Mustafa Vora, DY Patil University Navi Mumbai
Scientists have recently discovered two types of novel brain cells that are found to be glial cells. One of them is called a gordita, which is an astrocyte, a type of glial cells. The name ‘gorditas’ comes from the plum-shaped appearance of the squat and round cell bodies. The other type of cell is the oligodendrocyte progenitor cell (OPC). Both these novel brain cells have a non-neuronal function that helps in structural support, nutrients, insulation, and much more. Researchers have found that these two cells have emerged from a pool of stem cells.
Stem cells are capable of generating new cells. Since these stem cells remain dormant in the adult brain, scientists experimented on adult mice brains to activate these dormant regions of the brain. They activated the ventricular sub-ventricular zone (V-SVZ) area of adult mice brain where the stem cells are usually found. On comparing the dormant V-SVZ area of the mice with the activated one, they found that the dormant V-SVZ area contains a high level of platelet-derived growth factor-beta (PDGFR-beta). Whereas, only half of the active cells contained similar amounts of PDGFR-beta. This led the scientists in knowing what if the PDGFR-beta be stopped. So the researchers disabled PDGFR-beta in genetically modified mice. The GM mice started showing more active stem cells in the V-SVZ area of the brain as compared to the dormant state. They developed a mouse model with altered PDGFR-beta that was unable to bind to ligands and the adult V-SVZ stem cells were tagged with fluorescent protein for detection of activity in the brain
During their experiment, the researchers observed that the gorditas cells appeared as newly activated stem cells that were differentiated into new cell types. One domain of the septal wall produced a type of astrocytes that the researchers called gorditas because of their squat and round cell bodies. Astrocytes are a sub-type of glial cells in the central nervous system that perform various non-neuronal functions.
The researchers were also able to identify multiple domains that produced oligodendrocytes which included a region at the tip of ventricles that generated oligodendrocyte progenitor cells (OPC), an intermediate stem cell, and a mature oligodendrocyte. Oligodendrocyte is specialized glial cells that perform a non-neuronal function by being responsible for the maintenance and generation of the myelin sheath that surrounds axons. During their experiment, the researchers found that the oligodendrocytes didn’t mature when the V-SVZ region was activated and PDGFR-beta was disabled. It rather remained as progenitor cells which are was a rare condition. Contact with cerebrospinal fluid (CSF) and long-range axons are the roles that OPC performs.
The V-SVZ region of the adult mice brain remains dormant under normal conditions. So the team of researchers experimented to find out if causing an injury could prompt the OPC to get activated naturally. They injected lysolecithin, a compound that degrades myelin in the corpus callosum of wild-type mice. Successfully, in response to this experiment, the stem cells along with the septal walls began producing oligodendrocyte progenitor stem cells and gorditas.
As mouse brains have an analogous region as human brains, maybe one could test if such novel brain cells are present in the human brain as well.
Also read: The curious case of Covid-19 Re-infection
References:
- Delgado, A. C., Maldonado-Soto, A. R., Silva-Vargas, V., Mizrak, D., von Känel, T., Tan, K. R., Paul, A., Madar, A., Cuervo, H., Kitajewski, J., Lin, C.-S., & Doetsch, F. (2021). Release of stem cells from quiescence reveals gliogenic domains in the adult mouse brain. Science, 372(6547), 1205–1209. https://doi.org/10.1126/science.abg8467
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