Differences in levels of platelet-derived microparticles in platelet components prepared using the platelet rich plasma, buffy coat, and apheresis procedures.

BACKGROUND: There has been an increased interest in platelet-derived microparticles (PMPs) in transfusion medicine. Little is known about PMP status during the preparation of platelet concentrates for transfusion. AIM: The aim of this study is to compare the PMP levels in platelet components prepared using the buffy coat (BC), platelet-rich plasma platelet concentrate (PRP-PC), and apheresis (AP) processes. METHODS: Platelet components were prepared using the PRP-PC and BC processes. Apheresis platelets were prepared using the Trima Accel and Amicus instruments. The samples were incubated with annexin A5-FITC, CD41-PE, and CD62P-APC. At day 1 after processing, the PMPs and activated platelets were determined using flow cytometry. RESULTS: Both the percentage and number of PMPs were higher in platelet components prepared using the Amicus instrument (2.6±1.8, 32802±19036 particles/µL) than in platelet components prepared using the Trima Accel instrument (0.5±0.4, 7568±5298 particles/µL), BC (1.2±0.6, 12,920±6426 particles/µL), and PRP-PC (0.9±0.6, 10731±5514 particles/µL). Both the percentage and number of activated platelets were higher in platelet components prepared using the Amicus instrument (33.2±13.9, 427553±196965 cells/µL) than in platelet components prepared using the Trima Accel instrument (16.2±6.1, 211209±87706 cells/µL), BC (12.9±3.2, 140624±41003 cells/µL), and PRP-PC (21.1±6.3, 265210±86257 cells/µL). CONCLUSIONS: The study suggests high variability of PMPs and activated platelets in platelet components prepared using different processes. This result may be important in validating the instruments involved in platelet blood collection and processing.

Binding of phosphatidylserine-positive microparticles by PBMCs classifies disease severity in COVID-19 patients.

Infection with SARS-CoV-2 is associated with thromboinflammation, involving thrombotic and inflammatory responses, in many COVID-19 patients. In addition, immune dysfunction occurs in patients characterised by T cell exhaustion and severe lymphopenia. We investigated the distribution of phosphatidylserine (PS), a marker of dying cells, activated platelets and platelet-derived microparticles (PMP), during the clinical course of COVID-19. We found an unexpectedly high amount of blood cells loaded with PS+ PMPs for weeks after the initial COVID-19 diagnosis. Elevated frequencies of PS+ PMP+ PBMCs correlated strongly with increasing disease severity. As a marker, PS outperformed established laboratory markers for inflammation, leucocyte composition and coagulation, currently used for COVID-19 clinical scoring. PS+ PMPs preferentially bound to CD8+ T cells with gene expression signatures of proliferating effector rather than memory T cells. As PS+ PMPs carried programmed death-ligand 1 (PD-L1), they may affect T cell expansion or function. Our data provide a novel marker for disease severity and show that PS, which can trigger the blood coagulation cascade, the complement system, and inflammation, resides on activated immune cells. Therefore, PS may serve as a beacon to attract thromboinflammatory processes towards lymphocytes and cause immune dysfunction in COVID-19.

Platelet-Derived Microparticles: A New Index of Monitoring Platelet Activation and Inflammation in Kawasaki Disease.

OBJECTIVE: To investigate the dynamic changes of platelet-derived microparticles (PDMP) in Kawasaki disease (KD) and its clinical significance and to study its relationship with intravenous immunoglobulin (IVIG) resistance, inflammatory indicators and aspirin treatment in children with KD. METHODS: Twenty children with KD were enrolled as the experimental group, while 20 age- and gender-matched children with common febrile disease were included in the control group. Blood samples were drawn before and 7-10 d after IVIG infusion and thereafter at 1, 2, and 3 mo after the onset of KD to estimate the PDMP concentrations by enzyme linked immunosorbent assay (ELISA). C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), and cytokines [Interleukin-6 (IL-6), Tumor necrosis factor-α (TNF-α), and Soluble interleukin-2 (sIL-2R)] were also measured. RESULTS: The level of PDMP in KD children before IVIG was significantly higher than that in controls (P < 0.0001). The PDMP level in KD children decreased significantly at 7 to 10 d after IVIG (P < 0.0001) and then decreased to the lowest level in the course of 1 to 2 mo. Some children's PDMP level rebounded in the course of 3 mo (P = 0.047). In addition, the mean level of PDMP in IVIG-resistant children was higher than that in IVIG-effective children; however, there was no significant difference between the two groups (P = 0.1945). Furthermore, PDMP was positively correlated with hs-CRP, IL-6, and sIL-2R levels, but no correlation was observed with ESR, PCT, and TNF-α levels. CONCLUSIONS: PDMP can be used as an index to monitor inflammation in children at the acute stage of KD. And the duration of platelet activation in KD is individualized.

Effects of sarpogrelate, eicosapentaenoic acid and pitavastatin on arterioslcerosis obliterans-related biomarkers in patients with type 2 diabetes (SAREPITASO study).

