Stem cells from a patient's own heart have been used to restore function after heart attack.
Many heart attack survivors are left with badly damaged hearts and heart failure — a disabling disorder that causes breathlessness.
The heart can't heal itself but researchers hoped that by taking a small piece of the heart during bypass surgery that they'd be able to find heart stem cells, grow them in the lab and inject them back into the heart.
In this week's issue of the medical journal The Lancet, researchers reported on a preliminary trial on a small group of heart failure patients who were randomly assigned to the stem cell treatment or to a control group that received standard care.
"Our study is the first report of the administration of [cardiac stem cells] in people," Professor Roberto Bolli of the University of Louisville and his co-authors concluded.
"The results are a significant addition to the current data because they introduce a new potential treatment for heart failure."
In the study, called SCIPIO, doctors measured how efficiently the heart was pumping.
In the 14 patients given the treatment, that percentage increased from 30.3 per cent when the study started to 38.5 per cent after four months. There was no change in the control group.
Optimism but long-term questions
"The results from SCIPIO raise new optimism because the study is based on rigorous quality standards and the reported benefits are of an unexpected magnitude," Professor Gerd Heusch of the University School of Medicine, in Essen, Germany, said in a journal commentary.
To see whether the promise holds up, more patients will need to be followed over a longer time period, Heusch cautioned.
As well, the pumping improvements may not necessarily translate into longer survival or better quality of life.
The preliminary safety study also did not assign any participants to a sham treatment to take the placebo effect into account.
Prof. Peter Weissberg, medical director at the British Heart Foundation, called the findings positive.
It will be important to understand whether the stem cells are actually replacing damaged heart cells or if are secreting molecules that are helping to heal the heart, Weissberg noted.
Doctors still don't know which stem cells work best or when it is the ideal time to inject them.
The study was funded by the University of Louisville Research Foundation and the U.S. National Institutes of Health.