Endothelial progenitor cells in pathogenesis of new coronaviral infection

Pulmonary vascular endothelium dysfunction is one of the main pathogenic factors responsible for many clinical manifestations of the severe course of COVID-19. Circulating endothelial progenitor cells (EPCs) are the endogenous regenerative reserve that maintains the integrity of the vascular endothelium and its restoration in case of damage by pathogenic factors. A decrease in the circulating EPCs is regarded as a predictor of morbidity and mortality in conditions associated with development of endothelial dysfunction, including COVID-19. The exact phenotype of progenitor cells capable of differentiating into endothelial cells has not been determined. In most laboratories antigens CD133+, CD34+, VEGFR-2+ (CD 309) or combination of these are used to identify EPCs. The process of EPCs mobilization and migration is controlled by molecular signals from immune cells located in the damage area. Stromal cell factor 1 (SDF-1), produced by the bone marrow and many other tissues, is an important chemoattractant for EPCs which express its receptors. The results of studies carried out in 2020 indicate that SARS-Cov-2 infects both hematopoietic stem cells, transforming into EPCs, and directly circulating EPCs, causing inflammatory and procoagulant reactions that complicate the COVID-19 course. There is no consensus on the mechanism of EPCs infection with coronavirus – directly through the expression of angiotensin-converting enzyme (ACE2) receptor or through an ACE2-independent mechanism. Today there is no effective therapy for COVID-19. The use of the EPCs regenerative potential, and the search for ways to enhance the EPCs mobilization from the depot, and increase their functional activity may become a promising approach to the prevention of severe complications and mortality from COVID-19