Sept. 22 (UPI) -- For the second time, doctors have successfully transplanted a genetically modified pig heart inside a living patient.
Doctors at the University of Maryland School of Medicine announced on Friday that 58-year-old Lawrence Faucette underwent the procedure on Wednesday and is now in recovery and communicating with others.
Officials said Faucette was suffering end-stage heart disease and had been deemed ineligible for a traditional transplant with a human heart because of his pre-existing peripheral vascular disease and complications with internal bleeding.
Wednesday's surgery -- like the first successful transplant earlier this year -- was performed by University of Maryland School of Medicine faculty at the University of Maryland Medical Center.
In a release announcing the surgery, University of Maryland School of Medicine doctors say Faucette has shown no signs of rejecting the organ, though the next few weeks will be crucial to determining if his body might reject it.
Before the transplant procedure, the donor pig was routinely screened for multiple porcine viruses, bacteria and parasites, said doctors, who added that the testing did not reveal any unexpected pathogens.
"This accomplishment is an extremely significant historical milestone for us and for the health care field in general, as it leads us to filling an immense need for the approximate 110,000 Americans who are currently waiting for an organ transplant," said Dr. Mark Gladwin, dean of the University of Maryland School of Medicine. "More than 6,000 patients die each year before getting one. Our leading progress in xenotransplantation could save thousands of those lives."
Mohan Suntha, University of Maryland Medical System president and CEO, said now is "an exciting time for everyone in the xenotransplantation field."
"We've seen an astonishing amount of progress in a short period of time and our system is proud to be part of this incredible milestone," Suntha said. "This is the result of the resolve and tenacity of researchers who have held fast to the vision over decades. Those team members who have been directly involved in this work, as well as those who have watched in hopeful interest, are each part of a medical community that can feel the magnitude of this moment."
Doctors said three genes that are responsible for a "rapid antibody-mediated rejection" of pig organs by humans were "knocked out" in the donor pig. And six human genes responsible for immune acceptance of the heart were inserted into the genome. Doctors said one additional gene in the pig was knocked out to prevent excessive growth of the pig heart tissue, resulting in a total of 10 unique gene edits made in the donor pig.
Genetically modified pigs often are well-suited for human xenotransplantation because of the physiologic similarities between pigs and humans.
In January, 57-year-old terminal heart disease patient David Bennett became the first person to receive a heart transplant from a genetically modified pig. He died two months later.
Less than a year after his death, doctors reported that Bennett's heart showed unexpected changes in its electrical system before he ultimately died. Doctors say the changes were not the reason for his death, but understanding those changes will better aid future similar organ transplants.
Bennett's doctors had to get FDA emergency authorization for the transplant, just as they had to do with Faucette, as well.