We remember that, at first, it was the severe respiratory symptoms that received the most attention among the effects of the COVID-19 disease. However, many teams subsequently became interested in the vascular and neurological effects of the disease *, thus highlighting the possible brain complications of the disease. Among these effects, the particular incidence of stroke was noted, especially in young patients without known risk factors. However, to this day, it is still unclear how the virus increases the risk of stroke.
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Reproduce intracranial atherosclerosis to understand the underlying process
To carry out this study, Californian scientists pass a fluid enriched with a COVID-19-type protein through a 3D printed model of the arteries of a patient who had just suffered a stroke – in order to best reproduce the forces generated by blood pushing through an abnormally narrow artery, a condition called intracranial atherosclerosis. They show that when these forces act on the cells lining the artery, they increase the production of a molecule called angiotensin-converting enzyme 2, or ACE2, which the coronavirus uses to enter cells on the surface of the artery. blood vessels.
Blood flow directly influences the expression of ACE2: Dr. Jason Hinman, professor of neurology at the David Geffen School of Medicine at UCLA and lead author of the study explains that to confirm that the coronavirus “floating” in the bloodstream could cling to ACE2 on endothelial cells in the brain, the team has developed “model viruses” made up of fatty molecules packed with advanced proteins that the coronavirus uses to bind to ACE2. The researchers then confirmed that the particles do interact with cells lining the blood vessel, mainly in regions of the brain with higher levels of ACE2.
“This is a first explanation for the increased incidence of stroke observed with COVID-19”.
Identify the COVID-19 patients most at risk for stroke: when scientists look at which genes are turned on in endothelial cells after spike protein binding they find that these genes make up a specific set of immune response genes that are found in the cells of the brain’s blood vessels, but not in the cells of the brain. endothelial cells from other organs in the body.
“There is a unique brain endothelial response to the virus that may be a marker for this elevated risk of stroke in COVID-19 patients.”
Follow-up studies using a coronavirus living in the 3D printed blood vessel model should confirm these results.
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