Extracellular Vesicles Surface Protein Profile as Biomarkers to Characterize Allograft Rejection in Heart Transplanted Patients

Purpose Circulating extracellular vesicles (EVs) are raising considerable interest as a non-invasive diagnostic tool.We aimed to investigate differences in plasma-derived EV surface protein profiles as a biomarker to be used in combination with endomyocardial biopsies (EMBs) for the diagnosis of allograft rejection. Methods Plasma was collected from 90 patients (53 training cohort, 37 validation cohort) before EMB. EV concentration was assessed by nanoparticle tracking analysis. EV surface antigens were measured using a multiplex flow cytometry assay composed of 37 fluorescently labeled capture bead populations coated with specific antibodies directed against respective EV surface epitopes. According to differential EV-markers expression two diagnostic model were built and validated through supervised learning algorithms (linear discriminant analysis-LDA- and random forest model- RF) Results The concentration of EVs was significantly increased and their diameter decreased in patients undergoing rejection as compared with negative ones. The trend was highly significant for both antibody-mediated rejection and acute cellular rejection (p Conclusion Circulating EVs are highly promising as a new tool to characterize cardiac allograft rejection and to be complementary to EMB monitoring