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 The surgery, performed by a team at the University of Maryland
Medicine, is among the first to demonstrate the feasibility of a
pig-to-human heart transplant, a field made possible by new gene
editing tools.
If proven successful, scientists hope pig organs could help
alleviate shortages of donor organs.
“This was a breakthrough surgery and brings us one step closer to
solving the organ shortage crisis. There are simply not enough donor
human hearts available to meet the long list of potential
recipients,” Dr. Bartley Griffith, who surgically transplanted the
pig heart into the patient, said in a statement.
“We are proceeding cautiously, but we are also optimistic that this
first-in-the-world surgery will provide an important new option for
patients in the future,” Griffith added.
For 57-year-old David Bennett of Maryland, the heart transplant was
his last option.
"It was either die or do this transplant. I want to live. I know
it’s a shot in the dark, but it’s my last choice,” Bennett said a
day before his surgery, according to a statement released by the
university.
To move ahead with the experimental surgery, the university obtained
an emergency authorization from the U.S. Food and Drug
Administration on New Year's Eve through its compassionate use
program.
"The FDA used our data and data on the experimental pig to authorize
the transplant in an end-stage heart disease patient who had no
other treatment options,” said Dr. Muhammad Mohiuddin, who heads the
University's program on xenotransplantation - transplanting animal
organs into humans.
About 110,000 Americans are currently waiting for an organ
transplant, and more than 6,000 patients die each year before
getting one, according to organdonor.gov.
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 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 transplant team removed the pig's
heart and placed it into a special device to
preserve its function until the surgery.
Pigs have long been a tantalizing source of
potential transplants because their organs are
so similar to humans. A hog heart at the time of
slaughter, for example, is about the size of an
adult human heart. Other organs
from pigs being researched for transplantation into humans include
kidneys, liver and lungs.
Prior efforts at pig-to-human transplants have failed because of
genetic differences that caused organ rejection or viruses that
posed an infection risk.
Scientists have tackled that problem by editing away potentially
harmful genes.
In the heart implanted in Bennett, three genes previously linked
with organ rejection were "knocked out" of the donor pig, and six
human genes linked with immune acceptance were inserted into the pig
genome.
Researchers also deleted a pig gene to prevent excessive growth of
the pig heart tissue.
The work was funded in part with a $15.7 million research grant to
evaluate Revivicor's genetically-modified pig hearts in baboon
studies.
In addition to the genetic changes to the pig heart, Bennett
received an experimental anti-rejection drug made by Kiniksa
Pharmaceuticals based in Lexington, Mass.
(Reporting by Julie Steenhuysen; Editing by Bill Berkrot)
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