Platelet-derived Microparticles Research Articles

A study of platelet function in patients with chronic immune thrombocytopenia treated with thrombopoietin receptor agonists

BackgroundThrombopoietin receptor agonists (TPO-RAs) are widely used in immune thrombocytopenia (ITP) and are associated with increased thrombotic risk. However, data regarding their impact on platelet function is scarce. MethodsPlatelet function was evaluated in chronic ITP patients enrolled over one year, using light transmission aggregometry and platelet-derived microparticle (PMP) levels measurement with flow cytometry. Aggregation responses to various concentrations of ADP, collagen, ristocetin, and PMP levels were compared between TPO-RA-treated patients, patients treated with other agents and healthy individuals. ResultsTPO-RA-treated patients (n = 24) displayed significantly reduced aggregation responses to 2.5 μM, 5 μM, and 10 μM of ADP and collagen compared to 15 healthy individuals (59.5 % vs. 87.6 %, p < .0001, 43.6 % vs. 79.9 %, p < .0001, 26.1 % vs. 75.2 %, p < .0001, 67.2 % vs. 86 %, p < .0001, respectively). Reduced responses to ADP and collagen were also recorded in patients treated with other agents (n = 16) compared to healthy controls but without difference between the two treatment groups. Aggregation response to ristocetin was normal in all three groups. None of the patients yielded enhanced platelet aggregation. In TPO-RA-treated patients, a strong positive correlation between platelet counts and aggregation response to ristocetin was observed (rs = 0.65, p = .0005). PMP levels were significantly elevated in TPO-RA-treated patients compared to patients treated with other agents (49.5 vs 4.5 events/uL, p < .0001) and healthy controls (5 events/uL, p < .0001). ConclusionsThese results suggest that TPO-RAs may not enhance platelet aggregation responses, whereas impaired responses may be a disease feature. Furthermore, TPO-RAs may increase PMP levels and thus be implicated in the modulation of platelet function in ITP patients.

Advanced design of indented-standing surface acoustic wave (i-SSAW) device for platelet-derived microparticle separation from whole blood

Isolating submicron microvesicles (MVs) from blood has become important for clinical diagnosis and researches. Advanced design of indented-standing surface acoustic wave (i-SSAW)-based device with a U-shaped microchannel is proposed for extracting platelet-derived microparticles (PDMPs) from whole blood. Unlike the previous acoustic devices, the cross-sectional shape of the microchannel was manipulated to enhance the device performance, rather than the patterned interdigitated transducers. Cross-sectional shape-dependent device performance was evaluated using rectangular channels with different heights and U-shaped channel with whole blood sample with 40 % hematocrit. Effect of the flow rates on acoustic migration of red blood cells (RBCs) was examined at 20 V fixed voltage. In addition, RBC and platelet removal was examined using different applied voltages for i-SSAW operation. Finally, high-purity (approximately 100 %) and high-recovery (approximately 55.6 %) platelet-poor plasma was separated from whole blood at 30 μL/min without platelet activation.

Anti-Platelet Activity of Sea Buckthorn Seeds and Its Relationship with Thermal Processing.

