The Three Little (Cloned) Pigs

A Wisconsin biotech firm says it's cloned three miniature pigs that could advance research into transplanting animal organs into humans.

The Infigen Corp. says it successfully deactivated both copies of a gene in the piglets that would cause rapid human rejection of the tissue.

Scientists have turned to pigs as a potential source of organs and tissues because of a severe shortage of human organs for transplantation.

Several groups of researchers are trying to genetically modify and clone pigs to help meet that demand. Their main obstacle has been the immune system rejection that occurs when organs from one species are transplanted into another.

Miniature pigs are considered good candidates for human transplantation, in part because of their size -- about 180 pounds.