This week the Guardian reported that a pig’s heart, which was genetically modified, had been transplanted into a patient by doctors who were trying to save his life. The patient was reported to be in stable condition three days after the operation. The doctors acknowledged that at this juncture it is too early to determine whether the operation was successful.
Not only was the procedure the first to give evidence that an animal-to-human transplant could be successful, but it is a watershed moment for scientists. For decades scientists have struggled to prove that the heart of a genetically modified animal can continue to function without being immediately rejected.
About David Bennett
The patient, David Bennett age 57, was aware that there would be no guarantees. According to his son, David knew he was dying and that there was no other choice for him. He also realized that the operation may not be successful or that he may only survive a few days.
David’s surgeon, Dr. Bartley Griffith, said that David was not eligible for a human heart due to his irregular heartbeat and heart failure.
During the last five years, before presenting David with the opportunity for the transplant, Dr. Griffith performed transplants of pig hearts into fifty baboons. David is somewhat familiar with these procedures, as about ten years ago he was successfully implanted with a pig heart valve.
The day before the seven-hour operation, the University sent out a statement by David saying that he decided in favor of the transplant because he wanted to live. He realized the risk involved but felt it at least gave him a chance at survival.
On Monday, January 10th three days after the transplant, David was breathing independently while connected to a machine to support his heart. The doctors explained that the situation will be critical for a few weeks and that they will continue to observe how his heart is functioning. The heart used in David’s transplant was developed by Revivicor, one of several companies that are developing these organs to be used in human transplants.
The FDA allowed the surgery under an emergency authorization entitled “Compassionate Use.” The authorization is available for patients with a condition that is life-threatening when the patient is without any other recourse.
It the Transplant is Successful
The impetus behind the drive for using animal organs for transplant (xenotransplantation) is the shortage of human organs being donated. The staff at UNOS, the organization that manages the U.S. organ transplantation system, is anxiously awaiting the results of the transplant. Success could mean an endless number of organs for people who at times have been on a waiting list for over a year.
Currently, an average of 100,000 people in the U.S. are on the list to receive transplants. Approximately 90,000 people on the list are waiting for a kidney transplant.
One of the few notable transplant attempts occurred in 1984 when Baby Fae lived twenty-one days after receiving a baboon heart. Otherwise, most other attempts have failed due to the rapid rejection of the animal organ. This problem was rectified by the Maryland surgeons who removed a pig gene that encodes a sugar molecule in the animal’s cells that caused the rapid organ rejection.
The xenotransplantation field has seen Novartis and DNX spend billions in an effort to engineer animals as donors only to realize the full extent of modification that is required. There have, however, been several companies that were successful in creating new modifications on organs in primates with the result that the monkeys survived for many years.
In September 2021 a group of New York researchers attached the kidney of a pig to a woman and had some success. The woman, age 66, was brain dead. Her family wanted to donate her organs, but the organs were not suitable for transplant. The doctors approached the family with a request to connect a pig kidney to the woman’s leg. The offer was accepted and when attached, within minutes the kidney began to function normally and continued for the next two days. There was no evidence of rapid rejection.
Art Caplan, NYU’s renowned bioethicist, described how under the proper circumstances, the best initial test for xenotransplant would be with a brain-dead person.
Looking Forward
The kidney experiment was an indication that animal-to-human transplants may offer promise.
Regarding David, Dr. Griffith said that they are learning a lot from him and are happy that they went forward with the transplant. He added that David seems to be doing well.
