Circulating extracellular vesicles as non-invasive biomarker of rejection in heart transplant

• DOI: 10.1016/j.healun.2020.06.011
• Publication Date: 2020-06-20T11:09:16Z
• Authors: Chiara Castellani; Jacopo Burrello; Marny Fedrigo; Alessio Burrello; Sara Bolis; Dario Di Silvestre; Francesco Tona; Tomaso Bottio; Vanessa Biemmi; Giuseppe Toscano; Gino Gerosa; Gaetano Thiene; Cristina Basso; Sarah L. Longnus; Giuseppe Vassalli; Annalisa Angelini; Lucio Barile
• Keywords: Pulmonary and Respiratory Medicine; Adult; Graft Rejection; Male; 2747 Transplantation; Biopsy; 610; 610 Medicine & health; 11171 Cardiocentro Ticino; 2705 Cardiology and Cardiovascular Medicine; Extracellular Vesicles; 03 medical and health sciences; Humans; heart transplant; Aged; Transplantation; 0303 health sciences; allograft rejection; biomarker; extracellular vesicles; heart transplant; machine learning; allograft rejection; Middle Aged; Allografts; Flow Cytometry; 2746 Surgery; 3. Good health; machine learning; ROC Curve; 2740 Pulmonary and Respiratory Medicine; biomarker; Heart Transplantation; Surgery; Female; extracellular vesicle; Cardiology and Cardiovascular Medicine; extracellular vesicles; Biomarkers

Circulating extracellular vesicles (EVs) are raising considerable interest as a non-invasive diagnostic tool, as they are easily detectable in biologic fluids and contain a specific set of nucleic acids, proteins, and lipids reflecting pathophysiologic conditions. 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.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.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 < 0.001). Among EV surface markers, CD3, CD2, ROR1, SSEA-4, human leukocyte antigen (HLA)-I, and CD41b were identified as discriminants between controls and acute cellular rejection, whereas HLA-II, CD326, CD19, CD25, CD20, ROR1, SSEA-4, HLA-I, and CD41b discriminated controls from patients with antibody-mediated rejection. Receiver operating characteristics curves confirmed a reliable diagnostic performance for each single marker (area under the curve range, 0.727-0.939). According to differential EV-marker expression, a diagnostic model was built and validated in an external cohort of patients. Our model was able to distinguish patients undergoing rejection from those without rejection. The accuracy at validation in an independent external cohort reached 86.5%. Its application for patient management has the potential to reduce the number of EMBs. Further studies in a higher number of patients are required to validate this approach for clinical purposes.Circulating EVs are highly promising as a new tool to characterize cardiac allograft rejection and to be complementary to EMB monitoring.