Scientists Find Way to Track Stem Cells in Brain

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But research in this area has been stymied by the fact that scientists haven't had any means of tracking neural stem cells. A noninvasive technology called magnetic resonance spectroscopy (MRS) has long been used to track the brain's two dominant cell types -- neurons and glial cells -- because scientists discovered molecular markers that reliably identify them on MRS.

But a marker for brain stem cells has remained elusive -- until now.

Using cutting-edge scanning and computer technology, Maletic-Savatic's team has discovered a chemical signature -- as yet unnamed -- that distinctly characterizes neural stem cells. "We think that it's a complex lipid or lipoprotein," the Stony Brook researcher said. Further investigation is under way to define and describe the molecule's identity, she added.

In MRS imaging studies in mice and rats, as well as in healthy human volunteers, the researchers tracked the quantity and location of neural progenitor cells in the brain. They even transplanted some of these cells into an adult rat's brain and used MRS to verify the transplant's location.

And in another first, Maletic-Savatic's team compared the concentrations of neural progenitor cells in the brains of young children, adolescents and adult humans. They found that -- as had been suspected from animal studies -- the number of these cells in the brain decreases markedly with age.

"We were actually really surprised that there was such a dramatic decline," Maletic-Savatic said.

The researcher said she's already planning to use the new tracking technology in a variety of neurological studies.

For example, it is suspected that antidepressants work by boosting the creation of new brain cells. With that in mind, Maletic-Savatic's team will use MRS to "clarify whether abnormalities in these progenitors have any role in causing depression," she said.

And, because she is primarily a pediatric neurologist, Maletic-Savatic said she is also planning a study looking at the cells' role in early brain development, "particularly in premature babies who can develop cerebral palsy and mental retardation."