Posted on Oct 21, 2021, 3 p.m.
A surgical team led by Dr. Robert Montgomery at the New York University's Longone Health facility successfully transplanted a pig kidney into a human recipient last month, The Guardian reported. This marks the first instance where a kidney has been transplanted from a different organism, scientifically known as xenotransplantation, and has not been rejected by the host's immune system.
This successful demonstration offers a ray of hope to hundreds of thousands of Americans who are currently on waiting lists for organ transplants. The New York Times reported that about 90,240 individuals are waiting for a suitable kidney donor, and estimates suggest that 12 people die every day waiting for an organ. By sourcing these organs from pigs, we could shorten the wait and improve the quality of life for thousands of people.
The road to this milestone achievement was not easy, though. The concept of sourcing transplant material from animals has been around since the 17th century, The Guardian reported. Having attempted transfusions using animal blood, humankind has even attempted a transplant with a baboon heart but the recipient did not survive. Although pigs have been found to be more compatible with the human body with their heart valves and pig intestine-derived heparin working well in human recipients alongside skin grafts. The operation, however, needed a genetically engineered pig before an organ transplant could be successful.
Pig cells produce a sugar called alpha-galactose which is quite common in other mammals as well, except humans. So, when a regular pig organ is transplanted into a human, it comes with alpha-galactose, which is a foreign substance to the human immune system. The transplant is then attacked and eventually rejected by the human body.
A team of researchers at Revivicor, a biotech firm, engineered the genetic make-up of pigs so that they lack the gene that's responsible for alpha-galactose. The team raised a herd of 100 genetically modified pigs at a contained facility in Iowa.
Interestingly, the recipient of the pig kidney was a dead human being. The deceased woman wanted to donate her organs after death, but since they were not suitable for donation, her family agreed to this experiment. Her body was kept on a ventilator following her death and then the kidney from Revivicor's pigs was attached to large blood vessels outside her body. As blood flowed through the organ, the kidney worked, filtering waste and producing urine. The transplant was observed for a period of 54 hours during which urine and creatinine - a marker of kidney function, levels were normal, and no signs of organ rejection were observed, The New York Times reported.
Although Revivicor has FDA approval for gene alteration, it will need to do much more work before the organs can be transplanted into living humans. With shorter gestation and large litter sizes, pigs do offer a scalable way to source organs. However, the method will also, inevitably, raise ethical issues of whether this method should be used simply because it works.
No scientific data has been published about the transplant yet, and it will need technical evaluation before it can be deemed a total success.
This article was written by Ameya Paleja at Interesting Engineering.
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