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Brain Cell Factory Discovered Strip of stem cells could regenerate neurons, provide cancer insight By Gabe Romain, Betterhumans Staff 2/20/2004 A ribbon of stem cells has been identified in the brain that could regenerate neurons and provide insight into a common type of brain tumor. Researchers from the University of California San Francisco found the stem cells by studying a brain region called the subventricular zone. In this zone, the researchers discovered a sheet of cells called astrocytes and determined that they can function as neural stem cells. Astrocytes are star-shaped cells of the nervous system that provide nutrients, support and insulation for neurons. Bigger role For many years, researchers viewed astrocytes as playing a supportive role in the central nervous system. Then, in 1999, UCSF researcher Arturo Alvarez-Buylla reported that astrocytes actually function as stem cells in the subventricular zone of mice, churning out young neurons that travel to the olfactory bulb—an area of the brain that maintains the animals' keen sense of smell. Since then, researchers have demonstrated that adult stem cells exist in the subventricular zone of the human brain, but they have never detected the identity, organization or function of these cells. "We want to figure out what makes the astrocytes in the subventricular zone special," says UCSF researcher Nader Sanai. Astrocyte isolation For their study, the researchers worked with tissue from brain resections and autopsies. They discovered the ribbon of astrocytes and isolated them from the tissue's dense network of mixed brain cells. They then conducted a series of experiments in culture that revealed astrocytes to have the properties of adult neural stem cells. The researchers now want to determine if certain molecular signals or growth factors can coax the cells to generate neurons in culture. If so, such neurons could be transplanted into patients to regenerate tissue damaged by conditions such as Parkinson's disease, Alzheimer's disease and stroke. Cause of tumors? On another clinical front, the researchers are also investigating whether faulty astrocytic stem cells cause the most common type of human brain tumor—glioma. They don't yet know what initiates the process of uncontrolled cell replication that leads to the formation of these brain tumors, but some evidence suggests that they originate in the subventricular zone. To check this, the UCSF team aims to introduce into astrocytic stem cells genetic defects known to promote brain tumors, first in cell culture and then in animal models. If this causes tumor formations, strategies could be developed to block astrocytic stem cell proliferation at an early stage of tumor development. The research is reported in the journal Nature (read abstract) http://tinyurl.com/3yeuc SOURCE: Betterhumans, Canada http://www.betterhumans.com/News/news.aspx?articleID=2004-02-20-4 * * * ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn