Unexpected cells have been discovered in the protective membranes that enclose the brain, the so called meninges. These neural progenitors, stem cells that differentiate into different kinds of neurons , are produced during embryonic development.
The cross-domain study, directed by professor Peter Carmeliet of the Flanders Institute for Biotechnology (VIB - KU Leuven), shows 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.
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.
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 precursor stem cells can only be found inside actual brain tissue.
Prof. Carmeliet said:
“The neuronal stems cells that we discovered inside the meninges differentiate to full neurons, electrically-active and functionally integrated into the neuronal circuit. To show that the stem cells reside in the meninges, we used the extremely powerful single-cell RNA sequencing technique, a very novel top-notch technique, capable of identifying the (complex gene expression signature) nature of individual cells in a previously unsurpassed manner, a première at VIB."
When it comes to future leads for this discovery, the scientists also see possibilities for translation into clinical application, although future work is required.
Prof. Carmeliet adds:
“An intriguing question is whether these neuronal stem cells in the meninges could lead to better therapies for brain damage or neurodegeneration. However, answering this question would require a better understanding of the molecular mechanisms that regulate the differentiation of these stem cells.
How are these meningeal stem cells activated to become different kinds of neurons? Can we therapeutically ‘hijack’ their regeneration potential to restore dying neurons in, for example, Alzheimer' Disease, Parkinson’s Disease, amyotrophic lateral sclerosis (ALS), and other neurodegenerative disorders? Also, can we isolate these neurogenic progenitors from the meninges at birth and use them for later transplantation? These findings open up very exciting research opportunities for the future."
Carmeliet’s discoveries were made possible largely by funding through “Opening the Future: pioneering without boundaries”, a recently created Mecenas Funding Campaign for funding of high risk brain research but with potential for breakthrough discoveries.
Bifari, Francesco et al. Neurogenic Radial Glia-like Cells in Meninges Migrate and Differentiate into Functionally Integrated Neurons in the Neonatal Cortex Cell Stem Cell, DOI: http://dx.doi.org/10.1016/j.stem.2016.10.020