By Dr. Tim Millea
In September 2021, a kidney transplant was performed at the University of Alabama at Birmingham (UAB), one of nearly 300 performed per year at that medical center. However, three factors made this particular transplant unusual. In this case, two kidneys were implanted into the recipient patient rather than the usual one.
Secondly, both kidneys were harvested from a pig, not a human donor. Finally, the recipient of the kidneys had been declared brain-dead.
If the rationale for this surgery were unknown, the logical question would be, “Why?” We are very familiar with human-to-human organ transplants, whether living donors or organs donated at the time of someone’s death. The UAB case seems to be counter to our conventional understanding of organ transplants. However, scientific justification for this procedure does exist and for others performed since the UAB case. What about the ethical and religious questions raised?
Transplanting an animal organ into a human is known as a “xenotransplant.” The Greek word, xenos (zee-nos), means “stranger or foreigner,” which is appropriate for such a procedure. Whether it be a kidney, heart or other organ from an animal, the human immune system will identify it as a stranger. That can lead to the well-known concerns regarding organ rejection that require the recipient’s immune system to be suppressed medically. Such suppression unfortunately increases the recipient’s risk of infection, which can be severe and even fatal.
The transplanted pig kidneys were not selected haphazardly. They were obtained from pigs housed in an environment that minimized exposure to bacteria and viruses. In addition, the pigs were genetically modified to lessen the risk of two problems: 1) viruses that could be transferred to the recipient and 2) rejection of the organ by the recipient. If the procedure is successful, the risk of an infectious disease threatening the recipient is much lower, and that recipient may not require immune suppression therapy with its associated risks.
Since the UAB transplant, two xenotransplantations of pig kidneys have been performed at New York University/Lagone Hospital and the potential for more complex transplants is being investigated. In early 2022, surgeons at the University of Maryland implanted a genetically modified pig heart into a critically ill 57-year-old man in an attempt to prolong his life. He survived for 60 days but analysis of the transplanted heart after death demonstrated a viral infection common in pigs.
The most recent report involves two similar pig hearts transplanted to two patients in June and July at NYU/Lagone. These differed from the Maryland case in a significant manner, as both recipients were declared brain-dead. Both were maintained on ventilators and their families provided permission for the transplants and subsequent study of the bodies. The recipients remained on ventilators for 72 hours of observation after the transplants and then life support measures were discontinued. The transplanted hearts showed good function over the three-day period. An interesting side note: one of the physicians on the NYU transplant team is a human heart transplant recipient.
If xenotransplants are thoroughly studied and ultimately approved, the benefits could be dramatic. According to the United Network for Organ Sharing, at any time, more than 100,000 Americans are on a waiting list for an organ. Sadly, an average of 16 people die each day while waiting. If xenotransplants are found to be safe and effective, many lives could be saved.
What about the ethical implications in these cases? Xenotransplants are ethically acceptable if several criteria are met. These include a thorough assessment of the safety of the procedure, a reasonable degree of risk to the recipient and evidence of benefits that clearly outweigh risks and potential complications. Further, through the lens of social justice, the use of animal organs for human transplants could diminish the illegal “black market” trade in human organs that particularly afflicts those living in poverty worldwide.
The use of brain-dead individuals for research such as this, on first impression, can be understandably troubling from a moral perspective. However, the Catholic Church encourages the “gift of life” that occurs with organ donation. The source of the organ is not identified as a significant concern, with uncommon exceptions. As outlined by the National Catholic Bioethics Center, it is unethical to obtain organs from a person kept alive with ECMO (Extracorporeal Membrane Oxygenation), which uses a heart-lung machine to oxygenate the blood. Even more troubling is the use of EISOR (Extracorporeal Interval Support for Organ Retrieval) to keep an organ viable outside the donor’s body. The potential use of animal organs, if obtained humanely, is not seen as ethically problematic.
Currently, the most common organ donors are those who have consented to provide the “gift of life” in the event of their death or their families have approved this generosity on behalf of their loved one. In the future, the use of animal organs may be commonplace and the sanctity and dignity of life may be better protected because of the increased supply of organs. The study and use of transplants is a clear example of a critically important tenet of our Catholic beliefs. It is acceptable as long as it is both good and true, that is, morally and factually correct.
The words of St. John Paul II, who emphasized the importance and value of ethical science frequently, are pertinent: “Faith and reason are like two wings of the human spirit by which it soars to the truth.”
(Dr. Tim Millea is president of the St. Thomas Aquinas Medical Guild and a member of St. Paul the Apostle Parish in Davenport.)