FROM LEFT: LOMA LINDA UNIVERSITY HEALTH; COURTESY OF DAVID BENNETT JR.26 SCIENCE NEWS | March 12, 2022JOE CARROTTA FOR NYU LANGONE HEALTHFEATUREA
57-year-old Maryland man has now survived for
weeks with the transplanted heart of a genetically
engineered pig. His doctor has hailed the operation
as a “breakthrough surgery” that could help solve
the organ shortage crisis. But from a scientific standpoint, it’s
too early in the game to know how much this milestone will
move the ball.
The use of animal organs for humans is an idea with a long,
dramatic and often disappointing history. There’s an old saying
about xenotransplantation, as the field is known, says surgeon
Joseph Leventhal, who heads the kidney transplant program
at Northwestern University Feinberg School of Medicine in
Chicago. “It’s just around the corner. The problem is, it’s a very,
very, very long corner.”
But a rash of new experiments, including three using pig
kidneys for people being kept temporarily alive on ventilators,
has provided tantalizing evidence that achieving the decades-
old ambition may finally be in reach.
The recent animal-to-human operations come after an
extensive effort to develop genetically altered pigs with organs
that might avoid abrupt rejection, along with refinement of
drugs that suppress the immune system and boost survival.
That said, the Maryland heart operation was a Hail Mary
rescue attempt and not part of a clinical trial — the kind of
carefully designed study that is ultimately needed to show
whether pig organs can function in humans, and do so safely.
One case can provide some valuable information about how
the body responds to the organ, says Karen Maschke, a bio-
ethics scholar at the Hastings Center in Garrison, N.Y., who is
editor of the journal Ethics & Human Research. “You may findstuff that you didn’t expect to find,” she says.
But a single snapshot of data doesn’t have enough context
to draw conclusions, especially when it involves a gravely ill
patient and brand-new technology. Without a study comparing
several carefully selected patients, it’s hard to know whether
one individual’s experience is typical.
Yet the latest flurry of pig-to-human transplant experiments
could help open the door to the kinds of clinical trials that
researchers want. That’s the only way to significantly advance
the science, says heart surgeon David Cooper of Massachusetts
General Hospital in Boston, who has long researched the idea
of xenotransplantation. “We’ll learn much more if we are doing
clinical cases than if we are staying in the laboratory.”High on the hog
If clinical trials ultimately prove successful, animals could
help ease a critical shortage of donor organs. Of the more than
106,000 U.S. residents waiting for a transplant, about 90,000
need a kidney. Many will die before one is available.
Doctors have previously turned to animal organs in bold,
headline-grabbing endeavors. Famed Houston heart surgeon
Denton Cooley transplanted a sheep heart as a desperate
move to save a dying man in the 1960s; the man’s body quickly
rejected the organ.
One of the most high-profile tries at xenotransplantation
occurred in 1984, when doctors at Loma Linda University
Medical Center in California sewed a baboon heart into a
2-week-old baby born with a fatal cardiac defect. Baby Fae, as
she was known, lived for 20 days and her surgery left a wake
of controversy. Some medical ethicists called the operation aA High-Profile
Transplant
Milestone
Will the successful use of a
pig heart in one dying man
help others? By Laura BeilAs a step toward enabling
animal-to-human organ
transplants, doctors at NYU
Langone Health in 2021
attached a genetically modified
pig kidney to a person who was
clinically brain-dead.pig-transplants.indd 26pig-transplants.indd 26 2/23/22 10:08 AM2/23/22 10:08 AM