I’ve been following the stem cells for COVID arena for more than two years. During this time researchers have launched scores of trials. A few have been published including a new one.
Clinical trials of stem cells for COVID-19
On the science side, so far nothing clinical trial-wise ever seems to get clarity. However, at the same time many small, uncontrolled studies are touted as encouraging in publications. My former student Mina Kim and I found that most cell therapy trials for COVID-19 at that time earlier in the pandemic were too small and not properly controlled and designed to yield conclusive results.
It’s tempting to get caught up in the over-exuberance. I’ve even thought a few of the better-designed or relatively not-so-small studies were encouraging at first, but as you dig into them there are always limitations and potential other issues.
What we need are large, controlled, blinded clinical trial data. That’s not what we’ve gotten so far though.
New study highlights challenges
The new small trial published in Frontiers in Immunology is another example of a study that is very limited. The paper, entitled Bone Marrow-Derived Mesenchymal Stromal Cell Therapy in Severe COVID-19: Preliminary Results of a Phase I/II Clinical Trial, seems encouraging on the surface.
Somehow, 100% of the MSC infusion group survived, which seems almost too good to be right.
There were no matched controls in the study from the beginning. So how do we know what meaning to give the results? The team selected unrelated controls retrospectively from other data, which is not a strong approach.
The MSC recipients also received standard COVID care including steroids. These drugs are thought to work by a similar mechanism to help COVID as the one proposed for MSCs. For that reason, it would be notable if MSCs gave a benefit above and beyond steroids.
Another limitation to the study is that the retrospective control groups were older (control matched) and much older (whole cohort) than the MSC group.
Overall, the design, small size, and other issues make making conclusions very difficult despite the seemingly encouraging results.
I’m hoping we’ll see some large, well-controlled, blinded studies soon to clarify whether MSCs have much promise here. I’m still skeptical. Also see this STAT News piece: For now, stem cells for Covid-19 are still mostly a shot in the dark.