NEW YORK — Researchers are trying to find ways to regrow fingers _ and someday, even limbs _ with tricks that sound like magic spells from a Harry Potter novel. There’s the guy who sliced off a fingertip but grew it back, after he treated the wound with an extract of pig bladder. And the scientists who grow extra arms on salamanders. And the laboratory mice with the eerie ability to heal themselves. This summer, scientists are planning to see whether the powdered pig extract can help injured soldiers regrow parts of their fingers. And a large federally funded project is trying to unlock the secrets of how some animals regrow body parts so well, with hopes of applying the the lessons to humans. The implications for regrowing fingers go beyond the cosmetic. People who are missing all or most of their fingers, as from an explosion or a fire, often can’t pick things up, brush their teeth or button a button. If they could grow even a small stub, it could make a huge difference in their lives. And the lessons learned from studying regrowth of fingers and limbs could aid the larger field of […]