First pig-to-human liver transplant performed in China

A 71-year-old man became the first living person to receive a genetically modified pig liver transplant . The procedure was carried out in May this year at First Affiliated Hospital from the Anhui Medical University, in China. In an interview with Nature magazine, Sun Beicheng, lead transplant surgeon, says that the patient “is doing very well”.

This is the fifth xenotransplantation — a transplant carried out between different species — carried out in the world using a pig organ. In March of this year, the first pig kidney transplant was performed on a living human patient. In 2022 and 2023, pig heart transplants were performed on living humans. A little earlier, in 2021, a porcine kidney procedure was performed on a brain-dead patient.

Previously performed transplants have allowed researchers to obtain valuable information about the feasibility of xenotransplantation. The expectation of doctors and researchers in the field is that the procedure can provide organs to thousands of people waiting for a donor.

Pig liver xenotransplants are part of a growing field. In January, a US team plugged a genetically modified pig liver outside the body of a clinically dead person. In March, a transplant with the same type of organ was also performed on a clinically dead individual, with the authorization of his family. The liver remained in the body for ten days and showed no signs of rejection.

In May this year, another Chinese team also transplanted a pig kidney and liver into a clinically dead person.

How was the procedure performed?

In the recent pig liver transplant, the patient who received the organ had a large tumor in the right lobe of his liver and was not eligible to receive a human organ because tests indicated that his liver was “functioning too poorly” to guarantee a good outcome. post-surgery.

According to Beicheng, the left lobe of the liver alone would be unable to keep him alive and the situation was “very dangerous.” Therefore, the patient and his family would have shown interest in xenotransplantation. The surgical team then obtained approval from the hospital's ethics and transplant committees.

On May 17, an operation was performed to remove the patient's right lobe, in a surgery that lasted eight hours. The organ was replaced with a 514-gram liver from an 11-month-old pig that weighed 32 kilograms.

To prevent the pig organ from being rejected by the recipient's body after transplantation, the pig was subjected to ten genetic modifications, according to Hong-Jiang Wei, a geneticist at Yunnan Agricultural University in Kunming, China — his team was responsible for the genetic changes carried out in the organ. Three genes that contribute to the production of sugars on the surface of porcine cells, attacked by the human immune system, were deactivated, and seven genes that express human proteins were introduced.

According to Beicheng, the team did not detect the presence of porcine cytomegalovirus in pig liver tests, which reduces the chances of complications for the recipient.

After surgeons restored blood flow to the transplanted pig liver, the organ began secreting bile — from 10 milliliters on the first day, bile production gradually increased to 200-300 mL on the 13th day (a healthy person secretes, on average, 400 mL of bile per day). Furthermore, doctors have seen no signs of organ rejection in recent days.

“This is a very positive result,” Jay Fishman, a transplant infectious disease specialist at Massachusetts General Hospital in Boston, tells Nature. “In general, you don’t see these good signs if the organ is experiencing rejection.”

On day 10 after the transplant, doctors still haven't seen signs of liver growth, but they are optimistic. Beicheng hopes that the left lobe of the human liver will grow large enough to provide full liver function and that the pig liver will serve as a “bridge” to get to that point.