Pig Kidney Transplant Success: A Historic Medical Milestone

The field of organ transplantation changed forever in March 2024 when surgeons at Massachusetts General Hospital successfully transplanted a genetically edited pig kidney into a living patient. This event marks a significant leap forward in xenotransplantation, the process of transplanting organs from one species to another. For decades, this concept existed only in theory or limited experiments, but this surgery represents the first time a living human recipient has accepted a kidney from a non-human donor.

The Patient and the Procedure

The recipient of this groundbreaking transplant was Richard “Rick” Slayman, a 62-year-old man from Weymouth, Massachusetts. Slayman was suffering from end-stage kidney disease caused by Type 2 diabetes and hypertension. He had previously received a human kidney transplant in 2018, but that organ began to fail five years later, forcing him back onto dialysis.

With dialysis becoming increasingly difficult due to vascular access issues, Slayman was approved for the experimental procedure under the FDA’s “Expanded Access” protocol, often known as compassionate use. This protocol allows patients with life-threatening conditions to access experimental treatments when no other options exist.

The surgery took approximately four hours. Dr. Tatsuo Kawai, the transplant surgeon who led the team, reported that the kidney turned pink and began producing urine immediately after blood flow was restored. This immediate function is the primary indicator of a successful surgical connection and lack of hyperacute rejection.

The Science: eGenesis and CRISPR Technology

The kidney used in Slayman’s surgery did not come from a standard livestock animal. It was provided by eGenesis, a biotechnology company based in Cambridge, Massachusetts. Using CRISPR-Cas9 gene-editing technology, scientists made 69 specific genomic changes to the donor pig.

To ensure the human body would not attack the organ, the scientific team performed three distinct types of edits:

• Removal of Harmful Genes: Three specific pig genes identified as the primary triggers for rapid antibody-mediated rejection were knocked out (removed).
• Insertion of Human Genes: Seven human transgenes were added to the pig’s DNA. These genes are responsible for regulating inflammation and blood coagulation, helping the kidney appear “human” to the recipient’s immune system.
• Viral Inactivation: The team inactivated 59 endogenous retroviruses found in the pig genome. This step was critical to eliminate the risk of transmitting porcine viruses to the human patient.

Addressing the Organ Shortage Crisis

This medical milestone addresses one of the most persistent problems in modern medicine: the shortage of available organs. According to the United Network for Organ Sharing (UNOS), more than 100,000 people in the United States are currently on the waiting list for a transplant. The vast majority of these patients are waiting for a kidney.

The disparity between supply and demand is stark. Seventeen people die every day in the U.S. while waiting for an organ. By proving that porcine organs can be genetically modified to function in humans, researchers hope to create a sustainable, unlimited supply of organs. This would essentially eliminate the waiting list and reduce the need for dialysis.

Post-Surgery Outcomes and Legacy

Following the surgery, Rick Slayman recovered well enough to be discharged from the hospital two weeks later. His doctors noted that he was free from dialysis for the first time in nearly a year. This period of function provided critical data to researchers, proving that a gene-edited kidney could filter waste and balance fluids in a living human body.

Sadly, Mr. Slayman passed away in May 2024, approximately two months after the transplant. However, the transplant team at Massachusetts General Hospital stated there was no indication that his death was the result of the transplant itself. Slayman had a complex medical history involving multiple comorbidities. His willingness to undergo this procedure provided invaluable insights that will inform future clinical trials and potentially save thousands of lives.

Previous Xenotransplantation Attempts

While this was the first kidney transplant in a living patient, it builds on recent experiments involving brain-dead decedents. Researchers at NYU Langone Health and the University of Alabama at Birmingham (UAB) had previously connected pig kidneys to brain-dead human bodies maintained on ventilators to study rejection over short periods (days to weeks).

Additionally, the University of Maryland Medicine performed two separate heart transplants using pig hearts in living patients (David Bennett in 2022 and Lawrence Faucette in 2023). Both patients lived for several weeks, further advancing the science of immunosuppression and genetic editing required for cross-species survival. Slayman’s case is distinct because the kidney is a complex filtering organ, presenting different immunological challenges than the heart.

Frequently Asked Questions

Who was the donor of the pig kidney? The donor was a specially bred pig provided by eGenesis. The animal was raised in a sterile, bio-secure facility to minimize the presence of pathogens before the organ was harvested.

Did the patient reject the kidney? Initially, no. The genetic modifications successfully prevented “hyperacute rejection,” which usually happens within minutes of blood flow being restored. While long-term rejection remains a hurdle for xenotransplantation, the organ functioned successfully for the weeks following the surgery.

What drugs did the patient have to take? In addition to standard anti-rejection medications used in human-to-human transplants, the medical team utilized a novel experimental antibody called tegoprubart. This drug targets a specific immune system pathway to provide an extra layer of protection against rejection.

When will this be available to the public? This procedure is still in the early experimental stages. Before it becomes a standard treatment option, FDA-approved clinical trials involving more patients are necessary. These trials will determine the long-term safety and efficacy of the procedure. Experts estimate it could take several years before this becomes widely available.