Stem cells obtained from donors have been used in clinical trials to effectively treat damage caused by heart attacks. The trial, conducted by researchers at the University of Miami, USA, found that donor stem cells were 'just as safe' as stem cells derived from the person being treated. Results also suggest that, because they can be prepared in advance, the use of donated stem cells could mean some patients start treatment sooner.
'This trial shows that using stem cells, taken from either patients themselves or from donors, is safe, which gives us confidence in planning larger trials', said Dr Denis Buxton of the US National Institutes of Health's National Heart, Lung, and Blood Institute, which funded the study.
Thirty people with ischaemic cardiomyopathy as a result of heart attacks were treated with mesenchymal stem cells (MSCs), the stem cells found in bone marrow. Half received stem cells derived from their own body, and the other half received MSCs from healthy donors. Normally, a person's immune system would attack cells from another person, but MSCs are 'immunoprivileged', meaning, unlike most cells, they are not attacked by a person's antibodies.
As a great number of stem cells are required to rebuild heart muscle, it can take up to eight weeks to prepare them. However, donor cells could be prepared in advance, potentially speeding up treatment. 'Ideally, we could bank donor cells and use them immediately on patients, as needed', said Dr Alan Heldman of the University of Miami Miller School of Medicine and co-author of the study.
The trial was conducted over 13 months, and also tested different doses of MSCs. The treatment significantly improved some aspects of heart function and quality of life, and caused regeneration of damaged heart tissue.
'In many cases we observed clinically significant improvement', said Professor Joshua Hare, also of the Miller School of Medicine, who led the study. 'Even in patients who had heart attacks several decades before treatment, both donor and recipient stem cells reduced the amount of scarring substantially'.
Several previous studies have shown that stem cells can reduce the scarring that occurs after heart attacks (reported in BioNews 645,647 and 656) but unlike other trials, this study also showed the effectiveness and safety of using donor stem cells.
'As cardiologists, we have all been taught that damaged heart tissue cannot be repaired', said Mauro Moscucci, professor of medicine at the University of Miami, who was not part of the study.
However, Dr Buxton said, 'if future studies show similar safety and efficacy, patients with ischemic cardiomyopathy may have a treatment option beyond medical management'.
The group is now planning a larger trial, including placebo controls.