The technique could help patients awaiting transplant

US researchers have been able to keep a number of patients who had severe liver failure, some of whom were in a coma, alive using the technology.

They say the tissue could be used to help keep patients awaiting transplants alive in the same way patients with kidney disease waiting for transplants are kept alive using dialysis.

Seriously ill patients, who cannot be helped through other treatments, could benefit from the treatment, the researchers said.

It is often difficult to assess the beneficial effect of liver support machines Dr Robin Hughes, Kings College Hospital, London

The team from the University of Pittsburgh was able to grow functioning liver tissue from human liver stem cells taken from organs that had been deemed unsuitable for transplant because of damage or underlying disease.

They used bioreactors, 'tanks' supplied with nutrients, to culture the cells in.

Eight patients received treatment.

Approximately 5,000 people die from liver failure each year in England and Wales.

Only just over 500 liver transplants are carried out.

Patients with liver failure can be treated using mechanical filters which can remove some of the toxins from the blood, but scientists are looking for more effective methods.

Regeneration

Dr J�rg Gerlach, professor of surgery at the University of Pittsburgh School of Medicine, who led the research, said: "We have treated eight patients in acute liver failure - some of whom were in a coma - who were able to be bridged to transplant."

He told BBC News Online: "And for patients with acute liver failure, we could provide a bridge while their own liver regenerates.

"Then there are patients who have had to have surgery for liver cancer. They often don't have enough liver cells left. This technique could also help them."

Dr Gerlach said patients with chronic liver failure, caused by conditions such as hepatitis C, could also be helped by the bioreactor.

Dr Robin Hughes, a liver specialist at King's College Hospital, London, said: "In any study of liver failure it is often difficult to assess the beneficial effect of liver support machines, particularly if patients subsequently have a liver transplant."

But he added: "If the researchers have been able to purify liver stem cells and got them to grow and mature in his bioreactor then this would be important, and would potentially be a step forward.