Some of the earliest insights into how COVID-19 can act like a vascular disease came from studying the aftermath of the most serious infections. Those reveal that the virus warps a critical piece of our vascular infrastructure: the single layer of cells lining the inside of every blood vessel, known as the endothelial cells or simply the endothelium.
Dr. William Li, a vascular biologist, compares this lining to a freshly resurfaced ice rink before a hockey game on which the players and pucks glide smoothly along.
“When the virus damages the inside of the blood vessel and shreds the lining, that’s like the ice after a hockey game,” said Li.
In a study published this summer, Li and an international team of researchers compared the lung tissues of people who died of COVID-19 with those of people who died of influenza. They found stark differences: The lung tissues of the COVID victims had nine times as many tiny blood clots (“microthrombi”) as those of the influenza victims, and the coronavirus-infected lungs also exhibited “severe endothelial injury.”
“The surprise was that this respiratory virus makes a beeline for the cells lining blood vessels, filling them up like a gumball machine and shredding the cell from the inside out,” Li said.