A Look at Pig Kidneys in the Broader Transplantation Puzzle

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Last month’s breaking news that the kidney of a pig functioned normally when attached for 54 hours to the body of a brain-dead patient was hailed as an eventual solution for more than 100,000 people nationwide who are waiting for life-saving organs. While xenotransplantation, or animal-to-human transplantation, has been undergoing study and experimentation for quite some time, this was a huge step in the right direction.

As first reported on October 18, the team at NYU Langone Health obtained consent from the ventilated donor’s family to attach a pig kidney to her upper leg and monitor the results. They reported that the organ, which came from an animal whose genes had been modified to avoid early rejection by a human host, began to work almost immediately and produce urine and function as would a human kidney. The pig kidney functioned normally throughout the 54-hour trial.

The transplant team that orchestrated and performed the pig kidney procedure is rightly being credited with a medical breakthrough and the implications of this initial success are significant. But this first step must necessarily be followed by many more before xenotransplantation will be able to improve patients’ quality and length of life — the goal of organ transplantation.

Unfortunately, the next steps remain incredibly complex. Routine xenotransplantation of non-human organs into human bodies is many years away. One of the greatest hurdles is immunological: getting non-human organs to survive long-term, not just for a 54-hour trial. Due to the need for additional research and testing, it is unlikely that xenotransplantation will arrive in time to help most of those currently on the transplant waitlist, including more than 90,000 kidney transplant candidates.

On the other hand, the nation’s multifaceted transplant system is quickly moving forward with numerous technological and scientific advancements that — while less sensational than a pig organ functioning in a human body — are increasing transplant rates in the near term. And the transplant system’s efforts to maximize placement of organs and increase supply are accelerating in real time.

Several innovations are currently underway involving collaborations between donor hospitals, transplant centers, Organ Procurement Organizations (OPOs), and the United Network for Organ Sharing (UNOS), the entity responsible for shaping policy and orchestrating donor matches on behalf of the federal government:

  • Predictive analytics are being tested to improve the time-sensitive decision-making process transplant surgeons and patients must endure when an organ is offered. By applying statistical modeling to make predictions about an organ’s suitability for a particular patient, the system increases the likelihood of a timely match resulting in the best possible outcome.
  • Offer filters are a technological advancement of UNOS’ automated matching system that will allow transplant programs to filter certain types of kidneys for their patients. Offer filters save invaluable time that helps preserve organ viability during the matching process, thereby ensuring fewer organs go unused.
  • Physiologic preservation techniques using normothermic perfusion have already have saved many lives by making a new source of hearts available from donors classified as “donation after circulatory death.” This technology keeps hearts viable for longer periods of time by allowing assessment of their function prior to transplantation. Similar devices are approved for lung transplantation and are in clinical trials for liver transplantation.
  • Organ donations from older donors are broadening the donor pool as data demonstrates that older organs offered to the appropriate recipients can generate successful outcomes. In fact, a 95-year-old World War II veteran from West Virginia became the oldest donor in U.S. history in May when his liver was donated to a 60-year-old woman. She is reportedly doing well.

These are a few of the initiatives underway to accelerate an increase in both organ supply and successful transplant outcomes. Data confirms these types of innovations are making a difference. Transplants from deceased donors have been steadily increasing for the past 8 years. Furthermore, the U.S. organ donation and transplant system is on track to hit a record 40,000 transplants by December 2021, the most ever recorded in one year.

When these advancements are considered within the context of last month’s watershed pig kidney experiment, it becomes easier to view the recent xenotransplantation breakthrough as part of a larger movement and a greater mission: ensuring a successful transplant for every single American who needs one.

David Klassen, MD, is the chief medical officer of UNOS. He previously served as the medical director of the Kidney and Pancreas Transplant Programs at the University of Maryland.

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