A team of doctors at NYU Langone transplanted a pig kidney into a brain-dead patient and reversed its rejection twice during the 61-day study.
Currently, estimates of the number of organs needed in the U.S. for transplants has reached approximately 108,000 patients. One procedure being studied is pig kidney transplants. Faced with an immense shortage, scientists believe it has potential. However, although the organs have been modified and transplanted similar to human organs, the human body continues to reject them.
A New Study and Renewed Hope
A new study published in November 2025 by a team of international physicians and reported by NYU Langone Health provides details of the measures used on two occasions to reverse the pig organ rejection. This is just the beginning as the transplantation of animal organs is somewhat new in comparison to the entire field. Everything from knee cartilage and heart valves can currently be transplanted between humans.
For example, scientists have transplanted a kidney to a patient who was brain dead and his body had been donated. It was a sixty-one-day study and twice the body rejected the organ. However, on both occasions the doctors were able to reverse the rejection through medication.
Lead study author Robert Montgomery, NYU Langone director, spoke with Mary Kekatos of ABC News providing his opinion that within a few years pig organs that are gene edited will be alternatives to human organs.
Muhamad Mohiuddin is a surgeon at Maryland’s School of Medicine who, in 2022 led what is now the first pig to human transplant. Dr. Mohiuddin was not involved in the current study but spoke with Nature’s Rachel Fieldhouse expressing his opinion that the aforesaid procedure can be considered evidence of how to reverse organ rejection.
ABC reports that due to the daily research conducted on the patient, e.g. tracking the activity of his organs on a cellular level, researchers were prepared for the organ rejections at least five days earlier.
The team could understand and reverse the rejections so successfully because of the daily research they conducted on the patient, tracking his organ activity on a cellular level. This tracking allowed researchers to catch the two organ rejections five days earlier than they would have otherwise, ABC reports.
The doctor offered further evidence that blood samples, biopsies, and samples of body fluid can create an atlas of an immune response. Dr. Mohiuddin said that the study was unique and that this organ may be the most studied organ in human history.
Researchers were able to target certain antibodies and cells that caused rejections from analyzing the patient’s blood. For example, they found that the pig organ had higher levels of genes that the immune systems in humans interpret as foreign substances, so they proceed to immune defense.
Dr. Montgomery told Nature that the study shows that white blood cells play a much more significant role in responding to germs than previously thought.
Although the research team made a firm decision to close the study after sixty-one days, it still goes on record as being the longest time a pig organ survived in a patient who was brain dead.
Dr. Minnie Sarwal who co-directs San Francisco’s pancreas and kidney transplant program at the University of California spoke to CNN’s Jen Christensen.
The study, which researchers chose to end at the 61-day mark signals hope for future application of this method. Dr. Sarwal said that sixty-one days of stability in renal function confirms that pig kidneys which are genetically engineered are able to function.
The researchers are hopeful that such breakthroughs could cut wait times for patients in need. Less than half that number received a transplant in 2024.
Montgomery’s team will now test immune suppression techniques for pig transplants in 20 additional patients, Dr. Montgomery tells CNN, so these findings can be replicated in more than a single patient.
As a result of the study, the researchers noted that a pig which is minimally gene-edited is able to support life-sustaining clinical trials … to know that when you put a pig kidney in a human, from a physiological standpoint, it just does its thing,” Montgomery tells CNN. “The pig kidney is capable of doing most of the things that a human kidney can do.”
From their analyses of the patient’s blood, the researchers pinpointed specific cells and antibodies causing rejections. The pig organ expressed higher levels of genes that human immune systems consider foreign substances, they found, prompting an immune response. T cells—white blood cells that react to germs and unknown invaders—also play a larger role in rejection than previously thought, Montgomery tells Nature.
The study, which researchers chose to end at the 61-day mark, marks the longest time a pig organ has survived in a brain-dead patient and signals hope for future application of this method, Minnie Sarwal, a surgeon who co-directs the University of California San Francisco’s kidney and pancreas transplant program, tells CNN‘s Jen Christensen.
These breakthroughs may cut the waiting time for patients. Dr. Montgomery’s team is about to test various immune suppression techniques in an additional twenty patients.
Dr. Montgomery further stated that knowing this will give the team a sense of relief as they move towards clinical trials. He reiterated that it “just does its thing” as it can perform most functions similar to a human kidney.
