Dr. Paolo Macchiarini is world famous for his revolutionary stem cell-infused windpipe transplants. There's just one problem: His patients keep dying.Dr. Paolo Macchiarini is world famous for his revolutionary stem cell-infused windpipe transplants. There's just one problem: His patients keep dying.Dr. Paolo Macchiarini is world famous for his revolutionary stem cell-infused windpipe transplants. There's just one problem: His patients keep dying.