Sea buckthorn (Hippophae rhamnoides L.) is a tree or shrub with small, orange berries. Sea buckthorn seeds have shown many properties beneficial to human health, including antioxidant, anti-hypertensive, anti-hyperlipidemic, and retinoprotective activities. Seeds, as a component of food, are often exposed to high temperatures, which can increase or decrease their biological activity. In our previous study, we showed that both raw and roasted sea buckthorn seeds had significant antioxidant activity, which was measured in human plasma in vitro. In this paper, we evaluated the effect of extracts from raw and roasted sea buckthorn seeds on several parameters of hemostasis in vitro, including thrombus formation in full blood (measured by the Total Thrombus formation Analysis System-T-TAS), blood platelet activation (based on the exposition of P-selectin, the active form of GPIIb/IIIa on their surface and platelet-derived microparticles formation), aggregation (measured with impedance aggregometry), adhesion to fibrinogen and collagen, arachidonic acid metabolism in washed platelets stimulated by thrombin, and COX-1 activity. We also measured the levels of free 8-isoprostane in plasma and the total non-enzymatic antioxidant status of plasma. The extract from roasted seeds (50 µg/mL) significantly prolonged the time of occlusion measured by T-TAS-the AUC10 (area under the curve) value was decreased by approximately 18%. Both extracts decreased the exposition of the active form of GPIIb/IIIa on the surface of platelets activated with 10 μM ADP (by 38.4-62.2%) and 20 μM ADP (by 39.7-51.3%). Moreover, the extract from raw seeds decreased the exposition of P-selectin on the surface of platelets stimulated with 20 μM ADP (by 31.2-34.9%). The adhesion of thrombin-stimulated platelets to fibrinogen and collagen was inhibited only by the extract from roasted sea buckthorn seeds (by 20-30%). Moreover, the extract from raw seeds inhibited the level of TBARS (thiobarbituric acid-reactive substances, an indicator of enzymatic peroxidation of arachidonic acid) in washed platelets stimulated with thrombin; the activity of COX-1 was inhibited by both extracts, although the effect of the extract from raw seeds was stronger. These results indicate that sea buckthorn seeds have anti-platelet activity that is not decreased by thermal processing, but more research is needed to determine which exact chemical compounds and mechanisms are responsible for this phenomenon.

High Levels of Triggering Receptor Expressed in Myeloid Cells-Like Transcript-1 Positive, but Not Glycoprotein 1b+, Microparticles Are Associated With Poor Outcomes in Acute Respiratory Distress Syndrome.

To identify triggering receptor expressed in myeloid cells-like transcript-1 positive (TLT-1+) microparticles (MPs) and evaluate if their presence is associated with clinical outcomes and/or disease severity in acute respiratory distress syndrome (ARDS). Retrospective cohort study. ARDS Network clinical trials. A total of 564 patients were diagnosed with ARDS. None. Using flow cytometry, we demonstrated the presence of TLT-1+ platelet-derived microparticles (PMP) that bind fibrinogen in plasma samples from fresh donors. We retrospectively quantified TLT-1, glycoprotein (Gp) 1b, or αIIbβIIIa immunopositive microparticles in plasma samples from patients with ARDS enrolled in the ARMA, KARMA, and LARMA (Studies 01 and 03 lower versus higher tidal volume, ketoconazole treatment, and lisofylline treatment Clincial Trials) ARDS Network clinical trials and evaluated the relationship between these measures and clinical outcomes. No associations were found between Gp1b+ MPs and clinical outcomes for any of the cohorts. When stratified by quartile, associations were found for survival, ventilation-free breathing, and thrombocytopenia with αIIbβIIIa+ and TLT-1+ MPs (χ2p < 0.001). Notably, 63 of 64 patients in this study who failed to achieve unassisted breathing had TLT+ PMP in the 75th percentile. In all three cohorts, patients whose TLT+ MP counts were higher than the median had higher Acute Physiology and Chronic Health Evaluation III scores, were more likely to present with thrombocytopenia and were 3.7 times (p < 0.001) more likely to die than patients with lower TLT+ PMP after adjusting for other risk factors. Although both αIIbβIIIa+ and TLT+ microparticles (αIIbβIIIa, TLT-1) were associated with mortality, TLT-1+ MPs demonstrated stronger correlations with Acute Physiology and Chronic Health Evaluation III scores, unassisted breathing, and multiple system organ failure. These findings warrant further exploration of the mechanistic role of TLT-1+ PMP in ARDS or acute lung injury progression.

Platelet microparticles influence gene expression and modulate biological activities of chronic myeloid leukemia cells (K562).

