Spare parts from pigs
Organ transplants can save lives, but there aren't enough suitable human organs available for donation. So researchers have turned to pigs to try and meet the demand. Although the heart, kidneys and liver of a pig are very similar in size to our own, a human body would normally reject them within hours. But scientists have bred pigs whose organs carry human proteins on their surface, which fool the human immune system, and help prevent rejection.
