A team of American surgeons has successfully transplanted a pig kidney into a brain-dead woman, a medical milestone that brings the still-distant goal of using animal organs in humans. The kidney, obtained from a genetically modified specimen, functioned correctly for 54 hours, the researchers explained to USA Today, the newspaper that has revealed the news. The operation took place on September 25 at New York University Langone Medical Center.
The nephrologist Rafael Matesanz, founder of the successful Spanish National Transplant Organization, applauds the new advance. “The experience is fascinating because, at least in the short term, the genetic modification introduced has made it possible to overcome the interspecies barrier, something that has been pursued for decades,” he reflects. Matesanz emphasizes that there are still “many questions” before making the leap to the clinic, such as ruling out the rejection of the pig organ in the medium term. The expert recalls the case of Stephanie Fae Beauclair, an American girl who in 1984 endured 21 days with a transplanted baboon heart. “In the pig-to-monkey experiments developed in the 1990s, immediate rejection was avoided, but not a few weeks later,” Matesanz warns.
The new operation, led by surgeon Robert Montgomery, implanted the pig kidney in the woman’s left thigh, simply to have the organ in view and to be able to easily monitor it. Urine began to flow as soon as human blood flowed through the porcine organ, according to information published in USA Today. The brain-dead woman’s family had previously authorized the trial, considering that she — a donor and friend of people with kidney failure on dialysis — would have loved to participate. Montgomery himself has lived with the heart of a donor for three years.
The World Health Organization estimates that there are about 130,000 transplants a year on the planet, less than 10% of what is necessary. Having animal organs would be a solution to this shortage, according to scientists such as the Spanish Juan Carlos Izpisua, although Matesanz emphasizes that making the leap to the clinic “is not going to be easy at all,” especially for ethical reasons. A patient in need of a kidney can wait on dialysis until a human replacement is available, stresses the nephrologist. “Offering a pig kidney to a person is clearly substandard. The ethical committees are going to think about it five times, ”argues Matesanz. Spain has been the world leader in donation for three decades, but the drastic reduction in traffic accidents – the traditional source of organs – is also forcing the search for alternatives.
Behind the transplant in New York is the American company Revivicor, established in 2003 from the British company PPL Therapeutics, which in turn was involved in the creation of sheep in 1996 Dolly, the first mammal cloned from an adult cell. Revivicor modifies a specific gene in porcine embryos, called Gal, to obtain pigs with organs that are more compatible with primates, as several previous experiments with monkeys had already shown.
Spanish chemist Marc Güell is one of the co-founders of eGenesis, another American company dedicated to trying humanize pig organs for transplantation. Güell considers that the advancement of their competition is “fantastic news” and believes that it was “totally expected that they would be the first”. The researcher recalls that the field of xenotransplantation – transplants from one species to another – went through “a very hard time” at the beginning of the 21st century, after several failures. In recent years, however, the revolutionary CRISPR genetic engineering technique, capable of quickly and cheaply editing genes, has accelerated scientific advances. “Now there is a renaissance in pig engineering”, celebrates Güell, from Pompeu Fabra University, in Barcelona.
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