In a medical paper released on Tuesday in the journal of Nature Biotechnology, scientists from University Hospital Zurich unveiled a machine that successfully mimics the human body, allowing livers to survive outside a body for up to 10 days — far longer than the 12 hours most transplant experts consider safe using current methods.
Though the machine is still at least two years away from clinical use, researchers said, it aims to solve a continuous problem for transplant surgeons: Slowing down the race against the clock to transplant an organ, while ensuring every organ that can be used is.
“We offer a window of time to fix problems,” said Pierre-Alain Clavien, the study’s lead researcher and director of surgery at University Hospital Zurich. “Now, you can take a liver that is in poor shape … and to try to use medication or whatever you want to make [it] better.”
Transplant surgery is one of the most impactful innovations in modern medicine, experts note, allowing doctors to extend the lives of people who faced significant organ ailments. In 1954, surgeons at Brigham and Women’s Hospital in Boston performed the first successful transplant, giving a patient a new kidney donated from his twin brother. In the 1960s, liver, heart and pancreas transplants followed.
Since then, medical science has advanced transplant surgery techniques but has barely changed the way organs are physically moved and stored. When an organ comes up for donation, doctors furiously hop onto airplanes to retrieve it, and then shuttle back to the recipient — all within hours — trying to keep the organ in stable condition.
David Klassen, the chief medical officer for the United Network for Organ Sharing (UNOS), said having a machine that can expand the window for liver transplants from 12 hours to 10 days is a significant achievement. It could increase the supply of livers available for donation, a notable prospect given demand for liver donations outstrip supply across the world, he added. (Over 11,800 people were on the waiting list in America for a liver donation in 2021, according to U.S. government statistics, second only to those waiting for kidneys.)
With more time, transplant surgeons could make attempts to improve the state of livers that otherwise couldn’t be donated. Livers are often discarded for simply being too fatty, but with more time, surgeons could surgically reduce fat content. (In 2021, 944 of the 9,541 livers recovered for transplant were discarded, according to UNOS.)
Klassen also said it could alter the logistics of transplant surgery. Instead of patients being summoned to the hospital at odd hours of the night, they could schedule a procedure. Additionally, doctors wouldn’t have to rush patients into an operating room, giving them time to make sure their vital signs are stable or any infection in their body is dealt with. “It is a milestone,” he said.
In the past few years, other machines have landed on the market to improve the way organs — such as kidneys, lungs, hearts and livers — are stored. But Klassen said he does not believe any of these machines are used to extend transplant time into days.
“This differs from what has been done before,” he said, adding the Swiss researchers “have really extended the [transplant] window quite dramatically.”
Clavien’s team — a consortium of Swiss doctors and researchers from University Hospital Zurich, the University of Zurich and ETH Zurich — began working on their liver storage machine roughly six years ago. The device externally stores a human liver at 98.6 degrees and has machines attached to it that mimic heart, lung and kidney functions. Tubes attached to the liver can provide hormone and nutrient infusions, while flushing out toxins and providing the organ with antibiotics to keep it healthy while awaiting transplant.
But after making the machine, researchers had to prove it works. To do so, they found a liver available for donation in Europe. It was destined to be discarded because it had a tumor, but with three days to assess it in their machine, the researchers found the tumor to be benign and plied it with antibiotics to get it healthy. Once suitable for transplant, they put it into a patient. The study released this week noted the patient is not showing any adverse symptoms from the surgery, indicating the machine successfully stored the organ, researchers said.
In the next year or so, Clavien plans to replicate this process in 24 other patients, which would make a stronger case for clinical use, he said. Then his team will apply to the Food and Drug Administration, along with European regulators, for device approval. All told, he says the machine is roughly two years away from being in hospitals and is optimistic that it may be available for other organs.
“The machine [may] need some modification,” he said. “But I think the concept of preserving should apply to any solid organ.”
Shane Ottmann, a transplant expert and assistant professor of surgery at Johns Hopkins School of Medicine, said the machine is promising.
In the current system, where livers are stored over ice, the “preservation clock” can run out before doctors overcome logistical hurdles for an operation, such as coronavirus testing. They can also have limited time to improve the state of an organ to ensure it is suitable for donation.
“There are some livers that currently are not being used in the United States that could be used if you didn’t run out the clock,” he said. “This technology would help salvage some of those livers from discard.”
Despite that, Ottmann noted that challenges remain. Gaining FDA approval could be difficult. And given the price of the device is yet to be determined, it could prove prohibitive, especially because, he said, the current system for transplant operations works well.
“The current system works 90 percent of the time,” he said. “It [could] add a bunch of extra costs to transplants when it’s not needed.”