Cerebrospinal fluidthe clear and watery substance that bathes the brain and spinal cordis much more important to brain development than previously realized.
Howard Hughes Medical Institute investigator Christopher Walsh, his postdoctoral fellow Maria Lehtinen, former student Mauro Zappaterra, and their colleagues have discovered that cerebrospinal fluid (CSF) contains a complex mix of proteins that changes dramatically with age. In the lab, CSF by itself is enough to support the growth of neural stem cells, and this effect is particularly robust in young brains.
What's more, the protein make-up of CSF in people with malignant brain cancer is different from that of healthy people, the researchers found. "This suggests that the CSF can make a more supportive or less supportive environment for tumor growth," notes Walsh, Chief of Genetics at Children's Hospital Boston. The work is published in the March 10, 2011, issue of the journal Neuron.
Centuries ago, philosophers thought spinal fluid held particular importance for health. The French philosopher and mathematician Ren Descartes, for example, described the brain as a simple hydraulic machine, pumping fluidpneuma anima, or 'animal spirits'through the body's nerves like a Parisian water fountain.
"Recent history has not been so kind to CSF," Walsh notes. Today, most researchers think of it as a relatively simple salt solution that gives the brain buoyancy and helps protect it from knocking against the skull.
Several years ago, Walsh's work on brain development led him to suspect that there is much more to the unassuming fluid. He noticed that neural stem cells tend to line up around the brain's inner chambers, where CSF is stored, and stick cellular fingers, called cilia, into the pool of CSF. "That made us think, there's got to be something in CSF that's binding to cilia and controlling how the cell divides," Walsh says.
In 2007, Zappaterra and Walsh performe
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Howard Hughes Medical Institute