count was higher, and platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and platelet count were lower in patients with complete/near-complete response (TRG 0/1). In addition, TRG 0/1 patients had significantly lower levels of soluble galectin-9 than TRG 2/3 patients. Furthermore, platelet count was the only parameter that showed a significant difference among the three groups (TRG 0/1, TRG 2, and TRG 3). PLR demonstrated the highest sensitivity and specificity, with >80% for both measures. Conclusions: Lymphocyte count, PLR, NLR, platelet count, and galectin-9 may help predict favorable neoadjuvant treatment response in LARC patients, although without providing a definitive outcome. Personalized therapy based on these markers could enhance treatment decision making in LARC management.

Eltrombopag improves platelet engraftment after haploidentical bone marrow transplantation: Results of a Phase II study

Slow platelet recovery frequently occurs after haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with bone marrow graft and post-transplant cyclophosphamide (PCy)-based graft-versus-host disease (GVHD) prophylaxis. Improved platelet recovery may reduce the need for transfusions and improve outcomes. We investigated the safety and efficacy of eltrombopag, a thrombopoietin receptor agonist, at enhancing platelet recovery post-haplo-HSCT. The prospective study included patients ≥18 years of age who received haplo-HSCT with bone marrow graft and PCy. Patients received eltrombopag 300 mg/day starting on Day +5. The primary objective was to estimate platelet engraftment (>50 000/μL by Day 60). In a post hoc analysis, they were compared to a contemporary matched control group who did not receive eltrombopag. One hundred ten patients were included in the analysis (30 eltrombopag and 80 control). Seventy-three percent and 50% of patients in the eltrombopag group and control group, respectively, attained >50 000/μL platelet count by Day 60 (p = .043). No eltrombopag-related grade ≥4 adverse events were observed. Median time to platelet recovery (>20 000/μL) was 29 days with eltrombopag and 31 days for controls (p = .022), while its cumulative incidence was 90% (95% confidence interval [CI]: 78%-100%) with eltrombopag versus 67.5% (95% CI: 57%-78%) for controls (p = .014). Number of platelet transfusions received, overall survival, progression-free survival, GVHD rate, relapse rate, and non-relapse mortality were similar between groups. Overall, eltrombopag is safe and improves platelet recovery in patients undergoing haplo-HSCT with bone marrow graft and PCy.

Investigation of the impact of thirdhand e-cigarette exposure on platelet function: A pre-clinical study

INTRODUCTION

The use of e-cigarettes (ECs) has reached unprecedented levels, due to a variety of reasons, including the misconception regarding their safety. Thus, there have been efforts to characterize the effects of EC exposure, including in the context of thirdhand EC (THEC) on a host of disorders, such as cardiovascular disease (CVD).

METHODS

To address this issue, we sought to characterize the effects of THEC on platelet function and thrombus formation, using a novel mouse exposure protocol that resembles real life scenarios. To assess these effects, a host of related in vivo (i.e. tail bleeding time, and ferric chloride injury induced thrombosis model) assays and in vitro platelet specific (e.g. aggregation, and dense granule secretion) investigative assays were conducted.

RESULTS

Our in vivo characterization demonstrated that THEC exposed mice exhibited a prothrombotic phenotype reflected by their shortened tail bleeding (THEC: 37 ± 15 seconds, versus clean air: 183 ± 56 s) and occlusion times (THEC: 188 ± 39 s, versus clean air: 519 ± 70 s), relative to those exposed to clean air. Importantly, we found no difference in the platelet counts between the THEC and clean air mice. As for the underlying mechanism, separate experiments revealed significantly enhanced platelet aggregation, dense and alpha granule secretion, as well as integrin/GPIIb-IIIa activation and phosphatidylserine exposure in response to thrombin and ADP agonist stimulation.

CONCLUSIONS

Taken together, these results provide evidence that THEC does have the capacity to increase the risk of thrombotic disease, which should increase awareness regarding its underappreciated negative health effects.

Injectable platelet rich fibrin effect on laser depigmented gingiva: a clinical randomized controlled split mouth trial with histological assessment

OBJECTIVE

To determine whether intra-mucosal injection of injectable platelet-rich fibrin (i-PRF) can promote healing after Diode Laser Gingival Depigmentation (DLGD).

METHODOLOGY

A total of 20 arch sites of hyperpigmented gingiva of 10 patients underwent DLGD. For each patient, two arch sites were randomly assigned for either intra-mucosal injection of i-PRF (G1-i-PRF) (n=10 sites) or no treatment (G2-Control): (n=10 sites). Wound Healing Score (WHS), patient satisfaction, and Pigmentation Index (DOPI) were measured at 1 week and 1 and 3 months postoperatively. Histological assessment of tissue specimens was performed at baseline and 1 week.

RESULTS

The percentage change in WHS at 1 week was significantly higher in G1 (58.34±15.43) compared to G2 (37.50±11.79). At day 1, 50% of patients in G1 were pain free compared with 75% in G2, who had mild pain. Mean DOPI decreased significantly at 3 months in both groups (P-value <0.001), without significant differences between groups. G1 specimens showed significantly higher epithelial thickness (P-value <0.001), as well as a higher number of blood vessels and less percentage of inflammatory cells.

CONCLUSIONS

i-PRF demonstrated better clinical and histological healing potential and less patient discomfort compared to sites without treatment after DLGD. Registered at https://clinicaltrials.gov/ as (NCT05283668).

Sex Dependent Occlusive Cardiovascular Disease Effects of Short-Term Thirdhand Smoke Exposure

INTRODUCTION

Thirdhand smoke (THS) is associated with many public health and disease concerns, such as respiratory illness, cancer, lipidemia, and cardiovascular disease (CVD). We have previously shown a moderate to long-term exposure to THS increased risk of thrombosis. However, whether short-term exposure to THS would produce any effects in causing disease remains to be discovered. Therefore, this study investigated the impact of one-month THS exposure on platelet function and cytokine response in sex-dependent.

METHODS

Secondhand smoke or clean air (CA) exposed upholstery materials for 1 week were kept in cages housed with 5-6 mice, and the procedure was repeated for 4 weeks. These THS-exposed mice were evaluated for thrombogenesis and platelet function assays. In addition, the cytokines expressions were evaluated from pooled serum (n=5).

RESULTS

Compared to the CA group, the THS exposure significantly shortened tail bleeding time and carotid artery thrombus formation. Moreover, the female mice appeared more sensitive to THS exposure than males. Furthermore, platelet aggregation, dense granule secretion, and P-selectin activation markers were significantly elevated due to THS exposure. In addition, the high throughput screening showed at least 30 cytokines differentially modulated by THS in females relative to 26 in male mice.

CONCLUSION

Collectively, these results demonstrate that one month of THS exposure represents a high health risk, in part, by triggering a prothrombotic phenotype that appears to be more significant in females, who are at a much higher risk for occlusive CVD. Additionally, changes in cytokine levels mediate some of the THS-induced occlusive effects.

IMPLICATIONS

This study revealed that THS exposure in one month is detrimental to the cardiovascular health of both sexes; however, females could be more aggressively affected than males. In addition, interleukins and chemokines could be critical factors for initiating prothrombotic activity due to THS exposure.

Bioprinting Soft 3D Models of Hematopoiesis using Natural Silk Fibroin-Based Bioink Efficiently Supports Platelet Differentiation

Hematopoietic stem and progenitor cells (HSPCs) continuously generate platelets throughout one's life. Inherited Platelet Disorders affect ≈ 3 million individuals worldwide and are characterized by defects in platelet formation or function. A critical challenge in the identification of these diseases lies in the absence of models that facilitate the study of hematopoiesis ex vivo. Here, a silk fibroin-based bioink is developed and designed for 3D bioprinting. This bioink replicates a soft and biomimetic environment, enabling the controlled differentiation of HSPCs into platelets. The formulation consisting of silk fibroin, gelatin, and alginate is fine-tuned to obtain a viscoelastic, shear-thinning, thixotropic bioink with the remarkable ability to rapidly recover after bioprinting and provide structural integrity and mechanical stability over long-term culture. Optical transparency allowed for high-resolution imaging of platelet generation, while the incorporation of enzymatic sensors allowed quantitative analysis of glycolytic metabolism during differentiation that is represented through measurable color changes. Bioprinting patient samples revealed a decrease in metabolic activity and platelet production in Inherited Platelet Disorders. These discoveries are instrumental in establishing reference ranges for classification and automating the assessment of treatment responses. This model has far-reaching implications for application in the research of blood-related diseases, prioritizing drug development strategies, and tailoring personalized therapies.

