Progress seen in animal-to-human organ transplants

Only about 25 per cent of critically ill patients in need of a donor heart, kidney or liver receive the life-saving organs. Many die while waiting for a transplant.

Xenotransplantation, the use of animal organs or tissue, is considered a possible solution to the worldwide shortage of donor organs.

Professor Ian F C McKenzie, Australian president of the International Xenotransplantation Association (IXA), told a medical conference that scientists are making progress in overcoming the obstacles in animal-to human transplants.

"We are now at the dawn of a new era," he said.

Pigs, with organs approximately the same size as their human equivalents, are thought to be the best animals for organ transplants because they breed quickly and produce big litters.

But fears of pig viruses infecting human cells and problems of organ rejection have been major obstacles.

McKenzie told the week-long meeting of the 20th International Congress of the Transplantation Society that genetically modified pigs could be a new avenue to overcome organ rejection.

"I would predict that at least six genes will need to be modified or eliminated in transgenic pigs to allow for the survival of donor organs," McKenzie said in a statement.

"There are already pregnant pigs that have up to five of the genes that could be important for carrying out xenotransplantation," he added.

Financial analysts estimate that the total market for xenotransplantation could run into billions of dollars but early attempts to commercialise the technology have been held up by problems. McKenzie said the possible transfer of pig viruses to humans is still an issue, but one which he believes can be overcome.

"We are in the process of solving these difficulties," he said, adding that a receptor for pig viruses has already been identified. "This could provide a possibility of blocking it," he said.