Doctors look for liver transplant alternatives

This pig's liver was used to keep Pennington alive until a human donor could be found

October 3, 1999
Web posted at: 12:37 p.m. EDT (1637 GMT)

In this story: Pig liver used as a filter No replacement yet for human livers Procedure gets some patients off transplant list RELATED STORIES, SITES

From Medical Correspondent
Rhonda Rowland

DALLAS (CNN) -- Robert Pennington believes he's alive today because of a pig that his family calls Wilbur.

The 19-year-old suffers from liver disease. His name was put on a transplant waiting list, but no livers were available.

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CNN's Ronda Rowland describes the use of pig livers for those needing liver transplants Windows Media 28K 80K

Then Dr. Marlon Levy, a transplant surgeon at Baylor University Medical Center, offered an alternative: a procedure using a dead pig's liver.

But not a liver from an ordinary pig.

"They're genetically modified to try to prevent a reaction between the human blood and the pig liver," Levy said.

Pig liver used as a filter

The patient's blood is filtered through a pig's liver

Pennington didn't actually have the pig's liver transplanted into his body. Instead, his blood was run through the pig's liver in a procedure called xenoperfusion.

A tube was placed in a vein in Pennington's leg, and his blood was siphoned through a pump. The blood was heated, oxygen was added, then the blood was filtered through the pig's liver and returned to Pennington's body.

"I think it's impossible to say whether they would have lived long enough to receive their liver (transplant) had we not had this bridging technology," Levy said. "But I'd like to think that made the absolute difference in their survival."

No replacement yet for human livers

The pig liver was used to temporarily keep Pennington alive until a human liver became available, but surgeons at Baylor hope to one day transplant pig livers into humans. There is concern, though, that humans could pick up a virus from pigs.

"We need to have animals genetically altered to the point where we believe we do not see an immune response of that dangerous kind," said Dr. Goran Klintmalm, director of transplantation at Baylor University.

"The promise of xenotransplants has been around for many years, and still has not been fulfilled," said Dr. Achilles Demetriou of Cedars-Sinai Medical Center. "My guess is it will not be fulfilled in the immediate future."

Bioartificial liver also gives patients hope

Demetriou has been working on a device he calls a bioartificial liver. It would use cells from pig livers to remove toxins in a technique similar to kidney dialysis.

After sudden liver failure due to medication poisoning, Molly Koch was put on the device for two days until a human liver became available.

"I wouldn't be here right now if it wasn't for the machine," Koch said.

Doctors at Cedars-Sinai have used the machine on 26 patients, and 23 still are alive. Demetriou said there was an unexpected bonus.

"We did find in about six patients when we kept them alive for several days, their liver recovered spontaneously so they actually got better without the need for a transplant," Demetriou said.

Last year in the United States, there were more than 13,000 people on waiting lists to receive liver transplants. Fewer than 5,000 received new livers; many others died while waiting.

Many doctors believe that even if more donors become available, the real solution to ending the organ shortage is animal-to-human transplants. And they believe success stories like Pennington's and Koch's indicate that could become a reality in the next decade.