XENOTRANSPLANTATION: The Benefits and Risks of Special Organ Transplantation
Executive Summary
1. Human organ transplantation faces a significant challenge because the need for this procedure far exceeds the availability of donor organs. Each year fewer than half the people on transplant waiting lists receive organ transplants. Approximately 10 people die each day waiting for organs to become available. Even if all potential donors elect to donate, the supply of human organ donations will continue to fall short of the need.
2. One solution doctors along with pharmaceutical and biotechnology companies are investigating to end this acute shortage is "xenotransplantation," or the process of transplanting cells, tissues or organs from one species to another.
3. Rejection, in which the recipient’s body attacks the new organ like an infection, is the greatest practical obstacle to xenotransplantation. The breeding of transgenic pigs as well as new cloning techniques may be used to reduce the risk of organ rejection.
4. In August 1999, the results of a study were announced that found no evidence of infection among 160 people who had previously received medical treatment with living pig tissue. A number of patients in the study did show evidence of circulating pig cells, but no evidence of infection, potentially demonstrating that pig tissue can survive long-term in the human body with no ill effects.
5. At this time, there is no evidence that porcine viruses pose a risk to humans; however, researchers are proceeding with caution to address safety concerns. The U.S. Department of Health and Human Services is developing several important mechanisms to foster participation by the public, scientists and industry in the progress of xenotransplantation.
6. BIO supports public dialogue about xenotransplantation to further understanding and broaden knowledge that will offer innovative treatments for previously untreated conditions. BIO is committed to a responsible research program that is consistent with regulatory guidelines and the recommendations of ethics advisory boards within both industry and government.
Introduction
Human organ transplantation is a relatively new field of medicine that is now facing a significant challenge. Because of its clinical success, the need for this procedure far exceeds the availability of donor organs. More than 60,000 individuals in the United States (U.S.) were registered on transplant waiting lists by the end of 1998. Each year, however, less than half of the people listed receive solid organ transplants. Approximately 10 people die each day waiting for organs to become available. These numbers do not take into account the unknown number of people who are not eligible for transplants because of their age or health status. The demand for organ transplantation will continue to increase as improved technical skills and anti-rejection medication make transplant a realistic option for groups of people previously considered too vulnerable for example, those with diabetes. Also, many other people may benefit from transplantation of cells or tissues to treat countless other diseases such as diabetes, Parkinson’s, Huntington’s, cancer, and injuries to the spinal cord or other organs and limbs.
Despite significant educational efforts on both the national and local level to increase the awareness of the need for organ donation, the number of people who elect to donate their organs if they were to die remains stagnant. Even if all potential donors elect to donate, the supply of human organ donations will continue to fall short of the need.
One solution doctors along with pharmaceutical and biotechnology companies are investigating to end this acute shortage is "xenotransplantation," or the process of transplanting cells, tissues or organs from one species to another. While still in the experimental stages, xenotransplantation is a potentially life-saving option for people with such ailments as severe heart disease and kidney failure. Preliminary data from experiments using transplanted pig cells in patients with diabetes and Parkinson’s disease are encouraging. According to a 1997 survey by the National Kidney Foundation, nearly two-thirds of the American public accepts cross-species transplantation as a viable option to increase the number of organs and tissue transplanted and lives to be saved.
History of Xenotransplantation
Xenotransplantation, a subject of study and experimentation for almost a century, started to receive serious attention from the scientific community in the 1960s as a result of strides made in human-to-human transplantation. Between 1963 and 1993, 31 clinical procedures involving transplantation of solid organs from animal donors were performed in the United States and South Africa. These were extraordinary events. Physicians performed these operations as bridges to maintain life while awaiting a human donor organ.
The first experiments in transplanting chimpanzee kidneys into humans were conducted in 1963 and 1964. One of the patients who received chimpanzee kidneys lived for nine months.
Two of the most publicized xenotransplant operations in the last two decades involved Baby Fae, the infant who received a baboon heart in 1984, and Jeff Getty, an AIDS patient who received a bone marrow transplant from a baboon in 1995. Baby Fae lived with her xenotransplant for 20 days, while Getty rejected the transplanted marrow almost immediately. As of October 1998, Getty remained free of baboon-transmitted viruses and showed no signs of baboon bone marrow in his system.
