In light of recent scientific advances, the Holy See affirms that there is no theological obstacle to xenotransplantation — that is, the transplantation of an organ from one species to another — as long as certain ethical principles are strictly observed. Scientific and ethical guidelines on this technique, which is still in the experimental stage, were presented in the document “Perspectives on Xenotransplantation” by the Pontifical Academy for Life on March 24, 2026.
The Pontifical Academy for Life presented an updated version of its 2001 document on xenotransplantation, taking into account the latest scientific progress.
The Pontifical Academy for Life produced the 90-page document with the participation of 14 specialists from five countries. It’s an update of a previous document by the Academy published in 2001, at the initiative of Pope John Paul II, who had supported this technique in a letter published in 2000.
At the time, the Academy had determined that xenotransplantation was “morally legitimate” only if the transplanted organ did not alter “the psychological or genetic identity of the person who receives it” and if the operation could be performed with biological certainty of a possible success and without “excessive risks.”
An update based on “significant progress”
Archbishop Renzo Pegoraro, chancellor of the Pontifical Academy for Life, presented the revised document at the Vatican on Tuesday morning. A quarter-century after the first document, he explained, the Holy See maintains its position by incorporating the “significant progress” made by medicine in the field of xenotransplantation, as well as developments in bioethics and theology.
Three members of Harvard University’s xenotransplantation research unit—currently the most advanced in the world—personally contributed to drafting the text. Several doctors and veterinarians and specialists in bioethics, ethical philosophy, and theology from Austria, Italy, and the Netherlands, also participated.
Research on xenotransplantation, which began in the 1970s, primarily addresses the critical shortage of available organs. Professor Emanuele Cozzi of the University of Padua stated during the presentation that 170,000 transplants were performed worldwide in 2024, representing less than 10% of actual demand. He also emphasized that alternative treatments are very expensive: dialysis in the absence of a kidney transplant costs between about $45,000 and $60,000 per year.
“Many patients die while waiting for a transplant,” stated his colleague Monica Consolandi, a physician and researcher at the Bruno Kessler Foundation in Trent (Italy). Professor Cozzi added that 8 people die every day in the European Union due to the lack of a transplant. This figure rises to between 13 and 17 in the United States, reports American professor Daniel J. Hurst, an ethicist at the Rowan-Virtua School of Osteopathic Medicine.
A practice that remains very rare
Until now, xenotransplantations using pig organs (primarily kidneys, lungs, hearts, and livers) have mainly been tested on monkeys. Since 2022, however, the U.S. Food and Drug Administration (FDA) has issued temporary authorizations to certain doctors for patients with conditions that current treatments cannot cure.
To be successful, organs harvested from pigs must be “prepared” through a process of “genetic engineering” so that the recipient’s body does not reject them. This also aims to prevent the transmission of infectious diseases between species, as was the case during a recent xenotransplantation of a pig heart performed at the University of Maryland.
While progress is notable, Professor Cozzi states that only about 30 patients per year are likely to be eligible for a xenotransplant. Also, current results generally don’t allow them to live more than a few months after the operation. He encourages the public to continue donating organs, believing that it will take at least five years of in-depth research for xenotransplants to be viable.
The document’s recommendations
“Catholic theology does not have preclusions, on a religious or ritual basis, in using any animal as a source of organs or tissues for transplantation to man,” asserts the document from the Academy for Life, provided that the rules established in 2001 — respect for the patient’s identity and a reasonable chance of success — are observed.
The document also emphasizes the importance of thoroughly informing every patient about the risks involved, establishing medical and psychological follow-up to monitor the transplant’s progress, and respecting animal welfare to the greatest extent possible.
The text also advocates for the regulation of these practices under international law, particularly within the framework of the WHO. While highlighting the positive results achieved by certain researchers around the world, Professor Cozzi nevertheless said that his Chinese colleagues were “less proactive” in terms of communication than their American counterparts.
