Medical Milestone: Man Receives Heart from Genetically Modified Pig

A 57-year-old Maryland man has received a new heart from a genetically modified pig, possibly ushering in a new era of organ transplant procedures.

Though the method of using animal organs and skins, known as xenotransplantation, has been tried before on patients with varying degrees of success, the groundbreaking eight-hour procedure performed in Baltimore at the University of Maryland Medical Center could be a game-changer if the patient, Maryland resident David Bennett Sr., can survive past the initial threshold. According to the New York Times, doctors have been closely monitoring Bennett for the past three days; his new heart remains functional.

“It creates the pulse, it creates the pressure, it is his heart,” said Dr. Bartley Griffith, the director of the cardiac transplant program at the medical center. “It’s working and it looks normal. We are thrilled, but we don’t know what tomorrow will bring us. This has never been done before.”

While Dr. David Klassen, the chief medical officer of the United Network for Organ Sharing, expressed optimism over the new procedures, he cautioned that new medical frontiers often take time to fully mature into a reliable practice.

“This is a watershed event,” said Klassen. “Doors are starting to open that will lead, I believe, to major changes in how we treat organ failure.”

“Events like these can be dramatized in the press, and it’s important to maintain perspective,” he added. “It takes a long time to mature a therapy like this.”

The procedure occurred several months after surgeons in New York successfully transplanted a kidney from a genetically-modified pig into a brain-dead person. Scientists have focused on pig organs over primate organs over the past few decades due to the animal’s faster maturation rate and the relative ease of raising them. Per the Times:

Pigs offer advantages over primates for organ procurements, because they are easier to raise and achieve adult human size in six months. Pig heart valves are routinely transplanted into humans, and some patients with diabetes have received porcine pancreas cells. Pig skin has also been used as a temporary graft for burn patients.

Two newer technologies — gene editing and cloning — have yielded genetically altered pig organs less likely to be rejected by humans. Pig hearts have been transplanted successfully into baboons by Dr. Muhammad Mohiuddin, a professor of surgery at University of Maryland School of Medicine who established the cardiac xenotransplantation program with Dr. Griffith and is its scientific director. But safety concerns and fear of setting off a dangerous immune response that can be life-threatening precluded their use in humans until recently.

Bennett decided to undergo the procedure after becoming too sick to qualify for a human donor heart, putting him in a do-or-die type of scenario. Doctors predict that he will be able to detach from the heart-lung bypass machine that had previously kept him alive if his recovery continues at its current pace.

“It was either die or do this transplant,” Bennett said before the surgery. “I want to live. I know it’s a shot in the dark, but it’s my last choice.”

Should the procedure prove successful, it could dramatically alter the way in which humans receive organ transplants, the demand for which has increased year after year, with about a dozen potential recipients dying each day. Just last year, the United Network for Organ Sharing said that approximately 41,354 Americans received an organ transplant, more than half of which were for kidneys.