Novel heart repair therapy could be in the pipeline

The success of a new and experimental stem cell treatment used in animals could lead to a novel heart repair therapy for heart attack patients.

The treatment which involved using embryonic stem cells to repair the hearts of rats was so successful that scientists are encouraged to believe it could be adapted to be used in humans.

Stem cells are the body's master cell and act as a source for the various cells and tissues in the body; those taken from days-old embryos, called embryonic stem cells, are the most malleable and can produce all of the cell types.

The scientific team led by Professor Charles Murray at the University of Washington, used human embryonic stem cells to repair the hearts of rats with damage similar to that seen in heart attack patients.

The treatment entailed injecting heart muscle cells from human embryonic stem cells on to the inner surface of the ventricles which led to the recovery of the heart's activity and stimulated the growth of new blood vessels.

Having shown that the technique works in rats, the team are now testing it in sheep whose heart rate and size is closer to humans- if successful, clinical trials in humans will follow.

Heart attacks happen when heart muscle loses its blood supply, usually because the arteries become furred; as a result the muscle cells in the oxygen-starved part die and form a scar which reduces the heart's ability to pump.

Until now one problem has been preventing the injected cells from dying, but the team which included researchers from the Biotechnology company Geron, have concocted what they term a nutritious "survival cocktail" of chemical signals that prevents this from happening.

Professor Murray says the problem of cell death is common in stem-cell treatment and this is one of the most successful attempts so far using cells to repair solid tissues.

The experiment found that rats that were injected with heart muscle cells had better heart output compared with untreated control animals and also experienced a 2.5-fold increase in the volume of heart wall at the scar site.

Embryonic stem cells were the only human stem cells that had been shown to form cardiomyocytes - heart muscle cells - but as embryonic stem cells are so immature, it is very difficult to control what kinds of cells they produce.

The use of embryonic stem cells is a controversial issue because some people oppose the destruction of a human embryo.

U.S. President George W. Bush has strictly limited federal funding of human embryonic stem cell research but there are no restrictions on privately funded researchers.

Every year in the United States an estimated 865,000 people have heart attacks and more than a third eventually develop heart failure, a chronic condition in which the heart fails to pump blood properly; a third of heart failure patients die within two years.

Biotechnology company Geron Corp said it would try to develop the cells into a product to address the large unmet need in heart failure and hopes to market the treatment as an off-the-shelf therapy for heart attacks.

The research is published in Nature Biotechnology.