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Researchers achieve breakthroughs on the road to pig-to-human heart transplants

Researchers say they have successfully held a baboon living with a pig's heart for six months. [Credit: Dusan Petkovik /…

Researchers say they have successfully held a baboon living with a pig’s heart for six months. [Credit: Dusan Petkovik / Shutterstock]

Although 54 percent of adults in the United States have registered as organ donors, only one in three dies in a way that allows organ donation. It leaves more than 1

00,000 people in the United States waiting for a transplant. Many will die to wait.

As demand for organs exceeds the supply and probably always comes, researchers have looked at xenotransplantation – laying animal organs into human bodies – as an alternative. Getting to the point where xenotransplantation is safe enough for human trials has been a challenge for so many complications to occur. Now, a breakthrough by a group of researchers takes us one step closer to a day when organ shortage is one thing from the past.

A research team led by Bruno Reichart at Munich University in Germany has developed a technique that allows baboons to survive significantly longer than ever before with transplanted pig starvation. To figure out how to safely xenotransplant hearts is an important study area due to severe cardiac problems, researchers said.

“Heart failure in the United States is expected to reach more than eight million in 2030, and many of these people will die while waiting for a donor body,” wrote Christoph Knosalla from the German Heart Center in a comment published with the team’s research paper in Nature this week.

Despite 25 years of extensive study, the furthest one of the babies had survived after having had a pig heart every 57 days. On the other hand, researchers showed that it is possible for a baby to survive six months by modifying the typical cardiac transplant protocol and using redirectional techniques.

Beating Surgical Complications

Researchers refined the transplant protocol during three trials of 16 baboons. Baboons received hearts from pigs that were genetically edited to reduce interspecies immune responses and to prevent excessive blood clotting after surgery.

In the first attempt, they learned to use an ice cold storage solution, which is the typical method of organ storage before transplant procedures can cause tissue damage when the blood is recirculated through the heart. To prevent organ failure, they intermittently pumped an oxygenated blood-based solution containing nutrients and hormones held at 46 degrees Fahrenheit through the heart.

In the second attempt, they aimed at solving the problem of cardiac overgrowth in common-bone transplants. Although the pig iron is very similar to human and primary hearts, they are much larger and prone to complications that arise due to different hormonal and blood pressure differences. Transplanted hearts that continue to grow to a size larger than the recipient’s body can support can damage adjacent organs and cause death.

To prevent this happen, researchers gave babies medication to reduce blood pressure to levels found in pigs. In addition, they gave temsirolimus the primates – a drug that prevents overgrowth of the heart. Finally, they modified the typical treatment of cortisone therapy to combat immunosuppression in transplanted patients. Because cortisone can cause heart disease, they tapered the treatments a lot earlier than usual.

Using a combination of these techniques in the third trial, the post-transplant survival of the baboons was extended. Two lived healthy for three months – the duration of the study – before they were killed. Another two lived for six months before they were killed. A fifth baby involved in the trial developed complications and was euthanized after 51 days.

Although much more studies are needed before researchers can start xenotransplantation in humans, Reichart is optimistic on the horizon.

“I think technical expectations are resolved, but we need to produce more consistent results,” says Reichart. “We need further experiments and achievements. In addition to our funding from the German Research Foundation, we would need at least one private investor. Together, three years would be enough. “

In the short term, researchers said that the techniques used in the study could improve human transplant procedures. In addition, the discovery of pumping oxygenated blood and nutrients through stored hearts can increase the accessibility of the donor heart by preserving those who can not cope with a lack of normal blood supply due to age or underlying condition.

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