If you're looking for a long explanation on the technical aspect of xenotransplantation you are out of luck. It very simply is the insertion of non-human parts in humans for all aesthetic purposes of this project. There are two reasons that xenotransplantation has been stymied. One being ethics and procedure committees or groups. But, that is the most recent roadblock. The second stems from centuries of immunolgical defenses our bodies have developed. We have become medically able to take a good deal of bad parts out of human beings and put good replacement parts from other human beings in. Unfortunately, in most circumstances such practices are dependant on salvage of a cadaver's remaining useful pieces. Consider it poetic redemption of the death of a fellow human being, new life from death. That's great. What is not great is that dark guy with the sickle, Death, isn't with the program. There are more organ orders to fill than available organs. No parts, no miracles, no ABC special movie. One way to make more parts available is to use other sources of parts. Animals, pigs have hearts, and livers, and all sorts of good things. Come to think of it so do primates. All right let's plug those rat bastards in. And then this is where the immune system (duh da duh dut duh daa) swoops in to save the day, destroys the foreign object and/or renders it useless, and then kills the patient one way or another. I suppose that is one way to lower the amount of people looking for new organs and exercise population control.

As best I can tell this type of project was intended to save lives though. A modified game plan is to hide the parts and camouflage them on a cellular level. Another segment of that plan is to take the teeth out of the immune system so that it can do no harm. Methods include altering the genetic code of the donor animal to have certain genes removed or 'knocked out', specifically Gal from pigs which stimulates a humeric response in humans, creating 'knock out animals', preventing the expression of genes, the modification of extra cellular receptors that resist antibody binding, the addition of antibody inhibitors, and engineering resistance to leukocyte adhesion.

To just modify one cell in such a manner tinkering within the DNA is hard enough. One can imagine the pain in the posterior doing that so many times would be. So, this is where the fun stuff really happens. They create a whole animal from just one cell, that's right folks they clone their handiwork. Successful attempts are a good source for a butt load of cells. The other reason cloning is used is to keep sexual contamination and spontaneous mutation down. If one were to get rid of a red flag to the immune system, one wouldn't want to reintroduce it through mating.

The other method involves tinkering with the body's immune system. When transplants from one human to another are done they are referred to as allogenic and they need to be protected from cellular rejection which involves T-cells. Non-allogenic or xenogenic transplants are subject to a different kind of rejection, humoral rejection that involves B-cells. The introduction of certain drugs and immunosuppressants, so as to cripple the system are needed. Popular immunosuppressants are tacrolimus (FK506), cyclophosphamide, prostaglandin E, and prednisone used in conjunction with each other and various steroids. Tacrolimus is the star of the show though. It is a new high-power immunosuppressant developed by Thomas E. Starzl, M.D., Ph.D., F.A.C.S., an early allogenic transplant surgeon to use cocktails of immunosuppressants on his patients with high positive results.

Last but not to be forgotten are the great sums that are required for these ventures by the suppliers that make xenotransplantation possible. Animals of the highest quality are used in an attempt to abate the groups that protest because of the potential of disease to leech into the recipient from the donor tissue. They have a reasonable argument. Autopsies of ultimately failed attemps have had their donor organ's DNA found littered throughout the body creating a literal chimera. These aforementioned animals are raised under conditions that facilitate a disease free donor, which makes animal cruelty groups angry. They are costly. Recipients, should any have a life-preserving successful transplant, would need to be on immunosuppressants and various other supporting substances their entire life. Novartis, Immutran, Fujisawa, and Bristol-Myers Squibb; some of the most prominent producers of these things do not supply their products for the good of humanity. They are businesses, they are out for the Benjamins directly or indirectly.

In conclusion it is my opinion that people doing xenotransplants don't seem to have any business doing so. Moving ahead because they can, not because they should. I do have resounding fears, not about any retroviruses that maybe I should, but of current animal pathogens that just need a better bridge to evolve in so as to be able to make human tissues home. Especially since, the bridge host is having their immune system compromised and a half. I think the money would be better spent in that more research should go into the farming of human organs. Cloned organs. Donor organ systems that are grown in a jar or something. That would probably make the 'Stop-Playing-GOD' groups angry. Regardless, there are a lot of people with bum hearts, kidneys, livers, and "bad" brains. A solution should be found because; not everybody that gets sick, is sick because they sit on their ass all day, drinkin' beer, jus' watchin' TV, smoking their three packs of cigarettes every day. For those with bad pancreases there should be a cure, they shouldn't have to worry about losing a leg from a stubbed toe, they shouldn't be deprived of the wonderful things like desert after they finish their lima beans, or losing their sight little by little, day after day. I think the people behind xenotransplantation have their hearts in the right place by trying to find a cure, but they are going in the wrong direction.