The 62-year-old was sent home on Wednesday, two weeks after the ground-breaking surgery at Massachusetts General Hospital (MGH).

Organ transplants from genetically modified pigs have failed in the past.

But the success of this procedure so far has been hailed by scientists as a historic milestone in the field of transplantation.

The news was shared in a press release on Wednesday by MGH, which is Harvard Medical School's largest teaching hospital in the US city of Boston.

In the release, the hospital said the patient, Richard "Rick" Slayman of Weymouth, Massachusetts, had been battling end-stage kidney disease and required an organ transplant.

His doctors successfully transplanted a genetically-edited pig kidney into his body over a four-hour-long surgery on 16 March.

They said Mr Slayman's kidney is now functioning well and he is no longer on dialysis.

In a statement, Mr Slayman said being able to leave hospital and go home was "one of the happiest moments" of his life.

"I'm excited to resume spending time with my family, friends, and loved ones free from the burden of dialysis that has affected my quality of life for many years."

In 2018, he had a human kidney transplant from a deceased donor, however it began to fail last year, and doctors raised the idea of a pig kidney transplant.

"I saw it 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," he said.

The new pig kidney he received was modified by Cambridge-based pharmaceutical company eGenesis to remove "harmful pig genes and add certain human genes to improve its compatibility with humans," it said.

For the procedure, the hospital said it drew from its history as being behind the world's first successful human organ transplant - a kidney - in 1954, as well as research it had conducted with eGenesis on xenotransplantation (interspecies organ transplants) over the past five years.

The procedure was greenlit by the Food and Drug Administration, who offered a single Expanded Access Protocol - also known as compassionate use - that is used for patients with life-threatening illnesses to grant them access to experimental treatment.

The team behind the transplant hailed it as a historic step that can provide a potential solution to the world's organ shortage, especially to those from ethnic minority communities whom the shortage disproportionately affects.

"An abundant supply of organs resulting from this technological advance may go far to finally achieve health equity and offer the best solution to kidney failure - a well-functioning kidney - to all patients in need," said Winfred Williams, Mr Slayman's doctor at MGH.

According to data by US non-profit United Network for Organ Sharing, more than 100,000 Americans need a lifesaving organ transplant.

Meanwhile, the number of donors - deceased and living - in 2023 was just under 23,500.

It is estimated that 17 people die each day in the US while waiting for an organ, and kidneys are the most common organ needed for a transplant.

While this is the first pig kidney transplanted into a human, it is not the first pig organ to be used in an transplant procedure.

Two other patients have received pig heart transplants, but those procedures were unsuccessful as the recipients had died a few weeks later.

In one case, there were signs that the patient's immune system had rejected the organ, which is a common risk in transplants.

bbc