Man Receives Heart from Genetically Modified Pig in Groundbreaking Surgery

History was made on Jan. 7 when a 57-year-old Maryland man with deadly heart disease received a heart from a genetically modified pig. 

The eight-hour operation took place in Baltimore at the University of Maryland Medical Center. The patient, David Bennett Sr, is doing well, surgeons said. Bennett chose to “gamble on the experimental treatment” because he would have died without a new heart and had no other treatment options available.

Bennett’s doctor, Dr. Bartley Griffith, pointed out that while the heart is working and looks normal, no one knows what tomorrow will bring as this is the first time this procedure has been done. 

The new heart is functioning and doing most of the work, the New York Times reports, and doctors say he could be taken off the heart-lung bypass machine as early as Jan. 11. The first 48 hours are critical and he passed through those without incident.

A Growing Problem

In 2021, over 41,300 Americans received a transplanted organ, reports the United Network for Organ Sharing. About 12 people die each day because there is an acute shortage of organs.

Researchers have been working hard to develop pigs who organs would not be rejected by the human body. This research has been sped up in the past 10 years by new gene editing and cloning technologies, the New York Times reports. 

While using pig valves are now common practice in heart surgeries, procedures like this could change the face of modern medicine if replacement organs are no longer in short supply. But doctors are quick to point out that there are many hurdles to overcome first before such procedures could be broadly applied. Rejection of organs occurs even when the donors and recipients are well matched.

Science Offers Hope 

Xenotransplantation, the process of grafting or transplanting organs or tissues from animals to humans, goes back hundreds of years when efforts were first made to use the blood and skin of animals. Pigs offer advantages for organ procurements, because they are easier to raise and achieve adult human size in six months. For example, pig heart valves are often transplanted into humans, and some patients with diabetes have received porcine pancreas cells. Pig skin can also be used as a temporary graft for burn patients.

Gene editing and cloning have helped create genetically altered pig organs less likely to be rejected by humans. The heart transplanted into Bennett came from a genetically altered pig provided by Revivicor, a regenerative medicine company based in Blacksburg, Va.

The New York Times reports this pig had 10 genetic modifications. Four genes were knocked out, or inactivated, including one that encodes a molecule that can cause an aggressive human rejection response. A growth gene was also inactivated to prevent the heart from continuing to grow after it was implanted. 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.

The team used a new experimental drug to suppress the immune system and prevent rejection. It also used a new machine perfusion device to keep the pig’s heart preserved until surgery, the article said.

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