LOS ANGELES (CBSLA) – A case series on a new experimental treatment from researchers at Cedars-Sinai Medical Center points to an infusion of human heart tissue cells as a possible anti-inflammatory treatment for coronavirus patients.

Four of six patients who were critically ill with COVID-19 recovered after receiving an infusion of cells designed to reduce inflammation, according to a news release Tuesday from the hospital.

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The six patients received an infusion of a therapeutic called CAP-1002, which is made up of laboratory-grown cells from human heart tissues, known as cardiosphere-derived cells, or CDCs.

Of the six patients who received CAP-1002 infusions, five were on ventilators. Within four days of receiving the infusions, four of the five patients were able to be pulled off the ventilators and breath on their own, Cedars-Sinai said.

And by April 28, within three weeks of receiving the treatment, four of the patients had recovered enough to be released from Cedars-Sinai.

The other two remain in the ICU.

“None of the patients showed adverse effects from the infusions, and none died during the study period,” the hospital said.

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The immune systems for some critically ill coronavirus patients will overreact, what is known as a “cytokine storm,” in which the immune system begins to attack health organs and cause them to shut down. Anti-inflammatory treatments are designed to combat that.

“‘Friendly fire’ is what’s killing many coronavirus patients,” said Dr. Eduardo Marbán, executive director of the Smidt Heart Institute at Cedars-Sinai and a co-author of the study, in a statement. “The immune system unleashes a so-called cytokine storm into the blood, overwhelming the body with infection-fighting proteins that can trigger multiple-organ failure and death.”

The results of the study were published in the scientific journal Basic Research in Cardiology. Before the treatment could receive FDA approval, it would need to go through a clinical trial.

Last week, Children’s Hospital Los Angeles confirmed that at least three children being treated there were diagnosed with a mysterious new inflammatory condition which has been linked to coronavirus.

Pediatric Inflammatory Multisystem Syndrome (PIMS) is a condition which displays similar symptoms to Kawasaki disease, a very rare condition among young children in which the blood vessels become inflamed and arteries become abnormally dilated.

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According to CHLA, children diagnosed with PIMS have not presented symptoms associated with COVID-19, but all of them tested positive for the virus or the antibodies.