In a world first, surgeons in the United States successfully transplanted a genetically engineered pig kidney into a living person.
Scientists employed gene editing techniques to eliminate "harmful pig genes."
They also introduced "certain human genes" to increase the organ's compatibility with humans and the likelihood of the transplant's success.
Surgeons at Massachusetts General Hospital (MGH) in Boston conducted the transfer in four hours this week.
The receiver is a 62-year-old man with life-threatening kidney illness.
In a statement, the hospital stated: "The procedure marks a major milestone in the quest to provide more readily available organs to patients."
While the surgery was the world's first on a living patient, it was not the first time a kidney transfer was performed on a human.
Last year, surgeons at New York University's Langone Transplant Institute implanted a pig kidney into a man who had been declared brain dead. Doctors maintained the man's heart beating by using a ventilator.
The surgery revealed that genetically modified pig kidneys could "replace the function of a human kidney". After two months of successful kidney function, the man's life support was shut off.
Genetically modified pigs are being developed by researchers at eGenesis, a gene engineering and biotechnology company based in the United States.
The animals are selectively bred with changed genes. For example, one of the gene alterations protects people from viruses that pigs can transmit.
According to eGenesis, millions of individuals worldwide suffer from kidney illness, yet "the demand for organs far outpaces supply".
eGenesis believes that human-compatible donor organs, such as the pig kidney, will "alleviate the shortage of transplantable organs" and save lives.
MGH remarked that the success of the once "inimaginable" treatment would not have been possible without the kidney recipient's "courage and willingness to embark on a journey into uncharted medical territory."
The hospital stated that he is "recovering well" and "expected to be discharged soon".
U.S : World first pig kidney transplanted into human, a success
