Transplanting organs from non-human animals into people could revolutionise medicine, potentially saving . Scientists have previously experimented with giving people pig hearts and kidneys, and have now reported transplanting the animal’s liver into a living person for the first time.

“This is really, really groundbreaking,” says at Hannover Medical School in Germany, who wasn’t involved in the procedure. “The patient was close to dying, but due to the transplant, he survived for half a year.”

The liver’s complexity meant such surgeries had only been , with signs of success. “The heart is just a muscle pumping blood,” says Wedemeyer. “The kidney is also easy, because it needs only to clear things from the body. But the liver is different because it produces so many different proteins involved in so many metabolic processes.”

The heart and kidney transplants in living people similarly showed signs of early success, but complications later arose. With the heart transplant, this was linked to it possibly transferring over a pig virus.

Now, at Anhui Medical University in China and his colleagues have reported the transplantation of a pig’s liver into a 71-year-old man. The recipient’s liver function was considered too poor for a conventional transplant to have a good chance of success, due to a large tumour and heavy scarring from a hepatitis B infection. Thousands of people die each year waiting for a liver transplant, so each procedure must be carefully justified, says Sun.

The man still required some form of transplant, though, as his tumour could have fatally ruptured at any moment, says Sun. With the recipient’s permission, in May 2024, Sun and his team replaced the right part of his liver, containing the tumour, with one from an 11-month-old miniature pig. The five-hour operation involved them connecting blood vessels from the pig’s liver with those in the left side of his own organ.

Free newsletter

Sign up to 91ɫ��Ƭ Check

Sign up to newsletter

To prevent the liver being rejected by his immune system, three genes were deactivated in the pig and seven genes were introduced, so the organ functioned more like a human one. The man also took immune-suppressing drugs, and the team carefully checked that the liver wasn’t infected with any porcine viruses.

Almost immediately, the liver began secreting bile, a fluid the organ produces to help break down fat from food. Within weeks, the recipient’s levels of bile and albumin – a protein made by the liver that prevents too much fluid leaking from blood vessels – had increased to healthy amounts, says Sun.

But about a month after the procedure, he developed life-threatening clots in his blood vessels, forcing the team to remove the transplant. That was probably partly caused by it excessively activating part of the recipient’s immune system and producing abnormal levels of some blood-clotting proteins, which healthy livers also make. This is probably more likely to occur with pig transplants, due to how different the animal is to a human, says Sun.

The man lived for about another five months, with just the left side of his liver, then died from stomach bleeding, which is , says Sun. Both Sun and Wedemeyer say the bleeding was probably unrelated to the transplant.

Why everything you thought you knew about your immune system is wrong

Immunologist Daniel Davis wants to eradicate long-held myths and replace them with wonder at the complexity of the body’s defence system

Despite the man’s death, the procedure can still be considered a partial success, because he probably otherwise would have died soon after his tumour was removed, says Wedemeyer. What’s more, the recipient’s own liver partly regenerated while the transplant was functioning well, which is probably why he lived for months after it was removed, he says.

This procedure has furthered our understanding of xenotransplantation, raising the possibility that pig livers could buy time for those waiting for human transplants, says Wedemeyer. They could even enable remaining liver tissue to regenerate enough that people no longer need the procedure, says Sun.

But it will probably be at least a decade before pig livers can be used to permanently replace human ones, says Sun. We first need to substantially reduce the risk of complications, for instance through further genetic modifications, says Sun.

Instead of administering general anaesthesia, which is the default for such an operation, doctors gave a spinal anaesthesia, similar to that used during Caesarean sections. The transplant took less than 2 hours.

Nicholas was completely aware and awake during his surgery, but experienced “no sensation whatsoever” and was able to talk with the surgeons about the different milestones they reached during the procedure.

After a successful operation on 24 May, he was discharged the next day, walking out of Northwestern Memorial Hospital. The normal stay there for kidney transplant patients is two to three days.

This new option may increase access to transplantation for people who are at high risk of complications from general anaesthesia, while also decreasing time spent in hospital. ⁠

When children with heart failure await transplants, they typically stay at the hospital for months to years, tethered to a bulky blood-pumping device. But an implantable heart pump could allow them to wait at home.

Regulators in the US and Europe have approved one device, the Berlin Heart, for long-term use in younger children awaiting a heart transplant. But this life-saving tool comes with limitations, says at Stanford University in California. It attaches to the heart via two large tubes, hindering children’s movement. Berlin Heart also requires that children remain in hospital so they can be monitored for risks like stroke and infection.

Almond and his colleagues tested a newer device, the Jarvik 2015, in seven children with heart failure between 7 months and 7 years old. It can be implanted into the heart and connects to an external battery pack worn at the waist. The device works by pumping blood from the heart’s left ventricle into the main vessel that sends blood throughout the body.

