Pig Heart Beats for 620 Days – Now It May Help Save Dying Babies

A groundbreaking study has shown that pig hearts could keep critically ill babies alive while they wait for a transplant.

Using baboons as test subjects, researchers managed record survival times and even reversed rejection—an unprecedented success. The innovation could replace risky machines and offer hope to infants with no other options.

A Potential Lifesaver for Critically Ill Infants

A research team at Children’s Hospital Los Angeles has become the first in the world to demonstrate that genetically modified pig hearts could potentially serve as a temporary solution, or “bridge,” for critically ill infants awaiting heart transplants.

This breakthrough in preclinical research offers a promising alternative for babies with life-threatening heart conditions, especially those with single-ventricle heart disease. Currently, many of these infants die before a suitable donor heart becomes available.

The study was led by Dr. John David Cleveland, a congenital heart surgeon at the Heart Institute of Children’s Hospital Los Angeles. He presented the findings on April 28 during a plenary session at the International Society for Heart and Lung Transplantation Annual Meeting in Boston.

“The goal is to be able to use pig hearts instead of machines to support these babies until a suitable human heart can be found,” Dr. Cleveland says. “We still need to do more research, but our studies show this is a viable model.”

The Urgent Need for Alternatives

The idea of using animal organs, known as xenotransplantation, has long been explored as a potential solution to the global shortage of donor organs.

For many patients, mechanical devices like ventricular assist devices (VADs) can keep the heart functioning until a transplant is available. But for infants with single-ventricle heart disease, these devices often fall short.

Only about 30% of these infants survive beyond three months on a VAD due to complications such as strokes, bleeding, and infections. As a result, most do not survive long enough to receive a life-saving transplant.

“For those with single-ventricle disease, it’s difficult to balance their circulations with a VAD—to find a way to give enough blood to the body and enough blood to the lungs,” Dr. Cleveland explains. “A machine cannot constantly adapt to the physiology like an actual heart.”

Xenotransplant could offer these babies a much better chance at surviving the time it takes to match with a suitable heart for transplant. “Not only could the outcomes be better, but a pig heart could potentially allow babies to go home while they wait for a human heart, as opposed to being connected to a VAD in the hospital,” he adds.

Milestone Study: From Concept to Proof

The researchers began their studies five years ago, supported by an R33 Catalyze grant from the National Institutes of Health. So far, they have transplanted genetically modified pig hearts into 14 young, size-matched baboons at research facilities outside of California.

To date, eight of the 14 baboons have survived for several months with a pig heart. One of the baboons has so far lived for 620 days—nearly 21 months—the longest a nonhuman primate has ever lived with a pig heart. In addition, the team early on successfully reversed an episode of acute rejection in that baboon, the first time that’s been done for a xenograft. That work was recently published in Xenotransplantation.

Rewriting the Rules of Transplant Compatibility

Importantly, the team also has become the first in the world to replace a functioning xenograft with a same-species heart. That was done in two of the baboons, with one living to 105 days.

“We have shown that replacing a xenograft with an allograft is feasible, which no one has done before,” Dr. Cleveland says. “Based on those learnings, we are working to further modify and improve the protocol.”

Transformative Tech and Smarter Drugs

He notes that science has come a long way since 1984, when “Baby Fae” received a baboon heart, becoming the first infant to receive a cardiac xenotransplant. She died 21 days later after her body rejected the heart.

One key advance is the ability to genetically modify organs to make them more humanlike. Immunosuppression technology is also far superior now, increasing the ability of the immune system to accept a xenograft.

Pig Hearts Designed for Humans

The CHLA team is using an investigational medication called tegoprubart, an anti-CD40L antibody that aims to retrain the immune system to better accept a foreign organ as “self.” The researchers’ protocol also reduces the amount of time that the donor pig heart is out of circulation, which can help reduce the chances of rejection.

Through a partnership with eGenesis, a biotech company that specializes in xenotransplant, the researchers have also been using hearts from Yucatan miniature swine, a pig that grows more slowly than large white pigs.

Why Babies May Be Better Candidates

Dr. Cleveland also says that xenotransplant may have a greater chance of success in babies than in older adults. In earlier studies, the team found that children younger than 18 do not have significant antibodies to pigs, while most adults do.

“The immature pediatric immune system is much more capable of accepting something completely foreign than the adult system is,” he says. “We still have more research to do. But our hope is that we can eventually offer these babies a much better chance to live.”

Meeting: ISHLT 45th Annual Meeting & Scientific Sessions