The current understanding emphasizes the intricate interplay between the Leukemic cell and its environment. Platelet-derived microparticles play a crucial role in facilitating intercellular communication and contribute to the complex landscape of cancer pathology. This study aimed to investigate the influence of platelet-derived microparticles on cell proliferation, apoptosis, and the expression of key genes, including P53, P21, Cyclin D1, Bax, and Bcl-2, within the context of a chronic myeloid leukemia cell line (K562). Platelet-derived microparticles were obtained through centrifugation at various speeds, and their concentration was quantified using the BCA assay. To determine the size and immunophenotypic characteristics of the PMPs, both the DLS technique and flow cytometry were employed. Cell proliferation was assessed using the MTT assay and hemocytometer, and cell cycle analysis was conducted through DNA content evaluation. Real-time PCR was utilized for gene expression analysis of Bax, Bcl-2, Cyclin D1, P53, and P21. Flow cytometry was employed to examine cell apoptosis. The findings revealed that platelet-derived microparticles have the ability to decrease proliferation of the K562 cell line, while not exerting an impact on apoptosis and cell cycle progression. Analysis through real-time PCR indicated an upregulation in the gene expression of P53, P21, and Bcl-2, accompanied by a downregulation in Bax and Cyclin D1. This investigation sheds light on the intricate relationship between chronic myeloid leukemia and its microenvironment, particularly the involvement of platelet-derived microparticles. The study underscores the potential of platelet-derived microparticles to influence cell behavior and gene expression, providing a deeper understanding of their role in CML and its therapeutic implications.

Effect of hyperbilirubinemia and phototherapy on apoptotic microparticle levels in neonates.

We aimed to evaluate the effect of hyperbilirubinemia and phototherapy on total apoptotic, platelet-derived, endothelial-derived, and tissue factor (TF)-positive apoptotic microparticle (MP) levels in neonates with nonhemolytic pathologic hyperbilirubinemia. Thirty-three term neonates with nonhemolytic pathologic hyperbilirubinemia and 25 healthy term neonates were included. MP levels were analyzed by flow cytometry using peripheral blood samples only once for the neonates in the control group and twice for the neonates in the study group (before and after phototherapy). Annexin V-positive MPs were defined as apoptotic MPs. Platelet-derived MPs were defined as those containing CD31. MPs containing CD144 were defined as endothelial-derived MPs, and MPs expressing TF were identified as those containing CD142. The rates of total apoptotic and endothelial-derived apoptotic MPs were significantly higher in the study group than the control group before phototherapy (P = 0.012 and P = 0.003, respectively) and after phototherapy (P = 0.046 and P = 0.001, respectively). Total apoptotic, platelet-derived, endothelial-derived, and TF-positive apoptotic MPs did not show any significant differences before and after phototherapy in the study group (P = 0.908, P = 0.823, P = 0.748, and P = 0.437, respectively). Our study demonstrated that total apoptotic and endothelial-derived apoptotic MPs are increased in cases of nonhemolytic pathologic hyperbilirubinemia. We showed that phototherapy does not have a significant effect on apoptotic MP levels. Further studies are needed to evaluate the risk of elevated apoptotic MPs on the development of thromboembolism in neonates with nonhemolytic pathologic hyperbilirubinemia.

An Investigation of Size Distribution and Calcium Signaling in Human Platelets.

Background Platelets are thin disc-shaped blood cells that play a major role in hemostasis, maintenance of vascular integrity, and blood coagulation. Large platelets are more reactive and seen in patients with cardiovascular disease. This study aims to analyze the changes in platelet size of ex vivo activated platelets which phenotypically simulates that of a patient at risk of cardiovascular disease and elucidate the calcium signaling pathway responsible for this change. Methodology Platelets were isolated from adult human blood by differential centrifugation. Calcium was mobilized into platelets by treatment with calcium ionophore A23187 in the presence of Ca2+. Platelet size distribution was analyzed using Coulter Counter Multisizer 4. The following signaling parameters were studied: intracellular Ca2+ measurement (using Fura-2/AM by fluorescence spectrophotometry), Ca2+-dependent thiol protease calpain assay (using fluorogenic substrate t-butoxycarbonyl-Leu-metchloromethylcoumarin in fluorescence microplate reader), platelet-derived microparticles (using FACS Calibur flow cytometry), and cytoskeletal protein talin expression (by western immunoblotting). Results When adult platelets were treated with A23187 and Ca2+, two subcellular populations (<2 µm and between 2-4 µm) were noted. The mean size of the second cell population was significantly higher than that of resting platelets (2.94 ± 0.13 µm vs. 2.82 ± 0.15 µm, t = 4.605, p = 0.00). A23187 treatment led to elevated intracellular Ca2+, release of platelet-derived microparticles, increase in calpain activity, and cytoskeletal talin degradation. These events were inhibited by calpeptin (a specific calpain inhibitor). Conclusions Elevated calcium caused talin degradation by calpain activity. Breakdown of this cytoskeletal protein leads to relative swelling of cells reflected by the increase in platelet size.

