"I'm superwoman," Towana Looney told The Associated Press, laughing about outpacing family members on long walks around New York City as she continues her recovery.
"It's a new take on life," she said.
Looney's vibrant recovery is a morale boost in the quest to make animal-to-human transplants a reality.
Only four other Americans have received hugely experimental transplants of gene-edited pig organs – two hearts and two kidneys – and none lived more than two months.
"If you saw her on the street, you would have no idea that she's the only person in the world walking around with a pig organ inside them that's functioning," said Dr Robert Montgomery of NYU Langone Health, who led Looney's transplant.
Montgomery called Looney's kidney function "absolutely normal".
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Doctors hope she can leave New York – where she's temporarily living for post-transplant check-ups – for her Alabama home in about another month.
"We're quite optimistic that this is going to continue to work and work well for, you know, a significant period of time," he said.
Scientists are genetically altering pigs so their organs are more human-like to address a severe shortage of transplantable human organs.
More than 100,000 people are on the US transplant list, most who need a kidney, and thousands die waiting.
Pig organ transplants so far have been "compassionate use" cases, experiments the Food and Drug Administration allows only in special circumstances for people out of other options.
And the handful of hospitals trying them are sharing information of what worked and what didn't, in preparation for the world's first formal studies of xenotransplantation, expected to begin sometime this year.
United Therapeutics, which supplied Looney's kidney, recently asked the Food and Drug Administration for permission to begin a trial.
How Looney fares is "very precious experience," said Dr Tatsuo Kawai of Massachusetts General Hospital, who led the world's first pig kidney transplant last year and works with another pig developer, eGenesis.
Looney was far healthier than the prior patients, Kawai noted, so her progress will help inform next attempts.
"We have to learn from each other," he said.
Looney donated a kidney to her mother in 1999.
Later pregnancy complications caused high blood pressure that damaged her remaining kidney, which eventually failed, something incredibly rare among living donors.
She spent eight years on dialysis before doctors concluded she'd likely never get a donated organ – she'd developed super-high levels of antibodies abnormally primed to attack another human kidney.
So Looney, 53, sought out the pig experiment.
No one knew how it would work in someone "highly sensitised" with those overactive antibodies.
Discharged just 11 days after the November 25 surgery, Montgomery's team has closely tracked her recovery through blood tests and other measurements.
About three weeks after the transplant, they caught subtle signs that rejection was beginning – signs they'd learned to look for thanks to a 2023 experiment when a pig kidney worked for 61 days inside a deceased man whose body was donated for research.
Montgomery said they successfully treated Looney and there's been no sign of rejection since – and a few weeks ago she met the family behind that deceased-body research.
"It feels really good to know that the decision I made for NYU to use my brother was the right decision and it's helping people," said Mary Miller-Duffy.
There's no way to predict how long Looney's new kidney will work but if it were to fail she could receive dialysis again.
"The truth is we don't really know what the next hurdles are because this is the first time we've gotten this far," Montgomery said.
"We'll have to continue to really keep a close eye on her."
