For a primer on the promise of human embryonic stem (ES) cell technology as a powerful research tool for understanding neurodegenerative disease, download the talk by Larry Goldstein, University of California, San Diego. He suggests that ES cells offer a way to get around a major limitation of studying neurodegeneration in humans—that is, by the time symptoms appear, the damage has been accumulating, sometimes for years, making it hard to figure out root causes. Or, to paraphrase Goldstein, studying neurodegeneration by looking at patients is like trying to find out what caused a plane crash by looking at the wreckage on the ground. What you really want is to find the black box, so you can see what happened right before everything fell apart. The ability to find that black box may rest with the creation of disease-specific ES cells using nuclei from patients. As Doug Melton, Harvard University, made clear in his talk, this is a very different activity than trying to harness normal or genetically altered ES cells for therapies, and critically depends on researchers' ability to carry out nuclear transfer. Such cells, and neurons or other tissues derived from them, will also be useful for testing potential treatments in a fully human system, rather than relying on mouse models.

As a proof of concept, Kevin Eggan of the Harvard Stem Cell Institute created mouse ES cells carrying the gene for mutated human SOD1 as a model for ALS. His talk covered the preliminary characterization of these cells as they form spinal motor neurons and glial cells in culture. As the cells aged over several months, they started to display inclusion-like structures containing human SOD1 and abnormal neurofilament distribution, similar to the cell pathology seen in ALS. In the human arena, Eggan and colleagues have made spinal motor neurons from ES cells, and would like to introduce SOD1 into this system. Ultimately, the goal is to make ES cells from patients with sporadic forms of ALS, Parkinson's and AD and watch disease progression in culture. According to Eggan, initial efforts with SCNT will focus on ALS.

Several speakers sounded a recurring note that while the therapeutic applications of stem cells are still years away, their impact on research will be felt in the short term.

Tune in to the streaming videos on the Whitehead website to get the latest in embryonic stem cell challenges and controversies from Rudy Jaenisch, Richard Young, Fernando Camargo, and Harvey Lodish at the Whitehead Institute; George Daley, Children’s Hospital, Boston; Diane Krause, Yale University, New Haven, Connecticut; and Gordon Keller, Mount Sinai School of Medicine, New York.—Pat McCaffrey.