Xenotransplants are an experimental last resort for the terminally ill when they cannot or will not receive a human organ.

After the first gene-edited pig heart transplant patient died, a latent pig virus was discovered inside his xenotransplant.

Pig-to-human transplant work has raised concerns about donor pigs' living conditions.

Explore different pig-to-human xenotransplantation possibilities, including using pig pancreatic cells for treating diabetes.

Read why one man agreed to get a pig kidney in 2025 to replace his own failing organ

The 68-year-old New Hampshire man told USA Today that a motivator for the experimental surgery was his belief that he was going to die anyway, and other people suffering from kidney disease could gain valuable insights. Yet the surgery bought him time—he lived 271 days with a pig organ and later received a human kidney transplant. Clinical trials began in 2026 to test the pig xenotransplants in more people.

Chinese scientists transplanted a pig lung into a human being in 2025—but it had to be removed.

Pigs are of particular interest for xenotransplantation because they are close to human size, are easily raised in captivity, and have large litters.

Scientists may have discovered why gene-edited pig kidneys are rejected in humans

In November 2025, researchers studying how a brain-dead donor’s body responded to the transplantation of a genetically engineered pig kidney, published that they’ve identified immune system reactions that may explain why these pig organs get rejected. What’s more, they were able to reverse the rejections with an already available drug combination and the kidney functioned well. They also pinpointed a way to detect a potential rejection up to five days sooner.

One man lived with a gene-edited pig kidney for 271 days, setting a record, before he received a human kidney.

Cross-species transplantation has been attempted in medicine for more than 300 years.

See how pig heart valves have been placed in humans since 1965.

A first-of-its-kind clinical trial taps livers from gene-edited pigs to clean blood

The experimental dialysis-like treatment from United Therapeutics, eGenesis, and OrganOx, is designed to help people with liver failure. The therapy, which involves attaching the modified pig liver externally, filters a patient’s blood so their own livers can temporarily rest and perhaps heal.

In 1984, a dying infant lived for three weeks with a baboon heart inside her chest.

Pig organ transplants are apparently kosher—you just can’t eat them

Science writer Mary Roach speaks with journalist Terry Gross about her latest book, “Replaceable You: Adventures in Human Anatomy” and discusses topics including why pig organs have become of such interest and what religious leaders have told her about pig organs and compliance with Jewish dietary law.

The global xenotransplantation market may already be valued at more than $13B.

Donated hearts remain viable three times longer now with new tech

Advances in organ perfusion systems have significantly lengthened the amount of time donated hearts can remain viable for transplant, expanding the possibilities for donor organs to wider geographic areas. "Heart in a box" devices, developed in recent years, enable effective oxygen flow in the donor heart during transport, which means that hearts can now travel farther to potential recipients and still be in good condition.

The first successful organ transplant was performed in 1954

The successful kidney transplant procedure, at what's now-called Brigham and and Women's Hospital, ushered in a new medical era and gave hope to patients with organ failure. The recipient, 23-year-old Richard Herrick, lived eight more years after receiving the donated organ from his living twin brother, Ronald.

Transplant organs don't always last a lifetime—that's where retransplants come in

How long a transplanted organ lasts depends on a variety of factors including the type of organ and the health of the recipient. Sometimes organs can last many decades, but other times people may need retransplants, which means another transplant following a previous one. Retransplants are most common with kidneys.

How heart transplants work

Heart transplants require an old heart to be removed and a new one to be installed without killing the patient. How does that work? In this easy-to-understand five-minute video, learn each step of the intricate process, from donor matching to the preservative solution a heart is doused in while it is transported.

Pig brain cellular activity was restarted hours after death in study published in 2019

Yale University scientists restored basic cellular activity and circulatory function in pig brains about four hours after death with a synthetic cocktail of preservatives and nutrients. This work— which didn't restart electricity activity in the brain or consciousness—could help advance future human stroke and brain injury treatments.

Alpha-gal allergy is a problem for red meat lovers, and that same alpha-gal sugar is an issue for xenotransplants, too—since it's present in pigs, human bodies reject pig-to-human transplants as foreign once they detect the substance.

