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Xenografts are cells or sections of tissue that are removed from one species and grafted on or into a different species. Grafts of this type are sometimes used to provide temporary protection from infection for burn victims, as well as in the process of cancer research. In most cases, the xenograft is treated before the grafting takes place, which helps to reduce the chances of the host body rejecting the harvested tissue.
One common use of the xenograft is the treatment of human beings who are missing significant sections of skin. Burn victims are one example. In order to help facilitate the healing process, skin is harvested from animals, processed to help make the skin more compatible to the human body, then surgically connected or attached to the area of the burn. Doing so helps to minimize the risks of infection during the recovery period and allows the body time to begin rebuilding healthy skin cells on its own.
Along with burn victims, people suffering with other health issues may benefit from the use of xenografting. Diabetics in advanced stages may receive a xenograft as a means of restoring a section of skin on the feet or legs that has deteriorated as a result of the disease. Cancer victims may receive this form of graft in order to repair damage to an internal organ.
There is a difference between a xenograft and the process known as xenotransplantation. A xenotransplant involves the harvesting of a complete organ for transplant into a human host. This is likely to occur when there is no human organ readily available and the patient’s condition is critical. In some instances, organs are harvested from pigs and successfully transplanted into humans. While often used as a means of keeping the patient alive until a more suitable organ can be secured, some people are able to live years with the use of animal organs, as long as the anti-rejection medication continues to help the body accept the presence of the transplant.
It is not unusual for a xenograft to be utilized as part of cancer research. In this application, human tumors are removed from the host and are grafted into a lab animal, such as a rodent. The graft makes it possible for researchers to study the progress of the tumor closely as different experimental drugs and procedures are tried in an attempt to shrink the tumor and force the cancer into remission.
@KoiwiGal - In fact, pigs are less likely to spread new diseases among people than chimps or other apes, since they've been in close contact with people for so long. That's one of the reasons they use pigs instead of apes for xenotransplants of any kind, when apes make more sense. Of course, pigs are far easier to come by as well.
On the other hand, pigs don't live as long as humans and neither would their organs. While, as it says in the article, xenografts and xenotransplants are generally considered to be temporary, if they start doing them with the intention they be long term, they'll have to overcome this.
I have heard of pig heart valve replacements, but I don't know how common those are, or if they are considered xenografts or transplants.
@bythewell - I'm not even sure if that would count as a xenotransplant! After all, even though the organ came from a pig, it was a human organ, presumably originally made with human DNA.
They might need to change it slightly so the pig didn't reject it though? Or maybe just feed the pig anti-rejection drugs, as they do with people who have organ transplants.
It actually makes me think of my friend who is currently training as a tattoo artist, and practices on pig skin. It is so similar to human skin that it is almost as good to practice on.
Pigs are surprisingly close to humans in a lot of ways.
In fact one of the major barriers so far in xenografts from pigs is that they often carry diseases that we can catch.
I know we are still many years away from this, but reading about xenografts makes me think of people growing human organs in animals to keep as spares for transplants.
I read a story once in which an eccentric man kept his pig, the one which contains some of his organs, near by him as a pet and it freaked out the neighbors and his friends when they came to visit.
And at the end of the story, it turned out that he had been feeding the pig the wrong kinds of food and had actually ruined his spare liver for when he needed it.
It's the kind of story which would have once been considered ridiculous, but are we really all that far off it now? It seems like we're only a couple of decades off, considering how fast work with stem cells and cloning and so forth is going.