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)
From Medical Correspondent
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.
CNN's Ronda Rowland describes the use of pig livers for those needing liver transplants
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
"I wouldn't be here right now if it wasn't for the machine,"
Doctors at Cedars-Sinai have used the machine on 26 patients,
and 23 still are alive. Demetriou said there was an
"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,"
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
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.
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Children's Liver Alliance Inc.
Organ Transplant HomePage: The Only Place On The Web With Patient Waiting Times
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