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Scientists Find the Brain Repairs Itself after a Stroke

A previously unknown mechanism that lets the brain create new neurons after a stroke has been uncovered by researchers from Lund University and Karolinska Istitutet in Sweden.

Marc Maligalig, China Topix, Oct 13, 2014

The finding paves the way for methods that could replace dead neurons.

A stroke is a blockage of a blood vessel in the brain by a blood clot. It interrupts blood flow to the brain, depriving it of much needed oxygen. In the wake of a stroke, large numbers of nerve cells or neurons die, leading to cognitive, sensory and motor problems.

Scientists have demonstrated that after an induced stroke in lab mice, astrocytes, which are supporting cells in the brain, start to form neurons in the damaged region of the brain.

Using genetic techniques to track the fate of the cells, the team showed the astrocytes in the injured part formed immature nerve cells, which then develop into mature neurons.

"This is the first time that astrocytes have been shown to have the capacity to start a process that leads to the generation of new nerve cells after a stroke," said Zaal Kokaia, Professor of Experimental Medical Research at Lund University.

The signaling mechanism that manages the conversion of the supporting cells into neurons was also identified by researchers. In a healthy brain, the mechanism is active and inhibits the evolution of the supporting cells. Astrocytes don't turn into nerve cells as a consequence.

After a stroke, however, the signaling mechanism is inhibited, and supporting cells can then start the process of becoming nerve cells.

"Interestingly, even when we blocked the signaling mechanism in mice not subjected to a stroke, the astrocytes formed new nerve cells", said Kokaia. "This indicates that it is not only a stroke that can activate the latent process in astrocytes."

He said the mechanism could be used to produce new neurons when replacing deceased cells after the brain is damaged by stroke, trauma or diseases.

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