More progress to help stroke victims.

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Researchers at The University of Manchester have discovered that a potential new drug reduces the number of brain cells destroyed by stroke and then helps to repair the damage.

A reduction in blood flow to the brain caused by stroke is a major cause of death and disability, and there are few effective treatments.

A team of scientists at The University of Manchester has now found that a potential new stroke drug not only works in rodents by limiting the death of existing brain cells but also by promoting the birth of new neurones (so-called neurogenesis).

For many years, scientists believed that our brains were unable to produce new neurons once we had been born, and that we all had to make do with the brain cells we started life with. Later, it became clear that new brain cells are in fact created in some key brain regions, replacing those that become damaged and protecting us from dementia. Now, researchers have discovered that the stem cells giving rise to these neurons originate in the membranes encasing the brain, known as the meninges.

Publishing their findings in the journal Cell Stem Cell, the authors claim that their discovery of this source of stem cells could one day lead to new treatments for brain damage or neurodegenerative disorders.

Most neurogenesis in the adult brain occurs in a region called the hippocampus, where the creation of new brain cells ensures our memories remain in working order as we age. The meninges penetrate the brain at every level, encapsulating a number of different regions, including the hippocampus.

In a cross-domain study directed by professor Peter Carmeliet (VIB — KU Leuven), researchers discovered unexpected cells in the protective membranes that enclose the brain, the so called meninges. These ‘neural progenitors’ — or stem cells that differentiate into different kinds of neurons — are produced during embryonic development. These findings show that the neural progenitors found in the meninges produce new neurons after birth — highlighting the importance of meningeal tissue as well as these cells’ potential in the development of new therapies for brain damage or neurodegeneration. A paper highlighting the results was published in the leading scientific journal Cell Stem Cell.

Scientists’ understanding of brain plasticity, or the ability of the brain to grow, develop, recover from injuries and adapt to changing conditions throughout our lives, has been greatly broadened in recent years. Before the discoveries of the last few decades, neurologists once thought that the brain became ‘static’ after childhood. This dogma has changed, with researchers finding more and more evidence that the brain is capable of healing and regenerating in adulthood, thanks to the presence of stem cells. However, neuronal stem cells were generally believed to only reside within the brain tissue, not in the membranes surrounding it.

The meninges: unappreciated no more: Believed in the past to serve a mainly protective function to dampen mechanical shocks, the meninges have been historically underappreciated by science as having neurological importance in its own right. The data gathered by the team challenges the current idea that neural precursors — or stem cells that give rise to neurons — can only be found inside actual brain tissue.