Microvessels-on-chip: Exploring endothelial cells and COVID-19 plasma interaction with nitric oxide metabolites.

COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), primarily manifests as a flu-like illness with lung injury, often necessitating supplemental oxygen. Elderly individuals and those with pre-existing cardiovascular diseases are at increased risk of mortality. The endothelial barrier disruption observed in patients indicates systemic viral invasion and widespread endotheliitis. Endothelial dysfunction, characterized by impaired nitric oxide (NO) production, contributes to vasoconstriction, inflammation, and coagulation abnormalities seen in COVID-19. In this study, we investigated the impact of COVID-19 patient-derived plasma on the endothelium through NO metabolite analysis using an in vitro 3D micro vessel model. Our experiments revealed alterations in NO metabolites in response to COVID-19 patient plasma perfusion, with BH4+BH2 supplementation improving citrulline levels in severe COVID-19 patient models. Positive correlation between arginase activity and eNOS activity was observed in the severe COVID-19 patient model but not in the mild COVID-19 patient model. These findings underscore the importance of endothelial dysfunction in COVID-19 pathogenesis and highlight potential therapeutic targets for mitigating vascular complications associated with severe infection.