Xenotransplantation is the transplanting of organs or tissue from one species to another. Animal to human transplants were done in the past/ In 1682, the bone of a dog was used in repairing the skull of a Russian aristocrat, and the operation was a success.
Xenotransplantation came into its fame with the case of “Baby Fay”, who lived for twenty days, supported by a baboons heart. Xenotransplantation provided a hopeful alternative when human organs and tissue were not available, and several cases were in the highlight in the 1960s and 1970s. In 1964, a patient lived for nine months with a chimpanzees kidney.
In the 1970s, introduction of the drug Cyclosporin, which was one of the first immunosuppressants showed promise in reducing the immune systems ability to start the bodys reactions in rejecting foreign tissue. Until 1992, chimpanzee and baboon organs were deemed to be most suitable for xenotransplantation. In 1992, a pigs liver was attached and sustained, outside of the body, until a human liver was found.
But, by 1993, not one animal to human organ transplant patient survived more than a few years. No xenotransplants were deemed ultimately successful. The problem was primarily with the rejection of the tissue when the body mistakes the tissue for an infection. With the immunosuppressants, the greater chance of viral and bacterial infections is also a threat to the patient.
Now, with the dicey availability of human organs that qualify for transplant, xenotransplantation is again being reviewed. The development and breeding of transgenic pigs, combined with cloning technologies, show a promise to produce tissue that is less likely to be rejected.
Pig cells and tissue are showing promise in the treatment of Huntingtons disease, insulin dependent diabetes, and temporary replacement for livers, where the pig liver is kept outside of the body, yet functions to keep the patient alive.
A final concern, however is the chance of cross species viral transmission, a great issue, given the H1N1 virus that has human, swine and bird dna. No one is happy about introducing any new transgenic viruses. This single issue is the most powerful argument against xenotransplants.
The emotional, religous, and public spectacle issues will have to dealt with. Any successful transplant patient will become vulnerable to public scrutiny.
There are many issues to resolve: ethics, international guidelines, the infectious pathogen transfer issue, and others before xenotransplants will be widely available or even successful.
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