Could the fountain of youth be tucked inside a gene? In a recent study, an embryonic gene called Nanog rebooted the activity of adult stem cells, which help to regenerate tissues and organs. Under normal circumstances, as people age, fewer of these cells perform their job capably, leading to problems ranging from weak bones to clogged arteries. But introduce Nanog and things change: In a series of experiments led by Stelios Andreadis, chair of chemical and biological engineering, the gene jumpstarted crucial cellular processes that helped restore aged stem cells to working condition. Some of the rehabilitated cells are pictured here.