Lifesaving Stem Cell Procedure Halted by US Agency Dwayne Hunter Betterhumans Staff Wednesday, June 18, 2003, 11:25:09 AM CT A promising stem cell treatment has successfully repaired the severely damaged heart of a US teenager, but a government agency has told doctors to stop performing it.In February of this year, 16-year-old Dimitri Bonnville of Almont, Michigan was shot in the heart by a nail gun while working on a construction site.Bonnville suffered a massive heart attack that destroyed about one-third of his muscle cells when doctors from Beaumont hospital removed a three-inch-long nail from his heart.Doctors quickly determined that...