Non-Invasive Blood Test Uses Cell-Free DNA to Tracks Organ Injury from COVID-19

For several years, the research team has been exploring the biomedical applications of cell-free DNA - dead fragments of DNA that drift around the bloodstream and urine. The fragments are relatively easy to collect via the body’s plasma. By profiling the DNA molecules and logging the occurrence of methylation marks - a chemical modification that results from the expression of different genes - the researchers can follow the fragments, much like trail of breadcrumbs, back to the source of injury or infection.

In 2019, they developed a test that used the technique to identify the presence of urinary tract infections in kidney transplant patients while also quantifying the degree of damage to the kidney and bladder. As the COVID-19 pandemic emerged, the researchers realized their test could help search out and quantify the impact of COVID-19 on patients’ lungs and other organs and tissues. The researchers then profiled 104 plasma samples from 33 COVID-19 patients, then compared the results with patients who had other viral infections, as well as healthy controls. As expected, they found evidence of injury to the lungs, as well as the liver. More surprisingly, they noted an increase in DNA from red blood cell progenitors and found that a high concentration of cell-free DNA in the blood was itself a strong prognostic marker for severe COVID-19 cases.

“A lot of what we’ve learned about the involvement of the virus with different organs is from invasive biopsies, postmortem biopsies,” said corresponding author Iwijn De Vlaminck, an assistant professor in the Meinig School of Biomedical Engineering. “But a liquid biopsy is potentially very useful as a biological measurement, a way to study what is going on in patients who have different types of symptoms, for example.

“It could be used to assess disease severity and help stratify patients in the care system,” De Vlaminck added. “It could also potentially be a surrogate biomarker that you could include in randomized controlled trials of various anti-COVID therapies and anti-virals.”

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