Xenotransplants

There have been experiments of transplanting a chimpanzee heart into a human, but the individual did not live very long. Again, the immune system kicks in big time to destroy the foreign tissue.

Since the early 1960s, physicians have known that certain blood cells recognize tissue from a donor and mobilize an infantry of different cell types to destroy the foreign tissue. Now powerful drugs are used to block certain blood proteins from initiating the rejection response. These drugs are so effective that over 90% of organ recipients live normal lives for the first year. The results drop significantly after five years.

• Which cell types in the blood initiate the immune response against foreign tissue?
• What proteins need to be blocked to stop this immune response from rejecting tissue?

Xenotransplants will evoke a similar immune response. Tissue from other animals is so different, that tissue from other animals can be rejected within minutes to hours after being transplanted into a person. This response is called hyperacute rejection.

The first route of attack by the body is to cut off the blood supply to the new organ. Drugs cannot stop this attack. So what can be done?