For the first time, human arteries have been grown in a test tube. The achievement opens the way for a new kind of surgery, with patients "growing" their own blood vessels before a heart bypass.

Adults do not grow new blood vessels, which is why heart disease becomes such a threat later in life.

Four years ago, Laura Niklason, of Duke University, Durham, North Carolina, grew pig arteries in a laboratory system that mimicked the environment of a pig foetus. She ended up with blood vessels that could be implanted in a pig.

But the life-cycle of human artery cells proved too short for the same technique.

However, Chris Counter, at the Massachusetts Institute of Technology, had identified a gene product that permitted cancer cells to divide indefinitely.

The pair put the gene into smooth muscle cells and within 13 weeks the cells grew around a biodegradable polymer tube.

Dr Niklason said: "We found that the cells not only proliferated long beyond their normal lifespan, but retained the characteristics of normal smooth muscle. We were able to engineer mechanically robust human arteries, a crucial step toward creating arteries for bypass patients." She calculated that in 10 years, these "bio-engineered" blood vessels could be routinely implanted in patients with heart disease.