The preliminary trial was on patients with heart failure who were having heart bypass surgery. During the operation, a piece of heart tissue, from the right atrial appendage, was taken.
While the patient was being sewn up, researchers isolated cardiac stem cells from the sample and cultured them until they had about two million stem cells for each patient. The cells were injected about 100 days later.
Doctors measured how efficiently the heart was pumping using the left ventricle ejection fraction – what percentage of blood was leaving one of the heart’s main chamber with every beat.
In the 14 patients given the treatment, the percentage increased from 30.3% at the beginning of the trial, to 38.5% after four months.
There was no change in the ejection fraction in the seven patients who were not injected with stem cells.
Dr Roberto Bolli, one of the researchers from the University of Louisville, told the BBC: “We believe these finding are very significant.
The heart is not the only source of potentially useful stem cells. Trials have already taken place using stems cells from bone marrow.
Prof Anthony Mathur, from Barts and the London School of Medicine and Dentistry, and Prof John Martin, from University College London, are already conducting large randomised clinical trials.
They are investigating the effect of giving patients stem cells from their own bone marrow, in NHS hospitals, within six hours of a heart attack.
Prof Mathur said of the cardiac stem cell study: “Caveats very much apply. It’s a phase one trial so while the early results are great and promising, they need to design a big study to see if the results translate.”
Dr Bolli argues that stem cells from the heart might be more useful as “their natural function is to replace the cells that continuously die in the heart due to wear and tear”.
He hopes to start the next phase of clinical trials in 2012.