Babe the magnificent organ donor? The perils and promises surrounding xenotransplantation.

The number of xenotransplantations may increase despite the many concerns about the likelihood of spreading known and unknown infectious diseases. Regardless of the safety precautions employed in the early trials, the risks remain unknown. Zoonotic and even xenozoonootic diseases are not remote possibilities; they exist in various forms and come from various sources. The nature of transplantation requires the suppression of the immune system to levels where opportunistic infections may take route. Even if procedures to avoid increased levels of immunosuppression to the recipient were successful, risk to third parties, whose immune systems would not be equipped to fight off the infection, would remain. In this context, the PHS Guidelines provide a useful starting point, but they do not go far enough. First, the Guidelines are merely suggestions; this needs to be changed to require institutions undertaking xenotransplantation research and clinical trials to comply with the Guidelines. Second, every possible effort should be made to protect third parties from disease transmission. This requires and justifies placing restrictions on recipients that, in an ordinary context, would be unacceptable. Third, xenotransplantations should occur only after all other medical measures have been exhausted. Until the time when disease transmission risks are scientifically insignificant or cures for the transmitted diseases are found, mandatory guidelines with stringent requirements are the best means of balancing the interests of society against the potential beneficiaries of xenotransplantation.