Injury of vascular endothelium and erythrocytes in COVID-19 patients

Abstract

Aim. Caused by SARS-CoV2 virus coronavirus disease (COVID-19) is characterized not only by the lung deterioration but be serious injury of vascular endothelium and system of hemostasis. We investigated changes in blood cellular elements in patients at admission and discharge from the hospital. Materials and methods. Samples of venous blood of 31 patients of the hospital with a confirmed diagnosis of COVID-19 (28 with average and 3 with severe degree) were analyzed using electron microscopy and citofloumetry. The blood was taken from cubital vein at admission and on discharge the patients. Results. Electron microscopy showed that at admission to the hospital the number of circulating endothelial cells in all patients was significantly (40–100 times) greater compared to healthy persons. Numerous fenestrae are revealed in EC membrane. Their diameter comparable to the size of supercapsid in SARS-CoV-2 virus which attests the penetration of the virus into EC where it replicated and returned to circulation. As a result, the blood vessels denuded, their permeability increased resulting in tissue edema, inflammation, activation of the platelets, and pronouncedly augmented thrombosis. Infection with COVID-19 provoked formation of stacked (aggregated) red blood cells capable to clog microvascular bed and to diminish oxygen supply to the tissues. In some patients, such abnormalities persisted even on discharge from the hospital Conclusion. Analysis of the blood on discharge from the hospital showed that despite normalization of basic hematological parameters characteristic of inflammation, the virus-induced negative effects were not entirely eliminated. These sequelae can provoke the post-COVID syndrome in patients who endured COVID-19.