Investigation of electron microscopic equivalents of the neocortex vessels endothelium secretory activity of Syrian hamsters in the dynamics of SARS-CoV-2 infection

Abstract

Background. Hypercoagulation, changes in the functional state of endothelium and systemic microcirculation dysfunction play a leading role in the pathogenesis of coronavirus infection caused by SARS-CoV-2 (COVID-19). Taking into account the risk of cerebrovascular complications of COVID-19 in the acute period, as well as in post-COVID-19 syndrome, studies of ultrastructural changes in cerebral vessels are of particular importance for expanding knowledge about the pathogenesis of COVID-19-associated endothelial pathology and developing approaches to its pharmacological correction. The morphological equivalent of studying the vascular endothelium secretory activity can be the structural kinetics of Weibel-Palade bodies, organelles unique to endotheliocytes, the exocytosis of which determines the conditions of thrombosis.

The aim is to electron microscopic study the kinetics of Weibel–Palade body’s structure in the endothelium of the neocortex vessels of Syrian hamsters in the dynamics of SARS-CoV-2 infection.

Materials and methods. The experimental model was reproduced by intranasal administration to Syrian hamsters of a virus culture containing SARS-CoV-2 in an amount of 4 × 10⁴ TCD₅₀/ml. On days 3, 7, 14 and 28 after infection animals were euthanized with subsequent selection of neocortex tissue. The study of the material was carried out by transmission electron microscopy.

Results. The kinetics of accumulation and release of the secretion of Weibel-Palade bodies in the endothelium of the neocortex vessels of Syrian hamsters on an experimental model of SARS-CoV-2 infection was traced. It was found that secretory activity of neocortical vascular endotheliocytes in animals increases in the period 3–7 days after infection in the form of exocytosis of Weibel-Palade bodies. The revealed ultrastructural changes of the endothelium in experimental animals persist up to 28 days of the infectious process.

Conclusion. The results of electron microscopic examination of the neocortex vessels endothelium secretory activity of Syrian hamsters in the dynamics of SARS-CoV-2 infection allowed us to determine the risks of vascular catastrophes both in the acute and convalescent (28 days) periods of disease. The results obtained are significant for expanding knowledge about the pathogenesis of endothelial dysfunction, which determines the likelihood of cerebrovascular complications during critical periods of COVID-19, which is of particular importance when conducting research aimed at developing and studying new therapies for this pathology.