"Consistent life-supporting function of xenografted hearts for up to 195 days is a milestone on the way to clinical cardiac…
“Consistent life-supporting function of xenografted hearts for up to 195 days is a milestone on the way to clinical cardiac xenotransplantation,” the researchers wrote.
“Despite 25 years of extensive research, the maximum survival of a baboon after heart replacement with a porcine xenograft was only 57 days and this was achieved, to our knowledge, only once.”
Xenotransplantation refers to the process of transplanting organs or tissues between different species.
“Selv om de potentielle fordele er betydelige, bruken af xenotransplantation rejser bekymringer med hensyn til at anvende genetisk modificerede svinhjerter til menneskelig organtransplantationer. den potensielle infektion med modtagere med både anerkendte og ukendte infektionsmidler og den mulige efterfølgende overførsel til deres tætte kontakter og ind i den generelle humane befolkning, “siger US Food and Drug Administration.
” Of public health concern is the potential for cross -species infection by retroviruses, which may be latent and lead to disease years after infection. Moreover, new infectious agents may not be readily identifiable with current techniques, “according to the FDA.
A heart transplant involves re flytte en skadet eller sykt hjerte og erstatte det med en sund en fra en donor som har dødt.
Når tilførslen af humane donororganer ikke overstiger de kliniske behov for organer, patienter er ofte tilbage med at vente. .
As of August 2017, the most recent data available, there were more than 114,000 men, women and children in need of donor organs on the US transplant waiting list – and 20 people waiting for a transplant each day,
Donor animal tissue has been used to build heart valves when a human’s valve has to be replaced.
The new study, conducted between February 2015 and August 2018, involved transplanting hearts from 14 juvenile pigs into 14 male baboons. The hearts were genetically modified to express a human gene called CD46 and thrombomodulin, a membrane protein.
The researchers separated the baboons into three groups and performed the heart transplant procedure in each group using various approaches.
In the first group , the hearts were kept in plastic bags filled with ice cold solution and surrounded by ice cubes between their removal and when they were implanted. The results “were disappointing,” the researchers wrote. The animals, five total, survived for up to 30 days.
In the second group, the hearts were preserved with a solution containing nutrition, hormones and a type of blood cells called erythrocytes.
All four baboons in the second
In de derde groep kregen vijf baboons antihypertensive behandeling – omdat pigs hebben een lagere systolische bloeddruk dan baboons – en extra medication was used to counteract cardiac overgrowth, in which a transplanted heart experiences greater weight gain than non-transplanted hearts.
After four weeks, all five baboons had good heart function, the researchers found, and two of them lived in good health for three months. The researchers decided to extend the study and found that the last two recipients in the group survived in good general condition for 195 and 182 days, respectively.
Limitations of the new study include that it remains unclear whether the approach could work in humans, but the findings take the scientific community one step closer to exploring the idea of transplant in humans.
“The ability to keep a pig heart alive in a baboon for 195 days suggests that similar results could be obtained in human patients, “said Dr. Charles Murry, a cardiovascular pathologist and director of the Institute for Stem Cell and Regenerative Medicine at the University of Washington School of Medicine, who was not involved in the study.
“I do not think we are ready for this step just yet, neither scientifically nor societally. Scientificly, we need to learn more about the long-term immune response to the foreign body and whether there is evidence for viruses or other disease agents being transmitted, “Murry said.
” Societally, I think we need to let the public get their minds around this concept a bit and discuss it in coffee shops or wherever else civil discourse can take place. Perhaps the pig -pen is mightier than the sword? ” He said. “Speculatively, I could imagine a first-in-human trial being a bridge to transplant, in a patient whose heart is acutely failing and no donor body is available. This may get them through the waiting period until a donor heart can be transplanted. “
But the study has provided two technical advances in science, Murry said.
” The first was in organ preservation. The authors pumped a blood-like solution containing red blood cells through the circulation to keep the tissue oxygenated and remove metabolic waste. This gave them much better short-term cardiac function, “he said.” Then, they were dealing with the ongoing growth of the pig heart by slowing down protein synthesis, and this allowed them to go out to the planned endpoint of 195 days. “
The idea to use animal organs for transplantation has been discussed for decades but has never become a reality because the human body aggressively rejects animal organ transplants due to multiple and strong immune e-reactions, Barry Fuller, a professor of surgery and low temperature medicine at the University College London, said in a written statement released by the Science Media Center.
“Scientists have developed genetically modified pigs which could in theory reduce this strong immune response, but even then significant problems have remained, “Fuller said.
Yet the study has shown that by using a new drug regimen and a new way of preserving the donor pig heart,” pig hearts survived for more than six months after transplant into non-human primates (another version of xenotransplantation), “he said in part. “This new research can thus help both to bring organ xenotransplantation a step closer to human application, and to improve organ preservation techniques for human heart transplant.”