A man who lived for 271 days with a pig's kidney until a human kidney was received

Tim Andrews, a 66-year-old American who received a genetically modified pig kidney transplant at Massachusetts General Hospital in Boston, has set a new record in medical history by successfully living with the organ for 271 days. He became the person who lived the longest with an animal organ, freed from two years of prior dialysis treatments, and subsequently successfully received a human kidney transplant.

According to a report published in 'The Lancet' medical journal, doctors were able to transplant a human donor kidney into Andrews after removing the pig kidney. This marks the world's first instance where an animal organ was used as a temporary life-sustaining bridge until a human kidney became available, followed by a successful transition to a human organ.

Dr. Leonardo Riella, Medical Director of the Kidney Transplant Program at Massachusetts General Hospital, points out that organ shortage is the biggest crisis facing the current transplant field, and that transplanting animal organs into humans could provide a solution to this shortage. In 2025, 53,343 patients in the European Union and over 100,000 people in the United States were on organ transplant waiting lists, and while dialysis services sustain life, the patient's quality of life gradually deteriorates.

Attempts to transplant animal organs into humans have been ongoing since the early 20th century, with efforts to transplant hearts and kidneys from pigs, sheep, baboons, and chimpanzees. In 1964, a woman named Edith Parker lived for nearly nine months with a chimpanzee kidney, and Andrews succeeded in surpassing that duration six decades later.

Cutting-edge CRISPR gene editing technology has been used to prevent the human immune system from rejecting foreign organs. The American company eGenesis made 69 genetic modifications to the pig's DNA, which involved preventing immediate rejection, incorporating human genes to control inflammation and blood clotting, and deactivating retroviruses that could potentially transmit viral infections from animals to humans.

After the surgery, the pig kidney immediately began functioning, producing between four and five liters of urine per day and purifying the blood. However, after two weeks, doctors were able to control the immune attack on the organ by T-cells using standard immunosuppressive drugs.

Despite Andrews facing other serious health issues such as a foot infection and a heart condition, the kidney continued to function. However, after six months, when the medication dosage was reduced to treat a bacterial infection, the body's natural immune cells (macrophages and Natural Killer cells) damaged the kidney's blood vessels and caused blood clotting, necessitating the removal of the organ on day 271.

Approximately two months after the pig kidney was removed, a suitable human donor was found, and the new human kidney has been functioning successfully without complications for seven months since the transplant. Beatriz Dominguez-Gil, Director of the Spanish National Transplant Organization, states that this confirms the possibility of using animal organs as a bridge until a human organ becomes available in the future, while experts point out that further research is needed to control rejection caused by natural killer cells and to protect blood vessels.