Three years into the COVID-19 pandemic, the mechanisms behind the virus’s severe disease and multi-organ damage still puzzle scientists.
Recently, a multidisciplinary team from Emory University has shed new light on how COVID-19 inflicts widespread damage beyond the lungs, focusing on the dysfunction of blood vessels.
The Discovery
Published in Nature Communications, the research reveals that COVID-19 damages the cells lining the smallest blood vessels, resulting in reduced blood flow.
This vital discovery could lead to the development of new treatments to help save lives, particularly important as hundreds continue to die from COVID-19 each day.
The Study
The study was initiated early in the pandemic, seeking to understand why adults develop severe COVID-19 disease more frequently than children.
The research team used a “multi-omics” approach to analyze multiple data sets simultaneously, comparing the biochemistry of blood from COVID patients and non-COVID patients.
Unique Pathway in Adults
Surprisingly, the team found little overlap between adult and pediatric patients. Both groups exhibited abnormalities related to clotting, but one unique pathway stood out in adults, associated with blood vessel health and blood flow.
This finding was particularly interesting as blood from patients severely ill with COVID-19 was unusually viscous.
Studying the Smallest Blood Vessels
The researchers created models of the smallest blood vessels, which are expected to be the most sensitive to altered blood flow.
This allowed them to visualize how blood from COVID-19 patients versus other patients might be flowing in the human body.
These lab-made blood vessels, lined with real human vascular cells, provided a real-time view of how COVID-19 might be affecting our blood vessels.
Fibrinogen: A Key Culprit?
Physicians have noticed elevated levels of a blood protein called fibrinogen in patients with severe COVID-19 since the early days of the pandemic.
The Emory researchers discovered that extremely high fibrinogen levels cause red blood cells to clump together, altering blood flow and damaging a protective layer lining the microvessels.
Red Blood Cells Clumping Together
The researchers could visualize how red blood cells clump together and damage the microvessels when they combined plasma from COVID-19 patients with red blood cells in lab-made blood vessels.
Normally, capillaries are so narrow that red blood cells must pass through single file. But in COVID-19, these cell aggregates stick together even underflow, causing mechanical damage to the microvasculature.
Therapeutic Implications
This damage could be the major pathway by which COVID-19 causes organ damage and even death. Currently, no medications target high fibrinogen in the blood.
However, the team has done exploratory research using therapeutic plasma exchange, removing plasma with high fibrinogen from COVID-19 patients, and replacing it with donor plasma that has normal fibrinogen levels.
This discovery offers a promising target that might help save lives in the future.
If you care about COVID, please read studies about new evidence on rare blood clots after COVID-19 vaccination, and how diets could help manage post-COVID syndrome.
For more information about COVID, please see recent studies that low-sodium plant-based diets may prevent COVID-19 better, and results showing zinc could help reduce COVID-19 infection risk.
The study was published in Nature Communications.
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