US federal researchers are blocked from putting certain human cells in animals

In 2015, US policymakers put a halt to any government-funded work that would insert human stem cells into animals. The reasoning was that human cells might spread through the animal's body and perhaps to its brain, blurring the line between humans and nonhumans. The ban remains in place today even as gene-edited pig parts are being placed in humans.

Transplanted organs can be rejected by the body immediately, months after transplant, or slowly over years

Organ rejection remains a huge challenge for organ transplant recipients. Rejection occurs when a recipient's immune system identifies a transplanted organ as foreign and attacks it. Recipient-donor screening processes try to match antigens to help reduce this risk.

Living donations most commonly involve a kidney or part of a liver

In 2023, more than 6,900 transplants were made possible thanks to living donors. Living donation is when a living person donates an organ or part of an organ—usually one of their two kidneys or part of the liver, since that organ can regenerate in a healthy person. Much more rarely, living donors donate other organs. Living donations often occur when someone wants to ensure a loved one has certainty that they will quickly receive a needed organ.

When was the first blood transfusion?

In the 1600s, an English doctor transferred the blood from one dog to another via quills. The procedure ended when one of the dogs died. This article details the early days of blood transfusions, which turned toward humans shortly after the 1666 dog experiment and involved putting the blood of a sheep into a human recipient (who reportedly survived the encounter).

Organ transplants can come with a price tag of more than $2M without insurance

According to 2025 report data that was graphically represented by Statista, average costs for organ transplants can be as steep as $2.3M for a double lung transplant and $1.9M for a heart. These figures are based on what was actually charged to insurance companies—not what individual patients paid. Following the actual transplant there are also additional costs associated with the procedure, including lifelong immunosuppressant drugs.

In 2024, the US had more organ transplants than ever before—besting the 2023 record

More than 48,000 organ transplants were performed in 2024, and about 46,630 were performed in 2023. These record highs are illustrated here as part of data from 1988 to partway through 2025. Kidneys, livers, and the heart remain the most common transplanted organs. (Some users may encounter a paywall.)

As of 2025, perfect synthetic replication of natural organs remains elusive

Advancements such as 3D printing muscles, performing vaginal reconstruction with colon tissue, and growing organs in a lab have shown promise, but artificial options and transplanting substitutions continue to exhibit functional and performance limitations compared to their natural equivalents.

NSF-funded research into matching algorithms improved the success of organ transplants

Investigations in game theory, including concepts focused on creating mutually beneficial partnerships—matching theory—led to the design of computer systems that efficiently matched kidney recipients and live donors, resulting in higher-quality matches. By 2019, these matching algorithms were used for multi-organ exchanges.

Brain death is a top source of organ donation

Brain death is a significant source of organ donations—approximately 40% of organs in the US and the UK are recovered from people who experience brain death. Patients declared brain dead and hooked up to intensive care unit machines will still have oxygen flowing to organs like the heart, lungs, and kidneys—preserving those organs.

Without the option of modern blood transfusions, some doctors in the mid-1800s tried to help save cholera patients by injecting them with cow's milk, hoping it would boost their nutrition and hydration.

'Donation after circulatory death' is on the rise

This occurs when a patient in a coma is on life support and family members agree to donate the organs. Watch this video about a 2025 New York Times investigation that identified 12 instances across nine states of bungled or premature attempts to retrieve organs from people whose families had authorized withdrawal of life support.

A clinical trial is underway in 2026 to help kidney transplant recipients avoid a lifetime of immunosuppressing drugs

This later-stage clinical trial, in Chicago and Taiwan, evaluates the efficacy and safety of a new cellular therapy that may be swapped in for immunosuppressing drugs among kidney transplant recipients. The study randomizes people to either receive standard immunosuppressants or this cellular therapy and fewer immunosuppressants. It only includes kidney transplant recipients receiving organs from live donors so transplant surgery timing won't hinge on the unpredictable schedule of performing surgery and follow-up care when a donor dies.

Research advances suggest death takes much longer than we realized

Recent research indicates that organs, including the brain, are better at handling a lack of oxygen after the heart stops beating than previously known. Such findings may open up possibilities that include someday reversing certain death processes and expanding the availability of organs available for organ donations. (Some users may experience a paywall.)