Antifungal and Coagulation Properties of a Copper (I) Oxide Nanopowder Produced by Out-of-Phase Pulsed Sonoelectrochemistry

Copper (I) oxide (cuprite) is a material widely used nowadays, and its versatility is further amplified when it is brought to the nanometric size. Among the possible applications of this nanomaterial, one of the most interesting is that in the medical field. This paper presents a cuprite nanopowder study with the aim of employing it in medical applications. With regards to the environmental context, the synthesis used is related to green chemistry since the technique (out-of-phase pulsed electrochemistry) uses few chemical products via electricity consumption and soft conditions of temperature and pressure. After different physico-chemical characterizations, the nanopowder was tested on the Candida albicans to determine its fungicide activity and on human blood to estimate its hemocompatibility. The results show that 2 mg of this nanopowder diluted in 30 µL Sabouraud broth was able to react with Candida albicans. The hemocompatibility tests indicate that for 25 to 100 µg/mL of nanopowder in an aqueous medium, the powder was not toxic for human blood (no hemolysis nor platelet aggregation) but promoted blood coagulation. It appears, therefore, as a potential candidate for the functionalization of matrices for medical applications (wound dressing or operating field, for example).

Recent advances in vascular thiol isomerases and redox systems in platelet function and thrombosis

There have been substantial advances in vascular protein disulfide isomerases (PDIs) in platelet function and thrombosis in recent years. There are 4 known prothrombotic thiol isomerases; PDI, endoplasmic reticulum protein (ERp)57, ERp72, and ERp46, and 1 antithrombotic PDI; transmembrane protein 1. A sixth PDI, ERp5, may exhibit either prothrombotic or antithrombotic properties in platelets. Studies on ERp46 in platelet function and thrombosis provide insight into the mechanisms by which these enzymes function. ERp46-catalyzed disulfide cleavage in the αIIbβ3 platelet integrin occurs prior to PDI-catalyzed events to maximally support platelet aggregation. The transmembrane PDI transmembrane protein 1 counterbalances the effect of ERp46 by inhibiting activation of αIIbβ3. Recent work on the prototypic PDI found that oxidized PDI supports platelet aggregation. The a' domain of PDI is constitutively oxidized, possibly by endoplasmic reticulum oxidoreductase-1α. However, the a domain is normally reduced but becomes oxidized under conditions of oxidative stress. In contrast to the role of oxidized PDI in platelet function, reduced PDI downregulates activation of the neutrophil integrin αMβ2. Intracellular platelet PDI cooperates with Nox1 and contributes to thromboxane A2 production to support platelet function. Finally, αIIb and von Willebrand factor contain free thiols, which alter the functions of these proteins, although the extent to which the PDIs regulate these functions is unclear. We are beginning to understand the substrates and functions of vascular thiol isomerases and the redox network they form that supports hemostasis and thrombosis. Moreover, the disulfide bonds these enzymes target are being defined. The clinical implications of the knowledge gained are wide-ranging.

Modifying platelets at their birth: anti-thrombotic therapy without haemorrhage

Cardiovascular disease is a leading cause of death. The current approach to the prevention of arterial thrombosis in cardiovascular disease is dependent on the use of therapies which inhibit the activation of platelets. Predictably these are associated with an increased risk of haemorrhage which causes significant morbidity. The thrombotic potential of an activated platelet is modifiable; being determined before thrombopoiesis. Increased megakaryocyte ploidy is associated with larger and more active platelets carrying an increased risk of thrombosis. The reduction in the ploidy of megakaryocytes is therefore a novel area of therapeutic interest for reducing thrombosis. We propose a new therapeutic approach for the prevention and treatment of thrombosis by targeting the reduction in ploidy of megakaryocytes. We examine the role of a receptor mediated event causing megakaryocytes to increase ploidy, the potential for targeting the molecular mechanisms underpinning megakaryocyte endomitosis and the existence of two separate regulatory pathways to maintain haemostasis by altering the thrombotic potential of platelets as targets for novel therapeutic approaches producing haemostatically competent platelets which are not prothrombotic.

A primer on the restorative therapies for erectile dysfunction: a narrative review

INTRODUCTION

Erectile dysfunction (ED) is a common condition that affects millions worldwide. Patients and urologists alike are seeking alternative therapies that can provide long-lasting results in the treatment of ED. This review provides a comprehensive overview of restorative treatments available for ED, such as platelet-rich plasma, stem cell therapy, and shockwave therapy.

OBJECTIVE

The aim of this narrative review is to provide a primer for urologists and general practitioners on the basics of implementing ED restorative therapies in their practice.

METHODS

The PubMed, MEDLINE, and Google Scholar databases were searched for articles in the English language through August 31, 2023, that included key terms such as "erectile dysfunction," "restorative therapy," "shockwave therapy," "platelet-rich plasma," "stem cell therapy," and "stromal vascular fraction." Reference lists of selected studies were manually reviewed to find articles not identified by the initial database search.

RESULTS

Shockwave therapy has demonstrated effectiveness in treating ED, with devices like the Medispec ED1000 and Storz Duolith showing statistically significant improvements in patient scores for International Index of Erectile Function (IIEF)-Erectile Function scores in clinical trials. In reported studies of platelet-rich plasma injections, a substantial percentage of patients reached a minimal clinically important difference in the IIEF-Erectile Function scale after treatment. Studies of ED treatment with stem cell therapy, while limited and with small sample sizes, have demonstrated encouraging improvements in patient scores for the abridged 5-item version of the IIEF after treatment.

CONCLUSION

Shockwave, platelet-rich plasma, and stem cell therapies are important, novel, noninvasive restorative treatments for ED that can provide relief for patients wishing to avoid a more invasive approach. While these therapies have shown promising results in clinical trials, more research is required to establish them as standardized and efficacious options in the management of ED.

Differentiation route determines the functional outputs of adult megakaryopoiesis

Emerging evidence has revealed a direct differentiation route from hematopoietic stem cells to megakaryocytes (direct route), in addition to the classical differentiation route through a series of restricted hematopoietic progenitors (stepwise route). This raises the question of the importance of two alternative routes for megakaryopoiesis. Here, we developed fate-mapping systems to distinguish the two routes, comparing their quantitative and functional outputs. We found that megakaryocytes were produced through the two routes with comparable kinetics and quantity under homeostasis. Single-cell RNA sequencing of the fate-mapped megakaryocytes revealed that the direct and stepwise routes contributed to the niche-supporting and immune megakaryocytes, respectively, but contributed to the platelet-producing megakaryocytes together. Megakaryocytes derived from the two routes displayed different activities and were differentially regulated by chemotherapy and inflammation. Our work links differentiation route to the heterogeneity of megakaryocytes. Alternative differentiation routes result in variable combinations of functionally distinct megakaryocyte subpopulations poised for different physiological demands.

Increased platelet-CD8+ T cell aggregates displaying high activation, exhaustion, and tendency to death correlate with disease progression in people with HIV-1

Platelets engaged in HIV-1 infection by interacting with immune cells, which has been realized broadly. However, the potential interaction between platelets and CD8⁺ T cells remains unidentified. Here, treatment-naïve individuals with HIV-1 (TNs), complete immunological responders to antiretroviral therapy (CRs), and healthy controls (HCs) were enrolled. Firstly, we found that TNs had low platelet numbers and high CD8⁺ T cell counts when compared with CRs and HCs, leading to low platelet/CD8⁺ T cell ratio in peripheral blood which could effectively differentiate the status of HIV-1 infection. Moreover, cytokines that may be derived from platelets were higher in the plasma of people with HIV-1 despite viral suppression. Furthermore, we demonstrated that platelet-CD8⁺ T cell aggregates were elevated in TNs, which positively correlated with HIV-1 viral load, but negatively correlated with CD4⁺ T cell count and CD4/CD8 ratio. Finally, we revealed that platelet-CD8⁺ T cell aggregates with enhanced activation/exhaustion and pyroptosis/apoptosis than free CD8⁺ T cells. Moreover, platelets-induced caspase-1 activation of CD8⁺ T cells correlated with IL-1β and IL-18 plasma levels. In brief, we revealed the importance of platelets in HIV-1 infection, which might secrete more cytokines, and might mediate CD8⁺ T cell phenotypic characteristics by forming platelet-CD8⁺ T cell aggregates which were related to poor prognosis.

