David Bennett, a 57-year-old American who lived for two months with a genetically modified pig’s heart died on Tuesday March 8. “His condition began to deteriorate several days ago. When it became apparent that he would not recover, he received palliative care. He was able to communicate with his family during his final hours,” indicates, in a press release, the University Hospital of Maryland where this xenograft (transplantation from another animal species) was carried out, the first of its kind in the world with a genetically modified heart.
End-stage heart failure, David Bennett had been hospitalized in October 2021, and was initially treated by a so-called ECMO procedure (for extracorporeal membrane oxygenation): an extracorporeal circulation circuit with a membrane ensuring the oxygenation of the blood and the elimination of CO2.
Ineligible for a conventional heart transplant, but also for an artificial heart pump system, this patient had given his consent to benefit from an experimental transplant of a pig’s heart. The procedure, urgently authorized by the Food and Drug Administration (American health authorities) on a compassionate basis, was carried out on January 7 by surgeons Bartley Griffith and Muhammad Mohiuddin.
A heart named Uheart
To manufacture this heart called Uheart, the American firm Revivicor modified ten genes of the porcine organ, with genome editing techniques. Three genes responsible for the rapid rejection of pig organs by humans have been knocked out. In addition, six human genes responsible for the immune acceptance of pig hearts have been inserted into the genome. Finally, an additional gene was deleted in the animal, to prevent excessive growth of pig heart tissue. The patient then received an immunosuppressive treatment, also experimental.
Announced following a delay of a few days, this first was highly publicized and hailed as a feat by the medical world. Survival of the patient beyond seventy-two hours with a functioning heart meant in effect that there had been no hyperacute rejection of the organ, one of the main risks of cross-species transplants, along with infections. .
The first attempts at xenografts began at the beginning of the XXe century, with a monkey kidney transplant. In the 1980s, in California, a little girl of regarding 1 year old – Baby Fae – had received a baboon heart, and had succumbed in three weeks, due to an immune rejection phenomenon.
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