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The patient with acute neurological problems
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
Glial cells are classified as macroglia or microglia – big and small glial cells. There are several types of macroglia within the CNS: astrocytes, oligodendrocytes and ependymal cells. Microglia are the macrophages of the CNS, removing cell debris and microorganisms by phagocytosis.
Discussions (D)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
There are essentially three conflicting definitions of neuroglia commonly found in recent texts of neuroanatomy. The narrowest and probably oldest definition limits the neuroglia to types of cells intermixed with neurons in the CNS. Three basic types are usually listed: astrocytes (or astroglia), oligodendrocytes (or oligodendroglia), and microglia (e.g., Lock, p. 90; G&N, p. 7, M&M, p. 3–4).3.The astrocytes and oligodendrocytes are occasionally referred to collectively as the “macroglia” (e.g., C&S, p. 135; MarMar, p. 14).4
Ion Channels in Human Pluripotent Stem Cells and Their Neural Derivatives
Published in Tian-Le Xu, Long-Jun Wu, Nonclassical Ion Channels in the Nervous System, 2021
Ritika Raghavan, Robert Juniewicz, Maharaib Syed, Michael Lin, Peng Jiang
The generation of functionally mature neurons and glia from hPSCs is essential to understanding their neurophysiology and neuropathology. Overall, there are three approaches to generating human neurons and glia, including cell differentiation approach based on canonical neural developmental principle, accelerated differentiation approach using neural lineage-restricted transcription factors, and direct reprogramming of somatic cells (such as fibroblasts). In the first cell differentiation approach, hPSCs are usually deprived of their pluripotency by forming multicellular aggregates known as embryoid bodies (EBs) and/or by using inhibitors of TGFβ and BMP signaling pathways (dual SMAD inhibition) (7,8). These cells are re-plated to allow differentiation of primitive neuroepithelial cells (NE; neural rosettes—radial arrangements of elongated cells that resemble early neural tube morphology), which are neural progenitor cells (NPCs) and are able to further give rise to mature neurons and macroglia (9). Although the formation of neural lineage cells has long been considered one of the default pathways of hPSCs, the process can be facilitated at both the EB and neural rosette stage by adding different combinations of growth factors and signaling molecules to direct differentiation to various types of neurons or macroglia (10). In addition, region-specific patterning of the CNS is controlled by the concentration and gradient of various morphogens which can also be applied to NE cells to derive region-specific neural subtypes, such as interneurons (11). This cell differentiation approach allows hPSCs to undergo various neural developmental stages before reaching their neuronal or glial fates, which provide opportunities to manipulate and study neural cells at different developmental stages to understand neurogenesis and neurodevelopmental diseases.
Neuroinflammation and Optic Nerve Regeneration: Where Do We Stand in Elucidating Underlying Cellular and Molecular Players?
Published in Current Eye Research, 2020
Lien Andries, Lies De Groef, Lieve Moons
In this review manuscript, we will summarize the current knowledge that links inflammation, in particular, the innate immune system, to axonal regeneration in the optic nerve, and the molecules and pathways that connect these two processes. Whereas the inflammatory response has long been considered a harmful process in the past, it is now clear that both blood-borne and resident inflammatory cells contribute to and even trigger the regenerative growth state of axons.52,58 Indeed, where resident microglia, reactive macroglia (astrocytes and Müller glia) and infiltrating myeloid cells (neutrophils and monocyte-derived macrophages) were once considered dangerous players in CNS damage and disorders, we now know that these cells actually contribute to CNS recovery through their positive effects on neuronal survival, axonal regeneration, mobilization of precursor cells and/or remyelination.67–70 Of note, the advantageous effect of neuroinflammation on axonal regeneration (and neuroprotection) is not limited to the retinofugal system. It has also been observed after damage to the spinal cord and in other parts of the brain (e.g. hippocampus, cortex).3,41,42,47,71–74
Interaction between genetic factors, Porphyromonas gingivalis and microglia to promote Alzheimer’s disease
Published in Journal of Oral Microbiology, 2020
GWAS have indicated that genes, pathogens and the immune system act together to generate AD. In addition, neuroinflammation plays a pivotal role and this has made scientists ask the question if AD is an infectious disease. In this complex interaction of different players, microglia seem to be important in the host defense against invasion of the keystone periodontopathogen P. gingivalis. The latter may affect microglia in both direct and indirect ways. Whether other putative periopathogens and even intestinal bacteria also affect microglia of the AD brain remain to be tested. Astrocytes, which are macroglia, can also be activated by P. gingivalis. Such activation may have toxic effects on neurons. The chronic nature of low-level infections such as ‘chronic’ periodontitis and associated byproducts, e.g. endo/exotoxins and cytokines could affect susceptible brains’ defense capacity to a point where microglia involved in brain protection become adversely affected. Whether microglia will ‘remember’ inflammation caused by P. gingivalis and develop ‘tolerance’ to it, requires further research. However, it is plausible to suggest that once microglia are primed by P. gingivalis exposure, there remains the possibility of developing tolerance through the mastery of innate immunity manipulation by this bacterium, which may be the result of inadequate clearance of cellular debris (Aβ) from the AD brain.
Glia: from ‘just glue’ to essential players in complex nervous systems: a comparative view from flies to mammals
Published in Journal of Neurogenetics, 2018
The traditional classification of glia in vertebrates and, more specifically in mammals, is based on morphological features. This criterion divides glia in microglia and macroglia. Also, macroglia was divided into astrocytes, oligodendrocytes and Swchann cells. However, in the last decades, further investigations have uncovered molecular differences which allowed additional sub-divisions within the traditional types. Astrocytes are considered the most diverse and numerous subtype of glia (Kimelberg, 2010). However, many different cells have been allocated within this group. For instance, the NG2-expressing glia, were first considered astrocytes (Levine & Card, 1987) and later renamed as oligodendrocyte progenitor cells (OPCs) (Reynolds & Hardy, 1997), NG2-glia (Butt et al., 1999; Levine, 1994; Nishiyama, Chang, & Trapp, 1999), polydendrocytes (Nishiyama, Watanabe, Yang, & Bu, 2002), synantocytes (Butt, Kiff, Hubbard, & Berry, 2002), and finally NG2-cells (Trotter, Karram, & Nishiyama, 2010). The progress in the knowledge about these cells has resulted in a complex nomenclature that could lead to confusion and is worth to revise.