Magazine article Science News

Brain Fix: Stem Cells Supply Missing Enzyme

Magazine article Science News

Brain Fix: Stem Cells Supply Missing Enzyme

Article excerpt

Implanted stem cells grew into a range of beneficial brain-cell types and greatly extended the lives of mice missing an important enzyme, researchers report. Furthermore, stem cells from mouse brains, from human-fetal brains, and from human embryos proved equally adept at battling the mouse version of Sandhoff disease. In people, that congenital enzyme deficiency is similar to Tay-Sachs disease and causes severe mental retardation and early death.

Evan Y. Snyder, who led the work at the Burnham Institute for Medical Research in La Jolla, Calif., says that the implanted cells knew exactly how to repair the brain: "Even the dumbest stem cell is smarter than the smartest neurobiologist."

The stem cells created all the major brain-cell types, including active neurons and support cells called astroglia and oligodendrocytes, Snyder's team reports online in Nature Medicine.

This "milieu" restored enzyme production and reduced brain inflammation, a hallmark of many neurodegenerative diseases, says Snyder. "We saw a series of actions that try to return [the brain] to baseline."

Dennis Steindler of the University of Florida, Gainesville, says that Snyder is at the forefront of a movement that champions stem cells as "little molecular factories" that might repair and protect brain tissue, not just replace damaged neurons.

Sandhoff disease springs from the lack of the enzyme hexosaminidase (hex), which dears excess lipids from the brain. In the absence of hex, damaging lipids accumulate. Children with Sandhoff disease rarely live past age 6. Some 50 other diseases, including Tay-Sachs, result from similar genetic deficiencies in lipid metabolism. These lysosomal-storage diseases, as they're called, affect about 1 in 5,000 people in the United States. …

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