Pig kidney recipient Tim Andrews breaks GM xenotransplant records

For eight months US man Tim Andrews has been living with a pig kidney in his body.

"Sometimes it's the only thing I can think about, keeping Wilma alive," he said.

"Wilma is my kidney, we named her when we got her, and I take care of her."

Before his transplant at the end of January this year, Mr Andrews had been on dialysis for two years after an end-stage kidney disease diagnosis.

He was told by doctors that the average extension of life on dialysis was five years.

But with his rare O-type blood Mr Andrews was looking at a seven-year wait for a human kidney to become available. A two-year difference which he joked was "a little bit of a gap".

More than 100,000 people are on a waitlist for an organ transplant in the US, and 89,000 of them need a kidney.

Thirteen people from the list die each day.

So Mr Andrews decided to take a different route: experimental surgery at Massachusetts General Hospital in Boston to receive an animal organ genetically altered by scientists that, hopefully, would not be rejected by his body.

And now, eight months later, the 67-year-old has nearly doubled the previous record for living with a functioning pig kidney.

"I'm aiming for a year," Mr Andrews said. "I take it by day but that's my next hope.

"Because then it's worthwhile to take these kidneys and start using them so people can get out of that situation [dialysis] for at least a year."

Going over the six-month milestone is exciting researchers in the field of animal-to-human organ transplants, known as xenotransplantation.

Pre-clinical trials will soon ramp-up in the US with eGenesis, the biotech company that edited Wilma, receiving approval to do more transplants with 33 people over the age of 50 with end-stage kidney failure.

Another US company, United Therapeutics, has approval to trial up to 50 transplants with their own modified pig kidney.

Xenotransplantation researcher Wayne Hawthorne, a professor of transplantation at Westmead Hospital in Sydney, said it was exciting to see how far the field had come.

He said CRISPR had helped the field jump forward to be making multiple gene edits quickly.

"And as they [procedures] improve and the outcomes are extended for these patients, we'll actually be able to transplant more patients," he said.

"I think it's self perpetuating, the more we do, the better we get, the more we'll be able to do."

A long and controversial history

So how did we get to this point that a pig kidney could be placed into a completely different species of mammal?

The idea of xenotransplantation and transfer of living tissue between species goes right back to at least the 17th century.

One of the earliest recorded cases of an animal to human surgery was in 1667 when a French physician performed a blood infusion from a lamb into a 15-year-old boy.

The child survived. Others did not and France put a moratorium on blood transfusions a few years later.

Organ transplants were then attempted in 1906 by another French doctor who attached a pig or goat kidney to the elbow of two different patients. 

Both surgeries failed after three days due to blood clots.

Up until 1996, most attempts at pig and monkey kidney transplants into people lasted from a few hours to 70 days. Although there was one outlier in the 1960s where a woman lived for nine months after receiving a chimpanzee kidney.

The problem in most of these cases was that human bodies quickly rejected these organs because of their genetic differences.

Greater success has been seen in the field of xenografts where skin, bone and tendons from animals, which can be sterilised or decellularised, has been adopted in medicine.

Australian researchers are even hoping in the next year to be approved to trial kangaroo tendons for ACL repair in the knee.

Using animals for these kinds of surgeries provides a supply of biological material where human sources aren't available.

Along came CRISPR

New gene editing tools like CRISPR — a sort of molecular scissors that allows you to make cuts and alterations to the DNA of an organism — could make animal organ transplants just as commonplace.

Tim Andrews's new kidney had 69 genetic edits including the deactivation of a pig retrovirus and the addition of human genes to reduce inflammation and try to avoid rejection.

He was the fifth person to receive an edited pig kidney. A sixth recipient, 54-year-old Bill Stewart, has now gone three months with a pig kidney from the same hospital as Mr Andrews.

Other pig organs like lungs and hearts have been modified and transplanted to people in recent years. A pig heart recipient lived for two months in 2022 after his surgery but may have died in part due to a porcine virus that was missed.

Researchers are also looking into the prospect of sheep and pig corneas for xenotransplantation.

Pigs have become popular for these types of studies as they can be reared quickly and in large litters with organs close in size to a human.

Back in Australia, Professor Hawthorne's research is about transplanting insulin-producing islet cells from the pancreas of a pig into humans with type 1 diabetes.

That's so the recipient is able to make insulin again.

"Our hope is that we can start, potentially in the next few years, to do a small clinical trial treating type 1 diabetic patients," he said.

"But also then it could potentially expand to become a kidney transplant program ... that's the broader hope."

This would mean pig-to-human kidney transplants happening in Australia.

Australia's organ waitlist was 1,922 as of the start of September with the majority of those people — 76 per cent — in need of a kidney.

What are the ethics of xenotransplants?

A major issue for xenotransplantation is animal welfare.

The RSPCA is against the practice, but states that where it does occur, welfare standards should be monitored to ensure a good quality of life for the animals.

Syd Johnson, a professor of bioethics at Upstate Medical University in the US, is sceptical that pig-to-human transplants will become safe, effective and long-term options for patients.

And, she said, gene-edited donor animals were being treated like machines "for the sole purpose of growing a product and disassembling them to provide these spare parts for humans."

"I think this is an opportunity for us to reflect on what we are doing when we are creating animals and treating them in this way."

Professor Johnson was also concerned by how an organ market would be controlled by for-profit companies versus the current human donation model.

"What will be the cost to buy an organ? And who's going to pay that cost? And how will equity and justice be ensured?"

Organ equity is a concern shared by Dominique Martin, a professor of health ethics and professionalism at Deakin University School of Medicine.

She also wonders if there is a world where a pig donating a kidney could go on living.

"It's maybe not desirable from even the pig's perspective, but I think it would be good to start thinking about those animals as different," Professor Martin said.

But ultimately she thought the pigs were doing something of substantial benefit to humans.

"My hope at this stage is that we are going to very soon see several people who are surviving and doing well a year out from a pig kidney transplant," Professor Martin said.

And that's something Tim Andrews hopes to see for himself and others.

"To me, I think you should do it [xenotransplants] because it's the life of a human," he said.

"Meanwhile at every grocery store there's 25 feet of pork being cut up and people are eating it.

"I got a letter from the Vatican that said, basically they agree these are animals that were put on earth for man's service and what better service to man is keeping someone alive."

Living with a pig kidney isn't without its challenges. 

Mr Andrews has been in and out of hospital since his surgery and usually gets a check-up twice a week with his doctors.

"I'll tell you, I'm a warrior," he said.

"When I committed to this 100 per cent I didn't kid. No matter how bad it gets ... you struggle on, you fight on."

And by fighting on others might have hope and see there may be more options, said Mr Andrews, rather than sitting in a dialysis chair "waiting to die".

"To be able to step out of that and be alive again," he said.

"I'm sitting here by a beautiful lake with my sister. Life is beautiful. Weather's beautiful. What more can you ask out of life?"

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