Brain's response to injury better understood

[dignan]

This is research that will take a while to trickle down to therapies to help PwMS, but it seems like an important advance.



How the Brain Responds to Injury or Disease Described by University of Virginia Researchers

August 1 - AScribe Newswire - When the brain is threatened - from trauma or stroke or from diseases like AIDS, multiple sclerosis or cancer - the body's protective immune system is usually activated to try and repair the damage. Millions of tiny cells called microglia, the brain's resident immune cells, are called into action to initiate this response. But very little is known about their function because researchers were limited to studying isolated microglia in a dish.

Now, first the first time, researchers at the University of Virginia Health System have observed the migratory behavior of microglia in living tissue using high-tech laser imaging microscopy, revealing how these immune cells navigate and respond to brain injury and disease. Their findings are published in the July 27, 2005 issue of The Journal of Neuroscience, found on the Internet at http://www.jneurosci.org/current.shtml .

"These cells are a whole lot more dynamic than we had thought," said Dr. James W. Mandell, a professor of pathology at UVa and lead author on the paper. "Researchers made assumptions about what they saw in fixed tissue samples or cell cultures. But now we've been able to image microglia in living tissue."

Mandell and Shawn Carbonell, an M.D./Ph.D. student in UVa's Medical Scientist Training Program, describe the migration of microglia in response to a brain lesion as a "random walk" in three dimensions of the brain. They collaborated with UVa cell biologists Rick Horwitz and Shin Murase to use quantitative imaging methods to visualize the "walk."

"Earlier theories came from experiments in a dish showing that microglia migrate in a direct fashion," Carbonell said. "Our paper shows instead that in tissue they do this randomly. In brain injury, which is very complex, there's a lot more than just the area of primary injury to worry about. What random walk allows is for the microglia to cover a lot of brain tissue during the repair response."

Carbonell said microglia usually start migrating toward an injured site in the brain within 20 hours. He puts the peak of reactivity, including migration, at about three days. Interestingly, that time period correlates with the peak of brain swelling, a leading cause of death in brain-injured patients. This swelling compresses critical brain centers, including regions that control breathing.

Mandell and Carbonell believe the study of microglia can eventually be useful in treating brain trauma and other neurological diseases. "The inflammatory response in the brain, like in the rest of the body, can get too aggressive and actually worsen the initial injury," Carbonell said. "So, if we can slow microglia down in patients during the critical early periods after an injury or disease, we may be able to reduce tissue damage and improve outcome. That is a potential application of this research. Microglia can sometimes get out of hand, but are still necessary for repair."

http://www.ascribe.org/cgi-bin/behold.p ... 5&public=1