Scientists grow human livers in the laboratory

The research is being hailed as a major advance towards cutting the death toll of those who die waiting for donated organs, but could also have major benefits in developing a new generation of drugs.

A team of US scientists created the organs by sowing seeds of human cells on to collagen "scaffolds" derived from animal livers. The collagen, left behind after removing all the animal cells with detergent, gave the livers their shape and structure.

The original cells were then replaced with immature human liver cells, and the vital endothelial cells that line the walls of blood vessels.

After a week being nourished with nutrients and oxygen in a lab "bioreactor", the livers were seen to be growing and functioning like a human organ.

The next step is to see whether the organs will continue to function after they have been transplanted into animals. Only then will it be possible even to consider their use in humans.

Project director Professor Shay Soker, from the Wake Forest Institute for Regenerative Medicine in North Carolina, said: "We are excited about the possibilities this research represents, but must stress that we're at an early stage and many technical hurdles must be overcome before it could benefit patients."

Colleague Dr Pedro Baptista said: "Our hope is that once these organs are transplanted, they will maintain and gain function as they develop."

Professor Mark Thursz, consultant hepatologist at St Mary's Hospital, London, and spokesman for the British Liver Trust, said: "There is no doubt that this is a major breakthrough for patients with hepatitis C."

Earlier this year US scientists at Massachusetts General Hospital in Boston reported using a similar scaffold technique to construct miniature rat liver grafts. They were able to transplant the organs into live rats, where they survived for several hours.The new research was presented yesterday at the annual meeting of the American Association for the Study of Liver Diseases in Boston.

It could take five or more years for the technology to find its way from the laboratory into hospitals.In future it is hoped that stem cells donated by patients could be used to grow replacement livers that would not be rejected by the immune system.

The same approach to bioengineering may also help doctors grow other organs, such as the kidney and pancreas.

As well as the obvious benefits for transplants laboratory-grown livers would provide an invaluable tool for drug development, said the scientists.

"This would more closely mimic drug metabolism in the human liver, something that can be difficult to reproduce in animal models," said Baptista.

Liver disease kills more people in the UK than diabetes and road deaths combined, claiming more than 16,000 lives in 2008.

It is the only cause of death that is still increasing year-on-year. Numbers of liver disease deaths have increased by 12 per cent since 2005. Last year around 644 liver transplants from deceased donors were carried out in the UK.

The two top reasons for liver transplants are alcohol cirrhosis and damage caused by hepatitis C infection.