A 57-year-old Maryland man has now survived just over three 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 it moves the ball.
The use of animal organs for humans is an idea with a long, dramatic and often disappointing history (SN: 11/4/95). There’s an old saying about xenotransplantation, as the field is known, says Joe Leventhal, a surgeon 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 involving pig kidneys transplanted into people being kept temporarily alive on ventilators, has provided tantalizing evidence that achieving the decades-old ambition may finally be in reach.
recent human operations come after an extensive effort to develop genetically altered pigs with organs that might avoid abrupt rejection, along with further refining 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 bioethics scholar at the Hastings Center in Garrison, N.Y., who is editor of Ethics & Human Research. “You may find stuff 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 Americans waiting for a transplant, around 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 (SN: 11/3/84). Baby Fae, as she was known, lived for 21 days and her surgery left a wake of controversy. Some medical ethicists called the operation a “beastly business” that lacked moral clarity. Scientists “beat a hasty retreat back to the laboratory,” according to a 1995 report in the Journal of the American Medical Association.
In a controversial 1984 surgery, Stephanie Fae Beauclair, known as “Baby Fae,” received a baboon heart to replace her failing heart. The experiment at Loma Linda
You must be logged in to post a comment.