Pulmonary blood vessels have played an important role in the process of infection with SARS-CoV-2 virus. This important research will contribute to the development of COVID-19.
The medical journal of The New England Journal Medicine (USA) has published the research of pathologists and lung pathologists in Germany (Wuppertal, Mainz, Hanover), Belgium (Louvain), Switzerland (Bâle) and the USA (Harvard Medical University).
Compare the lungs of the corpse
The researchers compared seven lungs taken from the bodies of COVID-19-infected patients with seven lungs of patients who died in 2009 from H1N1 pneumonia and 10 healthy lungs without disease. control sample.
Many advanced techniques are used for lung analysis such as immunohistochemistry (combining chemicals with immune responses to find diseased cells in patient tissue), scanning electron microscopes, making network copies blood vessel.
Observation results showed that all lungs of patients with COVID-19 and H1N1 flu showed signs of diffuse damage in the alveoli, especially necrosis of small cells around the alveoli and fibers. fibrin in alveolar cavity.
In addition, CD4 + T lymphocytes near the pulmonary vessels were also infected in the two groups of patients with a higher number in the COVID-19 patient group.
Phenomenon of blood vessel formation
Examining the structure of the pulmonary vessels, the researchers found that the blood vessel network was deformed with distorted capillaries.
In COVID-19’s lungs, the capillaries have abruptly changed in size.
In particular, researchers found many new blood vessels. This phenomenon is called angiogenesis.
Usually angiogenesis occurs when endothelial cells proliferate from the head and walls of existing blood vessels and move and assemble into tubular structures connected to neighboring vessels.
But in the lungs of COVID-19 patients, the researchers found that angiogenesis forms a second pattern. It is angiogenesis by rearranging existing blood vessel structure.
The researchers found that the degree of angiogenesis increased significantly in accordance with length of hospital stay in COVID-19 patients.
In contrast, in the lungs of patients with H1N1 influenza, the phenomenon of angiogenesis occurs with a negligible level and does not increase with time of hospitalization.
Endothelial cell damage
Another observation is that for patients with COVID-19 infection, the cells lining the inner lining of the blood vessels and direct contact with the blood were severely damaged.
The researchers observed that the number of COVID-19 patients had a higher number of cells carrying ACE2 receptors on the surface (acting as the entry point of SARS-CoV-2 virus) than those with influenza. H1N1.
Similarly, endothelial cells in COVID-19 patients are no longer tightly bound together by joints.
They increase in mass and lose contact with the basement that they normally attach to.
In addition, researchers observed SARS-CoV-2 virus inside lung endothelial cells as well as in extracellular space.
The results of this observation coincide with the study of Swiss scientists published in late April 2020.
Research shows that the virus is present in endothelial cells in the kidney and small intestine.
Thus damaged lung endothelial cells may be the direct result of the SARS-CoV-2 virus and inflamed cells in the blood vessels.
This finding demonstrates the central role of endothelial cells in COVID-19 disease.
The blood clots in alveolar capillaries
In the lungs of two groups of patients COVID-19 and H1N1 flu patients have small blood clots in the pulmonary artery (1-2 mm in diameter) but do not block the block completely.
The researchers observed that the number of small blood clots in the alveolar capillaries of COVID19 patients was 9 times more than those of H1N1 flu.
Small blood clots are also found in daughter veins after capillaries less than 1mm in diameter.
Finally, the researchers analyzed 323 genes involved in angiogenesis. Results showed that only 69 genes were expressed in the lung tissue of COVID-19 patients.
The above study emphasizes the importance of autopsy work to accurately describe and further analyze the COVID-19-related injuries.
The study further clarified the inflammatory lesions of endothelial lung cells and their role in the formation of new blood clots and blood vessels.
Related studies of endothelial cells may promote the development of a COVID-19 treatment strategy.