EXTRACELLULAR VESICLES ISOLATED FROM THE PLASMA OF COVID-19 AND SEPSIS PATIENTS: CHARACTERIZATION AND ASSOCIATION WITH CLINICAL OUTCOMES

Abstract

BACKGROUND Extracellular Vesicles (EVs) are involved in the pathogenesis of SARS-CoV-2 infection. OBJECTIVE We analysed the concentration, size, cellular origin, and capacity for carrying viral components in plasma samples from patients with COVID-19 and sepsis. METHODS Plasma samples from COVID-19 patients admitted to the ICU with sepsis (N=42) and healthy individuals (N=19) were analysed. EVs were characterized by size and concentration using NTA, RT-qPCR for SARS-CoV-2 components, and flow cytometry for immunophenotyping. EVs were marked with phosphatidylserine, tetraspanins, and cellular origin markers for neutrophils, endothelial cells, T lymphocytes, and platelets. Cryo-EM was used to assess EV size and integrity. RESULTS: NTA showed an increased concentration of microparticles in patients. RT-qPCR analysis of EVs detected the virus in 14 samples, two of which were consistent with the Gamma variant. Extracellular vesicles (EVs) predominantly derived from T cells and platelets, with increased CD81 expression in individuals who died. Cryo-EM revealed extracellular vesicles with an average size of 200 nm. CONCLUSIONS: Our findings suggest that patients' extracellular vesicles likely harbour viral components, suggesting their potential role as carriers of SARS-CoV-2, and that extracellular vesicles from deceased patients demonstrate elevated CD81 expression.