Infections with the coronavirus are often mild or even symptom-free. On the other hand, some patients develop severe symptoms and may even die from them. Researchers have now looked for molecular fingerprints in the blood which are able to indicate a more severe course of the disease early on.
Taking a closer look at blood from COVID-19 patients
An international team of researchers has identified certain cell types in the blood that indicate more severe disease courses of COVID-19. They discovered a particularly large number of immature cells that are normally found in the bone marrow, but which are also washed into the blood in the event of blood poisoning. These are so-called megakaryocytes, precursor cells of blood platelets, which ensure that the blood clots. "This is particularly surprising because these precursor cells are not normally found in the blood, but in the bone marrow, "explains Florian Tran, who conducts research at the Institute for Clinical Molecular Biology at the University of Kiel. "We know of such precursor cells in the blood of seriously ill patients , for example in bacterial sepsis". However, no such extravasation of megakaryocytes has yet been reported for COVID-19. The researchers now suspect that these cells may lead to blood clotting problems - an interesting thesis given that blood clots in the lungs are one of the most common direct causes of death in COVID-19 patients.
A molecular fingerprint for COVID-19 severe outcomes
To this end, the researchers took multiple blood samples at different times of disease progression from patients who were hospitalized at the University Hospitals in Kiel, Bonn, Cologne and Nijmegen. Blood samples from healthy subjects were used as a comparison. "The special thing is that with the help of so-called single cell genomics we have been able to analyze hundreds of thousands of cells in parallel by sequencing. This has enabled us to also identify rarer cell types," explains Dr. Joana Pimenta Bernardes from the Institute of Clinical Molecular Biology at Kiel University. "Together with other data, such as clinical laboratory values and measurements of inflammatory messengers, we were able to create a kind of fingerprint, a signature of the changed function of these cells, and track it over time". The researchers have published their results in the journal Immunity. According to the scientists, the study could form the basis for diagnostic test procedures that use blood samples to detect severe disease at an early stage. This could specifically improve the care of particularly severely affected patients.