Supernatant of platelet-Klebsiella pneumoniae coculture induces apoptosis-like death in Klebsiella pneumoniae

Multidrug-resistant Klebsiella pneumoniae strains, especially carbapenem-resistant K. pneumoniae, have become a rapidly emerging crisis worldwide, greatly limiting current therapeutic options and posing new challenges to infection management. Therefore, it is imperative to develop novel and effective biological agents for the treatment of multidrug-resistant K. pneumoniae infections. Platelets play an important role in the development of inflammation and immune responses. The main component responsible for platelet antibacterial activity lies in the supernatant stimulated by gram-positive bacteria. However, little research has been conducted on the interaction of gram-negative bacteria with platelets. Therefore, we aimed to explore the bacteriostatic effect of the supernatant derived from platelet-K. pneumoniae coculture and the mechanism underlying this effect to further assess the potential of platelet-bacterial coculture supernatant. We conducted this study on the gram-negative bacteria K. pneumoniae and CRKP and detected turbidity changes in K. pneumoniae and CRKP cultures when grown with platelet-K. pneumoniae coculture supernatant added to the culture medium. We found that platelet-K. pneumoniae coculture supernatant significantly inhibited the growth of K. pneumoniae and CRKP in vitro. Furthermore, transfusion of platelet-K. pneumoniae coculture supernatant alleviated the symptoms of K. pneumoniae and CRKP infection in a murine model. Additionally, we observed apoptosis-like changes, such as phosphatidylserine exposure, chromosome condensation, DNA fragmentation, and overproduction of reactive oxygen species in K. pneumoniae following treatment with the supernatant. Our study demonstrates that the platelet-K. pneumoniae coculture supernatant can inhibit K. pneumoniae growth by inducing an apoptosis-like death, which is important for the antibacterial strategies development in the future.IMPORTANCEWith the widespread use of antibiotics, bacterial resistance is increasing, and a variety of multi-drug resistant Gram-negative bacteria have emerged, which brings great challenges to the treatment of infections caused by Gram-negative bacteria. Therefore, finding new strategies to inhibit Gram-negative bacteria and even multi-drug- resistant Gram-negative bacteria is crucial for treating infections caused by Gram-negative bacteria, improving the abuse of antibiotics, and maintaining the balance between bacteria and antibiotics. K. pneumoniae is a common clinical pathogen, and drug-resistant CRKP is increasingly difficult to cure, which brings great clinical challenges. In this study, we found that the platelet-K. pneumoniae coculture supernatant can inhibit K. pneumoniae growth by inducing an apoptosis-like death. This finding has inspired the development of future antimicrobial strategies, which are expected to improve the clinical treatment of Gram-negative bacteria and control the development of multidrug-resistant strains.

Study on the Mechanism of the Adrenaline-Evoked Procoagulant Response in Human Platelets

Adrenaline has recently been found to trigger phosphatidylserine (PS) exposure on blood platelets, resulting in amplification of the coagulation process, but the mechanism is only fragmentarily established. Using a panel of platelet receptors' antagonists and modulators of signaling pathways, we evaluated the importance of these in adrenaline-evoked PS exposure by flow cytometry. Calcium and sodium ion influx into platelet cytosol, after adrenaline treatment, was examined by fluorimetric measurements. We found a strong reduction in PS exposure after blocking of sodium and calcium ion influx via Na+/H+ exchanger (NHE) and Na+/Ca2+ exchanger (NCX), respectively. ADP receptor antagonists produced a moderate inhibitory effect. Substantial limitation of PS exposure was observed in the presence of GPIIb/IIIa antagonist, phosphoinositide-3 kinase (PI3-K) inhibitors, or prostaglandin E1, a cyclic adenosine monophosphate (cAMP)-elevating agent. We demonstrated that adrenaline may develop a procoagulant response in human platelets with the substantial role of ion exchangers (NHE and NCX), secreted ADP, GPIIb/IIIa-dependent outside-in signaling, and PI3-K. Inhibition of the above mechanisms and increasing cytosolic cAMP seem to be the most efficient procedures to control adrenaline-evoked PS exposure in human platelets.

Effects of Hemorrhage on Hematopoietic Cell Depletion after a Combined Injury with Radiation: Role of White Blood Cells and Red Blood Cells as Biomarkers

Combined radiation with hemorrhage (combined injury, CI) exacerbates hematopoietic acute radiation syndrome and mortality compared to radiation alone (RI). We evaluated the effects of RI or CI on blood cell depletion as a biomarker to differentiate the two. Male CD2F1 mice were exposed to 8.75 Gy γ-radiation (60Co). Within 2 h of RI, animals were bled under anesthesia 0% (RI) or 20% (CI) of total blood volume. Blood samples were collected at 4-5 h and days 1, 2, 3, 7, and 15 after RI. CI decreased WBC at 4-5 h and continued to decrease it until day 3; counts then stayed at the nadir up to day 15. CI decreased neutrophils, lymphocytes, monocytes, eosinophils, and basophils more than RI on day 1 or day 2. CI decreased RBCs, hemoglobin, and hematocrit on days 7 and 15 more than RI, whereas hemorrhage alone returned to the baseline on days 7 and 15. RBCs depleted after CI faster than post-RI. Hemorrhage alone increased platelet counts on days 2, 3, and 7, which returned to the baseline on day 15. Our data suggest that WBC depletion may be a potential biomarker within 2 days post-RI and post-CI and RBC depletion after 3 days post-RI and post-CI. For hemorrhage alone, neutrophil counts at 4-5 h and platelets for day 2 through day 7 can be used as a tool for confirmation.

Increased platelet mitochondrial function correlates with clot strength in a rodent fracture model

BACKGROUND

Thromboelastographic measures of clot strength increase early after injury, portending higher risks for thromboembolic complications during recovery. Understanding the specific role of platelets is challenging because of a lack of clinically relevant measures of platelet function. Platelet mitochondrial respirometry may provide insight to global platelet function but has not yet been correlated with functional coagulation studies.

METHODS

Wistar rats underwent anesthesia and either immediate sacrifice for baseline values (n = 6) or (1) bilateral hindlimb orthopedic injury (n = 12), versus (2) sham anesthesia (n = 12) with terminal phlebotomy/hepatectomy after 24 hours. High-resolution respirometry was used to measure basal respiration, mitochondrial leak, maximal oxidative phosphorylation, and Complex IV activity in intact platelets; Complex I- and Complex II-driven respiration was measured in isolated liver mitochondria. Results were normalized to platelet number and protein mass, respectively. Citrated native thromboelastography (TEG) was performed in triplicate.

RESULTS

Citrated native TEG maximal amplitude was significantly higher (81.0 ± 3.0 vs. 73.3 ± 3.5 mm, p < 0.001) in trauma compared with sham rats 24 hours after injury. Intact platelets from injured rats had higher basal oxygen consumption (17.7 ± 2.5 vs. 15.1 ± 3.2 pmol O 2 /[s × 10 8 cells], p = 0.045), with similar trends in mitochondrial leak rate ( p = 0.19) when compared with sham animals. Overall, platelet basal respiration significantly correlated with TEG maximal amplitude ( r = 0.44, p = 0.034). As a control for sex-dependent systemic mitochondrial differences, females displayed higher liver mitochondria Complex I-driven respiration (895.6 ± 123.7 vs. 622.1 ± 48.7 mmol e - /min/mg protein, p = 0.02); as a control for systemic mitochondrial effects of injury, no liver mitochondrial respiration differences were seen.

CONCLUSION

Platelet mitochondrial basal respiration is increased after injury and correlates with clot strength in this rodent hindlimb fracture model. Several mitochondrial-targeted therapeutics exist in common use that are underexplored but hold promise as potential antithrombotic adjuncts that can be sensitively evaluated in this preclinical model.

Full annotation of viral metagenomics in different components from Chinese blood donors using next-generation sequencing

BACKGROUND

Emerging viruses in the blood of healthy/qualified donors can seriously affect transfusion safety. However, the virus characteristics in different healthy blood donors and blood components are still not fully understood.

MATERIALS AND METHODS

Buffy coat (BC) and plasma specimens were collected from 32 whole blood donors, and platelet (PLT) and BC specimens from 30 apheresis platelet donors to explore the full annotation of viral metagenomics in different blood components from Chinese blood donors using next-generation sequencing technology.

RESULTS

The study detected 56 viruses in the plasma and BC groups of whole blood donors. The plasma group had a significantly higher viral abundance and more types of viruses than the BC group. We detected 20 viruses in the PLT and BC groups of apheresis platelet donors. Viral abundance and types were significantly lower in the BC group than in the PLT group. According to β-diversity analysis, the plasma group had a significantly different community structure and composition than the BC group.

DISCUSSION

Viral nucleic acid is found in the blood of healthy Chinese blood donors, with the highest concentration in plasma, which could explain the distribution of viruses in the blood of healthy individuals.

Downscaling platelet cryopreservation: Are platelets frozen in tubes comparable to standard cryopreserved platelets?

BACKGROUND

Platelet cryopreservation extends the shelf-life to at least 2 years. However, platelets are altered during the freeze/thaw process. Downscaling platelet cryopreservation by freezing in tubes would enable rapid screening of novel strategies to improve the quality of cryopreserved platelets (CPPs). The aim of this study was to characterize the effect of freezing conditions on the in vitro phenotype and function of platelets frozen in a low volume compared to standard CPPs.

METHODS

Platelets were prepared for cryopreservation using 5%-6% DMSO and processed using standard protocols or aliquoted into 2 mL tubes. Platelets were hyperconcentrated to 25 mL (standard CPPs) or 200 μL (tubes) before freezing at -80°C (n = 8). Six insulators/controlled rate freezing containers were used to vary the freezing rate of platelets in tubes. Platelets were thawed, resuspended in plasma, and then assessed by flow cytometry and thromboelastography.

RESULTS

The use of different insulators for tubes changed the freezing rate of platelets compared to platelets frozen using the standard protocol (p < .001). However, this had no impact on the recovery of the platelets (p = .87) or the proportion of platelets expressing GPIbα (p = .46) or GPVI (p = .07), which remained similar between groups. A lower proportion of platelets frozen in tubes externalized phosphatidylserine compared to standard CPPs (p < .001). The clot-forming ability (thromboelastography) of platelets was similar between groups (p > .05).

