Stem-cell patch may fix damaged hearts

LONDON (Reuters) - Scientists have made two significant advances in developing a stem-cell patch to repair the damage caused to the heart after an attack.

Sian Harding of London's Imperial College said on Thursday her team had successfully matured beating heart cells in a laboratory dish for up to seven months and developed a biocompatible scaffold to form the basis of a patch.

The idea is to stitch or glue a patch of new tissue derived from embryonic stem cells over the damaged area of the heart to make the muscle viable again.

During a heart attack, or myocardial infarct, part of the heart muscle loses its blood supply and the oxygen-starved cells die, causing scarring.

"We really would like to cover the area of the infarct scar as much as possible, so it might be quite a large patch," Harding said in an interview.

"We think the patch itself will stop the scar expanding, which is one of the big problems when you have a myocardial infarction because the scar becomes weak and can bulge out."

The biomaterial developed for the patch is designed to have the same elasticity as heart muscle and can also be programmed to degrade safely in anything from two weeks upwards.

Several groups around the world are working on different ways to use stem cells in heart repair but a key challenge is to get cells to function properly.

By showing stem cell-derived heart cells can beat in a co-ordinated fashion for months on end, the Imperial team believes their patch should function smoothly alongside normal heart muscle, without causing abnormal heart rhythms.

Harding, who will present her research at a UK Stem Cell Initiative conference, said initial human trials of the patch could be underway within five years -- after safety studies on animals and tests to see if the new cells are rejected.

Stem cells are controversial but the field received a boost last month when researchers reported they had turned ordinary human skin cells into batches of cells that looked and acted like embryonic stem cells, without using human eggs or embryos.

"That is a very promising development," Harding said. "They have made heart muscles from those cells and this technique has the potential both for getting round the ethical problems and for producing patient-specific cells."

Making stem cells from a patient's own tissue would avoid the problems of transplant rejection.

(Editing by Julie Steenhuysen and Matthew Jones)