New research published in the New England Journal of Medicine shows that the respiratory virus SARS-CoV-2, which causes COVID-19, causes severe damage to blood vessels, leading to widespread thrombosis, a press release by the Angiogenesis Foundation reports.
The study was conducted by an international team of medical scientists who compared the lungs of patients who died from COVID-19 with lungs of patients who died from influenza as well as with healthy lungs donated for transplantation.
The researchers discovered an unexpected disease pattern in COVID-19 lungs: the virus invaded the endothelial cells, and this was accompanied by blood clots. Compared to the flu, COVID-19 lungs had 9-fold more blood clots and the blood vessels were injured by the virus causing an unusual reaction of blood vessel growth.
One of the great mysteries of COVID-19 has been why blood clots, or thrombosis, form in some patients who are infected. These clots can become lethal because they severely compromise blood flow not only in the lungs, but also in other organs such as the brain and heart, among other tissues.
This research is the first to show that these clots are associated with damaged blood vessels. The damage causes a unique healing reaction called intussusceptive angiogenesis that was found in COVID-19 at levels 30-times above normal. In the NEJM study, the researchers found an association between the more intussusceptive angiogenesis present, the longer the hospital stay of the patient suggesting that severity of COVID-19 disease is linked to blood vessel damage. Intense inflammation was also found in all COVID-19 lungs.
The injured blood vessel lining helps to explain the serious blood clotting observed in patients. This damage may also underlie other problems seen with COVID-19, such as stroke, deep vein thrombosis, COVID toe, and damage to the heart, and also explain why anticoagulation may be helpful in preventing serious complications.
Link to the paper: https://doi.org/10.1056/NEJMoa2015432
Editorial Disclaimer: information published during the 2020 COVID-19 pandemic may be updated frequently to reflect the dynamic nature of current understanding.