For the second time in history, a genetically modified pig organ has been successfully used to transplant into a brain-dead human body.
Hundreds of thousands of people around the world are waiting for an organ donation. There are not enough human organs to go around. Many people die waiting for a transplant.
More than one million people in the US are living with kidney failure, and only around 25,000 transplants a year. Researchers around the world have been working to find a solution to this shortfall, and they've turned to animal organs to see if they could be a solution.
Thanks to years of hard work and the donation of the body of the recipient, James Parsons of Alabama, that hope is closer to reality.
The idea of being able to have an organ waiting on the shelf, waiting for the person who needs it, is just remarkable to think about.
I'm just a small part of a big puzzle that people have been working on for many years.
It has taken a long time to reach this point. In the 1960s, surgeons tried to transplant kidneys from Chimpanzees to 13 patients with end-stage kidney disease, but most of them died within weeks.
In the 1980s, researchers proposed pig organs might be more suitable due to their closer size to human organs, and last year a pig kidneys was transplant into a brain-dead human for 54 hours.
In order to advance this process clinically, the UAB set up an extensive program in 2015, called Revivicor, which involved dedicated xenotransplantation facilities and highly trained multidisciplinary teams.
Locke explained that in order to get the FDA's approval, they have to be able to demonstrate to them that they can carry out xenotransplantation in the same safe and feasible manner that they do every day. The only difference is that the pig's kidneys came from a human.
This experiment led by a surgeon allowed researchers to better understand the risks involved in this complicated operation to help them develop the first phase I clinical trials.
Our immune systems are fooled into accepting alien tissues as our own, one of the main barriers to successful xenotransplantations.
In non-human primates, the outer surface of the pig's kidneys was identified as a source of foreign invaders. The pigs were genetically modified to not have these antigens.
Modifications to genes to prevent blood clot and other immune reactions proved to be enough to prevent a human body from rejecting the pig's organ in the short term.
The researchers confirmed that the pig's blood pressure is normal.
Many measures were taken to mitigate the threat of Viruses to a successful transplant. The donor pigs were kept as pathogen-free as possible, with checks every three months for 14 infections, and in the lead-up to the transplant the donor was tested every day.
No pig cells or pig retroviruses were found in the recipient's blood after 77 hours of the experiment, but other pig tissues have shown similar results after a much longer period of time.
The procedure answered a lot of questions, but also highlighted some areas that need further investigation. We don't know if a pig's only organ is enough to support a human, or if two would be required.
The structure and function of the kidneys are thought to have been altered by genetic modifications, which will require further testing to tease out how much functional differences were also due to brain death.
"All of us at Revivicor are in awe of the historic achievements," said David Ayares. "We feel confident that this UKidney may be a life-saving solution for thousands of people on dialysis, subject to successful completion of our clinical trials and achievement of FDA approval in the next several years."
The study has established the safety and feasibility of using brain-dead patients as a model for future research. The researchers want to honor the recipient and his family with the name "The Parsons Model".
Locke said that the Parsons Model can be used to study the safety and feasibility of all sorts of things designed to improve the human condition, whether it be a medication or a new surgical procedure.
James was an organ donor who died in a dirt bike accident after his 57th birthday.
"Jim would have wanted to save as many people as he could with his death, and if he knew he could potentially save thousands and thousands of people by doing this, he would have had no hesitation," said Julie O'Hara, Jim's ex-wife.
Jim is very proud that his death could potentially bring so much hope to others, and our dream is that no other person dies waiting for a transplant.
The American Journal of Transplantation published this research.
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