Immunosuppressants enable organ transplants, but come with severe side effects

This drug cocktail helps to lower your body's natural response to attack a transplanted organ. Such medications usually need to be taken for a lifetime after receiving an organ and can come with serious side effects including high blood pressure, diabetes, increased risk of some cancers, and high cholesterol, among others.

Listen to why thousands of donated human kidneys are thrown away annually, even as thousands of people are awaiting a kidney transplant.

How personalized gene-editing saved a baby's life

KJ Muldoon had a 50% chance of surviving a genetic mutation until doctors developed a one-of-a-kind gene-editing therapy. In an interview with one of the researchers behind the treatment, learn what it will take to make personalized genetic medicine possible for everyone.

Scientists using gene therapy recently managed to regenerate retinal cells in the lab—a breakthrough for mammals that could potentially lead to future treatments for human retinal diseases.

Artificial intelligence may improve organ donation systems—and even organ health

Mayo Clinic transplant experts suggest that artificial intelligence could potentially improve organ donation systems in several ways, including better identifying patients most at risk for organ rejection, enhancing donor-recipient matching, and helping to avoid organ transplant needs by identifying health issues earlier.

Brain death is a top source of organ donation

Brain death is a significant source of organ donations because patients declared brain dead and hooked up to intensive care unit machines will still have oxygen flowing to organs like the heart, lungs, and kidneys—preserving those organs.

‘Hope for Healing’: The first-ever use of an in utero stem cell treatment

In 2023, researchers at UC Davis performed the first-ever fetal stem cell transplant, attempting to cure a case of spinal bifida prior to childbirth using stem cells derived from the placenta. The trial, and others including an effort to treat muscular dystrophy, highlight the potential power of stem cell therapy.

Gene therapy, a hope of the Human Genome Project, has successfully treated a baby born with a rare urea cycle disorder that causes toxic ammonia level buildup.

Using artificial wombs to improve preterm infant health outcomes

Researchers at a hospital in the US have successfully used artificial wombs to care for preterm lambs and are now looking at the possibility of human trials. This nine-minute video includes interviews with the researchers and explains the reasoning...

Leonard Thompson was the first human to receive an insulin injection for diabetes

In January 1922, the 14-year-old was the first person to receive an insulin injection to treat diabetes, just months after insulin was isolated in dogs and used to treat their induced diabetes. Thompson had an allergic response to an apparent impurity in the injection, but his second dose, 12 days later, was a success.

Tech entrepreneur Bryan Johnson's mission to live forever

Johnson has invested millions of dollars into developing a biohacking program he believes will extend his life beyond typical expectations, relying on medical professionals to reduce his "biological age." Most notably, he drew significant public attention with reports of blood-swapping with his teenage son.

Biotech is trying to boost drug production efficiency—using chicken eggs

A company called Neion Bio is genetically engineering birds in a bid to produce medical compounds, a herculean task that scientists have struggled with for decades. The US FDA has approved only one chicken-derived drug in the past—an expensive treatment for a rare liver disorder. (Some users may encounter a paywall.)

Eight British children have been born via mitochondrial replacement therapy

In July 2025, a decade after British lawmakers signed off on allowing three-parent IVF, scientists announced that eight healthy babies had already been born using this approach. The news was included in a pair of research articles published in a peer-reviewed journal that noted the oldest kids were already more than two years old, and that they were hitting developmental milestones as expected. (Some users may encounter a paywall.)

A scientist successfully treated her own breast cancer by injecting the tumor with lab-grown viruses.

A planned clinical trial to treat a rare lysosomal storage disorder in utero has buoyed hopes of providing prenatal gene therapies, but it was still awaiting FDA approval to begin enrolling patients as of May 2026.

Gene therapy can occur inside the body, but it can also be completed outside the body—with scientists treating cells in the lab, and then those corrected cells are transplanted back into the body.

See the first dog ever treated with insulin—a peptide

Frederick Banting and his graduate student Charles Best were the first to isolate the peptide insulin from dogs. They induced diabetes in the animals and then treated them with this peptide.