Adult Neurogenesis: Lessons from Crayfish and the Elephant in the Room

2016 ◽  
Vol 87 (3) ◽  
pp. 146-155 ◽  
Author(s):  
Barbara S. Beltz ◽  
Georg Brenneis ◽  
Jeanne L. Benton
Keyword(s):  
Stem Cells ◽  
Immune System ◽  
Neural Stem Cells ◽  
Adult Neurogenesis ◽  
Adult Brain ◽  
Neural Precursor ◽  
Neural Precursors ◽  
Neurogenic Niche ◽  
Fetal Microchimerism ◽  
The Brain

The 1st-generation neural precursors in the crustacean brain are functionally analogous to neural stem cells in mammals. Their slow cycling, migration of their progeny, and differentiation of their descendants into neurons over several weeks are features of the neural precursor lineage in crayfish that also characterize adult neurogenesis in mammals. However, the 1st-generation precursors in crayfish do not self-renew, contrasting with conventional wisdom that proposes the long-term self-renewal of adult neural stem cells. Nevertheless, the crayfish neurogenic niche, which contains a total of 200-300 cells, is never exhausted and neurons continue to be produced in the brain throughout the animal's life. The pool of neural precursors in the niche therefore cannot be a closed system, and must be replenished from an extrinsic source. Our in vitro and in vivo data show that cells originating in the innate immune system (but not other cell types) are attracted to and incorporated into the neurogenic niche, and that they express a niche-specific marker, glutamine synthetase. Further, labeled hemocytes that undergo adoptive transfer to recipient crayfish generate cells in neuronal clusters in the olfactory pathway of the adult brain. These hemocyte descendants express appropriate neurotransmitters and project to target areas typical of neurons in these regions. These studies indicate that under natural conditions, the immune system provides neural precursors supporting adult neurogenesis in the crayfish brain, challenging the canonical view that ectodermal tissues generating the embryonic nervous system are the sole source of neurons in the adult brain. However, these are not the first studies that directly implicate the immune system as a source of neural precursor cells. Several types of data in mammals, including adoptive transfers of bone marrow or stem cells as well as the presence of fetal microchimerism, suggest that there must be a population of cells that are able to access the brain and generate new neurons in these species.

Neurogenesis-An Overview

2021 ◽  
Author(s):  
Blossom Samuel Affia
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Adult Neurogenesis ◽  
Adult Brain ◽  
Long Time ◽  
The One ◽  
The Brain ◽  
Different Parts

Neurogenesis is a phenomenon that involves the formation of new neurons in the brain by neural stem cells (NSCs). Investigators have confirmed that neurogenesis occurs in discrete parts of the adult brain as opposed to the embryos [1]. However, this was not the case long time back. Researchers have always been interested in learning if humans or other large organisms could show regenerative properties like the one seen in specific small organisms which can regrow different parts of their own bodies [2]. If possible, this would lead to a new avenue in therapeutics as more scientists would try to stimulate regeneration to deal with injury or any harmful stimuli. Like mentioned previously, researchers were not convinced with this approach and deemed that there is no possibility of adult neurogenesis [3].

scholarly journals Neural stem cells: involvement in adult neurogenesis and CNS repair

2008 ◽  
Vol 363 (1500) ◽  
pp. 2111-2122 ◽  
Author(s):  
Hideyuki Okano ◽  
Kazunobu Sawamoto
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Cell Transplantation ◽  
Adult Neurogenesis ◽  
Embryonic Stem ◽  
Adult Brain ◽  
Therapeutic Interventions ◽  
Cell Transplantation Therapy ◽  
Transplantation Therapy

Recent advances in stem cell research, including the selective expansion of neural stem cells (NSCs) in vitro , the induction of particular neural cells from embryonic stem cells in vitro , the identification of NSCs or NSC-like cells in the adult brain and the detection of neurogenesis in the adult brain (adult neurogenesis), have laid the groundwork for the development of novel therapies aimed at inducing regeneration in the damaged central nervous system (CNS). There are two major strategies for inducing regeneration in the damaged CNS: (i) activation of the endogenous regenerative capacity and (ii) cell transplantation therapy. In this review, we summarize the recent findings from our group and others on NSCs, with respect to their role in insult-induced neurogenesis (activation of adult NSCs, proliferation of transit-amplifying cells, migration of neuroblasts and survival and maturation of the newborn neurons), and implications for therapeutic interventions, together with tactics for using cell transplantation therapy to treat the damaged CNS.

scholarly journals A neuronal molecular switch through cell-cell contact that regulates quiescent neural stem cells

2019 ◽  
Vol 5 (2) ◽  
pp. eaav4416 ◽  
Author(s):  
Jian Dong ◽  
Yuan-Bo Pan ◽  
Xin-Rong Wu ◽  
Li-Na He ◽  
Xian-Dong Liu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Granule Cells ◽  
Adult Brain ◽  
Cell Contact ◽  
External Signal ◽  
Neurogenic Niche ◽  
Functional Transition ◽  
Newborn Neurons ◽  
Cell Cell

