Groundbreaking Heart Transplant Between a Genetically Modified Pig and a Human

By Lilly Rosier, 2023

Published 1/19/22

On January 7th, 2022, the first successful xenotransplantation took place in Baltimore. To break it down, Xenotransplantation is the process of transplanting organs or tissues from animals to humans. This is a huge step for the science of modern medicine, as it has been attempted for many years.

David Bennett Sr., the 57-year-old man whom the procedure eventually was performed on recalled having irregular heartbeats for a while before the surgery. Medical action was needed, especially when he officially got diagnosed with arrhythmia. The patient was not a viable candidate for the heart transplant list or an artificial heart pump due to an organ shortage. Instead, Dr. Bartley Griffith, the director of the cardiac transplant program at the University of Maryland Medical Center, proposed an idea to Mr. Bennett where a genetically modified pig heart could be transplanted into his body. The doctor made him aware of the risks, but Mr. Bennett decided to go through with the procedure as well as contribute to a potentially huge scientific discovery.

Routine heart transplants usually can be performed in less than 4 hours, but this surgery took double that. The science behind the organ used in the procedure began when a medical team genetically modified the pig itself with 10 modifications. These modifications include four genes that were knocked out or inactivated, one which had 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 into the human. Additionally, there were six human genes implanted. Once these modifications were done, the heart was removed from the pig and ready for transplanting.

Calling this a risky operation is an understatement. Rejection of organs occurs surprisingly often, even between two human organs. To have the pig heart rejected would not have been a surprise at all to the surgery team. There were also worries the genetic modifications would not be enough to allow the organ to function in a human. There were also concerns about possible infections, and the procedure was highly monitored to prevent Mr. Bennett from developing viruses such as the porcine retrovirus. Despite the overwhelming concerns, the operation was a success.

Right now, there are roughly 106,000 people on the organ transplant waiting list in the United States, and 17 of those people die every day waiting for a transplant. The scientific developments from David Bennett Sr.’s surgery are groundbreaking. If the heart retains long-term functionality, the impacts of this research and experimentation can help people worldwide receive the care that they need.