2006 Holiday Lecturers Douglas A. Melton and Nadia Rosenthal.

Biomedical research can generate controversy, and HHMI believes that the next generation needs to understand the issues raised by controversial research and evaluate them scientifically. So in its annual Holiday Lectures on Science—two days of lectures and discussion—the Institute tackles topics that may inspire fervent debate. Previous lectures have focused on issues such as evolution, sex and gender determination, and obesity. In the most recent Holiday Lectures, in December 2006, stem cell research was the focus.

Douglas A. Melton, an HHMI investigator at Harvard University, and Nadia Rosenthal, director of the European Molecular Biology Laboratory in Monterotondo, Italy, were the featured speakers. They discussed their work and the potential of stem cell research in a series of talks, titled Potent Biology: Stem Cells, Cloning, and Regeneration, delivered to an audience of Washington, D.C.-area high school students.

Melton explained, among other things, how stem cells function and how they can be used to understand and potentially treat disease. "Stem cells are essential to normal development," he noted. "Differentiation occurs when different genes are turned on or turned off by internal or external signals."

A student in the audience asked what kinds of signals tell a stem cell to change its destiny. "You're talking about reprogramming signals, and that's a hot area of research," Melton replied. "That's what we want you to find out when you become scientists."

Rosenthal described how adult stem cells help repair and replace lost or damaged cells and how they might be stimulated to do a better job in human beings. She explained the concept of regeneration, her main area of research. Planaria, a simple flatworm, can regenerate a whole worm from any part of itself. If a salamander's limb is cut off, it can generate a new one. But such abilities seem to have weakened as vertebrates evolved, thus mammals cannot regenerate most body parts—yet.

Harnessing the potential of stem cells could one day mean nothing less than the end of aging, Rosenthal suggested, and "the fountain of youth appears to be in factors, or proteins, floating around in the blood serum." Young serum activates a factor that stimulates regeneration in injured, old muscle cells, she said.

Photos: Paul Fetters

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