Trapped in the microclots






Researchers analyzed the protein content of microclots from long covid and from healthy controls. The study was published in a BMC journal Sept. 2022.

So what did they find that was different about the microclots?

The researchers found that clots in long Covid patients had increased von Willebrand factor, increased platelet factor 4, and “a significant presence of antibodies entrapped inside these microclots.”

The researchers found that the long Covid patients had “significant fibrin amyloid microclot load in their circulation and that these persistent microclots are resistant to fibrinolysis.”

Some background — von Willebrand factor (VWF) is a clotting molecule that gets activated when the endothelial cells (lining of blood vessels) are injured. For example: you cut yourself while making dinner, and collagen is exposed in the damaged blood vessels. Von Willebrand factor binds to the damage and activates platelets — blocking the bleeding.

Platelet factor 4 is another part of the clotting cascade. It is released by activated platelets and binds with heparin in the endothelium.

The other proteins involved were also clotting proteins and immune response proteins.

Important here is also what the research discovered as far as things that were not different from the control group. For example, there was no correlation between previously having hypertension or having high cholesterol and getting long Covid. Ferritin (storage marker for iron) also didn’t differ between long Covid patients and the healthy control group.


Kruger, Arneaux, et al. “Proteomics of Fibrin Amyloid Microclots in Long COVID/Post-Acute Sequelae of COVID-19 (PASC) Shows Many Entrapped pro-Inflammatory Molecules That May Also Contribute to a Failed Fibrinolytic System.” Cardiovascular Diabetology, vol. 21, Sept. 2022, p. 190. PubMed Central,

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