Xenotransplantation: How Pig Organs Could End the Transplant Shortage

In January 2022, surgeons at the University of Maryland Medical Center transplanted a genetically modified pig heart into David Bennett Sr., a 57-year-old patient with terminal heart disease who was ineligible for a human transplant. Bennett survived for two months — a result that, while modest, sent shockwaves through the transplant world. For the first time, a pig organ had sustained a human life outside of a clinical trial. I remember reading about it and thinking: this could change everything.

The Science Behind Xenotransplantation

Xenotransplantation — the transplantation of organs between species — has been a scientific aspiration for decades. The primary obstacle has always been hyperacute rejection, in which the human immune system immediately attacks foreign animal tissue. The breakthrough came through genetic engineering. Companies like Revivicor and eGenesis have developed pigs with up to 10 genetic modifications, including the knockout of genes that produce sugars triggering human immune responses and the insertion of human genes that help regulate the immune system.

Why Pigs?

• Organ size: Pig organs are anatomically similar in size to human organs
• Breeding: Pigs reproduce quickly and can be raised in controlled, pathogen-free environments
• Genetic malleability: CRISPR technology has made precise genetic editing of pig embryos feasible at scale
• Ethical considerations: Pigs are already widely used in agriculture, making regulatory and public acceptance comparatively easier than with primates

Recent Milestones

Since the Bennett case, the field has accelerated. In 2023, NYU Langone researchers demonstrated that genetically modified pig kidneys could function in brain-dead patients for over a month. In 2024, the FDA authorized expanded compassionate-use studies, and additional living patients have received pig kidney transplants with promising early results. These developments suggest that clinical trials could begin within the next few years.

What This Means for the 103,000+

More than 103,000 Americans are currently on the organ transplant waiting list, and 17 people die every day waiting. The vast majority — roughly 85% — need a kidney. If xenotransplantation can be made safe and reliable, the implications are staggering. Unlike human donation, which depends on the tragic circumstance of a donor's death, pig organs could theoretically be produced on demand. This would not replace human donation — it would supplement it, potentially eliminating the waiting list entirely.

Challenges Ahead

Significant hurdles remain. Long-term organ survival in human recipients has not yet been demonstrated. The risk of porcine viruses crossing into humans — particularly porcine endogenous retroviruses (PERVs) — requires ongoing surveillance. Immunosuppression regimens must be refined. And regulatory frameworks for xenotransplantation are still being developed.

At YCOD, we see xenotransplantation as a powerful complement to our policy work. Even as we push for opt-out legislation like Bill A07954, we champion every scientific advance that brings us closer to a world where no one dies waiting for an organ. The future of transplant medicine is being written right now — and it might just have a pig at the center of it.