Scientists at NYU Langone Health made history last week when they attached a pig’s kidney to a deceased human host.
“It had absolutely normal function,” says lead surgeon Dr. Robert Montgomery, who underwent a heart transplant in 2018. “It didn’t have this immediately rejection that we were worried about.”
Immediate organ rejection in past experiments was found to be caused by alpha-gal, a non-human sugar molecule found in most mammals. This time around, the porcine donor was genetically engineered by United Therapeutics to eliminate the presence of alpha-gal.
To conduct the experiment, Montgomery and his team hooked the pig’s kidney to a pair of blood vessels outside the host. With permission from her family, the deceased woman was hooked to a ventilator to ‘keep the body going’ after death.
The pig’s kidney was observed to function normally – filtering waste ad producing urine – for two full days.
“This is an important step forward in realizing the promise of xenotransplantation, which will save thousands of lives each year in the not-too-distant future,” said Martine Rothblatt, CEO of United Therapeutics.
Scientists have been trying to effect xenotransplantation since the 17th century, when French physician Jean-Baptiste Denys performed deadly blood transfusions using sheep and calves.
Despite decades of failed experiments, surgeons in 1984 attempted to transplant a baboon heart into the body of a dying baby girl. The infant, known as Baby Fae, died 21 days after the procedure.
Over time, scientists moved from primate to pigs – which have larger litters and shorter gestation periods. There are also fewer ethical concerns when using pigs for experiments, as they are commonly used for food.
Pigs are already used for heart valve transplantation and skin grafts and to produce heparin (a blood thinner derived from porcine intestines). In China, they are used as donors for patients in need of cornea transplantation.
Given the success of his recent experiment, Montgomery hopes to see xenotransplantation using human hosts within the next five years.