Monday, August 2, 1999 Published at 22:24 GMT 23:24 UK
Gene hope for hearts
The technique may remove the need for surgery
A gene therapy that causes new blood vessels to grow around blocked arteries has been found to be safe for use in humans.
According to research published in the journal Circulation, the therapy can be applied using an injection without causing any adverse side effects.
The technique could offer an alternative to surgery for patients whose condition is too far advanced or too complex.
However, the British Heart Foundation has urged caution in interpreting the results as the study only looked at a small group of people.
A second study in the journal details a blood test that can identify people who are more likely to have the ability to grow new blood vessels spontaneously.
In coronary heart disease (CHD), fatty deposits build up on the insides of arteries, preventing blood flow.
This can lead to heart attacks and circulation problems.
Bypass surgery can divert blood around the blocked arteries, increasing the amount of oxygen carried to the heart, while a technique called angioplasty inflates a balloon in the artery to improve blood flow.
However, the gene therapy was found to increase growth of blood vessels around the heart.
Professor Ronald Crystal, of Cornell University where the research was carried out, compared the effect to workmen building enough roads to bypass a traffic jam.
"What we're doing is sending in a biological work crew for about a week to make new highways that go around the obstruction," he said.
"Once we've made the new highways - the new coronary arteries - the work crew is not needed and goes away."
The researchers gave injections to 15 patients who were about have heart surgery, and six who were not.
All experienced a reduction in chest pain and tests showed improved blood flow to the heart and evidence of blood vessel growth.
Dr Todd Rosengart, who led the research, said: "The implications are huge. To say anything less than that is an understatement.
"This addresses a tremendous problem of the large number of very sick patients for whom we can do nothing to help their coronary artery disease."
A spokesman for the British Heart Foundation said the organisation gave a "cautious welcome" to the study.
"In theory, techniques like this could be extremely helpful for treating patients with coronary heart disease," he said.
"However, although this research shows growth of new blood vessels in the heart, it must be stressed that the number of patients involved is too small to draw strong conclusions.
"And, importantly, it will take a great deal more research to show that any new blood vessels make a real contribution to treating CHD and to find out what, if any, side effects may be caused."
It was only once these questions had been answered that conclusions could be drawn as to the usefulness of the treatment.
The second study describes a blood test that can predict a person's ability to grow new blood vessels naturally.
Lead author Dr Andrew Levy said: "Coronary patients whose tests show little potential to generate new vessels could be treated with drugs to increase this potential or treated more aggressively with surgery."
It would also have the potential to improve treatments in other fields, he said.
"Cancer and diabetes patients, on the other hand, whose tests show a high potential, would require more aggressive treatment than patients who show a low potential for new vessel growth."
However, it was not yet clear exactly what impact the test would have on the treatment of these conditions, he said.