Daijiworld Media Network - New Delhi
New Delhi, Sep 22: A genetically engineered pig kidney kept a 66-year-old US man off dialysis for a record 271 days before he successfully received a human donor kidney, marking a significant development in efforts to use animal organs as a temporary “bridge” for patients awaiting transplants.
The patient, identified as Tim Andrews, received the genetically modified pig kidney on January 25, 2025, and lived with the organ for nearly nine months. His case was detailed in a research paper published in *The Lancet* this month, describing him as the first human patient to receive a human donor kidney after undergoing a pig kidney transplant.
Doctors from Harvard Medical School, Massachusetts General Hospital and associated institutions documented Andrews’ experience, highlighting the potential of xenotransplantation — the transplantation of organs from animals to humans — to help address the widening gap between the number of patients with end-stage kidney disease and the availability of human donor organs.
The case has particular relevance for India, where nearly two lakh new patients are estimated to require a kidney transplant every year, while only around 14,500 kidney transplants are performed.
“What is truly significant here is the pig kidney provided nearly nine months of dialysis-free renal function and acted as a bridge until a human kidney was available,” said Pune-based senior urosurgeon Dr Sanjay Kulkarni.
Andrews received the pig kidney under a US Food and Drug Administration (USFDA) ‘Expanded Access Investigational New Drug’ application, a mechanism that can allow patients with serious or life-threatening conditions to receive experimental treatments when other options are unavailable.
Following the procedure, Andrews was closely monitored for kidney function, rejection, immune responses and possible transmission of infections from the pig to the patient.
The pig kidney began functioning immediately after transplantation. However, doctors detected an early warning on the 14th day, when the patient’s immune T-cells began attacking the transplanted organ. The rejection was brought under control with treatment, and no transmission of pig-derived pathogens was detected.
The kidney continued to function well for around six months.
The situation changed after Andrews developed a bacterial infection that was not linked to the pig kidney. Doctors were subsequently required to reduce the medicines suppressing his immune system.
Soon afterwards, inflammation began damaging the lining of blood vessels in the pig kidney, resulting in microscopic blood clots and a condition known as thrombotic microangiopathy. The animal kidney gradually lost its function.
Andrews was subsequently given a kidney donated by a deceased human donor. The human kidney began functioning immediately after transplantation.
The successful human-to-human transplant also provided important evidence that exposure to the pig kidney had not sensitised Andrews’ immune system in a way that would cause it to reject a subsequent human donor organ.
His levels of anti-HLA antibodies, which can make it more difficult for transplant patients to match with and accept donor organs, had not increased.
“I would say this is a landmark development in xenotransplantation and an important proof-of-concept for genetically engineered organs. This is the longest a pig organ transplant has worked in a human,” said Dr Arvinder Soin, chief transplant surgeon at Medanta Medicity in Gurugram.
“It shows xenotransplantation is finally ready to move from just being a temporary bridge to becoming a source for organs with the potential for longterm survival,” he added.
Over the past three decades, researchers have made advances in preventing early rejection of animal organs and have also been working to understand and tackle mechanisms responsible for later rejection. These developments have gradually resulted in longer survival times following xenotransplantation.
In India, genetically modified pig kidneys could potentially serve as a temporary renal replacement option for patients who do not have a suitable living donor while they wait for a deceased-donor kidney.
However, several challenges remain before the technology can become part of routine clinical practice.
“The major hurdles include infection and zoonotic surveillance, immunosuppression, graft survival, regulatory oversight, ethical acceptance, genetically engineered animal sourcing, specialised infrastructure and, critically, affordability and access,” Dr Soin said.
He also pointed out that significant changes to India’s Human Organ Transplant Act would be required before xenotransplantation could be introduced in the country.
According to Soin, such transplants could eventually become part of routine medical practice if the survival of genetically engineered animal organs reaches levels comparable with conventional human donor transplants and the associated medical, regulatory and logistical challenges are adequately addressed.
He said the technology could significantly expand the available kidney donor pool.
Andrews’ human donor kidney is currently functioning well. Speaking to reporters in the US, he said he now spends his time fishing, kayaking and riding his bicycle.
“Every day I wake up, I’m like, this is another extra day because I should’ve been dead a year ago,” he was quoted as saying.