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Tracking Neural Progenitor Cells in the Human Brain

Scientists have developed the first noninvasive technique for detecting cells in the living human brain that give birth to new neurons and other types of brain cells. The new method may eventually lead to improved treatments and diagnostics for a host of brain-related disorders, including depression, Parkinson's disease and brain tumors.

Scientists have been actively pursuing the study of these cells, known as neural progenitor cells, since they were first spotted in the adult human brain several years ago. Earlier studies suggested that the development of new neurons from progenitor cells, called neurogenesis, is disrupted in a wide range of disorders. But until now, scientists had no way to monitor neurogenesis in the living human brain.

As reported in the November 9, 2007, issue of Science, researchers have developed a technique that uses magnetic resonance spectroscopy (MRS) to detect molecules within the brain that seem to be unique to neural progenitor cells. The research was funded in part by NIH's ×îÐÂÂ鶹ÊÓƵ Institute of Neurological Disorders and Stroke (NINDS) and ×îÐÂÂ鶹ÊÓƵ Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Like the more familiar magnetic resonance imaging (MRI), MRS involves placing subjects within a magnetic field to detect certain molecules within the body. But while MRI primarily reveals structural details, MRS can provide rich information about the chemical composition of tissues.

Led by scientists at the State University of New York-Stony Brook and Cold Spring Harbor Laboratory, the research team first analyzed different types of brain cells extracted from both embryonic and adult mice. They found that neural progenitor cells had a specific chemical signal, or "biomarker," that was less common in the other types of brain cells. The biomarker was especially prevalent in brain samples from embryonic mice. It was also more common in the mouse hippocampus, a brain region where neurogenesis occurs constantly, than in cells from the brain's cortex, where new neurons do not normally arise. Further study indicated that the biomarker probably corresponds to yet-unknown fatty molecules in the cells.

The researchers then developed an MRS technique to noninvasively detect the biomarker in the brains of live rats. After further development, the technique was tested on healthy people. As in the rodent experiments, the scientists found higher levels of the biomarker in the human brain's hippocampus than in the cortex. MRS scans of pre-adolescents, adolescents and adults showed that brain levels of the biomarker declined with age.

"The ability to track these cells in living people would be a major breakthrough in understanding brain development in children and continued maturation of the adult brain," says Dr. Walter J. Koroshetz, deputy director of NINDS.

The research team is now planning studies to refine the MRS technique and test its ability to help diagnose or monitor brain-related disease. It could prove a very useful tool for research aimed at restoring or maintaining brain health.