Baltimore surgeons have transplanted the heart of a genetically altered pig into a man with terminal heart disease who had no other hope for treatment, the University of Maryland Medical Centre announced last week, the second such procedure performed by the surgeons.
The first patient, David Bennett (57) died two months after his transplant, but the pig heart functioned well and there were no signs of acute organ rejection, a major risk in such procedures.
The second patient, Lawrence Faucette (58) underwent the transplant surgery last Wednesday and is “recovering well”, the medical centre said in a statement.
The New York Times reports that Faucette, who had terminal heart disease and other complicated medical conditions, was so sick he had been rejected from all transplant programmes that use human donor organs.
The transplantation was performed by Dr Bartley Griffith, who operated on the first patient. Dr Muhammad Mohiuddin, of the University of Maryland School of Medicine, designed the protocol.
Bennett had died after multiple complications, and traces of a virus that infects pigs were found in his new heart, raising concerns that so-called xenotransplants of organs from animals to people could introduce new pathogens into the human population.
Last week, hospital officials said they repeatedly tested the pig that was used in the latest transplant – for both the virus, called porcine cytomegalovirus, and antibodies – using a new assay that was not available at the time of Bennett’s transplant.
Before the surgery, Faucette said he recognised that it would be a miracle if he were able to leave the hospital and go home, and another miracle if he lived for months or a year longer.
“Realistically, this is in the early-stage learning process,” he said of the procedure.
In recent years, the science of xenotransplantation has taken huge strides, with gene editing and cloning technologies designed to make animal organs less likely to be rejected by the human immune system.
Transplant surgeons at the University of Alabama at Birmingham and NYU Langone Health have transplanted kidneys from genetically modified pigs into brain-dead patients maintained on ventilators, demonstrating that the kidneys can make urine and perform other essential biological functions without being rejected.
“There is a growing need for organs and for people with end-stage organ failure who are out of options,” said Dr Jay Fishman, a professor of medicine at Harvard and associate director of the Transplant Centre at Massachusetts General Hospital.
“While decedent trials are informative, transplants in living recipients are, of course, most relevant to advancing knowledge in the field,” he added. He was optimistic that the surgery would encourage scientists to enter the field and accelerate the path to clinical trials.
The heart transplanted into Faucette came from a pig that had received 10 genetic modifications. Scientists removed three pig genes that cause rapid rejection of pig organs by the human immune system, while inserting six human genes that allow the immune system to accept the organ.
An additional pig gene, responsible for the heart’s growth, was knocked out to prevent the organ from becoming too large.
The genetically altered pig was provided by Revivicor, a regenerative medicine that is a subsidiary of United Therapeutics Corporation. Before the transplant, the pig was screened for viruses, bacteria and parasites.
The US Food and Drug Administration (FDA) granted emergency approval to the transplant under a “compassionate use” process that allows experimental procedures to be performed on a single patient who has a life-threatening condition.
See more from MedicalBrief archives:
Pig heart used in US transplant may have been infected with porcine virus
World first: Transplant of pig heart on terminal US patient
Gene-edited piglets opening door to animal organ transplants