Article Highlights
- On July 14th, a genetically modified pig kidney was transplanted into a brain-dead human donor
- The transplanted kidney functioned for 32 days, the longest time a pig kidney has functioned in a human
- This record breaking procedure may offer new hope for the thousands of people waiting for a kidney transplant
Earlier this year, a 57 year old man named Maurice “Mo” Miller died suddenly from undiagnosed brain cancer. He was a registered organ donor, but due to his cancer, he was deemed unfit to donate his organs. After his death, his sister Mary-Miller Duffy consented to allow researchers at NYU Langone attempt a groundbreaking experiment – to transplant a pig’s kidney into a human.
I think this is what my brother would want. So I offered my brother to them
There are currently more than 100,000 Americans on the organ donation waiting list, and 88,000 of those people are waiting for a kidney. However, on average only a fraction of those on the waiting list will receive an organ, and seventeen people die every day while waiting for a kidney transplant.
To address this organ shortage, scientists have experimented using organs from other animals, like pigs. Pigs are considered ideal for animal-to-human transplants, called xenotransplants, for several reasons. First, pig breeding is a well developed and extremely cost-effective process. Pigs reproduce quickly and produce large litters. More importantly, the size of pig organs are comparable to those of humans.
The Transplant
The transplant team at NYU has a lot of experience in xenotransplantation. This procedure marked the fifth xenotransplant and the third pig kidney transplant conducted at NYU. The study was led by Dr. Robert Montgomery, chair of the Department of Surgery and director of the NYU Langone Transplant Institute.
The first step of the procedure is to obtain the donor organ. In this case, the pig kidney was obtained from Revivicor Inc., a biotechnology company whose vision is to generate “an unlimited supply of organs” using gene-edited pigs. The company breeds GalSafe pigs, genetically modified animals that lack the alpha-gal gene, a gene responsible for antibody-mediated organ rejection. These pigs were FDA approved in 2022 as a source for therapeutics. After extensive testing for potential pig-borne diseases, the kidney was ready for transplant.
To begin, the patient’s own kidneys were removed to ensure that any functional results were coming only from the pig kidney, with no assistance from the human kidneys. Then, the single pig kidney was transplanted. The surgeons also attached the pig’s thymus to the transplanted kidney in efforts to increase immune tolerance.
After the procedure, the research team found that the pig kidney almost immediately started producing urine, and successfully replaced the function of a human kidney for 32 days. During that period, researchers observed no signs of organ rejection. The investigators plan to continue monitoring the pig kidney transplant for another month, with the family’s permission.
He’s going to be in the medical books, and he will live on forever
Mary Miller-Duffy
One of Many Success Stories
This is one of several recent success stories involving pig organ transplants. On August 16th, a report from the University of Alabama at Birmingham (UAB) announced the successful transplant of two pig kidneys into a brain-dead human patient, and they functioned normally for seven days. This study was led by Dr. Jayme Locke, director of UAB’s Comprehensive Transplant Institute.
The researchers at UAB found that the transplanted kidneys produced urine within four minutes and produced more than 37 liters of urine in the first 24 hours. Furthermore, the kidneys effectively filtered creatinine from the blood, a waste product that is produced by the natural breakdown of muscle tissue. This waste filtration demonstrated, for the first time, that the pig kidneys are capable of performing life-sustaining function in a human. The results of this study were published as a research letter in JAMA Surgery.
The research team at UAB uses the Parson’s model, a preclinical model of human brain death, to evaluate the safety of pig-to-human transplants. The model was named after Jim Parsons, an organ donor whose body was donated to science to conduct the first clinical grade pig kidney transplant into a human. However, before pig kidney transplants can become a viable treatment option for patients with kidney failure, it will be necessary to test the transplants in a living human.
In January 2022, David Bennet became the first living human to receive a pig heart transplant. The heart transplant functioned for more than two months. Unfortunately, Mr. Bennet died due to a preventable disease contracted from the pig heart. Mr. Bennet was ineligible for a human heart transplant. Therefore, the pig heart extended his life when he had no other hope and showed that some day, pig organs may help save the lives of thousands of people who need an organ transplant.
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