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Future of Mankind: Half-Pig, Half Human, Med Times Copyright, All Rights Reserved, 2004-2005

By $ahar $attarzadeh

 

Have you ever heard of the term, "You are what you eat"? Many are hoping that this line might become an actual reality for the future. Intense research and experimentation have been performed worldwide in an attempt to transplant pig organs into humans. After all, the pig has been identified as the "most suitable donor".

Animal-to-human transplants, otherwise known as transgenic transplants or xenotransplants, are paving a new road for the future of medicine. However, the road may not be as smooth as one would expect it to be. Specifically, xenotransplantation refers to the transplantation from an animal of one species into another species. In regard to humans, xenotransplantation clearly refers to the use of a donor other than a human. Xenotransplantation consists of two types: concordant and discordant. Concordant xenotransplantation refers to the transplantation between closely related animal species, such as a baboon-to-human transplant. On the other hand, discordant transplantation refers to transplantation between distantly related species such as a pig-to-human transplant. Since the pig organs are more applicable to humans, the latter form of xenotransplantation is much more common. This whole spectrum of research was discovered due to a lack of sufficient organs needed for human recipients.

Unfortunately, the number of human cadaver organs available limits organ transplantation. According to UNOS (the United Network for Organ Sharing), in the United States, approximately 45,000 people are listed for solid organ transplantation, but less than 6000 cadaver donors are actually available each year, from which approximately 20,000 donor organs are obtained. Transplants require an unlimited supply of viable organs, which could only come from the carnage of road accidents. This results in an enormous incongruity between supply and demand. Far more transplants are necessary, yet only an insignificant amount of organs are ever available. This is why when a fresh corpse becomes obtainable, medical practitioners gather like vultures squabbling over the tastiest morsels. Due to a lack in an abundant supply of organs, alternatives are being found. This is where the whole concept of xenotransplantation comes into play. Xenotransplantation is one such alternative that has widened the eyes of many medical researchers and practitioners alike. The main reason for seeking the capacities of xenotransplantation has to deal with the fact that an unlimited supply of organs subsists in xenotransplants.

There are many advantages that have erupted from this area of research. For one thing, if xenotransplantation becomes the ultimate trend into the next millenium, all those who need organ transplants will definitely receive them. Since an unlimited supply of organs exists, everyone in need of organs would not have to wait for weeks, months, or even years. Many patients awaiting liver or heart transplantation may well die before a suitable donor becomes available. With xenotransplantation, this will not be a problem, because no waiting is necessary with so many organs available. There has also been some experimental success in the laboratories with pig-to-primate organ xenotransplantation. These transplants are now resulting in transplant function for days and weeks rather than minutes, and there is therefore optimism that we are on the threshold of a new era in the field of the transplantation of vital organs. Although, there is always the drawbacks that exist as well. Many kinks still have to be worked out in order to make this area of study more optimistic.

Xenotransplants may save a few lives (assuming the transplant is not rejected and no complications arise), but in doing so could put the whole human race at risk. A number of new diseases have arisen including Ebola and AIDS, against which the human population has no resistance. One possibility is that African tropical rainforest destruction has caused diseases to jump species. When a disease jumps species, both disease and host are ill-adjusted to each other and the result will most likely be rapid deterioration and death of the host. This has been seen with AIDS and Ebola. AIDS is thought to have jumped from monkeys to humans. Xenotransplants are likely to transfer unknown viruses against which we have no defenses and no cure. To a transplant surgeon, a pig-to-human organ transplant may be an ultimate dream, but it is a virologist’s worst nightmare. According to virologist, Jonathan Allen, "This is a big mistake. It only takes one transmission from one baboon to one human to start an epidemic. There’s no way you can make it safe."

The risks to the human race are great. In 1992, Thomas E. Starzl, a pioneer in xenotransplantation, transferred a baboon liver into an HIV patient suffering from Hepititis B. The patient survived for an intensively agonizing 70 days. His final death was gruesome and he suffered from septic intoxication, oesophagitis, viraemia (the presence of viruses in the blood), hemorrhage in the chest cavity, and later from circulatory collapse, among other side effects. He finally died of internal bleeding.

So as it turns out, xenotransplantation, like many other new discoveries, has its ups and downs. Like many other studies, all the answers are not all quite there. Many pitfalls and disappointments may lie ahead but new advances will be made. The future has probably best been summed up by Professor Roy Calne, the pioneering transplant surgeon, who recently stated, "Clinical xenotransplantation is just around the corner, but unfortunately it may be a very long corner."

Many others are very critical of xenotransplantation and what it can accomplish in the future. An International Treaty is required not only to ban xenotransplants but also to outlaw this whole area of research.