Stem cell therapy may help prevent heart failure after a severe heart attack. Digest
Heart failure is one of the most serious long-term complications following a heart attack, leading to fatigue, breathlessness, and repeated hospital stays. A new phase 3 clinical trial tested whether a one-time infusion of stem cells derived from umbilical cords could protect the heart and prevent a decline in heart function.
The study included 420 adults in Iran who had their first major heart attack which severely reduced their heart's pumping ability. Within 3–7 days of the heart attack, one group received about ten million mesenchymal stem cells delivered directly into the artery supplying the injured heart muscle through a tiny catheter, along with standard care. A comparison group received standard care alone.
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The trial revealed striking differences in heart failure outcomes and cardiac recovery:
- After 6 months, the stem cell group showed a greater improvement in ejection fraction (a measure of how much blood the heart pumps with each beat) than the control group.
- At about 3 years of follow‑up, participants who received stem cells were 57% less likely to develop heart failure.
- Hospitalizations caused by heart failure were 78% lower in the stem cell group.
- There was no effect on hospital readmissions for heart attacks, all‑cause or cardiovascular mortality.
- No adverse events, including heart arrhythmia, allergic reactions, or tumor formation, were noted during follow‑up.
The researchers believe these benefits do not occur because mesenchymal stem cells replace or repair heart tissue directly, but rather because they act through paracrine signaling, releasing protective molecules that reduce inflammation, prevent scarring, and promote the growth of new small blood vessels. These effects may help limit further damage and support the heart's natural repair processes, allowing it to maintain its pumping power.
While the results are promising, the trial included only patients younger than 65 and did not use a sham treatment, which limits how firmly the findings can be generalized. The study also did not measure blood markers or imaging signs of heart tissue repair that could have clarified how the stem cells helped protect the recovering heart. Even so, it provides strong evidence that stem cells may lower the risk of later heart failure in heart attack patients. Explore how stem cells could reshape regenerative medicine in my interview with Dr. Frans Kuypers.