Improving platelet function following prophylactic platelet transfusion in patients with hematological malignancies.

Platelet transfusion is a standard treatment to prevent bleeding in patients with hematological malignancies. Although transfusions can improve platelet count, their impact on platelet function remains controversial. We conducted flow cytometry to assess platelet function before and after transfusion and performed subgroup analyses to examine differences based on blood type, corrected count increment (CCI), and platelet microparticles. Overall, 50 patients who received prophylactic platelet transfusion were enrolled. CD42b expression increased, whereas CD41 expression decreased after transfusion. Apheresis platelets exhibited the lowest expression of PAC-1 and P-selectin when exposed to agonist stimulations. PAC-1 expression increased under high adenosine diphosphate (ADP) stimulation, while P-selectin expression increased under both high ADP and thrombin receptor-activating peptide stimulation. In the subgroup analysis, patients with a CCI >4500 and those with the same blood types exhibited a more significant increase in PAC-1 and P-selectin expression under agonist stimulation. When comparing apheresis platelets collected on different days, only the percentage of platelet-derived microparticles showed a significantincrease. Prophylactic transfusion improved platelet function. Platelet function significantly improved in patients with a CCI >4500, those with the same blood types as that of apheresis platelets, or those with platelet-derived microparticle levels <4.7%. No significant improvement in platelet function was noted after the transfusion of different blood types with acceptable compatibility or the transfusion of incompatible blood types. Our results suggest that transfusing platelets with the same blood type remains the optimal choice.

Differential effects of physiological agonists on the proteome of platelet-derived extracellular vesicles.

Arterial thrombosis manifesting as heart attack and stroke is the leading cause of death worldwide. Platelets are central mediators of thrombosis that can be activated through multiple activation pathways. Platelet-derived extracellular vesicles (pEVs), also known as platelet-derived microparticles, are granular mixtures of membrane structures produced by platelets in response to various activating stimuli. Initial studies have attracted interest on how platelet agonists influence the composition of the pEV proteome. In the current study, we used physiological platelet agonists of varying potencies which reflect the microenvironments that platelets experience during thrombus formation: adenosine diphosphate, collagen, thrombin as well as a combination of thrombin/collagen to induce platelet activation and pEV generation. Proteomic profiling revealed that pEVs have an agonist-dependent altered proteome in comparison to their cells of origin, activated platelets. Furthermore, we found that various protein classes including those related to coagulation and complement (prothrombin, antithrombin, and plasminogen) and platelet activation (fibrinogen) are attributed to platelet EVs following agonist stimulation. This agonist-dependent altered proteome suggests that protein packaging is an active process that appears to occur without de novo protein synthesis. This study provides new information on the influence of physiological agonist stimuli on the biogenesis and proteome landscape of pEVs.

Platelet-derived microparticles adoptively transfer integrin β3 to promote antitumor effect of tumor-infiltrating T cells

