The discovery of neural stem cells in the brain’s meninges could lead to new therapies for multiple sclerosis (MS), according to study results based on miouse models.
The belief that new neurons were added in the postnatal cerebral cortex was previously debated, and researchers chose to focus on the meninges as a source for neurogenic precursor for several reasons. Meninges hosts various cells, but these cells can differentiate without cell division in vitro; however, meningeal cells can produce neurons after transplantation in the postnatal brain in vivo.
The researchers injected coloring into the meningeal cells, but determined they were still unable to differentiate between the cells. The team analyzed the anatomical distribution of the colored cells at specific time points: 15 hours, 24-48 hours, 3-5 days, and 15-30 days after the initial injections.
The investigators determined that the injected cells had distributed to the ventricular zone (VZ) level after three to five days, while at 15-30 days post injection many of the cells were detected in the upper cortical layers and mostly confined to the retrosplenial and visual motor cortex regions. At the measures of the 15 and 24-hour marks, the injected cells did not migrate from their origin point.
Independently, the researchers confirmed that the cells migrated into the VZ through several methods, including various types of dye injections. They also compared the pathways of meningeal cells to that of RGtk cells using injections and at a 72-hour observation period.
According to the researchers, this observation outlined a lineage tracing for meningeal neural progenitor population, which migrate from the meninges to the cortex in the neonatal brain. They noted these cells could further differentiate into functionally integrated cortical neurons including radial glia like characteristics of meningeal neural progenitor cells.
“The key finding of our study is that the meninges contain a rare neurogenic cell population that gives rise to cortical neurons early after birth in the murine brain in vivo,” the study authors wrote in their paper, “Neurogenic Radial Glia like Cells in Meninges Migrate and Differentiate into Functionally Integrated Neurons in the Neonatal Cortex
,” published in Cell Stem Cell
. “The embryonically derived meningeal progenitors remain largely quiescent, and in the first days after birth, they migrate to the cortex and differentiate to cortical neurons, without further proliferation.”
One question about the future implications of this study, raised by a multiple sclerosis based news outlet
, is whether these findings can be used to progress multiple sclerosis treatments by grasping these migrating stem cells to replenish stores of dying neurons.
The researchers concluded that these findings are important because they broaden the concept of brain plasticity and they also challenge the current accepted observation that neural precursors reside only in the parenchyma, which highlights the importance of meningeal tissue as a source of neurogenic cells.
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