The quiescence of radial neural stem cells (rNSCs) in adult brain is regulated by environmental stimuli. However, little is known about how the neurogenic niche couples the external signal to regulate activation and transition of quiescent rNSCs. Here, we reveal that long-term excitation of hippocampal dentate granule cells (GCs) upon voluntary running leads to activation of adult rNSCs in the subgranular zone and thereby generation of newborn neurons. Unexpectedly, the role of these excited GC neurons in NSCs depends on direct GC-rNSC interaction in the local niche, which is through down-regulated ephrin-B3, a GC membrane–bound ligand, and attenuated transcellular EphB2 kinase–dependent signaling in the adjacent rNSCs. Furthermore, constitutively active EphB2 kinase sustains the quiescence of rNSCs during running. These findings thus elucidate the physiological significance of GC excitability on adult rNSCs under external environments and indicate a key-lock switch regulation via cell-cell contact for functional transition of rNSCs.

Neural Stem Cells in the Immature, but Not the Mature, Subventricular Zone Respond Robustly to Traumatic Brain Injury

2014 ◽  
Vol 37 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Matthew T. Goodus ◽  
Alanna M. Guzman ◽  
Frances Calderon ◽  
Yuhui Jiang ◽  
Steven W. Levison
Keyword(s):  
Traumatic Brain Injury ◽  
Stem Cells ◽  
Flow Cytometry ◽  
Brain Injury ◽  
Neural Stem Cells ◽  
Subventricular Zone ◽  
Proliferative Response ◽  
Fold Increase ◽  
Adult Brain ◽  
Neural Precursors

Pediatric traumatic brain injury is a significant problem that affects many children each year. Progress is being made in developing neuroprotective strategies to combat these injuries. However, investigators are a long way from therapies to fully preserve injured neurons and glia. To restore neurological function, regenerative strategies will be required. Given the importance of stem cells in repairing damaged tissues and the known persistence of neural precursors in the subventricular zone (SVZ), we evaluated regenerative responses of the SVZ to a focal brain lesion. As tissues repair more slowly with aging, injury responses of male Sprague Dawley rats at 6, 11, 17, and 60 days of age and C57Bl/6 mice at 14 days of age were compared. In the injured immature animals, cell proliferation in the dorsolateral SVZ more than doubled by 48 h. By contrast, the proliferative response was almost undetectable in the adult brain. Three approaches were used to assess the relative numbers of bona fide neural stem cells, as follows: the neurosphere assay (on rats injured at postnatal day 11, P11), flow cytometry using a novel 4-marker panel (on mice injured at P14) and staining for stem/progenitor cell markers in the niche (on rats injured at P17). Precursors from the injured immature SVZ formed almost twice as many spheres as precursors from uninjured age-matched brains. Furthermore, spheres formed from the injured brain were larger, indicating that the neural precursors that formed these spheres divided more rapidly. Flow cytometry revealed a 2-fold increase in the percentage of stem cells, a 4-fold increase in multipotential progenitor-3 cells and a 2.5-fold increase in glial-restricted progenitor-2/multipotential-3 cells. Analogously, there was a 2-fold increase in the mitotic index of nestin+/Mash1- immunoreactive cells within the immediately subependymal region. As the early postnatal SVZ is predominantly generating glial cells, an expansion of precursors might not necessarily lead to the production of many new neurons. On the contrary, many BrdU+/doublecortin+ cells were observed streaming out of the SVZ into the neocortex 2 weeks after injuries to P11 rats. However, very few new mature neurons were seen adjacent to the lesion 28 days after injury. Altogether, these data indicate that immature SVZ cells mount a more robust proliferative response to a focal brain injury than adult cells, which includes an expansion of stem cells, primitive progenitors and neuroblasts. Nonetheless, this regenerative response does not result in significant neuronal replacement, indicating that new strategies need to be implemented to retain the regenerated neurons and glia that are being produced.

scholarly journals A Common Language: How Neuroimmunological Cross Talk Regulates Adult Hippocampal Neurogenesis

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Odette Leiter ◽  
Gerd Kempermann ◽  
Tara L. Walker
Keyword(s):  
Immune System ◽  
Adult Neurogenesis ◽  
Immune Cells ◽  
Hippocampal Neurogenesis ◽  
Adult Brain ◽  
Adult Hippocampal Neurogenesis ◽  
Normal Brain ◽  
Intrinsic Cues ◽  
Normal Brain Function ◽  
The Brain

Immune regulation of the brain is generally studied in the context of injury or disease. Less is known about how the immune system regulates the brain during normal brain function. Recent work has redefined the field of neuroimmunology and, as long as their recruitment and activation are well regulated, immune cells are now known to have protective properties within the central nervous system in maintaining brain health. Adult neurogenesis, the process of new neuron generation in the adult brain, is highly plastic and regulated by diverse extrinsic and intrinsic cues. Emerging research has shown that immune cells and their secreted factors can influence adult neurogenesis, both under baseline conditions and during conditions known to change neurogenesis levels, such as aging and learning in an enriched environment. This review will discuss how, under nonpathological conditions, the immune system can interact with the neural stem cells to regulate adult neurogenesis with particular focus on the hippocampus—a region crucial for learning and memory.

