Meet some of the world's cleanest pigs, raised to grow kidneys and hearts for humans

Some of the world's cleanest pigs are being raised in the Virginia mountains to supply kidneys and hearts for animal-to-human organ transplants. Revivicor is one of several companies genetically engineering pigs so their organs are more humanlike, less likely to be rejected. Early experiments came from pigs born on a special biosecure research farm. Now Revivicor parent company United Therapeutics is preparing for clinical trials of those organs, from pigs raised in a first-of-its-kind facility with even more safeguards against any germs that might pose a risk to people.