CONCLUSION

Freezing platelets in tubes modified the freezing rate and altered some platelet characteristics. However, the functional characteristics remained comparable, demonstrating the feasibility of downscaling platelet cryopreservation for high-throughput exploratory investigations.

Expert opinion on bleeding risk from invasive procedures in cirrhosis

Background & Aims

Despite several recent international guidelines, no consensus exists on the bleeding risk nor haemostatic parameter thresholds that define the safety of invasive procedures in patients with cirrhosis. The aim of this study was to establish a position paper on the bleeding risk associated with invasive procedures in patients with cirrhosis among the experts involved in various guidelines.

Methods

All experts involved in recent guidelines on the management of invasive procedures in patients with cirrhosis were invited to classify 80 procedures as "high risk" or "low risk" with respect to bleeding. Procedures were considered high risk when the estimated risk of major bleeding was 1.5% or more, or when even minor bleeding might lead to significant morbidity or death. The experts were also asked to choose safety thresholds for laboratory test values at which elective invasive procedures could be safely performed. The predetermined threshold considered as "consensus" was ≥75% agreement.

Results

Fifty-two experts participated in the study. Out of 80 procedures, a consensus opinion was reached for 52 procedures (65%): 17 procedures were classified as "high risk", primarily interventional endoscopic procedures, percutaneous organ biopsies, or procedures involving the central nervous system; and 35 as "low risk", primarily "diagnostic" procedures. The lowest platelet counts at which performance of a low-risk procedure or a high-risk procedure/surgery were deemed acceptable were 30 × 109/L and 50 × 109/L, respectively. Experts did not believe that international normalised ratio should be considered before performing low-risk procedures; 71% also indicated that it should not be considered before performing high-risk procedures.

Conclusions

This experience-based classification may be helpful to refine future study designs and to guide clinical decision making regarding invasive procedures in patients with cirrhosis.

Impact and implications

Several risk classifications and management guidelines for invasive procedures in patients with cirrhosis have been proposed, but with conflicting recommendations. By providing a position paper, based on the opinion of a broad panel of experts, on the bleeding risk associated with 52 invasive procedures in patients with cirrhosis, this survey will help to provide a framework for future study design. The consensus on platelet count, international normalised ratio, fibrinogen and activated partial thromboplastin time identified in this survey will inform physicians regarding the laboratory test values considered acceptable by the experts prior to the performance of an elective invasive procedure in patients with cirrhosis.

Serum levels of CXCL5 are decreased and correlate with circulating platelet counts in systemic lupus erythematosus

OBJECTIVE

To identify disease-specific serum chemokine profiles and potential anti-inflammatory chemokines in three rheumatic diseases.

METHODS

The discovery cohort included 18 patients with rheumatoid arthritis (RA), 20 patients with primary Sjögren's syndrome (pSS), 24 patients with systemic lupus erythematosus (SLE) and 28 healthy subjects. Findings from the discovery cohort were validated in two replication cohorts, consisting of 23 patients with SLE matched with 23 healthy subjects and 62 patients with SLE, 16 patients with ANCA-associated vasculitis (AAV), and 32 healthy controls, respectively. Serum levels of chemokines were determined using multiplex assay or ELISA.

RESULTS

In the discovery cohort, serum levels of multiple chemokines were increased in one or more diseases in comparison to healthy subjects, including CCL2, CCL20, CXCL9, CXCL10, and CXCL11 in SLE, CCL2, CCL4, and CXCL11 in pSS, and CCL2, CCL4, and CXCL9 in RA. Notably, serum levels of CCL3 (p = .0003) and CXCL5 (p = .0003) were decreased in SLE. The SLE-specific decrease in CXCL5 serum levels was confirmed in the two replication cohorts, with p = .0034 and p = .0006, respectively. Moreover, a positive correlation between serum levels of CXCL5 and circulating platelet counts (R = .71, p = .00018) in SLE observed in the discovery cohort was confirmed in both replication cohorts (R = .52, p = .011 and R = .49, p = .00005, respectively).

CONCLUSION

In the present study, we demonstrate that serum levels of CXCL5 are decreased in patients with SLE and positively correlated with circulating platelet count. These findings suggest that platelet-associated CXCL5 is presumably involved in the development of SLE.

The Clinical Benefit of the Modified Neutrophil-Platelet Score as a Surrogate Prognostic Marker in Patients With Resectable Gastric Cancer

BACKGROUND/AIM

Gastric cancer is a common cause of cancer death worldwide, especially in East Asia. This study evaluated the impact of preoperative modified Neutrophil-Platelet Score (mNPS) on the survival and recurrence of patients with resectable gastric cancer.

PATIENTS AND METHODS

The study analyzed 168 patients who underwent curative gastrectomy and subsequently received adjuvant treatment for gastric cancer between 2015 and 2021. Univariate and multivariate analyses were performed to identify the risk factors for overall survival (OS) and recurrence-free survival (RFS).

RESULTS

Patients were divided into two groups: 76 patients with an mNPS of 0 were classified into the low-mNPS group, whereas 92 patients with an mNPS of ≥1 were classified into the high-mNPS group. The 3- and 5-year OS rates in the low-mNPS group were 65.6% and 56.2%, respectively, and those in the high-mNPS group were 45.3% and 36.9%, respectively. The difference in OS between the two groups was statistically significant (p=0.007). The 3- and 5-year RFS rates in the low-mNPS group were 45.6% and 38.7%, respectively, whereas those in the high-mNPS group were 33.4% and 28.1%, respectively. The difference in RFS between the two groups was statistically significant (p=0.043). A multivariate analysis showed that the mNPS was a significant independent prognostic factor for OS and RFS.

CONCLUSION

mNPS is a potential prognostic marker for patients with gastric cancer who underwent curative gastrectomy. Higher mNPS values were associated with lower 3- and 5-year OS and RFS rates, indicating a potential correlation between elevated mNPS and worse outcomes.

Development and experimental validation of an M2 macrophage and platelet-associated gene signature to predict prognosis and immunotherapy sensitivity in bladder cancer

Platelets and M2 macrophages both play crucial roles in tumorigenesis, but their relationship and the prognosis value of the relative genes in bladder cancer (BLCA) remain obscure. In the present study, we found that platelets stimulated by BLCA cell lines could promote M2 macrophage polarization, and platelets were significantly associated with the infiltration of M2 macrophages in BLCA samples. Through the bioinformatic analyses, A2M, TGFB3, and MYLK, which were associated with platelets and M2 macrophages, were identified and verified in vitro and then included in the predictive model. A platelet and M2 macrophage-related gene signature was constructed to evaluate the prognosis and immunotherapeutic sensitivity, helping to guide personalized treatment and to disclose the underlying mechanisms.

Platelet distribution width (PDW) as a significant correlate of COVID-19 infection severity and mortality

SARS-CoV-2 infection may cause a wide spectrum of symptoms, from asymptomatic, to mild respiratory symptoms and life-threatening sepsis. Among the clinical laboratory biomarkers analyzed during COVID-19 pandemic, platelet indices have raised great interest, due to the critical involvement of platelets in COVID-19-related thromboinflammation. Through an electronic literature search on MEDLINE, CINAHL, PubMed, EMBASE, Web of Science, and preprint servers we performed and updated a systematic review aimed at providing a detailed analysis of studies addressing the potential clinical utility of platelet distribution width, platelet distribution width (PDW), in laboratory medicine, exploring the possible association between increased PDW levels, disease severity, and mortality in COVID-19. Our systematic review revealed a wide heterogeneity of COVID-19 cohorts examined and a lack of homogenous expression of platelet indices. We found that 75 % of studies reported significantly elevated PDW values in COVID-19 infected cohorts compared to healthy/non-COVID-19 controls, and 40 % of studies reported that patients with severe COVID-19 showed increased PDW values than those with less-than-severe illness. Interestingly, 71.4 % of studies demonstrated significant increased PDW values in non survivors vs. survivors. Overall, these results suggest that platelets are critically involved as major players in the process of immunothrombosis in COVID-19, and platelet reactivity and morphofunctional alterations are mirrored by PDW, as indicator of platelet heterogeneity. Our results confirm that the use of PDW as prognostic biomarkers of COVID-19 sepsis still remains debated due to the limited number of studies to draw a conclusion, but new opportunities to investigate the crucial role of platelets in thrombo-inflammation are warranted.

Literature review details and supports the application of platelet-rich plasma products in canine medicine, particularly as an orthobiologic agent for osteoarthritis

Platelet-rich plasma (PRP) and other platelet-derived products represent a subset of regenerative medicine and have been researched in the veterinary community for the treatment of osteoarthritis, soft tissue wounds, tendinopathies, periodontitis, and fracture repairs. PRP is simple to produce, relatively affordable, safe, and can be delivered on site, making it an appealing therapeutic agent in veterinary medicine. As an orthobiologic for the treatment of osteoarthritis, it is one of few interventions with clinical study support that possess anabolic potential. Platelet product variability is wide ranging and often described in terms of cellular content or platelet enrichment. Growth factors associated with platelet activation and subsequent degranulation may mediate inflammation, modulate cellular immune response, and promote tissue repair. Product composition, dosage, and application likely influence treatment outcomes depending on the classification of the disease targeted. Sufficient canine data regarding the formulation and clinical application of canine PRP exist to warrant review. The aim of this narrative is to provide scientific background and clinical insight for veterinarians regarding platelet product content/formulation, mechanisms of action, considerations for use, and clinical application in dogs.

