A remarkable device called the spray on skin gun is featured in a YouTube video from an upcoming National Geographic TV special. The skin gun promises to be a boon to burn victims as much as penicillin was to people with infections. The way the spray on skin gun works is that a burn victim's healthy stem cells are taken from his skin, are cultured in a liquid bath, and then are sprayed on the burned parts of his body. Within days, the burn is healed. The man in the video, who had severe second-degree burns on his face and...