At NYU Langone Health Transplant Institute discovery isn’t confined to the laboratory or the operating room. It lives in the intersections — where science, ethics, and humanity meet. That spirit of progress has defined every step of our xenotransplantation program, from the first decedent study in 2021 to the clinical trials of today. This paper highlights one of the milestones we made to get here: the first successful treatment of xenograft rejection in a human decedent, sustained for 61 days.
This study, published in Nature, represents not only a scientific breakthrough but a cultural one — proof that when innovation is guided by trust, partnership, and respect for the donor and family extraordinary things become possible.
A Place Built for Progress
NYU Langone Health Transplant Institute has long been a place where discovery thrives on collaboration. Our unique model — combining transplant surgery, immunology, ethics, research, and public policy under one bold institutional mission — allowed a bold new concept to come to life in 2021: the decedent model for xenotransplantation research.
This model, developed within NYU Langone Health’s culture of innovation under the leadership of Dr. Robert Montgomery, gave researchers the ability to study a xenograft in a human body maintained on ventilatory and intensive care unit support after death. This ethical study — one that honors the donor, protects the public’s trust, and bridges the gap between laboratory science and living-patient transplantation.
“At NYU, innovation isn’t accidental — it’s designed into how we work together. The decedent model could only have been successful in a place where collaboration is part of the DNA.” —Adam Griesemer, MD, PhD
Through our Donor Care Center and partnerships with Organ Procurement Organizations, NYU built an infrastructure for progress with the decedent model that is both scientifically rigorous and ethically sound.
An Ethical Framework for Discovery
From the start, this work required a framework that treated the donor and their family with the same respect as any patient. Families who choose to participate in decedent xenotransplant studies make an extraordinary gift: they allow their loved one’s body to help unlock answers that could one day end the shortage of organs. The families who participate often see this contribution as an extension of organ donation — another way to save lives when their loved one cannot donate individual organs.
“Everything about the decedent model is grounded in respect — for the donor, for the science, and for the future patients who will benefit.” -Robert Montgomery, MD, PhD
That shared purpose — among families, clinicians, ethicists, and researchers — is the foundation upon which the 61-day study was built.
From 28 Days to 61: Extending the Frontier
What came next depended not only on scientific readiness — it required family trust and institutional courage.
With the family’s approval, the study was extended to 61 days, allowing the team to observe rejection, intervene, and treat it successfully. It became the longest and most detailed human xenograft observation in history.
This progress wasn’t simply about time — it reflected years of investment in infrastructure, protocols, and teamwork. NYU’s xenoinfrastructure — the physical and procedural ecosystem supporting these studies — enabled around-the-clock monitoring, serial biopsies, and real-time clinical decision-making.
Inside the Science: A Hypothesis Brought to Life
At the core of the study was a bold hypothesis drawn from decades of primate research: could human immune cells be “educated” to better tolerate a pig organ?
To test this, the team transplanted a porcine kidney from a genetically modified donor pig, along with the pig’s thymus, which was autotransplanted under the kidney capsule 5 months earlier. The thymus plays a crucial role in immune education — it’s where the body learns to recognize what belongs and what doesn’t.
By including the thymus, the team hoped to teach the human immune system to see the pig kidney as part of “self,” reducing the risk of cellular rejection.
The procedure mirrored a standard human kidney transplant — same surgical placement, same techniques, same post-transplant monitoring. Over the next 61 days, the team performed nine biopsies — an extraordinary amount by any standard — to track the immune response in real time.
The First Successful Treatment of Xenograft Rejection
An avenue of the research preformed to date looks at which specific immune cells are damaging the transplanted pig kidney by assessing the different layers of DNA, RNA, protein datasets generated. For the first month, the kidney functioned normally. Around day 30, early signs of rejection appeared — a pivotal moment that transformed observation into intervention.
For the first time, a xenograft rejection was successfully treated using the same therapies available to human transplant recipients: plasmapheresis and standard immunosuppressive drugs. Following treatment, kidney function returned to normal and remained stable through day 61.
This was a world first — no xenograft in any species had ever been successfully treated for rejection before. The achievement underscored the importance of the decedent model, which allowed human-specific drugs and clinical approaches to be tested safely and ethically.
“We were able to see, respond, and learn in real time. This is an extraordinary opportunity to change the future of transplantation”— Jeffrey Stern, MD
By the study’s end, the graft remained healthy, histologically intact, and rich with data that will inform the next generation of xenotransplant research.
The Power of N = 1
In science, scale matters — but sometimes depth matters more. This study was N = 1. Yet within that single case existed an entire universe of discovery. This is probably the most deeply studied human in history.
Few “N = 1” studies reach journals like Nature, but when they do, it’s because the insight transcends the sample size. The data from this study didn’t just advance understanding of xenograft immunology — it directly supported the expanded-access case for a living patient to receive a pig kidney, Lisa Pisano.
That bridge — from decedent model to living patient — demonstrates the extraordinary value of the model itself. Even one human body, when studied with precision and purpose, can change the future of medicine.
The Team, Trust, and Intangibles
Behind the paper is a team — surgeons, nephrologists, immunologists, infectious disease, nurses, critical care, ethicists, OPO partners, donor families, and countless supporters. Their steady collaboration is the quiet engine of progress.
There were no shortcuts: every biopsy, every family call, every 2 a.m. round reflected a deep belief that what they were doing mattered.
The “intangibles” — mutual trust, shared purpose, and resilience — are what made this 61-day success possible. This is the part of science that doesn’t fit neatly into methods sections or figures, but it’s the foundation of every major advance.
Looking Ahead
The 61-day decedent study isn’t an endpoint — it’s a beginning. It validated a safe, ethical framework for studying xenotransplants in humans. It proved that xenograft rejection can be treated. And it reaffirmed NYU Langone’s place as a leader in surgical and translational innovation.
Most importantly, it honored a donor family whose decision continues to save lives through knowledge.
The discovery was monumental, but so was the humanity behind it. Because even one gift — one body, one study, one act of trust — can reshape what’s possible for millions still waiting.