Doctors are hoping stem cell therapy could be a weapon in the fight against coronavirus. On Friday, regenerative medicine company Mesoblast announced a 300-person trial to determine whether stem cell treatments will work in COVID-19 patients suffering from severe lung inflammation.

One hospital in New York tried it as an experiment with 12 patients, 10 of whom were able to come off of ventilators.

"What we saw in the very first patient was that within four hours of getting the cells, a lot of her parameters started to get better," Dr. Karen Osman, who led the team at Mount Sinai, told CBS News' Adriana Diaz.

The doctor said she was encouraged by the results, though she was hesitant to link the stem cell procedure to her patients' recovery.

"We don't know" if the 10 people removed from ventilators would not have gotten had they not gotten the stem cells, she said. "And we would never dare to claim that it was related to the cells."

She explained that only a "randomized controlled trial" would be the only way "to make a true comparison."

Luis Naranjo, a 60-year-old COVID-19 survivor, was one of Mount Sinai's stem cell trial success stories. He told Diaz in Spanish that he was feeling "much better."

Naranjo's daughter, Paola, brought him to the emergency room, fearful she would not see her father again. Like so many families struck by the coronavirus, she was not allowed inside with him.

"I forgot to tell him that I love him," she said. "All I said was go inside, I hope you feel better."

During his hospital stay, Naranjo was unconscious and on a ventilator for 14 days.

Doctors proposed giving him stem cells from bone marrow in hopes it would suppress the severe lung inflammation caused by the virus.

Now, Naranjo credits the doctors who treated him for his survival. Though income from his family's jewelry business has been cut off and they found themselves falling behind on rent, Naranjo said he is focused primarily on his recovery and regaining the 25 pounds he lost at the hospital.

Although stem cell treatment, usually reserved for other diseases like rheumatoid arthritis, might end up being another step toward helping coronavirus patients recover, Dr. Osman was quick to say it would not be a "miracle treatment."

"The miracle treatment will be a vaccine," she said.

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Doctors experiment with unproven stem cell therapy on COVID-19 patients - CBS News