Amy Wagers, 37, stem-cell biologist, Harvard Medical School

Résumé: Amy Wagers knows stem cells, but not the controversial embryonic ones that have right-to-lifers up in arms. Her groundbreaking research on adult stem cells could lead to drastic changes in the way we treat diabetes, muscular dystrophy, and cancer.

Background check: "I wanted to be a scientist from age 10. I was on the science team and in the biology club, and I did an independent study with a college professor on lemurs in high school. My Ph.D. was in immunology, and then I focused in on stem cells."

Big break: "During my postdoctoral work at Stanford, we recognized an external control of stem-cell function that's actually reversible. This means we can take old stem cells and make them act like they're young, improving how the body handles injury and damage. It seemed far-fetched, yet the data was clear and compelling."

Toughest challenge: "I look young. I was speaking at a conference once, and I tried to check in at the speakers' table. They kept directing me to the grad students' table. When the distinguished salt-and-pepper-haired man walks in, people just react differently. But people who don't know I'm a professor talk to me in a more candid way, which can be useful."

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