SCIENCE NEWS SPOTLIGHT
First pig heart transplant "Will I oink?" asks David Bennett, recipient of the pig heart transplant Seven days into the new year, a ground-breaking operation was carried out in Baltimore, Maryland: the first ever transplant of a pig heart into a human. 57-year-old David Bennett suffered from end-stage cardiac failure. Having been deemed unsuitable for both a human heart transplant and a ventricular assist device (an artificial mechanical pump), he was permitted to receive the xenotransplant under compassionate use, which allows severely ill patients to receive unauthorised medicine as a last resort. Xenotransplantation entails inserting an organ of a different species into humans, an idea that has been around since the 1920s and still remains contentious. While the ethics that come with such a procedure are highly debated, the idea may offer hope to those awaiting transplants. A longstanding concern with all transplants is the risk of rejection from the recipient’s immune system. Using CRISPR, however, the organs can be genetically modified to reduce this risk. These organs typically come from pigs, as they are favoured over primates given they achieve human size in 6 months and are easy to raise. With pigs producing around 8 piglets per litter, many believe utilising their modified organs
Surgeons at the University of Maryland Medical Center transplanted a genetically altered pig heart into David Bennett.Credit: University of Maryland School of Medicine
may solve the urgent problem of organ shortages. The heart was derived from a pig developed by the US firm Revivicor, with 10 modified genes. Alpha-gal is a sugar found on the surface of pig cells which causes an aggressive immune response to flare up in humans. Of the 4 genes scientists inactivated, one coded for the enzyme that attaches this exact sugar. They also inactivated a gene which prevents the heart from continuously growing after transplantation by hindering its response to growth hormones. To boost acceptance, 6 human genes were further inserted into the heart.
Pigs stand in a barn of the of Ludwig-Maximilians-University Munich at the Badersfeld bog test farm in Oberschleissheim, Germany. (Photo: Reuters)
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On 7th January, David Bennett underwent this procedure under immunosuppressants, and the outcome seemed to be optimistic afterwards, with reports of Bennett slowly gaining strength. He was under close monitoring for signs of organ rejection, which could take weeks or longer to manifest. Albeit the low risk at the time, they were also on the lookout for signs of infections. Unfortunately, Bennett passed away in March. Recent news disclosed that a latent virus, compounded with his initial heart condition, may have been contributing factors. However, scientists have noted that the cause of his death may not fall solely on the infection.
David Bennett Sr. (centre) after his heart transplant pictured with his son, David Bennett Jr (left) (Image credit: University of Maryland Medical Center)
