Experiment by Penn surgeons shows how pigs might one day help people with liver failure

Surgeons at the University of Pennsylvania used a pig liver outside a brain-dead human body to filter blood, taking a step toward eventually trying the technique in patients with liver failure.

Surgeons at the University of Pennsylvania announced the success of a novel experiment Thursday, having attached a pig liver to a brain-dead human body and watched it filter blood.

The experiment was a different spin on animal-to-human organ transplants in that the pig liver was used outside the donated body, not inside, taking a step toward eventually trying the technique in patients with liver failure. This approach is a way for doctors to create a “bridge” to support failing livers by doing the organ’s blood-cleansing work externally, much like dialysis for failing kidneys.

Animal-to-human transplants, called xenotransplants, have failed for decades because people’s immune systems rejected the foreign tissue. Now scientists are trying again with pigs whose organs have been genetically modified to be more humanlike.

In the Penn experiment, researchers attached a liver from a pig — one genetically modified by eGenesis — to a device made by OrganOx that usually helps preserve donated human livers before transplant.

The family of the deceased, whose organs weren’t suitable for donation, offered the body for the research. Machines kept the body’s blood circulating.

The experiment, conducted last month, filtered blood through the pig liver-device for 72 hours. In a statement, the Penn team reported that the donor’s body remained stable and the pig liver showed no signs of damage.

In recent years, kidneys from genetically modified pigs have been temporarily transplanted into brain-dead donors to see how well they function, and two men received heart transplants from pigs although both died within months.

The US Food and Drug Administration is considering whether to allow a small number of Americans who need a new organ to volunteer for rigorous studies of either pig hearts or kidneys.

Some researchers also are looking to use pig livers. A liver has different complexities than kidneys and hearts: It filters blood, removes waste and produces substances needed for other bodily functions. About 10,000 people are currently on the national waiting list for a liver transplant.