Flow Cytometric Assessment of Endothelial and Platelet Microparticles in Patients With Atrial Fibrillation Treated With Dabigatran

The prothrombotic state in patients with atrial fibrillation (AF) is related to endothelial injury, the activation of platelets and the coagulation cascade. We evaluated the levels of platelet- (CD42b) and endothelial-derived (CD144) microparticles in the plasma patients with non-valvular AF treated with dabigatran at the time of expected minimum and maximum drug plasma concentrations. Following that, we determined the peak dabigatran plasma concentration (c_peak ). CD42b increased after taking dabigatran (median [IQR] 36.7 [29.4-53.3] vs. 45.6 [32.3-59.5] cells/µL; p = 0.025). The concentration of dabigatran correlated negatively with the post-dabigatran change in CD42b (ΔCD42b, r = -0.47, p = 0.021). In the multivariate model, the independent predictors of ΔCD42b were: c_peak (HR -0.55; with a 95% confidence interval, CI [-0.93, -0.16]; p = 0.007), coronary artery disease (CAD) (HR -0.41; 95% CI [-0.79, -0.02]; p = 0.037) and peripheral artery disease (PAD) (HR 0.42; 95% CI [0.07, 0.74]; p = 0.019). CD144 did not increase after dabigatran administration. These data suggest that low concentrations of dabigatran may be associated with platelet activation. PAD and CAD have distinct effects on CD42b levels during dabigatran treatment.

Increased Levels of Platelets and Endothelial-Derived Microparticles in Patients With Non-Valvular Atrial Fibrillation During Rivaroxaban Therapy

It is known that atrial fibrillation (AF) is associated with the procoagulant state. Several studies have reported an increase of circulating microparticles in AF, which may be linked to a hypercoagulable state, atrial thrombosis and thromboembolism. We evaluated in our study alterations in both platelet (PMP, CD42b) and endothelial-derived (EMP, CD144) microparticle levels on anticoagulant therapy with rivaroxaban in nonvalvular AF. After administration of rivaroxaban, PMP levels were increased (median, [IQR] 35.7 [28.8-47.3] vs. 48.4 [30.9-82.8] cells/µL; P = 0.012), along with an increase in EMP levels (14.6 [10.0-18.6] vs. 18.3 [12.9-37.1] cells/µL, P < 0.001). In the multivariable regression analysis, the independent predictor of post-dose change in PMPs was statin therapy (HR −0.43; 95% CI −0.75,−0.10, P = 0.011). The post-dose change in EMPs was also predicted by statin therapy (HR −0.34; 95% CI −0.69, −0.01, P = 0.046). This study showed an increase in both EMPs and PMPs at the peak plasma concentration of rivaroxaban. Statins have promising potential in the prevention of rivaroxaban-related PMP and EMP release. The pro-thrombotic role of PMPs and EMPs during rivaroxaban therapy requires further study.

Insights into the Diagnostic Potential of Extracellular Vesicles and Their miRNA Signature from Liquid Biopsy as Early Biomarkers of Diabetic Micro/Macrovascular Complications

Extracellular vesicles (EVs) represent a heterogeneous population of small vesicles, consisting of a phospholipidic bilayer surrounding a soluble interior cargo. Almost all cell types release EVs, thus they are naturally present in all body fluids. Among the several potential applications, EVs could be used as drug delivery vehicles in disease treatment, in immune therapy because of their immunomodulatory properties and in regenerative medicine. In addition to general markers, EVs are characterized by the presence of specific biomarkers (proteins and miRNAs) that allow the identification of their cell or tissue origin. For these features, they represent a potential powerful diagnostic tool to monitor state and progression of specific diseases. A large body of studies supports the idea that endothelial derived (EMPs) together with platelet-derived microparticles (PMPs) are deeply involved in the pathogenesis of diseases characterized by micro- and macrovascular damages, including diabetes. Existing literature suggests that the detection of circulating EMPs and PMPs and their specific miRNA profile may represent a very useful non-invasive signature to achieve information on the onset of peculiar disease manifestations. In this review, we discuss the possible utility of EVs in the early diagnosis of diabetes-associated microvascular complications, specifically related to kidney.