In a world first, surgeons at Massachusetts General Hospital accomplished the feat put a genetically modified pig kidney into a person with chronic kidney disease. The historic procedure is based on years of research into gene editing of animal organs and could be a turning point in efforts to reduce sometimes deadly long transplant wait times. Recent improvements in gene editing technology mean procedures like these could become more common.
The patient, a 62-year-old man from Massachusetts named Richard Slayman, has severe diabetes and hypertension and has been on dialysis for seven years. He eventually received a new kidney from a human donor but it began showing signs of failure after five years. Slayman was on a waiting list for another kidney when his doctors suggested the possibility of receiving an experimental kidney from a gene-edited pig.
“I saw [the transplant] not only as a way to help me, but a way to provide hope for the thousands of people who need a transplant to survive,” Slayman said in a statement.
The altered pig was created by a Massachusetts-based biotech company eGenesis. Scientists utilized CRISPR gene editing technology to produce a pig with 69 gene modifications. Several of these changes were meant to eliminate harmful pig genes that could provoke an immune response from the patent. Human genes were also added to the pig to enhance the kidney’s compatibility and reduce the likelihood of the human body rejecting it.
After approximately four hours of intense surgery, surgeons in the room reportedly said they witnessed the transplanted kidney producing urine, a significant indicator that the procedure was successful. The room filled with applause and cheers.
“This represents a new frontier in medicine and demonstrates the potential of genome engineering to change the lives of millions of patients globally suffering from kidney failure,” eGenesis CEO Mike Curtis said in a statement.
Why are scientists interested in gene-editing animal organs?
Scientists are optimistic that transplanting animal organs into humans, a practice known as “xenotransplantation,” could one day supplement human organ transplants and reduce long transplant wait times. An estimated 36 million people in the US are affected by chronic kidney disease, 800,000 of whom have end stage kidney disease or kidney failure according to the Centers for Disease Control. Once at that stage, patients are often forced to choose between going on a dialysis machine that filters their blood or applying for an organ transplant. Over 103,000 people in the US are currently on organ transplant wait list according to the Health Resource and Services Administration (HRSA).
But long wait times and a limited supply of willing organ donors means many of those patients never end up receiving a transplant. The HRSA estimates 17 people die everyday while waiting for a new organ. Those long wait times and lack of donors has also helped fuel an organ black market.
Potential animal organ transplants aren’t just limited to kidneys. Surgeons at the University of Pennsylvania, for example, successfully put a pig liver with modified genes inside a person's body into a someone whose brainstem is dead in 2022. Not long after, doctors from the University of Maryland Medical Center placed pig hearts into two very sick patients. Even though those two operations were successful, the final result was limited. Both patients reportedly passed away in less than two months after the surgeries. The human immune system reacts strongly to organs from other species and tries to reject them, which makes these procedures very challenging.
“If it were easy, we would be doing it by now, but it’s not,” MGH Transplant Center Director Joren Madsen said in a statement. “The barrier to pig xenotransplantation is formidable.”
Still, researchers are hopeful that improvements in gene editing could result in longer-term benefits. Doctors have previously transferred kidneys and livers with modified genes to baboons. In one case, eGenesis claims a monkey that received a gene-edited pig kidney lived for two years after the surgery. Doctors involved in Slayman’s procedure are also hoping that his new kidneys could help him live for two more years. The FDA quickly approved his particular procedure as part of its “compassionate use” program designed for patients who are nearing the end of their lives. Broader use of this procedure would require full FDA testing and approval.
And even though the historic procedure showcases impressive scientific and medical skill, the involved doctors say the real credit belongs to the patient for entering uncharted territory.
“The real hero today is the patient, Mr. Slayman, as the success of this pioneering surgery, once considered unimaginable, would not have been possible without his courage and willingness to embark on a journey into uncharted medical territory,” MGH Transplant Center Director Joren C. Madsen said in a statement.
