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Last Updated: Thursday, 5 June, 2003, 23:49 GMT 00:49 UK
Home-grown arteries a step closer
Operation
The arteries could be used in some bypass operations
New blood vessels grown from a patient's own muscle cells are a step nearer after a genetic success in a US laboratory.

The arteries could be used in many operations which currently mean surgeons have to insert plastic tubing to form new vessels.

However, it is still likely to be several years before trials in humans can begin, say experts.

A human blood artery is not simply a tube - it is made of a complex sandwich of muscle, lining cells and connective tissue that can expand and contract to regulate blood flow.

We were able to engineer mechanically robust human arteries, a crucial step toward creating arteries for bypass patients
Dr Laura Niklason, Duke University Medical Center
The normal formation of new blood vessels in the body is also complicated, with "smooth muscle cells" migrating to surround a lining of epithelial cells.

When scientists tried to replicate this process in the laboratory, however, the smooth muscle cells could not grow to form fully functional arteries because they did not have enough life in them to perform all the necessary cell divisions.

A human cell can only divide a finite number of times, and the muscle cells being used by the researchers simply ran out of time.

Ageless cells

Researchers from Duke University Medical Center in the US believe they have found a way around this, with a secret taken from cancerous cells.

Some tumours manage to cheat this limit because they have the genetic ability to perform many more divisions.

If it were possible to grow an artery that could contract and relax as well as carry blood that this would be a major breakthrough
Professor Tony Heagerty, Manchester University
One of the genes responsible for this "immortality" is called hTERT.

The Duke researchers introduced hTERT into smooth muscle cells, and found that this time, they could grow fully functional arteries.

Dr Laura Niklason, who led the research, said: "We found that the resulting cells not only proliferated long beyond their normal lifespan, but retained characteristics of normal smooth muscle cells.

"We were able to engineer mechanically robust human arteries, a crucial step toward creating arteries for bypass patients."

It is unlikely that an artificial artery would find favour with surgeons carrying out coronary artery bypass grafts.

Leg operations

The lengths of blood vessel needed are small, and good results can be achieved with veins or arteries extracted from the legs or chest of the patient.

However, where arteries in the legs have hardened and become blocked, a longer section of new artery would be needed, and it is at this point that plastic alternatives are generally used.

Professor Tony Heagerty, a researcher with an interest in cardiovascular medicine at the University of Manchester, UK, said that the production of "artificial" blood vessels was of "huge importance".

"It's a hot area," he told BBC News Online. "If it were possible to grow an artery that could contract and relax as well as carry blood, this would be a major breakthrough.

"But it isn't around the corner - this will take at least 10 years."


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