Two of the first recipients of genetically engineered pig kidneys have successfully received subsequent organs from human donors, according to an announcement by the biotech company eGenesis. While doctors ultimately removed the initial xenografts and both patients spent months back on dialysis before human organs became available, the period allowed them to live without needing to be hooked up to tubes, marking a major milestone for interspecies transplantation.
First Human Transplants of Gene-Edited Pig Kidneys Reach New Milestones
Scientists have been racing to find options besides human donors due to severe shortages. In the United States alone, over a hundred thousand people are waiting for an organ transplant, and an average of 17 people die on waiting lists per day. Inter-species transplants, known as xenotransplantation, offer a potential solution to bridge this gap and provide an abundance of organs for patients in need.
Addressing Rejection and Genetic Engineering
Organs from pigs have long been considered as potentially suitable for humans because pigs are already bred for food, have large litters, short gestation periods, and organs of similar size to human organs. Precedents already exist in medicine, including the use of pig skin grafts for burns and pig heart valves in humans, alongside experiments involving pig hearts in baboons.
However, natural pig cells include a sugar called alpha-gal that triggers immediate rejection by the human body. To overcome this hurdle, pigs are genetically engineered to not produce alpha-gal. Martine Rothblatt, chief executive of United Therapeutics—the company that genetically engineered the pig—noted that this work represents an important step forward in realizing the promise of xenotransplantation, which is expected to save thousands of lives in the future.
Early Tests and Research Progress
Prior to broader human applications, initial testing included a pig kidney transplanted into a human patient who was already brain dead and being kept alive artificially. Tested for 54 hours during a procedure led by surgeon Robert Montgomery at NYU Langone Health in New York City, the kidney was observed filtering out waste products from the blood and producing urine while connected. Surgeon Robert Montgomery described the performance as even better than hoped, while Dorry Segev, professor of transplant surgery at Johns Hopkins School of Medicine, called it a huge breakthrough.
Questions regarding post-transplant complications have also been addressed. When doctors consider inter-species organs, a key concern is whether patients might produce antibodies that complicate a subsequent human-to-human transplant. Primate studies conducted by eGenesis suggested this would not be a barrier, a finding later confirmed when their initial xenograft recipients successfully received human organs following months of interim dialysis.
Future Clinical Hurdles and Ethical Considerations
Despite the promise shown in early procedures and trials, experts note that several hurdles remain before widespread adoption, including regulatory approval. While there is currently no peer-reviewed scientific report of the operation, experts estimate that trials involving pig kidneys on critically ill humans with no other options could happen within two years.
Ethical concerns also surround the practice. While the family of the brain-dead patient in the initial test consented to the procedure, not everyone is comfortable with breeding animals specifically to harvest organs. Nevertheless, researchers continue to advance the technology as a potential way to help both critically ill patients and the hundreds of thousands dealing with demanding kidney dialysis procedures.
