Pulmonary Artery Vasa Vasorum Damage in Severe COVID-19–Induced Pulmonary Fibrosis

COVID-19 patients exhibit higher incidence of thrombosis in arteries and veins, including those in lungs. Vasa vasorum, which support large blood vessels, have shown involvement in these pathologic processes. To further explore the extent of microvascular damage caused by COVID-19 infection, we examined resected main, right, or left pulmonary artery specimens from patients undergoing bilateral lung transplantation for COVID-19– or non–COVID-19–induced pulmonary fibrosis compared with organ donors by histologic and immunohistologic analyses. Vasa vasorum density was found to be higher in specimens procured from patients with COVID-19 and associated with pulmonary artery hypertension compared with lung transplant donors. In addition, we found immunothrombosis within vasa vasorum in specimens from COVID-19 patients with more immune infiltration, including CD15+, CD44+, and CD68+ cells. These findings reveal that COVID-19 affects the vasa vasorum of pulmonary arteries and suggest that infection may lead to large-vessel dysfunction and organ failure.