October 2, 1995
Web posted at: 10:50 a.m. EDT
From CNN Correspondent Al Hinman
DURHAM, North Carolina (CNN) -- When the human liver quits working, a transplant usually is the only alternative to death. But nearly one-third of those waiting for a transplant die before a suitable organ is found.
But doctors now believe livers from pigs could offer a life-saving bridge for many of those on the transplant waiting list.
Doctors at Duke University Medical Center are ready to use genetically-engineered pig livers as a life-support system for patients with acute liver failure.
"Our goal is to be able to use a pig liver as an external device, to pass the patient's blood through it and cleanse the blood in order to help maintain the patient's life, and improve their condition so that they can potentially get a liver transplant," says Duke's Dr. Jeffrey Platt. (178K AIFF sound or 178K WAV sound)
The process: the pig liver is hooked up to the patient --
outside the body -- connected through a system that pumps the
blood and adds oxygen. It's similar to those used for heart
bypass surgery. (1.2M QuickTime movie)
"As it goes through the liver it is cleansed in a way that is very similar to what happens in the human liver," Platt explains.
Unlike dialysis, which can keep patients with kidney failure alive while they await a transplant, doctors have yet to find a reliable, similar "bridge" for those whose livers fail. Work is underway on an artificial liver, but it's proving tough because of the organ's complex blood filtering and digestion-related functions.
"The solution for the patient is a liver transplant -- or potentially the restoration of function in their own liver, if they can be allowed to survive for a long enough period of time," says Platt.
Researchers want to extend the length of time the pig liver
is able to function. Scientists at Nextran, a New Jersey-
based biotechnology company, developed the process that
breeds pigs with several key human genes in their livers.
The result, Platt says, is a decrease in the amount of inflammation that is the normal reaction of human blood in pig liver. Without the genetic changes, the inflammation could destroy the liver in a matter of hours.
The researchers' ultimate goal is be able to transplant pig livers into humans. But first, they've got to overcome major rejection problems.
But why pigs? They're easy to breed, and their organs are an easy match with humans'.
And, doctors hope, pigs' livers can help bridge an often- deadly transplant gap.
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