ABSTRACT Approximately two-thirds of hepatocellular carcinoma (HCC) is considered a “cold tumor” characterized by few tumor-infiltrating T cells and an abundance of immunosuppressive cells. Cilengitide, an integrin αvβ3 inhibitor, has failed in clinical trials as a potential anticancer drug. This failure implies that integrin αvβ3 may play an important role in immune cells. However, the expression and potential role of integrin αvβ3 in T cells of HCC patients remain unknown. Here, we established two HCC models and found that cilengitide had a dual effect on the HCC microenvironment by exerting both antitumor effect and immunosuppressive effect on T cells. This may partly explain the failure of cilengitide in clinical trials. In clinical specimens, HCC-infiltrating T cells exhibited deficient expression and activation of integrin β3, which was associated with poor T-cell infiltration into tumors. Additionally, integrin β3 functioned as a positive immunomodulatory molecule to facilitate T-cell infiltration and T helper 1-type immune response in vitro. Furthermore, T cells and platelet-derived microparticles (PMPs) co-culture assay revealed that PMPs adoptively transferred integrin β3 to T cells and positively regulated T cell immune response. This process was mediated by clathrin-dependent endocytosis and macropinocytosis. Our data demonstrate that integrin β3 deficiency on HCC-infiltrating T cells may be involved in shaping the immunosuppressive tumor microenvironment. PMPs transfer integrin β3 to T cells and positively regulate T cell immune response, which may provide a new insight into immune therapy of HCC.

Comparative analysis of the quality of platelet concentrates produced by apheresis procedures, platelet rich plasma, and buffy coat.

Platelet concentrates (PCs) could be prepared using either whole-blood processes or apheresis instruments. During collection, processing and storage, some biochemical and functional changes occur, which may result in quality reduction. Quality evaluation of PCs may be helpful for the precise control of platelet (PLT) inventory to reduce the risk of refractoriness and adverse effects caused by platelet transfusion. The study was aimed to evaluate the quality of PCs which were produced by five processes: apheresis (AP) procedures (using three different cell separators: Amicus, Trima Accel and MCS+ instruments), platelet rich plasma (PRP), and buffy coat (BC). A total of 100 PCs (20 of each group) were assessed in respect of routine quality control, morphology, size distribution, destroyed and activated platelets, and production of platelet-derived microparticles (PMPs). All PCs have satisfied the recommended quality of volume, platelet count, residual WBC count, residual RBC count, pH, and sterility according to the Chinese Technical Manual. There was no difference among the 5 groups in morphology and size of PLT and PMPs. Dynamic light scattering test showed that apheresis PCs showed peaks around 10-20 nm, but not whole blood-derived PCs. PCs prepared by Amicus had the relatively high percentage of destroyed platelet, activated platelets and PMPs than other groups. The data suggested high heterogeneity of PMPs, destroyed and activated platelets in PCs produced by different processes, which might be helpful to manage the platelet inventory for targeted use.

Platelet Exosome-Derived miR-223-3p Regulates Pyroptosis in the Cell Model of Sepsis-Induced Acute Renal Injury by Targeting Mediates NLRP3.

The present study investigated the roles and mechanisms of platelet-derived exosomes in sepsis-induced acute renal injury. The blood samples of septic patients and healthy controls were collected for clinical examination. The plasma levels of miR-223-3p and NLRP3 mRNA were analyzed by qRT-PCR and the serum IL-1β and creatinine levels were quantified by enzyme-linked immunosorbent assay (ELISA). C57BL/6 mice injected with LPS (lipopolysaccharide) were employed as the animal model for sepsis-induced acute renal injury. Human coronary artery endothelial cells (HCAECs) were treated with TNF-α as a cellular model for sepsis-induced endothelial damages. The number of PMP (platelet-derived microparticles) in patients with sepsis was increased. The level of miR-223-3p in the platelet exosomes isolated from the serum sample in patients with sepsis was significantly lower than that of the healthy controls. The level of miR-223-3p was also decreased in the platelet exosomes of mouse model with sepsis-induced acute renal injury. Downregulating miR-223-3p promoted sepsis-induced acute renal injury in mice model, while the administration of miR-223-3p reduced the inflammation in endothelial cells of sepsis-induced acute renal injury. NLRP3 (NLR Family Pyrin Domain Containing 3) was identified as one target of miR-223-3p in the platelet exosomes of sepsis-induced acute kidney injury. miR-223-3p attenuated NLRP3-induced pyroptosis in endothelial cell model of sepsis-induced acute kidney injury. Our data suggest that platelet exosome-derived miR-223-3p negatively regulates NLRP3-dependent inflammasome to suppress pyroptosis in endothelial cells. Decreased miR-223-3p expression promotes the inflammation in sepsis-induced acute renal injury. Targeting miR-223-3p may be developed into a therapeutic approach for sepsis-induced acute renal injury.

