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Mice Brains Can Fix Themselves By Kristen Philipkoski 02:00 PM Nov. 01, 2004 PT Harvard scientists have manipulated stem cells already present in the brains of mice to induce the birth of new neurons, an advance once considered impossible by most scientists. They induced the birth of new cells by killing nearby neurons in mice, which set off a cascade of events that led to stem cells, also called precursor cells, producing new neurons in the cerebral cortex. If scientists can turn this into a therapy for humans, it would mean that patients could literally heal themselves with stem cells already present in their brains. The researchers' goal is not to create a therapy that would kill neurons in order to activate the birth of new ones. Rather, they hope experiments like this one, which appeared in the Proceedings of the National Academy of Sciences online, will lead to new ways to grow neurons. Researchers could eventually identify key molecules involved with neuron birth and translate them into drugs, said Jeffrey Macklis, a researcher at Harvard Medical School who led the study. "(The neurons) developed into mature neurons that not only took up proper locations within the brain, but reconnected to the spinal cord," Macklis said. The newborn neurons took the place of many damaged neurons in the mice. The work could be a model for neuron replacement in spinal cord injury or diseases including Alzheimer's, Parkinson's and Lou Gehrig's. And such a therapy would avoid any immune or other complications that might result from stem-cell transplantation. Researchers long thought the adult central nervous system had little or no ability to regenerate. But recent studies have shown some regeneration, mainly in the hippocampus and olfactory regions. In 2000, Macklis and his colleagues showed for the first time they could induce neurogenesis (the birth of new cells) in complex brain regions such as the cerebral cortex. Other experiments showed that surrounding brain cells turn on molecular signals when certain types of neurons die. In this latest work, the Harvard researchers wanted to see if they could specifically generate corticospinal motor neurons, which are located in the cerebral cortex and which play important roles in neurodegenerative diseases. The researchers used a special molecule activated with long- wavelength light to kill neurons, injecting it into the brains of adult mice. The photo-activated molecules selectively killed corticospinal motor neurons, which live in the cortex and control voluntary motor function. Neurogenesis occurred shortly after the neurons died. Immature neurons emerged from another region of the brain, the subventricular zone, and migrated into the cortex. They matured into neurons that resembled corticospinal neurons. Some of them survived for more than a year and even sent signals all the way into the spinal cord. SOURCE: Wired News http://tinyurl.com/6rnpp * * * ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn