The calls and emails started pouring in to NYU Langone Health and Massachusetts General Hospital soon after doctors began experimenting with pig organs for human transplants. Patients, anxious about the scarcity of human organs, wondered aloud: When could they receive a pig kidney instead? Alex Berrios, hailing from Louisville, Kentucky, is one such patient. He desperately needs a second kidney transplant, but finding another human match proves elusive. "It may not work, and I have to be OK withthat," Berrios said. "I think it's worth the shot."
Across the United States, excitement builds as two companies prepare to start the world’s first clinical trials of xenotransplantation, targeting 2025 for pig kidney and heart transplants aimed at saving human lives. Potential volunteers are impatiently waiting to see if they'll be eligible for these groundbreaking studies.
The anticipation heightened following the successful kidney transplant of Alabama resident Towana Looney at NYU Langone on November 25, making her the fifth American to receive such a gene-edited pig organ. Previous recipients had all experienced short-lived successes; the two recipients of pig hearts and two kidney transplant patients did not survive longer than two months. Yet these outcomes have not deterred research efforts amid a dire shortage of transplantable human organs. "We have to have the courage to continue," said transplant surgeon Dr. Bartley Griffith from the University of Maryland, emphasizing the need for perseverance.
The quest for xenotransplantation has been uniquely compelling. It was back in 2022 when Dr. Griffith struggled to find the right words to approach his dying patient about undertaking the first-ever transplant of a gene-edited pig heart. Amazingly, patient David Bennett reacted with humor, joking about oinking and advising Griffith to press on, stating, "maybe you'll learn something for others like me." Fast forward to late 2023, where patients at the National Kidney Foundation meeting shared their dialysis woes, prompting many to express willingness to try animal organs. “Why not try? That was really what we took back,” remarked Mike Curtis, CEO of eGenesis, the company spearheading organ development. “It felt like we almost have an obligation to try.”
“The patients drove us to proceed with this,” agreed Dr. Tatsuo Kawai, who performed the first gene-edited pig kidney transplant for one of his long-time patients back in March. Meanwhile, California native Carl McNew eagerly emailed NYU, hoping to volunteer before his health declines drastically.
Berrios himself, depending on dialysis thrice weekly, struggles with the burden of his condition. Born with only one kidney, he saw his transplant fail after 13 years. Now highly sensitized, he is left watching others receive transplants as he remains tethered to the dialysis machine for hours each week. The stress of seeking human matches compounds his health struggles, fueling his interest in xenotransplantation.
Yet, the path to successful xenotransplantation isn’t merely wishful thinking. The FDA requires extensive testing, first researching pig organs on primates like monkeys and baboons before extending the trials to human patients. While researchers have recorded positive outcomes with primate survival extending to one year, real-world human experience remains scant. Experimentally, pig organs have been administered under “compassionate use” regulations for individuals with few options left. This leads to the disheartening fact: transplant recipients to date have not fared well, but lessons learned from these trials have led to enhancements. For example, one significant finding resulted from discovering the risk of pig virus from the initial heart transplant, which now informs comprehensive risk assessments for future candidates.
Looney, for example, spent eight long years on dialysis, yet she wasn’t as ill as previous recipients. “She’s kind of like our litmus test for trial candidates,” said NYU's Dr. Robert Montgomery, who performed her transplant. Similarly, gene editing plays a pivotal role—scientists previously attempted animal-to-human transplants without success, but gaining the ability to alter pig genes to prevent human rejection offers renewed hope.
Currently, Revivicor, a subsidiary of United Therapeutics, is producing kidneys and hearts using complex gene editing techniques. They have engineered organs with ten gene edits, targeting rejection and excessive growth patterns by removing specific pig genes and integrating human elements to improve compatibility. Meanwhile, eGenesis, utilizing up to 69 gene edits, is paving the way for future developments, focused on establishing longevity for pig organs.
The entries and responses from patients like Berrios and Looney reflect the growing urgency. A staggering number of patients express willingness to undergo xenotransplantation, highlighting the need for doctors to balance participant health with the urgency of finding candidates for clinical trials. Dr. Silke Niederhaus, another transplant surgeon with shared experience, acknowledges the gravity of the situation, emphasizing the importance of informed consent for potential volunteers.
Towana Looney’s remarkable transition since her transplant emphasizes the potential of xenotransplantation. Attending her post-surgery press conference, she expressed her joy, stating, “I’m blessed to have received this gift, and I want to go to Disney World.” Her hopes mirror those of countless others waiting for the possibility of viable organ donations.
Looney's success story could signal paradigm shifts for future organ transplants, providing meaningful pathways forward, particularly as 13 Americans die daily waiting for kidneys. With the promise of extending lives through pig organ transplantation on the horizon, the collective determination of patients, doctors, scientists, and innovators pushes forward this revolutionary field.
