Heart attack scars healed in stem cell safety trial

A stem cell-based therapy aiming to reverse the damage caused by heart attacks has shown positive results in an early clinical trial.

Seventeen heart attack patients were treated with an infusion of cardiac stem cells grown from their own heart cells and their hearts regrew healthy muscle. The scars from the attack shrank significantly in size. Eight patients served as controls in the study, receiving conventional medical care.

As a phase I trial, the principal aim of the study was to assess the safety of the treatment. It was hoped that, as the cells involved come from a person's own body, there would be no risk of rejection and they would be more likely to form heart tissue. The trial team report that the increases in viable heart tissue were 'unprecedented' and that the therapy should now be moved into phase II trials.

'This has never been accomplished before, despite a decade of cell therapy trials for patients with heart attacks', said Dr Eduardo Marbán, the director of the Cedars-Sinai Heart Institute in the US, who led the study. 'Now we have done it. The effects are substantial, and surprisingly larger in humans than they were in animal tests'.

In the procedure, doctors used a catheter inserted into a vein in the patient's neck to take a small sample of heart tissue from patients about a month after they had had a heart attack. These heart cells are then grown into specialised cardiac stem cells. Up to 25 million of these are then injected into the patient's coronary arteries.

The scar tissue that the procedure aims to repair is formed in the aftermath of a heart attack. Although it represents part of the healing process, it does not beat and reduces the heart's ability to pump blood around the body. Until just a few years ago, many scientists and physicians believed that heart muscle damaged after a heart attack could not be repaired or replaced.

Professor Jeremy Pearson, associate medical director of the British Heart Foundation, who was not involved in the study, said that it was 'early days' for this therapy but added that 'it could be great news for heart attack patients who face the debilitating symptoms of heart failure'.

The study is available on The Lancet's website and will be published in a future issue of the journal's print edition.