scholarly journals Neural stem cells-from quiescence to differentiation and potential clinical uses

2021 ◽  
Vol 4 (1) ◽  
pp. 23-41
Author(s):  
Alexandra-Elena Dobranici ◽  
Sorina Dinescu ◽  
Marieta Costache
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Molecular Mechanisms ◽  
Adult Brain ◽  
Quiescent State ◽  
Multipotent Stem Cells ◽  
Pathological Conditions ◽  
Mature Neurons ◽  
Direct Cell ◽  
The Brain

Specialised cells of the brain are generated from a population of multipotent stem cells found in the forming embryo and adult brain after birth, called neural stem cells. They reside in specific niches, usually in a quiescent, non-proliferating state that maintains their reservoir. Neural stem cells are kept inactive by various cues such as direct cell-cell contacts with neighbouring cells or by soluble molecules that trigger intracellular responses. They are activated in response to injuries, physical exercise, or hypoxia condition, through stimulation of signaling pathways that are usually correlated with increased proliferation and survival. Moreover, mature neurons play essential role in regulating the balance between active and quiescent state by realising inhibitory or activating neurotransmitters. Understanding molecular mechanisms underlying neuronal differentiation is of great importance in elucidating pathological conditions of the brain and treating neurodegenerative disorders that until now have no efficient therapies.

DNA Methylation Abnormality and Brain Dysfunction of Neural Stem Cells Caused by Chronic Inflammation by Nanoparticle Exposure

Impact ◽  
2020 ◽  
Vol 2020 (7) ◽  
pp. 28-30
Author(s):  
Ken Tachibana
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Neural Development ◽  
Broad Class ◽  
Cell Types ◽  
Associate Professor ◽  
Adult Brain ◽  
Wide Range ◽  
The Creation ◽  
The Brain

The biological development of a human is an extremely complex and delicate process. It starts from fertilisation and continues until long after birth. The creation and development of the brain is particularly complicated and susceptible to disruptions to its progression. The primary cells responsible for the development of the brain are the neural stem cells. These are a broad class of cells that can differentiate into the wide range of cell types that form the adult brain. To achieve this complex process, different cells need to undergo a range of gene expression changes at the right time. This is delicate and its disturbance is a key cause of pathology in a wide range of diseases. There are many external factors that are known to disrupt neural development however, there are several common chemicals whose effects remain largely unknown. One such group are broadly described as nanoparticles. These are small particles that are being increasingly used by many industries as they can help in the creation of products with better properties. However, their effect on the environment and the human body – particularly that of a developing brain – have been largely unexamined. Associate Professor Ken Tachibana of the Division of Hygienic Chemistry, Sanyo-Onoda City University, Japan is researching the effects of nanoparticles on neural development.

scholarly journals Adult Neurogenesis and the Promise of Adult Neural Stem Cells

2019 ◽  
Vol 13 ◽  
pp. 117906951985687 ◽  
Author(s):  
Hiyaa S Ghosh
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Neural Stem Cells ◽  
Neural Stem Cell ◽  
Adult Neurogenesis ◽  
Therapeutic Potential ◽  
Precursor Cells ◽  
Adult Brain ◽  
Adult Neural Stem Cell ◽  
Dividing Cells

The adult brain, even though largely postmitotic, is now known to have dividing cells that can make both glia and neurons. Of these, the precursor cells that have the potential to make new neurons in the adult brain have attracted great attention from researchers, anticipating their therapeutic potential for neurodegenerative conditions. In this review, I will focus on adult neurogenesis, from the perspective of the overall neurogenic potential in the adult brain, current understanding of the ‘adult neural stem cell’, and the importance of niche as a decisive factor for neurogenesis under homeostasis and pathologic conditions.

scholarly journals Spinal cord neural stem cells heterogeneity in postnatal development

STEMedicine ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. e19
Author(s):  
Jelena Ban ◽  
Miranda Mladinic
Keyword(s):  
Spinal Cord ◽  
Stem Cells ◽  
Stem Cell ◽  
Neural Stem Cells ◽  
Cell Types ◽  
In Vitro Models ◽  
Cell Potential ◽  
Neurogenic Niche ◽  
The Brain

Neural stem cells are capable of generating new neurons during development as well as in the adulthood and represent one of the most promising tools to replace lost or damaged neurons after injury or neurodegenerative disease. Unlike the brain, neurogenesis in the adult spinal cord is poorly explored and the comprehensive characterization of the cells that constitute stem cell neurogenic niche is still missing. Moreover, the terminology used to specify developmental and/or anatomical CNS regions, where neurogenesis in the spinal cord occurs, is not consensual and the analogy with the brain is often unclear. In this review, we will try to describe the heterogeneity of the stem cell types in the spinal cord ependymal zone, based on their origin and stem cell potential. We will also consider specific animal in vitro models that could be useful to identify “the right” stem cell candidate for cell replacement therapies.   

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