Big Warning About Animal-To-Human Transplants
US Scientists Urge Wait On Transplants
By Maggie Fox
Health and Science Correspondent
"The experts argued in their letter that this risk (of massive viral epidemics) involves society as a whole -- and thus society as a whole must first be educated about the risk, and then consulted about it."
WASHINGTON (Reuters) - Scientists, some of them top transplant researchers, called for a moratorium on animal-to-human transplants Wednesday, saying it was just too dangerous. The main risk is that animal organs, especially pig organs, could carry viruses that could mutate and cause epidemics across whole populations, they said.
Their letter, published in the science journals Nature and Nature Medicine, coincides with a public hearing being held by the U.S. National Institutes of Health (NIH), the Food and Drug Administration (FDA) and other agencies trying to come up with a policy toward xenotransplants, as they are called.
More than 55,000 Americans are on the waiting list for an organ transplant, according to the U.S. Department of Health and Human Services. But only about 20,000 transplants are done each year -- mostly due to a shortage of organs -- and so 4,000 people die every year because organs did not become available in time to save them.
``The demand for human cells, tissues and organs currently exceeds the available supply,'' Dr. Amy Patterson of the FDA's Division of Cellular and Gene Therapy, told Wednesday's public hearing.
Several hospitals and private companies have turned to the possibility of using animal organs for transplants. But the letter, signed by nine scientists including Harvard Medical School xenotransplantation researcher, Dr. Fritz Bach and Dr. Harvey Fineberg, a Harvard public health professor, says there are more important concerns.
``Despite the fact that lives of patients needing transplantation may be lost with delay, we believe that the risks are sufficient to warrant refraining from human xenotransplantation until public deliberations on the ethical issues have occurred,'' they wrote.
They said the public needed to be educated and then join scientists, ethicists and government regulators in discussing how to go ahead.
The biggest public risk comes from viruses. Pigs are considered the most likely candidates for animal-to-human transplants, also known as xenotransplants. Their cells are already being injected experimentally into the brains of people with Huntington's and Parkinson's disease and into the pancreases of people with diabetes.
Pigs are similar in size to humans and are easily bred. But they carry viruses known as porcine endogenous retroviruses. No one knows if the viruses can pass to humans or if they would cause disease.
Under the worst scenario, the viruses would mutate in people and cause epidemics.
The experts argued in their letter that this risk involves society as a whole -- and thus society as a whole must first be educated about the risk, and then consulted about it.
``While news reports of breakthroughs in the use of animal tissue are appearing frequently, many in the lay community still fear the idea of organ farming and regard the exchange of body parts between animals and humans as macabre and the stuff of horror films,'' they wrote.
Transplant recipients, and their sexual partners, would face lifelong surveillance -- and would have to understand the implications of this.
There were also animal welfare issues, with experimental animals doomed to life in a sterile laboratory. But, the doctors added, research should be strongly encouraged.

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