Prouesse médicale assortie d’interrogations éthiques inédites, le New-York Times évoque la xenotransplantation d’un coeur de porc, pratiquée sur un patient le 7 janvier dernier aux Etats-Unis et explique de quelle manière cette première pourrait bien constituer un pas décisif vers la fin de la pénurie d’organes : “The heart transplanted into Mr. Bennett came from a genetically altered pig provided by Revivicor, a regenerative medicine company based in Blacksburg, Va. The pig had 10 genetic modifications. Four genes were knocked out, or inactivated, including one that encodes a molecule that causes an aggressive human rejection response. A growth gene was also inactivated to prevent the pig’s heart from continuing to grow after it was implanted, said Dr. Mohiuddin,who, with Dr. Griffith, did much of the research leading up to the transplant. In addition, six human genes were inserted into the genome of the donor pig — modifications designed to make the porcine organs more tolerable to the human immune system »…. “Scientists have worked feverishly to develop pigs whose organs would not be rejected by the human body, research accelerated in the past decade by new gene editing and cloning technologies. The heart transplant comes just months after surgeons in New York successfully attached the kidney of a genetically engineered pig to a brain-dead person » (1).
Cet évènement ravive le débat ancien de l’apport d’organes et de tissus animaux pour raisons médicales chez des patients humains : “Scientists have been toying with animal-to-human tissue grafting and organ donation, collectively known as xenotransplantation, for centuries. Throughout the 1800s, doctors treated wounds with skin grafts from a variety of animals — most popularly, frogs. In the 1960s, 13 people received kidneys from chimpanzees. One lived an additional nine months, but the others died within weeks. In a more controversial episode, doctors at Loma Linda University Medical Center in California transplanted a baboon heart into a premature baby born with a fatal cardiac defect in 1984. She lived for 21 days. It was later revealed that the surgical team had not sought out a human heart before opting for the riskier (and more headline-worthy) primate option“.
Si la pratique est ancienne, le recours à la technologie du genome editing pose des questions nouvelles, ainsi que le résume le magazine en ligne Statnews : “There’s still relatively little known about how safe this is to try in humans, so I’m viewing this with a little apprehension,” said Arthur Caplan, the founding director of New York University School of Medicine’s Division of Medical Ethics. The transplant was not performed as part of a formal clinical trial, as generally required for experimental treatments. And the immunosuppressive drugs the patient was administered are also novel and have not yet been tested for this use in non-human primates. It’s also renewing a debate about pigs and other animals as the source of human organs. Animal rights activists have condemned the surgery as dangerous and unethical. In a statement released Mo nday evening, PETA raised the potential for xenotransplantation to transmit animal viruses to humans and urged researchers to look elsewhere for solutions to organ shortages. “Animals aren’t toolsheds to be raided but complex, intelligent beings,” the organization said”(2).
1- Roni Caryn Rabin. In a First, Man Receives a Heart From a Genetically Altered Pig. The New-York Times. 10 janvier 2022.
2- Megan Molteni. First transplant of a genetically altered pig heart into a person sparks ethics questions. Statnews. https://www.statnews.com/2022/01/10/first-transplant-of-genetically-altered-pig-heart-into-person-sparks-ethics-questions/