Massachusetts General Hospital, a founding member of the Mass General Brigham healthcare system, announced the successful completion of its second transplant of a genetically edited pig (porcine) kidney into a living recipient (xenotransplant). The 2.5-hour procedure was performed on Saturday, January 25, 2025, by surgeons at the Mass General Transplant Center. This achievement builds on Mass General’s historic milestone in March 2024, when it became the first hospital in the world to transplant a genetically edited pig kidney into a living human. Xenotransplantation, the transplantation of organs from one species to another, is being hailed as a potential solution to the global organ shortage.
Under the leadership of Leonardo V. Riella, MD, PhD, medical director for kidney transplantation, and lead surgeon Tatsuo Kawai, MD, PhD, director of the Legorreta Center for Clinical Transplant Tolerance, along with Nahel Elias, MD, surgical director for kidney transplantation, and Shimul A. Shah, MD, division chief of transplant and clinical director of the Mass General Transplant Center, a genetically edited pig kidney with 69 genomic edits was successfully transplanted into a living patient.
“I am extremely proud of our surgical and clinical teams for taking on this endeavor and completing it with great precision and professionalism. Their work is a testament to the high standards set within the Mass General Brigham system, their tireless efforts to advance the field of transplantation, and tremendous energy to find solutions to the worldwide organ shortage,” Dr. Shah said. “I also want to thank our patient for his willingness to undergo this transplant. None of this would have been possible without him, and we are grateful for his enthusiasm for spreading awareness of xenotransplantation.”
The recipient, 66-year-old Tim Andrews of Concord, New Hampshire, has been on dialysis for more than two years due to end-stage kidney disease (EKSD). The treatment took a significant toll on his daily life, leaving him feeling constantly fatigued and unable to keep up with his usual activities. In addition to the daily struggles of dialysis, Mr. Andrews faced severe complications, including a heart attack in July 2023. His path to a kidney transplant was further complicated by his O-group blood type, which significantly extended his wait time. While most patients wait three to five years for a kidney, those with O-positive or O-negative blood types often wait five to 10 years, making their chances of receiving a donor organ even more difficult.
Andrews was successfully discharged from Mass General on Saturday, February 1, 2025, and is now recovering, off dialysis for the first time in over two years, with his new kidney functioning as expected.
“As soon as I woke up after the surgery, the cloud of dialysis disappeared. I felt re-energized and revitalized. It was a miracle. The magnitude of what these doctors and nurses accomplished is unbelievable and I want to thank them for giving me a new lease on life. But this transplant isn’t about me. It’s about all the people who I met at the dialysis clinic, and I saw what they were going through. There are more than 500,000 people on dialysis, and I want to inspire them to never give up hope because that’s what this transplant provides. It’s a glimmer of hope,” Mr. Andrews said.
Andrews is now the fourth person in the world to receive a genetically edited pig kidney and is one of two people currently living with one. Mass General surgeons and physicians have more than three decades of experience with xenotransplantation research and clinical care, and the team is eager to continue its work with government agencies and outside industry partners to make xenotransplantation widely available to patients. According to the United Network for Organ Sharing (UNOS), more than 100,000 people in the United States await an organ for transplant and 17 people die each day waiting for an organ.
The pig kidney was provided by eGenesis of Cambridge, Massachusetts, from a pig donor that was genetically edited using CRISPR-Cas9 technology to remove harmful pig genes and add certain human genes to improve its compatibility with humans. Additionally, scientists inactivated porcine endogenous retroviruses in the pig donor to eliminate any risk of infection in humans. eGenesis also provided the pig organ for the world’s first kidney xenotransplant in 2024 conducted at Mass General. Apellis Pharmaceuticals of Waltham, Massachusetts, and Eledon Pharmaceuticals of Irvine, California, provided novel immunosuppressant medications for this transplant.
“This second xenotransplant provides us with another excellent opportunity to learn how we can make genetically edited pig organs a viable, long-term solution for patients. Although we have a long way to go to make that a reality, this transplant is an important next step that has given us optimism to achieve that goal,” Dr. Kawai said.
“This procedure is more than a scientific milestone — it represents a new frontier in medicine,” said Michael Curtis, PhD, chief executive officer, eGenesis. “We stand at the beginning of a future where organ shortages may no longer dictate patient outcomes. We are immensely grateful to Mr. Andrews, who has placed his trust in our groundbreaking innovation. His willingness to participate in this pioneering effort will help turn the promise of human-compatible organs into a reality. We are thrilled to continue our collaboration with the remarkable team at Mass General, whose expertise and dedication have been instrumental in making this vision possible.”
“I want to express my deepest gratitude to Mr. Andrews for his remarkable courage and selflessness in helping advance the xenotransplantation program at Mass General and across Mass General Brigham. By embracing this groundbreaking transplant, he has become a medical pioneer and a source of hope for thousands of patients on dialysis waiting for a kidney. This milestone reminds us of the transformative potential of xenotransplantation, and we remain committed to learning from this experience to make it a safe, viable option for every patient in need. Together, we are working toward a future where no one has to die waiting for a kidney.”
The procedure was performed under the Food and Drug Administration (FDA) Expanded Access Protocol (EAP), commonly known as compassionate use. This pathway allows patients with serious, life-threatening illnesses or conditions to access experimental treatments when no comparable options are available. In December 2024, Mass General received FDA approval to proceed with this transplant and plans to perform two additional xenotransplants this year, further advancing the field of xenotransplantation.
“I want to express my deepest gratitude to Mr. Andrews for his remarkable courage and selflessness in helping advance the xenotransplantation program at Mass General and across Mass General Brigham,” said Dr. Riella, Mr. Andrews’ nephrologist. “By embracing this groundbreaking transplant, he has become a medical pioneer and a source of hope for thousands of patients on dialysis waiting for a kidney. This milestone reminds us of the transformative potential of xenotransplantation, and we remain committed to learning from this experience to make it a safe, viable option for every patient in need. Together, we are working toward a future where no one has to die waiting for a kidney.”
This press release first appeared on Mass General news.
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