Two research groups have found ways to guide embryonic stem cells to become brain cells. Their findings, reported in the December issue of Nature Biotechnology, open the door to possible new treatments for neurological diseases.
To tap embryonic stem cells' therapeutic potential, researchers must learn how to coax them to become a specific type of cell that can then be transplanted into the body. Three months ago, researchers at the University of Wisconsin, Madison, succeeded in making precursors for blood cells.
Now, two groups working independently have developed techniques to obtain precursors to human brain cells. Su-chun Zhang and his colleagues at the University of Wisconsin, Madison, and the University of Bonn, Germany, directed the development of embryonic stem cells stage by stage, using the same growth factors the body uses. Benjamin Reubinoff, Tamir Ben-Hur, and their colleagues at Hadassah University Hospital in Jerusalem, Israel, and Monash University in Melbourne, Australia, took a simpler approach, letting the stem cells multiply in a culture dish until they differentiated on their own. Then they picked out the neural progenitor cells by hand and grew them in culture with growth factors.
Both groups transplanted their preparations into the brains of newborn mice, where the cells behaved just like the mice's own brain cells; they migrated along established paths, which shows that they respond to cues from the host brain. Neither group saw cells developing into anything but brain cells, but more studies will be needed before the technique can be considered safe to test in humans. For example, researchers must learn how to further differentiate the "basic" brain cells into functional neurons, such as the kind that are deficient in Parkinson's disease.
"The most important part is that they got such a high purity of brain cells," says neuroscientist Lorenz Studer of Memorial Sloan-Kettering Cancer Center. Higher purity means less chance of rogue cells developing into nonbrain cell types and mucking things up. Studer cautions that it will be years before such cell preparations can be used clinically, but he says it's just "a matter of time."
--CAROLINE SEYDEL
Related sites
Zhang lab Web site
Reubinoff lab Web site
PNAS abstract on getting blood cells from stem cells
Background on stem cells, from the National Institutes of Health