BACKGROUND: The aim was to evaluate the significance of arteriosclerosis obliterans-related biomarkers in patients with type 2 diabetes mellitus (T2DM), and to compare the effects of sarpogrelate, eicosapentaenoic acid (EPA) and pitavastatin on these markers. PATIENTS AND METHODS: Seventy-two arteriosclerosis obliterans patients with T2DM were classified into two groups, pitavastatin with either sarpogrelate (PS) or EPA (PE). We observed no differences in all biomarkers between the PS and PE groups before treatments. RESULTS: The levels of body mass index, hemoglobin A1c, soluble E-selectin, soluble vascular cell adhesion molecule 1, plasminogen activator inhibitor-1 and platelet-derived microparticle in the PE group decreased significantly after treatment. The ankle branchial pressure index and adiponectin levels significantly increased in the PE group after treatment compared with the PS group. CONCLUSION: These results suggest that combination therapy using pitavastatin and EPA possesses an antiatherosclerotic effect and may be beneficial for prevention of vascular complications in patients with T2DM.

New prognostic biomarkers and therapeutic effect of bevacizumab for patients with non-small-cell lung cancer.

BACKGROUND: Several biomarkers have emerged as potential prognostic and predictive markers for non-small-cell lung cancer (NSCLC). Successful inhibition of angiogenesis with the antivascular endothelial growth factor antibody, bevacizumab, has improved the efficacy seen with standard cytotoxic therapy of NSCLC. However, despite such enhanced treatment strategies, the prognosis for patients with advanced NSCLC remains poor. PATIENTS AND METHODS: We assessed potential biomarkers in 161 NSCLC patients and 42 control patients. Enzyme-linked immunosorbent assay methods were used to evaluate three biomarkers: platelet-derived microparticle (PDMP), high-mobility group box-1 (HMGB1), and plasminogen activator inhibitor-1 (PAI-1). We studied the effects of bevacizumab on the expression of these markers. We also analyzed the relationship of the newly designed risk factor (NDRF) to overall survival and disease-free survival. The NDRF classification of patients was determined from the levels of PDMP, HMGB1, and PAI-1. To determine the individual prognostic power of PDMP, HMGB1, and PAI-1, we evaluated associations between their levels and patient outcomes by Kaplan-Meier survival analysis in a derivation cohort. RESULTS: PDMP, HMGB1, and PAI-1 levels were higher in NSCLC patients compared with control patients. Notably, the difference in PDMP levels exhibited the strongest statistical significance (p<0.001). Multivariate analysis showed that HMGB1 and PAI-1 levels were significantly correlated with PDMP levels. Patients who received standard chemotherapy with bevacizumab exhibited significantly reduced levels of all three markers compared with patients who received standard chemotherapy. NDRF3 status (high levels of all three markers) was significantly correlated with a poor prognosis (p<0.05 for overall survival and disease-free survival). CONCLUSION: Our results demonstrate that abnormal levels of PDMP, HMGB1, and PAI-1 are related to each other in NSCLC. Moreover, our findings suggest that the vascular complications associated with these markers may contribute to a poor prognosis for NSCLC patients.

Platelet microparticle-inspired clot-responsive nanomedicine for targeted fibrinolysis.

Intravascular administration of plasminogen activators is a clinically important thrombolytic strategy to treat occlusive vascular conditions. A major issue with this strategy is the systemic off-target drug action, which affects hemostatic capabilities and causes substantial hemorrhagic risks. This issue can be potentially resolved by designing technologies that allow thrombus-targeted delivery and site-specific action of thrombolytic drugs. To this end, leveraging a liposomal platform, we have developed platelet microparticle (PMP)-inspired nanovesicles (PMINs), that can protect encapsulated thrombolytic drugs in circulation to prevent off-target uptake and action, anchor actively onto thrombus via PMP-relevant molecular mechanisms and allow drug release via thrombus-relevant enzymatic trigger. Specifically, the PMINs can anchor onto thrombus via heteromultivalent ligand-mediated binding to active platelet integrin GPIIb-IIIa and P-selectin, and release the thrombolytic payload due to vesicle destabilization triggered by clot-relevant enzyme phospholipase-A2. Here we report on the evaluation of clot-targeting efficacy, lipase-triggered drug release and resultant thrombolytic capability of the PMINs in vitro, and subsequently demonstrate that intravenous delivery of thrombolytic-loaded PMINs can render targeted fibrinolysis without affecting systemic hemostasis, in vivo, in a carotid artery thrombosis model in mice. Our studies establish significant promise of the PMIN technology for safe and site-targeted nanomedicine therapies in the vascular compartment.

Elevated RANTES level is associated with metabolic syndrome and correlated with activated platelets associated markers in healthy younger men.

The objective of this study was to clarify the relationship of regulated on activation normal T cell expressed and secreted (RANTES) levels with metabolic syndrome (MS) and activated platelets-associated markers. We conducted a cross-sectional study of 210 healthy Japanese male volunteers (mean age 41 years old) who did not take any medications and were free of cardiovascular or cerebrovascular disease. The RANTES is correlated with age, diastolic blood pressure, and fast glucose by multivariate analysis using the cardiovascular risk factors (R (2) = .396, P < .001). The plasma RANTES level is significantly associated with MS after adjusting for age (P = .040). Once plasma interleukin 6, an activator of platelets, and plasma platelet-derived microparticles, a marker for activated platelets, are put into the equation, plasma RANTES level is significantly correlated with the activated platelet-associated markers (R (2) = .396, P < .001). These suggest the possible role of elevated RANTES in the forerunner of atherosclerosis in healthy younger men.