Platelets: Physiology and Biochemistry.

This article represents a republication of an article originally published in STH in 2005. This republication is to help celebrate 50 years of publishing for STH. The original abstract follows.Platelets are specialized blood cells that play central roles in physiologic and pathologic processes of hemostasis, inflammation, tumor metastasis, wound healing, and host defense. Activation of platelets is crucial for platelet function that includes a complex interplay of adhesion and signaling molecules. This article gives an overview of the activation processes involved in primary and secondary hemostasis, for example, platelet adhesion, platelet secretion, platelet aggregation, microvesicle formation, and clot retraction/stabilization. In addition, activated platelets are predominantly involved in cross-talk to other blood and vascular cells. Stimulated "sticky" platelets enable recruitment of leukocytes at sites of vascular injury under high shear conditions. Platelet-derived microparticles as well as soluble adhesion molecules, sP-selectin and sCD40L, shed from the surface of activated platelets, are capable of activating, in turn, leukocytes and endothelial cells. This article focuses further on the new view of receptor-mediated thrombin generation of human platelets, necessary for the formation of a stable platelet-fibrin clot during secondary hemostasis. Finally, special emphasis is placed on important stimulatory and inhibitory signaling pathways that modulate platelet function.

Mitochondria Transfer by Platelet-Derived Microparticles Regulates Breast Cancer Bioenergetic States and Malignant Features.

We show that the transfer of foreign mitochondria by microparticles modulates recipient cancer cell metabolic plasticity, leading to greater malignant processes.

Gelatin In Situ Zymography to Study Gelatinase Activity in Colon Cancer Cells Treated with Platelet Microparticles (PMPs).

The platelet-derived microparticles (PMPs) have been connected with tumor progression and metastatic dissemination. PMPs infiltrate solid tumors and transfer platelet-derived cargo to cancer cells. The functional roles of PMPs in cancer progression are still poorly understood. PMPs, incorporated by colorectal cancer (CRC) cells, were shown to upregulate the expression and activity of matrix metalloproteases (MMPs). To investigate the impact of PMPs on the invasive potential of CRC, we established the protocol of dequenched gelatin(DG), fluorescein conjugate assay. The procedure confirms the activity of two gelatinases, namely, MMP2 and MMP9, that digest denatured collagen (gelatin). This "step-by-step" protocol, with notes and comments implemented to human CRC lines with different phenotypes and migratory potentials, should be sufficient to obtain representative and elegant results.

The Comparison of Platelet-Derived Microparticles between Ambulatory Cancer Patients and Controls

Background: Elevated levels of microparticles in cancer have been associated with hypercoagulability; however, the specific subtypes of microparticles are still unclear. We hypothesize that active cancer may increase the level of platelet-derived microparticles from platelet activation and play a role in cancer-associated thrombosis. Moreover, chemotherapy is also an important factor playing a role in platelet activation which may affect the levels of platelet-derived microparticles in ambulatory cancer patients. Objectives: To evaluate the hypothesis that platelet-derived microparticles will increase in cancer patients compared with non-cancer patients. To extrapolate the hypothesis that levels of platelet-derived microparticles will increase after receiving chemotherapy. Methods: This was a prospective, cross-sectional study, where, we enrolled ambulatory cancer patients who were about to receive the first cycle (pre-chemotherapy) and those who already received a cycle of chemotherapy (post-chemotherapy). Controls were age- and sex- matched healthy individuals. Patients who had venous thrombosis or who were currently receiving anticoagulants were excluded. Flow cytometry was used to detect, quantify and specify platelet-derived microparticles using the co-expression of both Annexin V for phosphatidylserine and CD41a for platelet marker, and then reported as the unit of event/mL. All outcomes were compared among three groups. Results: A total of 45 patients and 15 controls were enrolled with a mean age of 58.09 years; of which, most patients were female. There was not any significant difference in age, sex, BMI, and platelet count among these groups. Gynecologic malignancy and lymphoma covered almost three-fourths of all patients, which were 51.11% and 24.44% of the total cancer patients, respectively. There was no significant difference in platelet-derived microparticles between cancer patients and controls [411,600 events/mL (331,200-722,400 events/mL) versus 563,640 events/mL (273,720-1,625,580 events/mL), p=0.3179]. Platelet-derived microparticles were significantly higher in cancer patients who had already received chemotherapy (post-chemotherapy) in comparison to cancer patients in the pre-chemotherapy group [582,000 events/mL (346,500-149,3220 events/mL) versus 402,300 events/mL (141,000 - 624,600 events/mL), p=0.0391], Figure 2. There was no significant difference in platelet-derived microparticles between hematologic and non-hematologic malignancy; however, the levels tend to be higher in the non-hematologic malignancy group. Conclusions: Platelet-derived microparticles were not significantly higher among cancer patients who have not received their first cycle of chemotherapy as compared to controls. However, after receiving chemotherapy, cancer patients exhibited significantly higher levels of platelet-derived microparticles. Chemotherapy is an important factor in platelet activation in cancer patients which may increase the levels of platelet-derived microparticles and play a role in cancer-associated thrombosis.

