Monkeys that received genetically modified pig kidneys in xenotransplants as part of a study in the journal Nature, have lived for about two years, regarded in medical history as one of the longest survivors of interspecies organ transplantations. Scientists are hopeful that this research can help make replacement organs for humans that are currently waiting on the organ transplant list due to organ shortages.
In just the United States, over 1,00,000 people are on the organ transplant list, waiting for life saving organs to be donated to them and about 17 of them die each day without that hope being realized. Such technology could save millions of lives around the world and could have optimistic medical implications for those who suffer from some chronic and terminal illnesses. This might also be a good opportunity for all of us to mull about organ donation as something to consider including in our medical details.
Hopeful Future of Xenotransplants
The process of transplanting an animal organ into humans is termed as xenotransplantation. It involves both the genetic modification of the donor organ in order to make the host accept it without triggering an immune response, and also the neutralization of any pathogens such as viruses that the donor organ could contain, to ensure that the host is not infected due to the transplantation.
Researchers say that this trial will be able to provide more data in order to consider undertaking human trials of xenotransplants with non-human organs. However, scientists deem it necessary to thoroughly explore the success of this trial of xenotransplants, and study how feasible it could really be to attempt to mass-produce pigs with such extensive genetic edits.
Details of this Experimental Trial
This experiment was published in the famous peer review journal Nature. The researchers made use of Crispr – a gene editing tool, to alter genes in miniature pigs to make their kidneys non resistive, before conducting the xenotransplant into monkeys.
This process was done to 21 monkeys that had their own kidneys removed, and the monkeys survived with these altered kidneys for about six months, with at least two monkeys living for more than two years. ”Not only can we get up to a year, we can reach up to two years in the monkey. It sets the foundation to go to the clinic with confidence,” said Mike Curtis, one of the authors.
Prior to this study however, typical xenografts only survived for about three to six months. This makes it quite necessary to observe and analyze why this specific study did better than studies performed until now.
Pigs as a potential Organ Farm
In the past few years, researchers have transplanted pig hearts into two living people, and demonstrated that pig hearts and kidneys can function in xenotransplants for people who have been declared legally dead.
Research for animal organ transplant into humans has mainly focused on pigs as the organ donors, in part because their organs seem to be of a size and anatomical makeup that is quite similar to that of humans, making them ideal for xenotransplants. They have large litters that grow rapidly and are already raised as a food source, possibly making it easier to use them for large amounts of organ cultivation, if a sustainable method is created.
But the immune systems of humans are still hostile to such organs – attacking pig cells, causing them to reject these organs. In order to make such transplants possible, researchers have begun using CRISPR–Cas9 genome-editing to edit out the genes that encode enzymes that produce molecules that mark these pig organs as foreign to human immunity cells, thus masking them so as to avoid organ rejection, preparing them for xenotransplants.
In previous studies done using pig organs for transplantation into brain-dead humans, the organs seemed to swell up after some time due to uncontrollable reasons. The researchers were not able to successfully edit out the genes causing this swelling with their trials. In this study published in Nature however, the genetic modifications made to the organs caused this swelling to slow. However, such extensive gene editing could also be difficult to replicate and also to reproduce on a large scale.