Looking at Recovery Years Later
For some people who experienced severe COVID-19, recovery continued long after leaving the hospital. A 2025 study followed patients for three years after treatment with umbilical cord-derived mesenchymal stem cells, or UC-MSCs, to see how they were doing over the long term. The study focused not only on possible benefits, but also on an important question in regenerative medicine: Does the treatment remain safe years later?
Following Patients for Three Years
The research followed participants from an earlier randomized, double-blind, placebo-controlled trial. Originally, 100 patients with severe COVID-19 received either UC-MSC therapy or placebo alongside standard medical care.
- 65 patients received UC-MSCs
- 35 received placebo
- UC-MSC patients received three IV infusions on days 0, 3, and 6
At the three-year follow-up, researchers were able to evaluate 78 participants, including 49 from the UC-MSC group and 29 from the placebo group.
They looked at lung scans, breathing tests, walking ability, quality of life, ongoing symptoms, and long-term safety.
What Did the Researchers Find?
One of the more encouraging findings involved lung imaging. After three years, 46.9% of patients in the UC-MSC group had normal lung CT scans, compared with 34.5% in the placebo group.
While this difference was not statistically significant, earlier follow-ups suggested that lung recovery may have happened sooner in the UC-MSC group. Other measurements, including lung function and six-minute walking distance, were similar between the two groups.
Better Self-Reported General Health
Researchers also looked at how patients felt about their overall health and quality of life. Patients who received UC-MSCs had an average general health score of 67, compared with 50 in the placebo group. This was one of the more noticeable differences between the groups.
That matters because recovery after a serious illness is not only about what appears on a scan. Energy, daily activity, physical ability, and overall well-being can all play a major role in how someone feels after treatment.
What About Long-Term Safety?
Long-term safety was one of the most important parts of this study. Researchers monitored participants for new illnesses, changes in tumor markers, tumor development, and other possible complications.
After three years, there was no significant difference in new health problems or tumor-related concerns between the UC-MSC and placebo groups.
No new deaths were reported during the three-year follow-up period.
This extended monitoring provides useful information because many regenerative medicine studies only follow patients for several months or a year.
Did UC-MSCs Reduce Long COVID?
Persistent symptoms associated with Long COVID were generally similar between the two groups after three years. This means the study did not show that UC-MSC therapy eliminates Long COVID.
Instead, the strongest findings were the treatment’s reassuring long-term safety profile, encouraging trends in lung recovery, and better self-reported general health.
Why This Study Matters
This study stands out because researchers followed patients for a full 36 months after UC-MSC treatment. The results showed no significant increase in long-term complications, while some measures of lung recovery and overall health were encouraging.
More research is still needed to understand exactly how much benefit UC-MSC therapy may provide. Still, this study offers valuable evidence that the treatment remained well tolerated years later.
For regenerative medicine, that long-term perspective is especially important. It helps researchers understand not only what happens shortly after treatment, but also how patients are doing years down the road.
Source
Yuan MQ, Song L, Wang ZR, et al. Long-term outcomes of mesenchymal stem cell therapy in severe COVID-19 patients: 3-year follow-up of a randomized, double-blind, placebo-controlled trial. Stem Cell Research & Therapy. 2025;16:94. doi: 10.1186/s13287-025-04148-1. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11863646/
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