Presurgical circulating platelet-derived microparticles level as a risk factor of blood transfusion in patients with valve heart disease undergoing cardiac surgery

BackgroundCell-derived microparticles (MPs) are membrane vesicles that have emerged as a potential biomarker for various diseases and their clinical complications. This study investigates the role of MPs as a risk factor for blood transfusion in patients with valve heart disease undergoing cardiac surgery. MethodsForty adult patients undergoing heart valve surgery with cardiopulmonary bypass (CPB) were enrolled, and venous blood samples were collected prior to surgical incision. Plasma rich in MPs was prepared by double centrifugation, and the concentration of MPs was determined using the Bradford method. Flow cytometry analysis was performed to determine MPs count and phenotype. Patients were divided into “with transfusion” (n = 18) and “without transfusion” (n = 22) groups based on red blood cell (RBC) transfusion. ResultsThere was no significant difference in MPs concentration between the “with transfusion” and “without transfusion” groups. Although the count of preoperative platelet-derived MPs (PMPs), monocyte-derived MPs (MMPs), and red cell-derived MPs (RMPs) was higher in “without transfusion” group, these differences were not statistically significant. The preoperative PMPs count was negatively correlated with RBC transfusion (P = 0.005, r = -0.65). Multivariate logistic regression analysis revealed that the count of CD41+ PMPs, Hemoglobin (Hb), and RBC count were risk factors for RBC transfusion. ConclusionThis study suggests that the presurgical levels of PMPs, Hb, and RBC count can serve as risk factors of RBC transfusion in patients with valve heart disease undergoing cardiac surgery. The findings provide insights into the potential use of MPs as biomarkers for blood transfusion prediction in cardiac surgery.

Association of Acute Hyperglycemia and Diabetes Mellitus with Platelet-derived Microparticle (PDMP) Levels During Acute Myocardial Infarction.

This research investigates whether there is an association between acute hyperglycemia and diabetes mellitus and the level of circulating platelet-derived microparticles (PDMPs) during an initial episode of acute myocardial infarction (AMI). This was a cross-sectional study involving hospitalized AMI patients. Demographic and clinical data were obtained from hospital records. Diabetes mellitus was defined by the history of the disease, anti-diabetes medication use and/ or level of HbA1C ≥6.5%. Levels of HbA1c, admission random and fasting blood glucose levels were measured. Flow-cytometry method was used to determine the levels of PDMPs from collected venous blood through tagging with CD-41 FITC and CD-62 PE markers and a threshold size of <1 μm. The number of circulating PDMPs was compared according to glucometabolic state, namely acute hyperglycemia (admission random glucose ≥200 mg/dL and fasting glucose ≥140 mg/dL) and diabetes mellitus. The comparative analysis between groups was conducted with Student T-test or Mann-Whitney test, where applicable. A total of 108 subjects were included and their data analyzed. The level of circulating PDMPs was significantly lower in subjects with admission random glucose ≥200 mg/dL as compared to those with below level [median (interquartile range (IQR)]: 2,710.0 (718.0-8,167.0) count/mL vs. 4,452.0 (2,128.5-14,499.8) count/mL, p = 0.05) and in subjects with fasting glucose ≥140 mg/dL as compared to those with below level (median (IQR): 2,382.0 (779.0-6,619.0) count/mL vs. 5,972.0 (2,345.7-14,781.3) count/mL, p = 0.006). The level of circulating PDMPs was also significantly lower in patients with diabetes mellitus as compared to those without (median (IQR): 2,655.0 (840.0-5,821.0) count/mL vs. 4,562.0 (2,128.5-15,055.8) count/mL; p = 0.007). Acute hyperglycemia and diabetes mellitus are significantly associated with a lower circulating PDMP level during an initial AMI episode.

