New York researchers transplanted two brain-dead individuals with pig hearts over the past month. This is the latest development in a long line of developments to save human lives using animal organs.
The Tuesday announcements follow a failed attempt to save a Maryland man from death using a pig's heart earlier in the year. It was a sort of rehearsal before scientists make another attempt at saving lives.
One of the most important lessons is to practice with the dead.
Dr. Nader Muzazi, who was responsible for the NYU Langone Health operations, said that "we learned so many things from the first one that we believe the second one will be even better." Moazami stated, "You stand there in amazement" when the heart of a pig starts beating in a human body.
Moazami's team replicated heart transplants every day this time. Researchers visited a facility that houses genetically modified pigs twice last week. They removed the hearts and put them on ice before flying them hundreds of miles back home to New York.
Before sewing the heart into each recipient's chest, they used new techniques to screen for animal viruses. One was a Vietnam vet from Pennsylvania with a history of heart disease. The other was a New York woman who had received a transplant earlier in her life.
Three days of intense testing, including frequent biopsies and biopsy of the organ, were then performed before doctors removed life support.
The Food and Drug Administration is already considering whether to allow Americans who require a new organ to participate in rigorous research of pig hearts and kidneys. NYU Langone is one of three transplant centers that are currently in the process of trials. In August, a meeting was scheduled with FDA to discuss requirements.
According to Dr. David Klassen, of the United Network for Organ Sharing (which oversees the country's transplant system), testing in the dead could be a way to fine-tune the design of the first trials in living patients.
Klassen said that they serve as a stepping stone. She wonders if next time researchers might be able to track the organs for up to a week in a donor body, rather than only three days.
Scientists call it xenotransplantation. Xenotransplantation is an animal-to-human transplant. This has been attempted for decades with no success. People's immune systems nearly immediately attacked foreign tissue. Now, pigs have been genetically modified to make their organs more human-like. This increases the possibility that they will one day fill the shortage of organs. There are more than 100,000 people on the national transplant waiting list, many of whom are kidney patients. Thousands die each year before they get their chance.
January was the most ambitious attempt. Doctors at the University of Maryland Medical Center transplanted an organ from a pig into a 57-year old patient. David Bennett survived for two more months, proving that xenotransplantation is at least possible. Initial testing revealed that the organ was infected with an animal virus. Researchers from Maryland recently reported in The New England Journal of Medicine that Bennett's new heart failed. It is not known if the virus was responsible.
Months before, researchers at the University of Alabama in Birmingham and the NYU team were conducting separate tests on pig kidney transplants in deceased people.
The FDA will decide whether formal studies can be conducted on living patients as a result of NYU's heart experimentation.
Robert Montgomery of NYU Langone, a surgeon for kidney transplants, stated that it is crucial to continue careful experiments with the deceased in order to find the best method "in a setting where the life of the person isn't at risk."
This is not an easy situation. Montgomery said that it will take years to learn what is important and what isn't important in order for this to work. He has almost 50 people on his waiting list who are desperate to donate a kidney to a pig.
FDA has not yet indicated when it may decide to allow such studies. The FDA's scientific advisors stated that it was time to experiment despite many questions at a recent public meeting. These include how to best modify the pigs. Many biotech companies, including Revivicor which provided the NYU organs, are exploring different options.
In a clinical trial, it is not clear which organ should be tried first. A patient can still survive on dialysis if a pig's kidney fails. Some FDA advisers suggested that starting with the heart may be a better option. Experiments on deceased pig kidneys showed that the organs produce urine. It is not yet known if pig kidneys perform another important function -- that of processing medication -- in the same way as human kidneys.
