Scientists from the University of Sheffield have developed a way of blasting DNA into cells using ultrasound.

Angina is a severe chest pain caused when the heart is starved of blood due to narrowed arteries.

In some cases it may precede a heart attack.

In many cases this is treated by inflating a tiny balloon in the artery to help clear the blockage responsible for the problem.

But even when the blockage is cleared, it returns in 40% of cases.

Scientists believe the new technique of putting therapeutic genes into large numbers of cells in the artery wall could prevent such relapses.

However, they warn that it will be very difficult to achieve.

Many pioneering gene therapy experiments have used viruses to carry genes into cells.

However, this technique raises concerns over safety.

Encouraging results

The Sheffield researchers are investigating an entirely new method of inserting genes, using ultrasound to "drive" them into the target cells. Early laboratory tests look encouraging.

Dr Christopher Newman, one of the team, said: "Gene therapy could be a great way of controlling the growth of cells in arteries to stop blockages returning.

"But the practical problem of getting tiny molecules of DNA into thousands of cells in an artery wall is huge.

"However, our techniques certainly show promise.

Hopefully this new phase of research will bring our aim one step nearer."

The work is being supported with a grant of more than �75,000 from the British Heart Foundation.