For more than a decade, researchers have touted stem cells as the most promising advance in medicine since antibiotics. And this winter, when President Obama lifted the Bush administration's ban on federal funding for embryonic-stem-cell research, talking heads buzzed that his decision could bring scientists that much closer to cures — not just treatments — for conditions like heart failure, spinal-cord injuries and Alzheimer's disease. Biologists around the world toasted their new prospects with champagne. "Lifting the ban will free us up to use additional cell lines," says Jack Kessler, director of the Feinberg Neuroscience Institute at Northwestern University. "It's very important for science."