Xenotransplantation - Nuffield Council on Bioethics

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Animal-to-Human Transplants : the ethics of xenotransplantation the sensitivity of potential organ donors to adverse publicity, more contentious measures to obtain human organs might backfire. Advocates of such changes argue that such legal frameworks have been successful in increasing the supply of human organs in Belgium and Singapore. Yet, establishing that specific policy changes have led to increased transplantation is not easy. In Belgium, for example, an important factor may have been the simultaneous improvement in transplant coordination. 2.9 Another procedure for increasing the supply of human organs is elective ventilation. Elective ventilation involves placing a patient for whom death is inevitable on a ventilator in order to maintain their organs in a suitable state for transplantation. This procedure was used with eight patients in Exeter, between 1988 and 1990. 14 Elective ventilation is contrary to the principle that treatment should be in the best interests of an incapacitated patient, however, and the Department of Health has issued guidance that it is unlawful. 15 This conclusion was supported in a recent report of the Law Commission. 16 A number of bodies, including the British Medical Association 17 and the British Transplantation Society, 18 have concluded that elective ventilation would not be unethical, however, and have recommended that the law should be changed to make it legal. Thus, the issue remains controversial. 2.10 Since 1990 the number of human organ donors has levelled out at about 950 a year. 19 Increased provision of intensive care and transplant facilities, and increased use of donors whose hearts are no longer beating and live donors would go some way to improving transplantation rates. Other measures, such as changing the consent law or introducing elective ventilation, are more controversial and would be regarded by some as unacceptable. Even if all human cadaveric organs were somehow made available for transplant, the supply would still not meet the potential demand. 20 So it is necessary to consider how far the use of artificial organs and tissue may provide an alternative to human organ transplantation. 14 Feest T G et al. (1990) Protocol for increasing organ donation after cerebrovascular deaths in a district general hospital. Lancet, 335:1133-5. 15 Acute Services Policy Unit (1994) Identification of potential donors of organs for transplantation. London: Department of Health (HSG(94)1). The situation has been criticised as being unclear due to the existence of another, previously issued, code of practice (Departments of Health of Great Britain and Northern Ireland (1983) Cadaveric organs for transplantation: a code of practice including the diagnosis of brain death. London: HMSO). The guidance in this code of practice is ambiguous (Francis R (1995) A legal comment. Letter to British Medical Journal, 310:718). 16 Law Commission Report No 231 (1995) Mental Incapacity. London: HMSO. pp 94-5. 17 BMA’s Ethics, Science and Information Division (1993) Medical Ethics Today: its practice and philosophy. BMJ Publishing Group. 18 Report of the British Transplantation Society Working Party on Organ Donation. (1995) British Transplantation Society. 19 Information supplied by United Kingdom Transplant Support Service Authority. 20 Caplan A (1992) Is xenografting morally wrong? Transplantation Proceedings, 24:722-7, quoted in Tania Woods’ submission to the Working Party 16
Alternatives to xenotransplantation Artificial organs and tissue 2.11 Artificial body parts, from glass eyes to wooden legs, have been used for centuries and offer a possible means of addressing the shortage of organs and tissue for transplantation. Technological advances and modern materials have increased the range and sophistication of artificial implants, but many difficulties remain in replicating the complicated functions of certain human organs. Artificial implants currently under development range from totally mechanical devices to organs consisting of a combination of artificial materials and human cells. The rest of this chapter describes the latest developments in producing artificial organs and indicates where they may become a viable alternative to xenotransplantation. 2.12 The human body is a demanding and hostile environment for artificial tissue and organ replacements: blood has a tendency to clot, it is in constant motion and can be corrosive; tissues may need to bend or stretch and can be subject to sudden shocks; organs may need to adjust their function and output according to the changing demands of the body. The human immune system has evolved to reject substances it recognises as foreign, causing inflammation and blood clots. In addition, artificial devices are susceptible to infectious organisms: even organisms which are not normally dangerous can become deadly when they colonise a foreign object implanted inside the body. Faced by such difficulties, it is perhaps not surprising that most devices currently in use perform fairly basic mechanical or cosmetic functions, and are often located where the blood supply is limited. However, researchers are attempting to develop artificial organs capable of carrying out more sophisticated functions in more difficult environments. Kidneys 2.13 The longest established procedure for replacing the function of a failing organ with an alternative is dialysis of body fluids in patients with kidney failure. A synthetic membrane, or the peritoneum, is used as a dialysing medium across which the blood can be freed of toxic waste products normally excreted by the kidneys. Patients spend several sessions a week having dialysis, and can live relatively normal lives between treatments, which is not the case when most other organs fail. There has been little research into developing implantable artificial kidneys because patients can be successfully kept alive by dialysis while awaiting transplantation. For many patients, however, dialysis is far from ideal, because it requires lengthy sessions of treatment, restrictions in diet and cannot prevent a general decrease in overall health. As the length of the waiting list for kidney transplants testifies, dialysis does not offer a complete solution to the shortage of kidneys for transplantation. 17
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Xenotransplantation - Nuffield Council on Bioethics

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