Convolutional neuronal network for identifying single-cell-platelet-platelet-aggregates in human whole blood using imaging flow cytometry

Imaging flow cytometry is an attractive method to investigate individual cells by optical properties. However, imaging flow cytometry applications with clinical relevance are scarce so far. Platelet aggregation naturally occurs during blood coagulation to form a clot. However, aberrant platelet aggregation is associated with cardiovascular disease under steady-state conditions in the blood. Several types of so-called antiplatelet drugs are frequently described to reduce the risk of stroke or cardiovascular diseases. However, an efficient monitoring method is missing to identify the presence and frequency of platelet-platelet aggregates in whole blood on a single cell level. In this work, we employed imaging flow cytometry to identify fluorescently labeled platelets in whole blood with a conditional gating strategy. Images were post-processed and aligned. A convolutional neural network was designed to identify platelet-platelet aggregates of two, three, and more than three platelets, and results were validated against various data set properties. In addition, the neural network excluded erythrocyte-platelet aggregates from the results. Based on the results, a parameter for detecting platelet-platelet aggregates, the weighted platelet aggregation, was developed. If employed on a broad scale with proband and patient samples, our method could aid in building a future diagnostic marker for cardiovascular disease and monitoring parameters to optimize drug prescriptions in such patient groups.

Identification of platelet-related subtypes and diagnostic markers in pediatric Crohn's disease based on WGCNA and machine learning

Background

The incidence of pediatric Crohn's disease (PCD) is increasing worldwide every year. The challenges in early diagnosis and treatment of PCD persist due to its inherent heterogeneity. This study's objective was to discover novel diagnostic markers and molecular subtypes aimed at enhancing the prognosis for patients suffering from PCD.

Methods

Candidate genes were obtained from the GSE117993 dataset and the GSE93624 dataset by weighted gene co-expression network analysis (WGCNA) and differential analysis, followed by intersection with platelet-related genes. Based on this, diagnostic markers were screened by five machine learning algorithms. We constructed predictive models and molecular subtypes based on key markers. The models were evaluated using the GSE101794 dataset as the validation set, combined with receiver operating characteristic curves, decision curve analysis, clinical impact curves, and calibration curves. In addition, we performed pathway enrichment analysis and immune infiltration analysis for different molecular subtypes to assess their differences.

Results

Through WGCNA and differential analysis, we successfully identified 44 candidate genes. Following this, employing five machine learning algorithms, we ultimately narrowed it down to five pivotal markers: GNA15, PIK3R3, PLEK, SERPINE1, and STAT1. Using these five key markers as a foundation, we developed a nomogram exhibiting exceptional performance. Furthermore, we distinguished two platelet-related subtypes of PCD through consensus clustering analysis. Subsequent analyses involving pathway enrichment and immune infiltration unveiled notable disparities in gene expression patterns, enrichment pathways, and immune infiltration landscapes between these subtypes.

Conclusion

In this study, we have successfully identified five promising diagnostic markers and developed a robust nomogram with high predictive efficacy. Furthermore, the recognition of distinct PCD subtypes enhances our comprehension of potential pathogenic mechanisms and paves the way for future prospects in early diagnosis and personalized treatment.

The effect of oscillation depolymerization on ethylenediaminetetraacetic acid-dependent platelet aggregation samples: A cross-over study

INTRODUCTION

Ethylenediaminetetraacetic acid (EDTA)-dependent platelet aggregation (PA) can cause medical errors. Currently, there is no reliable method for completely solving this problem. This study aims to solve this problem that has plagued clinical practice for many years by using oscillation method.

METHODS

Sixty-one EDTA-PA samples were collected, divided, and disaggregated using the oscillation method at various times and speeds. The samples were analyzed using routine blood tests and blood smears.

RESULTS

Platelet counts (PLT) were increased significantly after oscillation. PLT in the 3000 rpm for 0.5 min group was significantly higher than that in the 500 rpm for 0.5 min group (p < 0. 01). After 3000 rpm oscillation, the PLT gradually increased with time, while compared with the 10-min group, the PLT in the 13-min group showed no significant differences. The effective disaggregation rates in the EDTA-PA samples using the oscillation method and sodium citrate anticoagulant were 96.72% and 65.57%, respectively. There were no significant changes in white blood cell (WBC) or red blood cell (RBC) counts or morphology after the use of the oscillation method.

CONCLUSION

The oscillation method effectively depolymerized EDTA-PA without adverse effects on WBC and RBC. The implementation of this technique promises to resolve the issue of EDTA-PA.

An Evaluation of Hemostatic Dysregulation in Canine Multicentric Lymphoma

Multiple hemostatic abnormalities are associated with paraneoplastic syndrome and some malignant tumors. Lymphoma is the most common hematopoietic neoplasm in dogs, sometimes associated with hemostatic changes. The objectives of this study were to evaluate the behavior of coagulation parameters in dogs with multicentric lymphoma compared with diseased dogs without lymphoma, to separately evaluate the effect of immunophenotype (B lymphoma versus T lymphoma) on the variables of interest as well as the effect of disease stage (stage II to IV versus stage V). Specifically, a cross-sectional study was performed with a matched comparison group considering 170 dogs with B or T lymphoma (group 1) and 170 dogs with no lymphoma or other neoplastic processes but other diseases (group 0). Eight coagulation parameters were evaluated: platelet count (Plt), activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), fibrinogen, fibrin/products of fibrinogen degradation (FDPs), fibrin D-dimers, and antithrombin (AT). Dogs with lymphoma showed prolonged PT and TT, decreased fibrinogen, increased FDP, and decreased Plt compared with group 0. The effect of disease stage was evaluated separately for dogs with stage II to IV lymphoma and dogs with stage V lymphoma; patients with stage II-IV lymphoma showed no significant differences, while in dogs with stage V lymphoma, a prolongation of PT and TT, a decrease in fibrinogen, an increase in FDPs and a decrease in Plt were found compared with the group 0. Finally, the comparison between B lymphoma and T lymphoma showed no significant differences in coagulation parameters between the two groups. Logistic regression analysis demonstrated that low fibrinogen and platelet levels were the most significant predictors of lymphoma in a cohort of canine patients. These hemostatic abnormalities in lymphoma appeared to be associated with the stage of the disease rather than the lymphoma immunophenotype. These findings pave the way for the possible scenario of lymphoma-associated fibrinolysis and the so far undescribed pattern of hyperfibrinolysis associated with the most severe stage of lymphoma.

The Factors Associated With Decreasing Hemoglobin Levels and Platelet Counts After Trauma

Objective In this study, we investigated the factors related to anemia and platelet reduction in patients with moderate to severe trauma to gain a deeper understanding of these phenomena. Methods Our study spanned the period from April 2021 to September 2023, and it involved a retrospective review of the hospital medical charts of all emergency outpatients of all ages who were transported by a physician-staffed helicopter and treated at our hospital and were diagnosed with an Injury Severity Score (ISS) of >8 by CT on arrival. The following data were analyzed: sex; age; mechanism of injury; vital signs upon arrival at the hospital; ISS; hemoglobin level and platelet count on arrival and day two; fibrin degradation product (FDP) level, lactate dehydrogenase (LDH) level, and diameter of the inferior vena cava (IVC) on arrival; and infusion volume on day one. We then statistically calculated the independent risk factors for differences between hemoglobin levels and platelet counts on arrival and those on day two. Results The study included a total of 209 subjects, with an average age of 58 years and a male predominance. Multivariate analysis showed that the FDP level, IVC diameter, and age were significantly associated with changes in hemoglobin levels on arrival and day two, whereas the IVC diameter, LDH, age, systolic blood pressure, and sex were significantly associated with changes in the platelet count on arrival and day two. Conclusions A noteworthy correlation was found between certain factors and changes in hemoglobin levels and platelet counts between the initial assessment and the second day in our cohort. We recommend further prospective research to determine whether our findings hold true for a larger population of trauma patients.

Novel hemizygous CORO1A variant leads to combined immunodeficiency with defective platelet calcium signaling and cell mobility

Background

To date, fewer than 20 patients have been identified as having germline biallelic mutations in the coronin-1A gene (CORO1A) and its protein with clinical features of combined immunodeficiency characterized by T-cell lymphopenia ranging from the severe phenotype to the mild phenotype, recurrent infections, and lymphoproliferative disorders. However, the effects of CORO1A protein disruption on actin-dependent functions in primary cells have not been fully delineated.

Objective

We sought to characterize the underlying defects of actin-dependent cellular functions in a female patient with combined immunodeficiency caused by a novel missense variant in the CORO1A gene in combination with a de novo heterozygous microdeletion of chromosome 16p11.2 and also to provide evidence of the pathogenicity of this gene mutation.

