Stem cells look promising for treating heart disease

Stem cell therapies could potentially reduce numbers of deaths from heart disease when used in addition to standard heart drugs and surgery, research suggests.

Taking stem cells from a patient's bone marrow and injecting them into damaged heart tissue may become an effective way to treat heart disease, suggests a new study. Researchers reviewed data from the clinical trials that have been conducted so far of these novel therapies.

"This is encouraging evidence that stem cell therapy has benefits for heart disease patients. However, it is generated from small studies and it is difficult to come to any concrete conclusions until larger clinical trials that look at longer-term effects are carried out," says Dr Enca Martin-Rendon of the University of Oxford and a member of the Cochrane Heart Review Group that carried out the study.

The Cochrane group found that stem cell therapy using bone marrow cells resulted in fewer deaths due to heart disease and heart failure, compared to a placebo or standard treatment alone. The stem cell therapy also reduced the likelihood of patients being readmitted to hospital, and improved heart function.

However, the researchers say that we need to wait for the results of much larger clinical trials currently underway to be more certain about the effects of stem cell therapy.

The group used data from 23 randomised controlled trials involving a total of 1,255 people, where all participants received standard treatments for heart disease. Their findings are published in The Cochrane Library.

Stem cell therapies are experimental treatments that are currently only available in facilities carrying out medical research. The procedure involves collecting stem cells from a patient's own blood or bone marrow and using the cells to repair damaged tissues in the patient's heart and arteries.

If eventually found to be effective, stem cells might offer an alternative or complementary treatment to standard drug and surgical treatments for some patients with chronic heart disease.

The Cochrane review found that within the first year, there were no clear benefits of stem cell therapy over standard treatment alone. But when longer term data were analysed a year or more later, about 3 per cent of people treated with stem cells had died compared with 15 per cent of people in the control groups. Hospital readmissions were reduced to 2 in every 100 people compared to 9 in every 100 in the control group, and adverse effects were rare.

Dr Martin-Rendon of Oxford University's Radcliffe Department of Medicine says: 'It isn't clear which types of stem cells work best or why stem cell therapies seem to work for some people but not for others. We need to find out what's different in the people who aren't responding well to these treatments, as it might then be possible to tailor therapies to these patients so that they work better.'

Dr David Tovey, editor-in-chief of The Cochrane Library, says, "This review should help to raise awareness of the potential of stem cell therapy to improve patient outcomes. But it also demonstrates the importance of recognising the uncertainty of initial findings and the need for further research."