A US man with terminal heart disease has had a genetically modified pig heart implanted during his first similar surgery, and the patient is on track three days later, his doctor reported Monday.
The surgery performed by a team at the University of Maryland School of Medicine is one of the first surgeries to demonstrate the feasibility of human heart transplants from pigs, an area made possible by new gene editing tools.
If proven successful, scientists hope that pig organs will help alleviate the lack of donor organs.
“This is a groundbreaking operation and brings us one step closer to solving the organ shortage crisis. We don't have enough donor human hearts to fill our long list of potential recipients,” Dr. Bartley Griffith, who surgically implanted the patient, said in a statement.
“We are proceeding with caution, but we are also optimistic that this world's first surgery will provide patients with important new options in the future,” added Dr. Griffith.
For David Bennett, 57, of Maryland, a heart transplant was his last option. “It's dead or I did this transplant. I want to live. I know it's a shot in the dark, but that's my last choice,” Bennett said the day before his surgery, according to a statement released by the university.
To advance experimental surgery, the university received emergency approval from the US Food and Drug Administration (FDA) on Great Vehicle Day through a compassionate use program.
“The FDA has used data and data from experimental pigs to allow transplants of terminal heart disease patients without other treatment options,” said Dr. Muhammad Mohiuddin, who heads the university's program on xenotransplants — transplanting animal organs into humans.
Approximately 110,000 Americans await organ transplants, with more than 6,000 patients dead each year, according to organdonor.gov.
Bennett's genetically modified pig heart was provided by Revivicor, a regenerative medicine company based in Blacksburg, Virginia. On the morning of the surgery, the implant team removed the pig's heart and placed it in a special device to preserve its function until surgery.
Pigs have long been an attractive source of potential transplants, as their organs are very similar to humans. For example, the pig's heart at the time of slaughter is the size of the heart of an adult human.
Other organs of pigs being studied for human transplantation include the kidneys, liver and lungs.
Previous efforts in pig-to-human transplantation have failed due to genetic differences that caused organ rejection or viruses that pose a risk of infection. Scientists are addressing the issue by editing potentially harmful genes.
In the heart embedded in Bennett, three previously linked genes associated with organ rejection were “knocked out” in donor pigs, and six human genes associated with immune acceptance were inserted into the pig genome.
The researchers also deleted pig genes to prevent excessive growth of pig heart tissue.
This work was funded in part with a $15.7 million research grant to assess Revivicor's genetically modified pig hearts in the BABOON study.
In addition to genetic changes in pig hearts, Bennett received an experimental anti-rejection drug created by Lexington, Massachusetts-based Kinixa Phalmathewl.