Methods

To identify the genetic defect, next-generation sequencing followed by Sanger confirmation and array comparative genomic hybridization were performed. Western blot and quantitative PCR tests were used to assess the effects on the protein. Flow cytometry and live microscopy were performed to investigate cellular motility and immune cell counts and function.

Results

We demonstrated that the CORO1A hemizygous variant c.19C>T, p. A7C induces significant decreases in cellular levels of the CORO1A protein while leaving mRNA concentrations unaffected. The observed mutation resulted in impaired natural killer cell cytotoxicity and platelet calcium signaling. In addition, primary granulocytes and mesenchymal cells showed significant defects in motility.

Conclusion

Collectively, we added new data about the CORO1A gene as a key player in actin cytoskeleton dynamics and cell signaling. Our findings expand the clinical spectrum regarding CORO1A protein deficiency and confirm the importance of a personalized therapeutic approach for each patient.

Analysis of the Healthy Platelet Proteome Identifies a New Form of Domain-Specific O-Fucosylation

Platelet activation induces the secretion of proteins that promote platelet aggregation and inflammation. However, detailed analysis of the released platelet proteome is hampered by platelets' tendency to preactivate during their isolation and a lack of sensitive protocols for low abundance releasate analysis. Here, we detail the most sensitive analysis to date of the platelet releasate proteome with the detection of >1300 proteins. Unbiased scanning for posttranslational modifications within releasate proteins highlighted O-glycosylation as being a major component. For the first time, we detected O-fucosylation on previously uncharacterized sites including multimerin-1 (MMRN1), a major alpha granule protein that supports platelet adhesion to collagen and is a carrier for platelet factor V. The N-terminal elastin microfibril interface (EMI) domain of MMRN1, a key site for protein-protein interaction, was O-fucosylated at a conserved threonine within a new domain context. Our data suggest that either protein O-fucosyltransferase 1, or a novel protein O-fucosyltransferase, may be responsible for this modification. Mutating this O-fucose site on the EMI domain led to a >50% reduction of MMRN1 secretion, supporting a key role of EMI O-fucosylation in MMRN1 secretion. By comparing releasates from resting and thrombin-treated platelets, 202 proteins were found to be significantly released after high-dose thrombin stimulation. Complementary quantification of the platelet lysates identified >3800 proteins, which confirmed the platelet origin of releasate proteins by anticorrelation analysis. Low-dose thrombin treatment yielded a smaller subset of significantly regulated proteins with fewer secretory pathway enzymes. The extensive platelet proteome resource provided here (larancelab.com/platelet-proteome) allows identification of novel regulatory mechanisms for drug targeting to address platelet dysfunction and thrombosis.

Evaluation of the hematological inflammatory parameters in the patients with immune thrombocytopenic purpura: A case-control study

Background and Aims

Inflammation is one of the immune thrombocytopenic purpura (ITP)'s aggravating elements due to inflammatory cells' function. This study aims to identify and evaluate hematological inflammatory parameters, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and hemoglobin-to-platelet ratio (HPR), in patients with ITP compared to the control group.

Methods

We retrospectively analyzed the profile of 190 ITP patients from August 2019 to January 2021 at Imam Reza Hospital of Mashhad, Iran, along with 100 healthy individuals who had no ITP-related clinical or laboratory symptoms. Immune cell counts, NLR, PLR, and HPR were calculated using the complete blood count at the time of diagnosis and after the treatment. The results were analyzed through MedCalc, SPSS software, and the receiver operating characteristic curve.

Results

The result showed that white blood cell (WBC) and neutrophil counts were higher in ITP patients (WBC: p: 0.001, neutrophil: p: 0.001), and conversely, platelet and lymphocyte counts were higher in the control group compared to ITP patients (platelets: p: 0.001, lymphocytes: p: 0.001). The indices analysis between the two groups revealed that NLR was significantly increased in ITP patients (p: 0.001), but PLR was significantly reduced in ITP patients (with the mean platelet count of 23.44 ± 35.26 × 109/L) compared to the control group (with the mean platelet count of 234.04 ± 55.88 × 109/L). The HPR index also significantly increased in ITP patients (p: 0.001).

Conclusion

An increase in NLR, PLR, and a decrease in HPR can be considered a valuable diagnostic algorithm in patients with ITP.

Can Red Blood Cell and Platelet Transfusions Have a Pathogenic Role in Bronchopulmonary Dysplasia?

OBJECTIVE

To evaluate whether transfusions in infants born preterm contribute to the pathogenesis of bronchopulmonary dysplasia (BPD).

STUDY DESIGN

We conducted a multihospital, retrospective study seeking associations between red blood cell or platelet transfusions and BPD. We tabulated all transfusions administered from January 2018 through December 2022 to infants born ≤29 weeks or <1000 g until 36 weeks postmenstrual age and compared those with BPD grade. We performed a sensitivity analysis to assess the possibility of a causal relationship. We then determined whether each transfusion was compliant with restrictive guidelines, and we estimated effects fewer transfusions might have on future BPD incidence.

RESULTS

Eighty-four infants did not develop BPD and 595 did; 352 developed grade 1 (mild), 193 grade 2 (moderate), and 50 grade 3 (severe). Transfusions were given at <36 weeks to 7% of those who did not develop BPD, 46% who did, and 98% who developed severe BPD. For every transfusion the odds of developing BPD increased by a factor of 2.27 (95% CI, 1.59-3.68; P < .001). Sensitivity analyses suggested that transfusions might contribute to BPD. Fifty-seven percent of red blood cell transfusions and 68% of platelet transfusions were noncompliant with new restrictive guidelines. Modeling predicted that complying with restrictive guidelines could reduce the transfusion rate by 20%-30% and the moderate to severe BPD rate by ∼4%-6%.

CONCLUSIONS

Transfusions were associated with BPD incidence and severity. Lowering transfusion rates to comply with current restrictive guidelines might result in a small but meaningful reduction in BPD rates.

Platelet RNA sequencing reveals profile of caffeic acid affecting hemostasis in mice

Background

Caffeic acid (CA) is a naturally occurring phenolic compound with diverse pharmacologic properties. CA plays a crucial role in hemostasis by increasing platelet count. However, the mechanism by which CA regulates platelets to promote hemostasis remains unclear.

Objectives

We aim to identify the potential target pathways and genes by which CA regulates platelets to promote hemostasis.

Methods

We performed RNA sequencing (RNA-seq) analysis of mouse platelet pools in both the CA-gavaged group and phosphate-buffered saline-gavaged group.

Results

The 12,934 expressed transcripts had been annotated after platelet RNA-seq. Compared with the phosphate-buffered saline group, 987 differentially expressed genes (DEGs) were identified, of which 466 were downregulated and 521 were upregulated in CA group. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Reactome gene set enrichment analysis demonstrated that upregulated DEGs were enriched in the pathways of hemostasis, platelet activation, signaling, aggregation, and degranulation. Moreover, Kyoto Encyclopedia of Genes and Genomes and Reactome gene set enrichment analysis revealed that 5 of the 25 cosignificantly upregulated DEGs were essential in CA-mediated platelet regulation to promote hemostasis.

Conclusion

Our findings of platelet RNA-seq analysis demonstrate that CA regulates the gene expression of hemostasis and platelet activation-related pathways to increase platelet count and promote hemostasis. It will also provide reference molecular resources for future research on the function and mechanism by which CA regulates platelets to promote hemostasis.

Antiplatelet drugs do not protect from platelet-leukocyte aggregation in coronary artery disease

BACKGROUND

Despite advances in cardiovascular medicine, coronary artery disease (CAD) remains a leading cause of mortality. Among the pathophysiological features of this condition, platelet-leukocyte aggregates (PLAs) require further attention, either as diagnostic/prognostic disease markers or as potential interventional targets.

OBJECTIVES

In this study, we characterized PLAs in patients with CAD. Primarily, we investigated the association of PLA levels with CAD diagnosis. In addition, the basal levels of platelet activation and degranulation were assessed in patients with CAD and controls, and their correlation with PLA levels was analyzed. Finally, the effect of antiplatelet treatments on circulating PLA numbers, basal platelet activation, and degranulation was studied in patients with CAD.

METHODS

Participants were recruited at the Department of Cardiology of the University Heart and Vascular Centre Hamburg Eppendorf. Among patients admitted with severe chest pain, the diagnosis of CAD was made angiographically, and patients without CAD were used as controls. PLAs, platelet activation, and platelet degranulation were assessed by flow cytometry.

RESULTS

Circulating PLAs and basal platelet degranulation levels were significantly higher in patients with CAD than in controls. Surprisingly, there was no significant correlation between PLA levels and platelet degranulation (or any other measured parameter). In addition, patients with CAD on antiplatelet therapy did not display lower PLA or platelet degranulation levels compared with those in controls.

CONCLUSION

Overall, these data suggest a mechanism of PLA formation that is independent of platelet activation or degranulation and highlights the inefficiency of current antiplatelet treatments for the prevention of basal platelet degranulation and PLA formation.

