Pig Kidney Transplants in Humans: Xenotransplantation Explained by Experts

• Pig kidney transplantation (xenotransplantation) is now being tested in humans
• Scientists use gene editing to make pig kidneys more compatible with the human body
• Early results show pig kidneys can function in humans
• Kidney xenotransplantation clinical trials have started.
• Experts are hopeful the treatment will be approved within the next 5 to 10 years

To understand what this breakthrough could mean, we spoke with:

Xenotransplantation is the process of transplanting organs between different species.

“When a kidney is transplanted from one human to another, we call that allotransplantation,” Dr. Kumar said. “Xenotransplantation means transplanting organs or cells from another species into humans.”

In terms of kidney xenotransplantation, researchers are using donor kidneys from pigs. 

But these aren’t ordinary farm pigs. Scientists carefully edit the pigs’ genes to make their organs more compatible with the human immune system.

Learn more about xenotransplantation.

More than 90,000 people in the U.S. are currently waiting for a kidney transplant. There aren’t enough kidneys available. 

“The demand for kidneys far exceeds the number of available kidneys,” Dr. Riella said. “Even with living donation and deceased donation, we’re not able to meet the need. That’s why exploring alternative sources of organs is so important.”

Researchers hope pig kidneys could help bridge the gap–especially for people who don’t have a clear or quick path to transplantation. 

Learn more about the kidney waitlist. 

One of the biggest challenges is the human immune system, which will quickly recognize a pig kidney as foreign and destroy it.

To solve this problem, scientists use advanced gene-editing tools like CRISPR. 

Researchers use gene editing to:

• Remove pig genes that trigger immune rejection
• Add human-compatible genes
• Reduce the risk of infections being passed from pigs to humans

Dr. Riella described these tools as “magical scissors” that change the pig's DNA to make it less likely to reject.

Learn the history of xenotransplantation.

Yes, but only in carefully controlled research settings.

Scientists first tested pig kidneys in animals. Then, researchers performed experimental xenotransplants in deceased donors to study how pig kidneys function in the human body.

These studies helped answer important questions about:

• Kidney function
• Immediate rejection risks
• Safety monitoring

Then, NKF partnered with the FDA to bring the patient and caregiver voice to the table. NKF’s Patient-Focused Drug Development Meeting on Kidney Xenotransplantation is credited with laying the groundwork for the FDA to move forward with the first compassionate use case. 

In March 2024, scientists performed the first living kidney xenotransplant under compassionate use. Compassionate use allows doctors to perform experimental procedures with people who are terminal with no other treatment options. 

In 2025, the findings from these studies suggested that these pig kidneys could be used in humans. Only then did the FDA approve clinical trials with living patients starting in the fall of 2025.

Read about Tim and Towana’s kidney xenotransplantation. 

As exciting as xenotransplantation is, it’s also new. That means there are still some common myths that need to be busted. 

This is not true.

“The pig kidney remains genetically different from the patient,” Dr. Riella said. “It performs the job of filtering blood and maintaining balance in the body, but it does not integrate into the patient’s DNA or alter their genetic makeup in any way.”

In other words, the kidney does its job, but it does not rewrite the body’s genetic code.

“We’ve been using pig-derived medical therapies, like pig heart valves, for a long time,” Dr. Kumar said. “These kinds of technologies have safely helped people for many years.”

Another major concern is whether infections could pass from pigs to humans and potentially to others.

While this will still be discussed with patients interested in clinical trials, Dr. Riella describes the extensive screening and very low risk:

“There are multiple layers of safety built into the process, from screening and monitoring the donor animals to closely following patients after transplant,” Dr. Riella said. “We use sensitive testing methods to detect any potential infections early. So far, the data we have is reassuring.”

This is a very reasonable concern, and one researchers are actively studying.

People have asked questions like:

• Will a pig kidney work in a human body long-term?
• Does it function differently because pigs walk on four legs and humans stand upright?

“These are thoughtful, important questions,” Dr. Kumar said. “Pig kidneys can function the same as human kidneys. We still need more data to understand how well they perform long term and in a wider group of patients.”

Right now, there are multiple trials underway, testing different types of genetically engineered pig kidneys.

These trials include: 

• United Therapeutics’ EXPAND trial: Studying a kidney with 10 gene edits (UKidney)
• United Therapeutics’ Extend trial: Studying a one gene-edited kidney combined with thymus tissue, which plays a role in the human immune system. (UThymoKidney)
• EGenesis Trial: Studying a 69 gene-edited pig kidney (EGEN-2784)

“These are different products with subtle differences,” Dr. Kumar said. “The outcomes will shape the future immunologic protocols, biosafety standards, and ethical frameworks aimed to position xenotransplant as a potential long-term solution.”

Because pig kidney xenotransplants are still in early clinical trials, eligibility has both clinical and geographic limitations. 

“At this point, patients need to be within a certain geographic vicinity of the transplanting center,” Dr. Kumar said. “There is a lot of follow-up and monitoring required after transplant.” 

For example, the first participants will likely need to live close to a participating transplant center due to the need for long-term monitoring and as a precautionary measure if any adverse events occur after transplant. 

Participants will likely also require a strong support system. 

“We won’t accept a patient who wouldn’t have a family member or a loved one also accepting the protocol and agreeing to help after the transplant,” Dr. Riella said. “It needs to be a partnership between all sides.” 

As of March 2026, only a small number of centers are participating in the clinical trials, including: 

• NYU Langone Health
• Massachusetts General Hospital

This list may expand as the trials progress.

People interested in participating are encouraged to share their interest with their healthcare team and the centers participating in the trials. Even if you don’t live near a current site, sharing interest can help you stay informed as more centers begin offering trials.

Stay up-to-date with clinical trials. 

Before pig kidneys become available, the clinical trials need to prove that pig kidneys are safe, effective, and capable of long-term function.

“I’m optimistic that xenotransplant will be available in five to ten years,” Dr. Kumar said. 

Dr. Riella agreed.

“This field has moved from theory to reality much faster than many people expected,” he said. “It’s still early, but it represents a very real and important step forward.”

Learn more about NKF’s role in the xenotransplant clinical trials. 

Yes. Both doctors stress that xenotransplantation will not replace human donation anytime soon.

“We’re optimistic, but also cautious,” Dr. Riella said. “There’s still a lot we need to learn through clinical trials before this becomes a standard treatment. Our goal is to move forward responsibly while continuing to build on what we’ve learned so far.”

Living kidney donors and deceased donor organs remain the best treatment options currently available.

“People on dialysis know how to endure. Xenotransplantation gives that endurance a future,” Dr. Kumar said. “This isn’t the end of the road. It’s the first light at the end of the tunnel.”

Xenotransplantation won’t be available overnight. But the clinical trials represent real, meaningful progress.

Watch videos from kidney donor recipients to learn how to find your own donor.