Few medical research scandals are as spectacular as Paolo Macchiarini’s. Five years ago he was a celebrity surgeon at the Karolinska Institute in Sweden, one of Europe’s premier medical centers, which awards the Nobel Prize in Physiology or Medicine. Macchiarini was implanting the world’s first artificial tracheas into patients—and by his account, doing it with great success. But soon there were murmurs about his methods. His patients appeared to be dying.