German 
New research shows that overloading various inflammatory molecules literally “trapped” in insoluble microscopic blood clots (micro-clots) could be the cause of some of the persistent symptoms individuals with Long COVID experience.
This unexpected finding was made by Prof. Resia Pretorius, a researcher at the Institute of Physiological Sciences at Stellenbosch University (SU), when she started studying microclots and their molecular content in blood samples from people with Long COVID. The results have since been peer-reviewed and published in the journal Cardiovascular Diabetology in August 2021.
“We found high levels of various inflammatory molecules trapped in micro-clots that are present in the blood of people with Long COVID. Some of the trapped molecules contain coagulation proteins such as fibrinogen and alpha (2) antiplasmin, ”explains Prof. Pretorius.
Alpha (2) antiplasmin is a molecule that prevents blood clots from breaking down, while fibrinogen is the main clotting protein. Under normal conditions, the body’s plasmin-antiplasmin system maintains a fine balance between clotting (the process by which blood thickens and coagulates to prevent blood loss after an injury) and fibrinolysis (the process of breaking down fibrin in the coagulated Blood to prevent blood clots from forming).
With high levels of alpha (2) antiplasmin in the blood of COVID-19 patients and those suffering from Long COVID, the body’s ability to break down the clots is significantly inhibited.
The insolubility of the micro-clots became apparent when Dr. Maré Vlok, a senior analyst in the mass spectrometry unit of the SU central analytical facilities, noted that after dilution, blood plasma samples from those with Acute COVID and Long COVID continued to deposit insoluble pellets at the bottom of the tubes
He alerted Prof. Pretorius to this observation and investigated it further. They are now the first research group to report on finding microclots in the blood samples of people with Long COVID by using fluorescence microscopy and proteomic analysis, solving another mystery related to the disease.
Of particular interest is the simultaneous presence of persistent abnormal micro-clots and a pathological fibrinolytic system, ”they write in the research paper. This means that the plasmin and antiplasmin balance may be central to pathologies in Long COVID, and provides further evidence that COVID-19 and now Long COVID have significant cardiovascular and coagulation pathologies.
Further research into a therapy regimen to support coagulation and fibrinolytic system function in individuals with persistent long-term COVID symptoms is recommended.
In cooperation with the vascular internist Dr. Jaco Laubscher from Mediclinic Stellenbosch (co-author of the article) they are now planning to carry out the same analysis on a larger patient sample. To date, they have collected blood from a hundred Long COVID people who participated in the Long COVID Register, which was launched in May 2021, as well as from 30 healthy people. The research is funded by the Long COVID Research Charitable Trust, a trust established with an initial donation from Mr Koos Pretorius of ENSafrica. It is intended that this trust will be used as a vehicle to raise further funds for research into the causes and effective treatment of people with Long COVID.
The article “Persistent coagulation protein pathology in long COVID / post-acute sequelae of COVID-19 (PASC) is accompanied by increased antiplasmin levels” was published in August 2021 in cardiovascular diabetology and is online at https://pubmed.ncbi.nlm.nih.gov /34425843/ available.