The primary target of SARS-CoV-2 is the epithelial cells of the lung (1), through the Angiotensin Converting Enzyme-2 (ACE-II) receptor, which is also expressed on endothelial cells (ECs) (2). Recent evidence suggest SARS-CoV-2 directly infect endothelial cells and cause diffuse endothelial inflammation (3).
SARS-CoV-2 is thus directly targeting both components of the ephitelial-endothelial barrier.
The damaged and/or activated endothelium could contribute to a pro-inflammatory cascade, which perpetuates and amplifies lung damage and respiratory distress and could lead to the most severe complication represented by Acute Respiratory Distress Syndrome (ARDS).
Although the major clinical manifestations of COVID-19 are respiratory symptoms, publications are reporting that, in a number of patients there are associated cardiovascular complications (4, 5) and these can lead to acute myocardial injury and chronic damage to the cardiovascular system .
Endothelial damage and consequent clotting is reported to be common in severe COVID-19 by Chinese Clinicians (6) and it is suggested that COVID-19- endotheliitis could explain the systemic impaired microcirculatory function in different vascular beds (3) and may have implications for treatment.
Circulating Endothelial Cells (CECs) are a specific and sensitive marker of endothelial damage in a variety of pathological conditions and an increase in the CEC count has been reported to be linked to cardio-vascular events (7-14).
The CEC count may resemble the pulmonary and systemic endothelial damage and an increase in the CEC count may predict the extent of pro-inflammatory cascade activation.
Hence, the CEC count could become a potential biomarker for the risk of activation of the coagulation cascade, cardio vascular events and the onset of severe respiratory distress during SARS-CoV-2 infection.
The CELLSEARCH system enables the enrichment and enumeration of rare cell types — from circulating tumor cells (CTCs) to circulating endothelial cells from blood. The system is based on ferrofluid technology which allows the immune-magnetic capture of rare cells in the whole blood.
The CELLSEARCH platform, in combination with the CELLSEARCH Circulating Endothelial Cell Kit*, is able to enumerate CECs by immuno-magnetically capturing CD146-positive cells. The technology has been extensively validated in different settings, such as cardiovascular, neoplastic and autoimmune diseases (10-14).