Since mid February, one approach that has gained increasing traction is stem cell therapies, treatments that have often been viewed as a potential panacea by desperate patients suffering from degenerative incurable conditions ranging from Parkinson's to ALS. In many of these diseases, reality has yet to match the hype.
In COVID-19, there are hopes it might, though some experts are warning not to count on it. At Beijing's YouAn Hospital, doctors have been treating patients at various stages of the illness with intravenous infusions of so-called mesenchymal stem cells taken from umbilical cord tissue, as part of an ongoing clinical trial since January 21. The outcomes of the initial seven patients – published last month – appeared promising and the trial has since been expanded to 31 patients according to Dr. Kunlin Jin, a researcher at University of North Texas Health Science Center who is collaborating with the doctors in Beijing.
"Sixteen of these patients had mild symptoms, eight are severe, and seven are critically severe," Jin told leapsmag. "But all patients have shown improvements in lung function following the treatment, based on CT scans -- most of them in the first three days and seven have now been completely discharged from hospital. This treatment is particularly aimed at older patients who are seriously ill. These kinds of patients are in the danger zone; it's essential that they receive treatment, but right now we have nothing for most of them. No drugs or anything."
The apparent success of the very small Beijing trial has since led to a nationwide initiative to fast-track stem cell therapies for COVID-19. Across China, there are currently 36 clinical trials intending to use mesenchymal stem cells to treat COVID-19 patients that are either in the planning or recruiting phases. The Chinese Medical Association has now issued guidelines to standardize stem cell treatment for COVID-19, while Zhang Xinmin, an official in China's Ministry of Science and Technology, revealed in a press conference last week that a stem cell-based drug has been approved for clinical trials.
The thinking behind why stem cells could be a fast-acting and effective treatment is due to the nature of COVID-19. The thousands of fatalities worldwide are not from the virus directly, but from a dysfunctional immune response to the infection. Patients die because their respiratory systems become overwhelmed by a storm of inflammatory molecules called cytokines, causing lung damage and failure. However, studies in mice have long shown that stem cells have anti-inflammatory properties with the ability to switch off such cytokine storms, reducing such virus-induced lung injuries.
"The therapy can inhibit the overactivation of the immune system and promote repair by improving the pulmonary microenvironment and improve lung function," explained Wei Hou, one of the doctors conducting the trial at YouAn Hospital.
However not everyone is convinced, citing the small number of patients treated to date, and potential risks from such therapy. "We just don't know enough to believe that stem cells might be helpful with COVID-19," said Paul Knoepfler, professor of cell biology at UC Davis. "The new stem cell studies are too small and lack controls, making it impossible to come to any solid conclusions. The chance of benefit is low based on the little we know so far and there are going to be risks that are hard to pin down. For instance, what if a stem cell infusion impairs some kind of needed immune response?"
Other scientists are even more skeptical. "I am concerned about all treatments that use mesenchymal stem cells," warned Jeanne Loring, the Director of the Center for Regenerative Medicine at Scripps Research in La Jolla, Calif. "There has been an enormous amount of hype about these cells, and there is scant scientific evidence that they have any therapeutic effect in any situation. Typically, these treatments are offered to people who have diseases without cures. I'm certain that there will be evidence-based treatments for COVID19, but I understand that they are not yet available, people are desperate, and they will try anything. I hope the sick are not taken advantage of because of their desperation."
Despite such concerns, the steadily rising death toll from COVID-19 means other nations are preparing to proceed with their own clinical trials of mesenchymal stem cells. Jin said he has been contacted by researchers and clinicians around the world seeking information on how to conduct their own trials, with the University of Cambridge's Stem Cell Institute in the U.K. reportedly looking to initiate a trial.
The scale of the global emergency has seen governments repeatedly calling on the corporate world to invest in the search for a cure, and the Australian company Mesoblast – a global leader in cell-based therapies for a range of diseases – are expecting to receive the green light to initiate clinical trials of their own stem cell based product against COVID-19.
"We're talking to at least three major governments," said Silviu Itescu, CEO and Managing Director of Mesoblast. "We are working with groups in Australia, the U.S. and the U.K., and I expect there'll be trials starting imminently in all those jurisdictions."
Itescu is bullish that the therapy has a good chance of proving effective, as it recently successfully completed Phase III trials for severe steroid-refractory acute graft versus host disease (GVHD) – a condition which leads to a very similar disease profile to COVID-19.
"The exact same cytokine profile is occurring in the lungs of COVID-19 infected patients as in GVHD which is destructive to the local lung environment," he said. "If our cells are able to target that in GVHD, they ought to be able to switch off the cytokine response in COVID lung disease as well."
Jin is hopeful that if the imminent trials yield successful results, the U.S. FDA could fast-track mesenchymal stem cells as an approved emergency therapy for COVID-19. However, Knoepfler cautions that there is a need for far more concrete and widespread proof of the benefit before regulatory bodies start ushering through the green light.
"What we should be focusing on now is not the possible boost to the stem cell field, but rather doing rigorous science to test whether stem cells can help COVID-19 patients," he said. "During a pandemic, it's reasonable to do some testing of unproven interventions like stem cells in small studies, but results from them should be discussed in a sober, conservative manner until there is more evidence."
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