WASHINGTON (AP) — U.S. researchers will soon test whether livers from a gene-edited pig could treat people with sudden liver failure — by temporarily filtering their blood so their own organ can rest and maybe heal.

The first-of-its-kind clinical trial has been cleared by the Food and Drug Administration, according to pig producer eGenesis, which announced the step Tuesday with its partner OrganOx.

An estimated 35,000 people in the U.S. are hospitalized each year when their liver suddenly fails. There are few treatment options and death rates as high as 50%. Many don’t qualify for a liver transplant or can’t get a match in time.

The new study, which is expected to get underway later this spring, is a twist on the quest for animal-to-human organ transplants. Researchers won’t transplant the pig liver but instead will attach it externally to study participants.

The liver is the only organ that can regenerate, but the question is whether having the pig’s liver filter the patient’s blood for several days could give it that chance.

In experiments with four deceased bodies, that “bridge” attempt showed the pig liver could support some functions of a human liver for two or three days, said Mike Curtis, CEO of Massachusetts-based eGenesis, which genetically modifies pigs so their organs are more humanlike.

The trial will enroll up to 20 patients in intensive-care units who don’t qualify a liver transplant, he said. A device made by Britain’s OrganOx, currently used to preserve donated human livers, will pump participants’ blood through the pig liver.

It’s the latest step in attempts to use gene-edited pig organs to save human lives. Pig kidneys from eGenesis and another pig producer, United Therapeutics, are being used in experimental transplants.