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September 8, 2020

How the coronavirus causes 'carnage' in the heart

Daily Briefing

    New research shows that the novel coronavirus can essentially dice the muscle fibers of the human heart into pieces, sparking concerns about the potential for heart failure among Covid-19 survivors, Elizabeth Cooney reports for STAT News.

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    Study details

    For the study, which was published preprint on bioRxiv and has not yet been peer reviewed, researchers added the new coronavirus, SARS-CoV-2, to three types of human heart cells—cardiomyocytes, cardiac fibroblasts, and endothelial cells—that were grown in lab dishes from stem cells.

    Only the cardiomyocytes, which are muscle cells, showed indication of viral infection that spread to other muscle cells, the researchers said. However, what they found in the infected cells was remarkable: The sarcomeres, which are the long muscle fibers that keep the heart beating, had been sliced into small bits. According to the researchers, the fibers looked as if they had been surgically sliced.

    The researchers also found black holes where DNA was supposed to be in the nucleus of the infected cells. The researchers said they found similar, but not identical, changes when they observed autopsy specimens from patients with Covid-19, the disease caused by the novel coronavirus.

    'Carnage' like no other

    It's unclear whether the heart is able to reassemble the sarcomeres after they're severed, but that might be possible after the coronavirus infection clears, the researchers said. However, the researchers said they felt an urgency to share their results as quickly as possible, because their findings may help to further scientists' understanding of how the coronavirus causes heart damages—and possibly how to prevent or treat the injuries.

    "When we saw this disruption in those microfibers … that was when we made the decision to pull the trigger and put out this preprint," Todd McDevitt, a senior investigator at Gladstone Institutes and a co-author of the study, said. "I'm not a scientist who likes to stoke these things [but] I did not sleep, honestly, while we were finishing this paper and putting it out there."

    Bruce Conklin, also a senior investigator at Gladstone and a co-author of the study, said the virus caused "carnage in the human cells" unlike anything seen with other diseases. "Nothing that we see in the published literature is like this in terms of this exact cutting and precise dicing," he explained.

    Conklin said the findings should alter the way providers and scientists think about the novel coronavirus and Covid-19. "We should think about this as not only a pulmonary disease, but also potentially a cardiac one."

    Gregg Fonarow, interim chief of the UCLA Division of Cardiology and director of the Ahmanson-UCLA Cardiomyopathy Center, said the study is "really important and elegant work, helping to define the potential mechanisms by which SARS-CoV-2 is leading to the observed heart damage and clinical manifestations."

    Sahil Parikh, an interventional cardiologist at Columbia University Irving Medical Center, called findings "provocative," but added, "[t]he challenge here is that this paper has not been peer-reviewed by people who are experts in cardiology, who have not had a chance to tear it apart." She said, "I am reluctant to make a lot out of a pre-publication manuscript, no matter how provocative the finding."

    The researchers who worked on the study agreed that their work should be reviewed, and they've submitted the study to a leading scientific journal (Cooney, STAT News, 9/4).

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