APRI as a predictor of severe dengue fever

Introduction

The AST/platelet ratio index (APRI) is a well-researched indicator of liver fibrosis. Some studies have shown that APRI can be used as a predictor of severe dengue, but the data is limited. As dengue epidemics are common in our country with limited healthcare resources, we believe APRI can help emergency physicians/primary physicians in predicting the severity of dengue and plan for the appropriate use of limited healthcare resources.

Objective

1) To determine the utility of APRI as a predictor of severe dengue. 2) To determine the association of APRI with length of hospital stay and platelet requirement.

Materials and Methods

A retrospective cross-sectional study was done on patients presented to the Emergency Medicine department at Travancore Medicity Medical College with a positive Dengue NS1 antigen or IgM antibody.

Results

We found from the univariate analysis results that ALT > 74.5 IU/L has a sensitivity of 59.6 and a specificity of 76.3 (AUC: 0.696; 95% CI: 0.606-0.786), AST > 160.5 IU/L has a sensitivity of 42.3 and a specificity of 93.7 (AUC: 0.747; 95% CI: 0.665-0.829), and APRI > 3.2 has a sensitivity of 69.2 and a specificity of 84.2 (AUC: 0.806; 95% CI: 0.72-0.884) to predict severe dengue. Patients with an APRI of >3.2 required a mean hospital stay of 5.47 days (P = 0.005); 27 (81.8%) requiring platelet transfusion had an APRI of > 3.2 (P = 0.00).

Conclusion

APRI is a straightforward index that can be easily derived from AST and platelet values. APRI values of >3.2 can predict severe dengue with a sensitivity of 69.2 and a specificity of 84.2. APRI values of >3.2 are also associated with the length of hospital stay and requirement of platelet transfusion.

Platelet Proteome Reveals Novel Targets for Hypercoagulation in Pseudoexfoliation Syndrome

Pseudoexfoliation syndrome (PEX) is characterized by the accumulation of abnormal extracellular matrix material in ocular and non-ocular tissues, including blood vessel walls. Clot-forming dysfunction might be responsible for venous thrombosis in PEX. We investigated global coagulation, the proteome, and functions of platelets in PEX patients and aimed to determine prognostic biomarkers for thrombosis risk in PEX. Peripheral blood was collected from PEX and retinal vein occlusion (RVO) patients, and age-sex matched controls. Viscoelastic hemostasis was evaluated by rotational thromboelastometry (ROTEM). Platelet markers (CD41, CD42, CD61, and CD62p) and endothelial markers (P-selectin, E-selectin, and von Willebrand factor) were investigated by flow cytometry and ELISA, respectively. The platelet proteome was analyzed by 2D fluorescence difference gel electrophoresis followed by mass spectrometry. Clot formation time (CFT) is significantly reduced in PEX patients compared to the controls (p < 0.05). P-selectin levels were higher in PEX patients than in controls (p < 0.05); E-selectin and von Willebrand factor remained unchanged. The monitorization of CFT by ROTEM, and soluble P-selectin, may help assess thrombotic risk in PEX patients. Proteomic analysis revealed differential expression of Profilin-1 in platelets. Profilin-1 regulates the stability of actin-cytoskeleton and may contribute to impaired platelet hemostatic functions. Increased P-selectin levels together with impaired coagulation dynamics might be responsible for the thrombotic events in PEX disease.

Pretreatment Circulating Albumin, Platelet, and RDW-SD Associated with Worse Disease-Free Survival in Patients with Breast Cancer

Objective

Breast cancer is the second most common malignancy globally and a leading cause of cancer death in women. Analysis of factors related to disease-free survival (DFS) has improved understanding of the disease and characteristics related to recurrence. The aim of this study was to investigate the predictors of DFS in patients with breast cancer to enable the identification of patients at high risk who may benefit from prevention interventions.

Methods

We retrospectively analyzed 559 women with breast cancer who underwent treatment between 2004 and 2022. The study endpoint was DFS. Recurrence was defined as local recurrence, regional recurrence, distant metastases, contralateral breast cancer, other second primary cancer, and death. Baseline tumor-related characteristics, treatment-related characteristics, sociodemographic and biochemical data were analyzed using Cox proportional hazards analysis.

Results

The median DFS was 45 months (range, 2 to 225 months). Breast cancer recurred in 86 patients (15.4%), of whom 10 had local recurrence, 10 had regional recurrence, 17 had contralateral breast cancer, 29 had distant metastases, 10 had second primary cancer, and 10 patients died. Multivariate forward stepwise Cox regression analysis showed that AJCC stage III, Ki67 ≥14%, albumin, platelet, and red cell distribution width-standard deviation (RDW-SD) were predictors of worse DFS. In addition, the effects of albumin, platelet, and RDW-SD on disease recurrence were confirmed by structural equation model (SEM) analysis.

Conclusion

In addition to the traditional predictors of worse DFS such as AJCC stage III and Ki67 ≥14%, lower pretreatment circulating albumin, higher pretreatment circulating platelet count and RDW-SD could significantly predict worse DFS in this study, and SEM delineated possible causal pathways and inter-relationships of albumin, platelet, and RDW-SD contributing to the disease recurrence among Chinese women with breast cancer.

Differential Proteoglycan Expression in Atherosclerosis Alters Platelet Adhesion and Activation

Proteoglycans are differentially expressed in different atherosclerotic plaque phenotypes, with biglycan and decorin characteristic of ruptured plaques and versican and hyaluronan more prominent in eroded plaques. Following plaque disruption, the exposure of extracellular matrix (ECM) proteins triggers platelet adhesion and thrombus formation. In this study, the impact of differential plaque composition on platelet function and thrombus formation was investigated. Platelet adhesion, activation and thrombus formation under different shear stress conditions were assessed in response to individual proteoglycans and composites representing different plaque phenotypes. The results demonstrated that all the proteoglycans tested mediated platelet adhesion but not platelet activation, and the extent of adhesion observed was significantly lower than that observed with type I and type III collagens. Thrombus formation upon the rupture and erosion ECM composites was significantly reduced (p < 0.05) compared to relevant collagen alone, indicating that proteoglycans negatively regulate platelet collagen responses. This was supported by results demonstrating that the addition of soluble biglycan or decorin to whole blood markedly reduced thrombus formation on type I collagen (p < 0.05). Interestingly, thrombus formation upon the erosion composite displayed aspirin sensitivity, whereas the rupture composite was intensive to aspirin, having implications for current antiplatelet therapy regimes. In conclusion, differential platelet responses and antiplatelet efficacy are observed on ECM composites phenotypic of plaque rupture and erosion. Proteoglycans inhibit thrombus formation and may offer a novel plaque-specific approach to limit arterial thrombosis.

Identification and validation of platelet-related diagnostic markers and potential drug screening in ischemic stroke by integrating comprehensive bioinformatics analysis and machine learning

Background

Ischemic stroke (IS), caused by blood and oxygen deprivation due to cerebral thrombosis, has links to activated and aggregated platelets. Discovering platelet-related biomarkers, developing diagnostic models, and screening antiplatelet drugs are crucial for IS diagnosis and treatment.

Methods and results

Combining and normalizing GSE16561 and GSE22255 datasets identified 1,753 upregulated and 1,187 downregulated genes. Fifty-one genes in the platelet-related module were isolated using weighted gene co-expression network analysis (WGCNA) and other analyses, including 50 upregulated and one downregulated gene. Subsequent enrichment and network analyses resulted in 25 platelet-associated genes and six diagnostic markers for a risk assessment model. This model's area under the ROC curve outperformed single genes, and in the peripheral blood of the high-risk group, immune infiltration indicated a higher proportion of CD4, resting CD4 memory, and activated CD4 memory T cells, along with a lower proportion of CD8 T cells in comparison to the low-risk group. Utilizing the gene expression matrix and the CMap database, we identified two potential drugs for IS. Finally, a rat MACO/R model was used to validate the diagnostic markers' expression and the drugs' predicted anticoagulant effects.

Conclusion

We identified six IS platelet-related biomarkers (APP, THBS1, F13A1, SRC, PPBP, and VCL) for a robust diagnostic model. The drugs alpha-linolenic acid and ciprofibrate have potential antiplatelet effects in IS. This study advances early IS diagnosis and treatment.

Low HALP (Hemoglobin, Albumin, Lymphocyte, and Platelet) Score Increases the Risk of Post-Stroke Cognitive Impairment: A Multicenter Cohort Study

Objective

The HALP (hemoglobin, albumin, lymphocyte, and platelet) score is a novel indicator that measures systemic inflammation and nutritional status that has not been correlated with the risk of post-stroke cognitive impairment in patients with acute ischemic stroke or transient ischemic attack (TIA).

Methods

Study participants were recruited from 40 stroke centers in China. The HALP score was derived using a weighted sum of hemoglobin, albumin, lymphocytes and platelets, and study participants were categorized into 4 groups of equal sizes based on quartiles cutoffs of the HALP score. The Montreal Cognitive Assessment (MoCA)-Beijing Cognitive Assessment Scale (MoCA-Beijing) was performed at 2 weeks and 12 months following stroke onset. Post-stroke cognitive impairment was considered in patients with MoCA-Beijing≤22. Multiple logistic regression methods were employed to evaluate the relationship between the HALP score and the subsequent risk of developing post-stroke cognitive impairment.

