Transplants of insulin-producing cells from pigs could provide a diabetes cure within a decade, scientists say.
Pig body parts are already used in treating many human conditions
A US team has reversed the condition in monkeys by transplanting cell clusters, known as islets, from pig pancreases, a study in Nature Medicine reports.
UK teams have cured type 1 diabetes by transplanting human pancreas cells - but donated organs are in short supply, hence the interest in the pig solution.
The University of Minnesota hopes to start trials in humans by 2009.
The university's researchers argue that animal-to-human transplants may be necessary to make islet transplantation a viable solution for the tens of thousands of people who suffer from diabetes.
To overcome rejection of the pig cells, which has been a problem in the past with work such as this, the team worked to perfect a combination of drugs.
With the final drugs regime, all five monkey transplant recipients survived and their diabetes was reversed.
Associate professor of surgery and lead investigator Bernhard Hering said: "These results suggest it is feasible to use pig islet cells as a path to a far-reaching cure for diabetes."
He said the work had crucially allowed for a better understanding of the monkey's immune response following islet transplantation.
This was key if pig islet cells were to be used ultimately in humans, Professor Hering said.
However, the drugs used to suppress cell rejection have severe side-effects in humans and need to be refined.
"Now that we have identified critical pathways involved in immune recognition and rejection of pig islet transplants, we can begin working on better and safer therapies with the eventual goal of bringing the treatment into people," he added.
Nonetheless, Professor Hering suggested if clinical trials in humans began within three years, and everything went to plan, the procedure could be used more widely in humans within a decade.
Trials involving the transplant of islets from a donated human pancreas to a diabetes patient are currently ongoing at Oxford's Centre for Diabetes, Endocrinology and Metabolism.
Once the cells are removed from the donated organ they are injected directly into the patient's liver in what is a fairly simple procedure.
If successful, the cells will enable the patient to make his own insulin, which regulates blood sugar levels, like non-diabetics.
The advantage of islet transplantation is that it stops patients from having to have the regular insulin injections.
Jo Brodie, islet project coordinator at Diabetes UK, said: "A major limiting factor in the use of either whole pancreas or islet cell transplantation is the lack of available donor organs.
"This research offers the potential for a new source of islet cells without the need for patients to be given anti-rejection drugs which have serious side effects.
"This research may have huge future potential in the treatment of people with Type 1 diabetes, but a great deal more work is needed.
"Also, serious ethical issues still need addressing as xenotransplantations are not currently undertaken in the UK."
'Work to do'
Paul Johnson, director of the Oxford islet transplantation programme, said there was no doubt islet transplantation could cure a significant number of people.
"The shortage of donor organs means we either have to turn to human stem cells or animal cells as an alternative.
"This is an advance but there's still a lot of work to be done before we can apply it to humans."
The Minnesota team is now building bio-secure laboratories that meet US federal regulations for using animal tissues in humans.
The goal is to have suitable donor pigs available when the team has refined its methods of preventing the recipient from rejecting the donated cells.
The heart valves of pigs have been used in hundreds of thousands of heart transplants, and pig cells have shown promise in the treatment of Parkinson's disease.