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

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

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.

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

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

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

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.

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

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

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

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.

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

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.

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.

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

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.

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.

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.

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

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

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.

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).

Using mosquitoes to vaccinate bats could curb the spread of deadly diseases.

60 years after seeing Henrietta Lacks as a patient, her doctor still remembered the unique cervical tumor that gave rise to the 'immortal' cell line now commonly used in biomedical research—it was purple, shiny, and soft—an appearance he said is very different from a typical tumor.

Gene therapy treats a disease by editing the disease's underlying DNA, replacing it with a functional variant.

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.

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.

Epigenetic editing—altering gene expression by removing or adding chemical groups on DNA—is making significant strides in the lab, even lowering cholesterol in monkey experiments by about 70%. (Free w/email.)

Henrietta Lacks' tumor cells became the first recognized 'immortal' cell line about 75 years ago, but researchers are still investigating the specific mechanisms that enabled the cells to continuously grow and divide in the laboratory.

Synthetic biology can prevent extinction by creating create disease-resilient plants and animals

Through gene editing and the deployment of artificial cells, scientists can leverage learnings from the genetic sequencing of animals with known resistances to protect endangered species. Gene editing of certain species, such as mosquitoes, can also reduce their ability to spread diseases like malaria between humans.

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.

Scientists now know that Henrietta Lacks, a Black woman whose 'immortal' cancer cells were nonconsensually sampled and used for research, had been infected with human papillomavirus, a group of pathogens responsible for most cervical cancers.

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.

Two festival-goers were hospitalized after receiving trendy peptide injections, raising safety questions that may extend beyond the event.

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.)

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.

The scientist that biohacked a buff frog

If a tree frog was injected with a DNA mixture containing follistatin, a gene that may influence muscle growth, would it become buff? Josiah Zayner hopes so. By learning how to biohack animals, he hopes people are one step closer to feeling more comfortable "whipping up DIY gene therapy."

Despite the rules, a Nobel Prize in medicine has been awarded posthumously

Ralph Steinman, whose work revealed how dendritic cells activate immune responses, passed away just days before being named a Nobel laureate. Although Nobel Prizes cannot be awarded posthumously, the committee made an exception because they believed he was alive at the time of the decision.

Mosquitoes are the world's deadliest animal, but gene drives could kill them.

How to repair a baby’s broken heart

A rare disorder that prevents some babies from getting enough oxygen to their organs can be repaired through a series of three intricate surgeries. This article and graphic explain the process behind correcting single-ventricle defects, also known as SVDs.This disorder happens when one of the heart's lower chambers doesn't work correctly, resulting in deoxygenated and oxygenated blood circulating the body rather than just the latter.

Before vaccines, there was 'variolation': what was it?

Before the technology behind vaccinations was discovered, some keen observers of medicine around the globe noticed how previous infections could impact future ones. Learn about the techniques early physicians used before they had vaccines.

‘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.

Watch an expert's take on the rare disease hantavirus—and why it's not of great concern to the general population

This rare zoonotic disease, transmitted to humans primarily through infected rodent droppings, urine, or saliva, is rarely spread between people. The disease was of particular concern in spring 2026, when an outbreak occurred on a 150-person cruise ship, prompting a flurry of action, including contact tracing for passengers in their home countries. The disease can be fatal. But early care—primarily oxygen support—can help patients survive.

'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.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

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.

Brain death is a uniquely modern problem stemming from modern ventilators.

The deadly genetic disease that steals shut-eye

Few are haunted by fatal familial insomnia. This neurodegenerative disease is typically carried through bloodlines via genetic mutation of the prion protein gene, forcing the body to create abnormal and pathological protein variations that can corrupt normal versions. This article follows a musician as they attempt to come to terms with the FFI plaguing their family (and, possibly, their future).

The scandal that rocked stem cell research

In 2014, a Japanese research group published a paper suggesting ordinary cells could be reverted to pluripotent stem cells by subjecting them to external stressors. The results generated interest but could never be replicated. The lead researcher was accused of fraud, and the group’s supervisor committed suicide.

The US military, concerned about potential deployments worldwide, has long funded experimental hantavirus vaccines and therapies.

Collaborations between the military, biotech, and academic researchers led to an experimental antibody treatment for the Andes hantavirus strain—the one that more readily passes between humans. As of spring 2026, it had only been tested in animals. The US Army has also tested a potential hantavirus vaccine in people. It published early findings in 2023 that seemed promising, eliciting some immune system response. (Some users may encounter a paywall.)

Four frozen embryos in the US were created via 3-parent IVF technique

Columbia University researchers created four embryos using mitochondrial replacement therapy for four female patients who didn't want to pass on mitochondrial diseases to their children. Yet US law restricts the researchers from implanting the embryos so they remain frozen. (Some users may encounter a paywall.)