Differences in coagulation-relevant parameters: Comparing cryoprecipitate and a human fibrinogen concentrate.

Variable fibrinogen content within cryoprecipitate makes accurate dosing challenging in patients with coagulopathic bleeding, in addition to pathogen transmission risks associated with its administration. Purified and standardized human fibrinogen concentrates (HFCs) represent reliable alternatives. Full cryoprecipitate characterization is required to inform selection of an appropriate fibrinogen source for supplementation therapy. Extended biochemical comparison of pooled cryoprecipitate and HFC (Fibryga, Octapharma) was performed using commercially available assays to determine levels of variability in cryoprecipitate and HFC. In addition to standard procoagulant factors, measurements included activities of platelet-derived microparticles (PMPs) and plasminogen, and levels of fibrin degradation products. Cryoprecipitate contains lower fibrinogen levels than HFC (4.83 vs.19.73 g/L; p<0.001), translating to approximately half the amount of fibrinogen per standard cryoprecipitate dose (two pools, pre-pooled from five donations each) vs. HFC (2.14 vs. 3.95 g; p<0.001). Factor XIII (FXIII) levels were also lower in cryoprecipitate vs. HFC (192.17 vs. 328.33 IU/dL; p = 0.002). Levels of procoagulants in cryoprecipitate, such as von Willebrand Factor (VWF) and factor VIII (FVIII), were highly variable, as was PMP activity. A standard cryoprecipitate dose contains significantly higher levels of measured plasminogen and D-dimer fragments than a standard HFC dose. The tested HFC is a more reliable fibrinogen and FXIII source for accurate dosing compared with cryoprecipitate. Cryoprecipitate appears considerably less predictable for bleeding management due to wide variation in pro- and anticoagulation factors, the presence of PMPs, and the potential to elevate VWF and FVIII to prothrombotic levels.

Pro-Tumorigenic and Thrombotic Activities of Platelets in Lung Cancer.

Aside from their key protective roles in hemostasis and innate immunity, platelets are now recognized as having multifaceted, adverse roles in the pathogenesis, progression and outcome of many types of human malignancy. The most consistent and compelling evidence in this context has been derived from the notable association of elevated circulating platelet counts with the onset and prognosis of various human malignancies, particularly lung cancer, which represents the primary focus of the current review. Key topics include an overview of the association of lung cancer with the circulating platelet count, as well as the mechanisms of platelet-mediated, pro-tumorigenic immunosuppression, particularly the role of transforming growth factor beta 1. These issues are followed by a discussion regarding the pro-tumorigenic role of platelet-derived microparticles (PMPs), the most abundant type of microparticles (MPs) in human blood. In this context, the presence of increased levels of PMPs in the blood of lung cancer patients has been associated with tumor growth, invasion, angiogenesis and metastasis, which correlate with disease progression and decreased survival times. The final section of the review addresses, firstly, the role of cancer-related platelet activation and thrombosis in the pathogenesis of secondary cardiovascular disorders and the associated mortality, particularly in lung cancer, which is second only to disease progression; secondly, the review addresses the potential role of antiplatelet agents in the adjunctive therapy of cancer.