Results

The study population comprised 1022 patients (mean age 61.6±11.0 years, 73% men). The proportion of individuals with MoCA-Beijing≤22 at 2 weeks was 49.2% and 32.4% at one year. Patients in the lowest quartile of HALP score (<36.56) were observed to harbor the highest risk of post-stroke cognitive impairment at 12 months post-stroke/TIA compared to those in the highest quartile (odds ratio=1.59, 95% CI=1.07-2.37, p=0.022), and lower domain scores for executive function, naming, and attention. There were no statistically significant differences between patients in the different quartiles of HALP score and HALP score at 2 weeks post-stroke/TIA.

Conclusion

The HALP score is a simple score that could stratify the risk of post-stroke cognitive impairment in stroke/TIA patients to facilitate early diagnosis and interventions.

New insights of platelet endocytosis and its implication for platelet function

Endocytosis constitutes a cellular process in which cells selectively encapsulate surface substances into endocytic vesicles, also known as endosomes, thereby modulating their interaction with the environment. Platelets, as pivotal hematologic elements, play a crucial role not only in regulating coagulation and thrombus formation but also in facilitating tumor invasion and metastasis. Functioning as critical components in the circulatory system, platelets can internalize various endosomal compartments, such as surface receptors, extracellular proteins, small molecules, and pathogens, from the extracellular environment through diverse endocytic pathways, including pinocytosis, phagocytosis, and receptor-mediated endocytosis. We summarize recent advancements in platelet endocytosis, encompassing the catalog of cargoes, regulatory mechanisms, and internal trafficking routes. Furthermore, we describe the influence of endocytosis on platelet regulatory functions and related physiological and pathological processes, aiming to offer foundational insights for future research into platelet endocytosis.

Role of Perturbated Hemostasis in MASLD and Its Correlation with Adipokines

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) continues to rise, making it one of the most prevalent chronic liver disorders. MASLD encompasses a range of liver pathologies, from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH) with inflammation, hepatocyte damage, and fibrosis. Interestingly, the liver exhibits close intercommunication with fatty tissue. In fact, adipose tissue could contribute to the etiology and advancement of MASLD, acting as an endocrine organ that releases several hormones and cytokines, with the adipokines assuming a pivotal role. The levels of adipokines in the blood are altered in people with MASLD, and recent research has shed light on the crucial role played by adipokines in regulating energy expenditure, inflammation, and fibrosis in MASLD. However, MASLD disease is a multifaceted condition that affects various aspects of health beyond liver function, including its impact on hemostasis. The alterations in coagulation mechanisms and endothelial and platelet functions may play a role in the increased vulnerability and severity of MASLD. Therefore, more attention is being given to imbalanced adipokines as causative agents in causing disturbances in hemostasis in MASLD. Metabolic inflammation and hepatic injury are fundamental components of MASLD, and the interrelation between these biological components and the hemostasis pathway is delineated by reciprocal influences, as well as the induction of alterations. Adipokines have the potential to serve as the shared elements within this complex interrelationship. The objective of this review is to thoroughly examine the existing scientific knowledge on the impairment of hemostasis in MASLD and its connection with adipokines, with the aim of enhancing our comprehension of the disease.

Platelet transfusion practices among neonatologists in Saudi Arabia: A nationwide cross-sectional survey

The etiologies of thrombocytopenia are highly diverse; however, early neonatal thrombocytopenia might be more common among extremely low-weight neonates. Therefore, in this study, we aimed to examine the current neonatal platelet (PLT) transfusion practices in Saudi Arabia. This is a cross-sectional online survey study that was conducted between October and December 2022. Convenience sampling was used to recruit the participants. In this study, we developed a questionnaire based on an extensive literature review to examine current neonatal PLT transfusion practices. A total of 81 neonatologists participated. The vast majority of them (85.2%) were practicing in a level 3 neonatal intensive care unit, with 60.0% of them reporting that they transfuse PLTs over 1 hour. Around 53% reported that they typically order 10 mL/kg per PLT transfusion. Up to 34.6% of the study participants reported that they use pooled whole-blood-derived PLT products in their practicing unit. Almost half (48.0%) of the study participants reported that they have written guidelines for PLT transfusion in their practicing unit, with 81.1% reporting that the PLT transfusion threshold was stated in the guidelines. Neonatal thrombocytopenia is typically treated with PLT transfusions. PLT transfusion criteria should be lowered in light of recent evidence suggesting that doing so may be counterproductive. However, there is some disagreement about whether a PLT count constitutes a medical emergency requiring a transfusion for a newborn baby. Furthermore, there is a great deal of variation in the administration of PLT infusions in Saudi Arabia because of the absence of clear protocols. Strict neonatal PLT transfusion standards and carefully planned clinical research are needed to address the risks and/or benefits of these diverse methods.

FIB-4 and APRI scores for progressive liver fibrosis diagnosis in children with biliary atresia

Introduction

Finding non-invasive methods to predict the degree of liver fibrosis is very important in managing children with biliary atresia. Therefore, we explored the predictive value of APRI, FIB-4, and serological markers for liver fibrosis in children with biliary atresia.

Methods

This study retrospectively reviewed data from children diagnosed with BA between March and December 2022. Liver tissue pathology specimens were obtained during surgery. The serum markers were measured within 2 days before the Kasai procedure or liver transplantation. The aspartate aminotransferase-to-platelet ratio index (APRI) and the four-factor-based fibrosis index (FIB-4) were calculated. The outcome was the diagnosis of progressive liver fibrosis.

Results

This study reviewed the data from 41 children with biliary atresia. APRI had 52% sensitivity and 83% specificity for progressive liver fibrosis, while FIB-4 had 83% sensitivity and 67% specificity. Their areas under the curve were not significantly different from those of conventional markers.

Conclusion

Although they were not better than conventional markers, APRI and FIB-4 can be used as follow-up markers for progressive liver fibrosis in patients with biliary atresia, but their predictive value was moderate. Additional studies are necessary to determine whether they could be combined with other markers to improve their predictive value.

Development of the Integrated Computer Simulation Model of the Intracellular, Transmembrane, and Extracellular Domain of Platelet Integrin α IIb β 3 (Platelet Membrane Glycoprotein: GPIIb-IIIa)

Background  The structure and functions of the extracellular domain of platelet integrin α IIb β 3 (platelet membrane glycoprotein: GPIIb-IIIa) change substantially upon platelet activation. However, the stability of the integrated model of extracellular/transmembrane/intracellular domains of integrin α IIb β 3 with the inactive state of the extracellular domain has not been clarified. Methods  The integrated model of integrin α IIb β 3 was developed by combining the extracellular domain adopted from the crystal structure and the transmembrane and intracellular domain obtained by Nuclear Magnetic Resonace (NMR). The transmembrane domain was settled into the phosphatidylcholine (2-oleoyl-1-palmitoyl-sn-glycerol-3-phosphocholine (POPC)) lipid bilayer model. The position coordinates and velocity vectors of all atoms and water molecules around them were calculated by molecular dynamic (MD) simulation with the use of Chemistry at Harvard Macromolecular Mechanics force field in every 2 × 10 -15 seconds. Results  The root-mean-square deviations (RMSDs) of atoms constructing the integrated α IIb β 3 model apparently stabilized at approximately 23 Å after 200 ns of calculation. However, minor fluctuation persisted during the entire calculation period of 650 ns. The RMSDs of both α IIb and β 3 showed similar trends before 200 ns. The RMSD of β 3 apparently stabilized approximately at 15 Å at 400 ns with persisting minor fluctuation afterward, while the structural fluctuation in α IIb persisted throughout the 650 ns calculation period. Conclusion  In conclusion, the integrated model of the intracellular, transmembrane, and extracellular domain of integrin α IIb β 3 suggested persisting fluctuation even after convergence of MD calculation.

Platelet-targeted gene therapy induces immune tolerance in hemophilia and beyond

Blood platelets have unique storage and delivery capabilities. Platelets play fundamental roles in hemostasis, inflammatory reactions, and immune responses. Beyond their functions, platelets have been used as a target for gene therapy. Platelet-targeted gene therapy aims to deliver a sustained expression of neo-protein in vivo by genetically modifying the target cells, resulting in a cure for the disease. Even though there has been substantial progress in the field of gene therapy, the potential development of immune responses to transgene products or vectors remains a significant concern. Of note, multiple preclinical studies using platelet-specific lentiviral gene delivery to hematopoietic stem cells in hemophilia have demonstrated promising results with therapeutic levels of neo-protein that rescue the hemorrhagic bleeding phenotype and induce antigen-specific immune tolerance. Further studies using ovalbumin as a surrogate protein for platelet gene therapy have shown robust antigen-specific immune tolerance induced via peripheral clonal deletions of antigen-specific CD4- and CD8-T effector cells and induction of antigen-specific regulatory T (Treg) cells. This review discusses platelet-targeted gene therapy, focusing on immune tolerance induction.