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Jefferson scientists show low lead levels can affect development of brain cells

Thomas Jefferson University

Neuroscientists at Jefferson Medical College have shown for the first time that low levels of lead have a profound effect on the growth and development of embryonic stem cells.

According to Jay Schneider, Ph.D., professor of neurology, pathology, anatomy and cell biology at Jefferson Medical College of Thomas Jefferson University, researchers have known for years the potentially devastating effects of even low levels of lead exposure on the cognitive abilities of children. Lead exposure is particularly dangerous in utero, given the "efficient transfer of lead" from a mother to her developing fetus, he notes.

Dr. Schneider asked, What impact does lead have on the birth and development of brain cells, and more specifically, how does lead affect what the brain stem cells become?

Dr. Schneider, who is also director of the Parkinson's Disease Research Unit at Jefferson, and his co-workers took neural stem cells from different parts of the rat brain and grew them in a dish. Neural stem cells are cells that can become one of three cell types: a neuron, an oligodendrocyte or an astrocyte. The latter two cell types play supportive roles in the brain.

Dr. Schneider and his colleague, Funan Huang, a visiting scientist from China, found that low levels of lead - below the levels of exposure deemed safe for humans by the Centers for Disease Control and Prevention - can significantly affect the proliferation and development of neural stem cells. Lead significantly inhibited the ability of stem cells to differentiate into either neurons or oligodendrocytes, but increased their ability to become astrocytes, he explains. Dr. Schneider presented these findings Sunday, Nov. 9 at the annual meeting of the Society for Neuroscience in New Orleans.

Young women who were lead poisoned as youngsters can, when pregnant, pass lead to their fetuses, Dr. Schneider says. Lead has been stored in their bones, and bone resorption due to increased demands for calcium during pregnancy releases this stored lead back into the circulation. Prenatal exposure to lead is particularly dangerous because toxic effects on the fetus, as well as detrimental effects on the cognitive and motor development of the infant, have been documented.

"We think our results could indicate that early in development, the presence of lead could significantly affect the development and organization of the fetal brain," Dr. Schneider says. Next, he and his team plan to examine the effects of lead in an animal model. They plan to compare the effects of lead exposure both before and after birth, particularly the effects on the fate of neural stem cells and the influences of lead on cognitive abilities.

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