The researchers implanted the pump during open-heart surgery, monitoring children in hospital afterwards. On average, children used it for 115 days. All seven survived and five received heart transplants. Of the other two, one spontaneously recovered while the other switched to a device that also supports right ventricle function after their heart’s right side failed, unrelated to the Jarvik 2015. One child experienced a severe stroke, a known risk of cardiac assistive devices.

Most children didn’t experience any pain with the device and they were able to engage in most activities. “With less material outside the body and not being tethered to a large pump, that child is actually able to be a bit more free and move around,” says Almond.

Larger trials must investigate whether the pump could enable children to wait for a transplant at home, says Almond. Children in the US typically wait three to 12 months for a transplant, while those in Europe may wait up to two years.

Free newsletter

Sign up to 91ɫ��Ƭ Check

Sign up to newsletter

“The Berlin Heart is very successful, bridging patients to transplant, and we’ve become quite expert in the use of it,” says at Boston Children’s Hospital. “[But] we hope that new devices will be able to allow children be discharged home, like adults.”

Is this the first ever pig kidney transplant?

When did the surgery take place?

Where did the pig kidney come from?

Free newsletter

Sign up to 91ɫ��Ƭ Check

Sign up to newsletter

What do we know about the recipient?

Have there been xenotransplant procedures involving other organs?

In a world first, surgeons have performed an eyeball transplant. It is uncertain if the recipient will be able to see using his new eye, but the procedure remains a significant step towards one day restoring vision in people who have experienced severe eye injuries.

On 27 May, at NYU Langone 91ɫ��Ƭ in New York and a team of more than 140 others performed the eye transplant alongside a partial face transplant in Aaron James, a 46-year-old power line worker from Arkansas. To date, fewer than 50 facial transplants have been performed and none included an eye. Whole-eye transplants were previously deemed nearly impossible due to the organ’s complexity.

“I would like to thank the donor and the donor family. Without them, none of this could have been possible. I have the utmost respect for them to make this decision, to help people they don’t know, to give me this gift,” said James during a press conference on 9 November. “Before the transplant, emotionally, I was a little down. My confidence level was a little low. But since the transplant, I tell people I can’t walk past the mirror without looking at it. It has made me stand up taller. It’s great.”

James was severely injured in June 2021 after his face touched a live wire, sending a 7200-volt shock through his body. He lost most of the left side of his face, including his left eye, as well as much of his left arm.

Rodriguez and his team transferred the nose, lips and bone segments underlying the left cheek and chin of a deceased donor to James, along with most of the tissue beneath the right eye. They also transferred the donor’s entire left eye including the eyelids, eyebrows and eye socket. The procedure lasted about 21 hours.

The first challenge was extracting the intricate network of blood vessels surrounding the eyeball. Unlike other facial features, the eye receives blood from the brain region directly behind the eyeball. So, the surgeons had to partially remove the donor’s skull to access these vessels.

Free newsletter

Sign up to 91ɫ��Ƭ Check

Sign up to newsletter

To avoid having to remove part of James’s skull too – which would have meant operating near his brain – the surgeons connected the vessels to others in the donor’s face. This allowed the team to re-establish blood flow to the eye within 25 minutes of the surgical procedure and bypass the brain. Then later, during the transplant itself, they connected these vessels to some in James’s neck.

Removing the donor’s skull also gave surgeons better access to the optic nerve. This bundle of nerve fibres transmits information from the eye to the brain, enabling us to see. Doctors have never successfully reconnected a severed optic nerve. In an attempt to do so, Rodriguez and his team preserved as much of the donor optic nerve’s length as possible. This, they reasoned, would maximise the chances of the nerve fibres regenerating and establishing a connection with James’s brain.

They also took stem cells – which can develop into different types of specialist cells – from the donor’s bone marrow, and injected them into the site where the donor optic nerve and James’s optic nerve met, to further stimulate nerve growth.

More than five months after the surgical procedure, the eyeball appears to be healthy. It has sufficient blood flow and internal fluid pressure and can produce tears. Some of the nerve cells critical for sight are also alive, though James is unable to see using the eye and might never be able to do so, says Rodriguez.

“That’s an achievement, just keeping the globe viable, alive and healthy,” says at Johns Hopkins University in Maryland, who wasn’t involved in the surgery. “[But] we need to be careful about raising people’s expectation or hopes in excess of what’s technically feasible at this point.”

“I think from our standpoint, the fact the individual survived the operation, the fact we’ve not had any complications whatsoever – and there could have been many – is a success,” says Rodriguez.

James can also eat and breathe on his own thanks to the surgery. “We forget about those [aspects] because everyone’s so focused on the eye. But the fact that we can given this person another chance at a normal life with the possibility of some form of sight is wonderful,” says Rodriguez.