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Revolutionary Approaches of Induced Stem Cells in Disease Prevention
Published in Jyoti Ranjan Rout, Rout George Kerry, Abinash Dutta, Biotechnological Advances for Microbiology, Molecular Biology, and Nanotechnology, 2022
Many neurodegenerative diseases are complex and progressive, with a lack of clear mechanisms and effective treatment methods, as the differences between animal and human brain are wide and this remains one of the major challenges in animal-based models of human brain disease. Furthermore, animal-based models of neurodegenerative diseases are time consuming and resource intensive. However, iPSCs give us novel approaches to combating neuronal diseases. Many researchers have successfully developed induced pluripotent stem cell lines from patients with neurodegenerative diseases. (Alves et al., 2015) to study the etiology and mechanism of diseases. Neurogenesis has been found to occure in two neuronal niches in the adult brain, the subependymal zone lining the lateral ventricles and the subgranular zone of the dentate gyrus. This fascinating finding opened up the possibility of converting nonneurogenic astroglia into neurons when induced with an appropriate transcriptional factor (Alonso et al., 2012).
Neural Stem Cells and Oligodendrocyte Progenitors in the Central Nervous System
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
Jennifer A. Jackson, Diana L. Clarke
Proliferative stem cell compartments are not exclusive to the developing CNS. However, after embryonic development, the exact characteristics of the neural stem cell in the CNS have remained elusive and controversial. Numerous pioneering experiments have demonstrated that specific regions of the mammalian CNS undergo a moderate, yet continuous level of neurogenesis postnatally and throughout adult life21-24 (Fig. 3). To date, neurogenesis in the adult mammalian CNS is known to utilize at least one dividing progenitor cell population25 and two different multipotent stem cell populations.26-28 The putative progenitor cell population resides in the subgranular zone of the dentate gyrus located in the hippocampus, the region of the brain involved in learning and memory. The two remaining stem cell populations have been reported to exist in and near the anterior lateral ventricular wall of the cerebral cortex, both of which exist in the adult as highly differentiated glial cell types; SVZ astrocytes and ventricular ependymal cells. While there is only a limited amount of neurogenesis that occurs in the adult hippocampus, stem cells located in the SVZ are thought to continuously replace interneurons in the olfactory bulb. It remains controversial whether the rapidly dividing multipotent stem cells in the SVZ are a distinct stem cell population that contributes to the generation of olfactory interneurons. It has been suggested that the adjacent ependymal cell layer, which has been shown to divide at a comparatively slower rate in vivo, may give rise to the SVZ cells.26,29 Although glial cells in the SVZ are derived from the VZ during early embryonic development, a lineage relationship between these two multipotent adult cell types has not been firmly established. However, the location of these two adult neural stem cell populations has some surprising parallels to early neurogenic development of the ventricular regions in the embryonic brain. The ependymal cells, within the lateral ventricular wall, occupy a position analogous to the embryonic VZ cells and are thought to be derived directly from a subset of embryonic VZ cells. While the ependymal cells are highly differentiated glial cells that line the luminal surface of the adult ventricular system, these seemingly differentiated cells express several proteins expressed by neural stem cells during normal development including nestin, musashi, and Notch 1 receptors.
Consequences of space radiation on the brain and cardiovascular system
Published in Journal of Environmental Science and Health, Part C, 2021
Catherine M. Davis, Antiño R. Allen, Dawn E. Bowles
The hippocampal formation undergoes structural changes throughout the human lifespan. It is capable of dramatic reorganization, enabling environmental stimuli to impose functional and structural changes on the brain.7 The plasticity of neuronal connections functions through the generation of new neurons and synapses, which enables the brain to store memories.8 Neurogenesis is defined as the series of developmental steps that lead from the division of a neural stem or progenitor cell to a mature, functionally integrated neuron.9 The generation of new neurons from neural stem cells occurs in only two areas of the adult brain: the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) of the DG in the hippocampus.7 In mammals, precursor cell proliferation occurs in the SGZ throughout life,10,11 resulting in newly born cells that are capable of migrating into the dentate granule cell layer.11 Newborn granule cells pass through several developmental steps, from a dividing progenitor to a mature granule cell that is indistinguishable from granule cells born during embryonic development.12 They develop granule cell morphology, then become functionally integrated into the local circuitry13 and have action potentials and functional synaptic inputs14 about 4 weeks after division.
Neurophysiological and molecular approaches to understanding the mechanisms of learning and memory
Published in Journal of the Royal Society of New Zealand, 2021
Shruthi Sateesh, Wickliffe C. Abraham
The two primary brain regions for which adult neurogenesis is well-known are the subventricular zone (SVZ) lining the lateral ventricles and the subgranular zone (SGZ) of the dentate gyrus. The SGZ neurogenesis of dentate granule cells has attracted significant attention given its positioning in the hippocampus, suggesting a possible role in the contextual and spatial learning and memory functions of this structure. Indeed, disruption of adult neurogenesis by a variety of means, genetic, pharmacological and x-ray irradiation has been shown to impair water maze learning and contextual fear conditioning, along with complex pattern discrimination (Saxe et al. 2006; Dupret et al. 2008; Clelland et al. 2009; Seo et al. 2015). Neurogenesis also acts to impair retention of recently learned information, a function that may reduce proactive interference of new learning (Akers et al. 2014). The contribution of a particular cohort of adult-born granule cells is particularly prominent during the 4–6 weeks after their genesis, when the granule cells are highly excitable and have a lower threshold for LTP compared to mature granule cells (Ge et al. 2007). However the excitability state of adult-born cell is not fixed upon maturity, as it can be enhanced by enriched environment exposure or LTP induction. This suggests that there may be a prolonged capability for plasticity and contribution to behaviour after their maturity, throughout adulthood (Ohline et al. 2018).