XENOTRANSPLANTATION The transplantation of an organ or tissue between members of different species

Number of patients on U.S. waiting lists in 1999 Number of patients receiving organ transplants in 1997 Source: United Network for Organ Sharing (UNOS)

THE CHIMPANZEE Their DNA sequence differs form ours by only 2%

THE BABOON Its organs are not large enough to adequately support the life of a large adult human

THE PIG Easy and cheap to maintain Surprisingly similar to our anatomy and physiology Easy and cheap to maintain Organs are large enough for a large adult humans

KINDS OF REJECTION Hyperacute Rejection: Extremely rapid. Associated with an attack on the transplanted organ by antibodies. Acute Vascular Rejection: The immune response travels in the blood to the organ, which invades and destroys. Chronic Rejection: Slow process. Results from the combination of the effects of the T lymphocytes and the antibodies on the transplanted organ.

PREVENTING HYPERACUTE REJECTION Therapy can be aimed at the recipient by depleting him of the donor’s antibodies using the method of plasma exchange. Process combined with the administration of immunosuppressive drugs.

PREVENTING OTHER KINDS OF REJECTION Acute Vascular Rejection: Creation of transgenic pigs. Dr. Platt’s experiment. Chronic Rejection: No effective treatment yet.

OTHER PROBLEMS WITH XENOTRANSPLANTATION New dimension in the possible transfer of microbes between two species. Organisms transferred from pigs may not be identifiable by routine laboratory tests. The infecting microbe might undergo changes in biological behavior or mutational adaptation. PERVs

ALTERNATIVES Artificial organs Increase the number of human donors Cloning of individual cells as opposed to whole animals

SIDE-EFFECTS