Neurogenic Niche Research Articles

Quantitative Assessment of Tumor Contact with Neurogenic Zones and Its Effects on Survival: Insights beyond Traditional Predictors.

So far, the cellular origin of glioblastoma (GBM) needs to be determined, with prevalent theories suggesting emergence from transformed endogenous stem cells. Adult neurogenesis primarily occurs in two brain regions: the subventricular zone (SVZ) and the subgranular zone (SGZ) of the hippocampal dentate gyrus. Whether the proximity of GBM to these neurogenic niches affects patient outcome remains uncertain. Previous studies often rely on subjective assessments, limiting the reliability of those results. In this study, we assessed the impact of GBM's relationship with the cortex, SVZ and SGZ on clinical variables using fully automated segmentation methods. In 177 glioblastoma patients, we calculated optimal cutpoints of minimal distances to the SVZ and SGZ to distinguish poor from favorable survival. The impact of tumor contact with neurogenic zones on clinical parameters, such as overall survival, multifocality, MGMT promotor methylation, Ki-67 and KPS score was also examined by multivariable regression analysis, chi-square test and Mann-Whitney-U. The analysis confirmed shorter survival in tumors contacting the SVZ with an optimal cutpoint of 14 mm distance to the SVZ, separating poor from more favorable survival. In contrast, tumor contact with the SGZ did not negatively affect survival. We did not find significant correlations with multifocality or MGMT promotor methylation in tumors contacting the SVZ, as previous studies discussed. These findings suggest that the spatial relationship between GBM and neurogenic niches needs to be assessed differently. Objective measurements disprove prior assumptions, warranting further research on this topic.

Agomirs upregulating carboxypeptidase E expression rescue hippocampal neurogenesis and memory deficits in Alzheimer’s disease

BackgroundAdult neurogenesis occurs in the subventricular zone (SVZ) and the subgranular zone of the dentate gyrus in the hippocampus. The neuronal stem cells in these two neurogenic niches respond differently to various physiological and pathological stimuli. Recently, we have found that the decrement of carboxypeptidase E (CPE) with aging impairs the maturation of brain-derived neurotrophic factor (BDNF) and neurogenesis in the SVZ. However, it remains unknown whether these events occur in the hippocampus, and what the role of CPE is in the adult hippocampal neurogenesis in the context of Alzheimer’s disease (AD).MethodsIn vivo screening was performed to search for miRNA mimics capable of upregulating CPE expression and promoting neurogenesis in both neurogenic niches. Among these, two agomirs were further assessed for their effects on hippocampal neurogenesis in the context of AD. We also explored whether these two agomirs could ameliorate behavioral symptoms and AD pathology in mice, using direct intracerebroventricular injection or by non-invasive intranasal instillation.ResultsRestoration of CPE expression in the hippocampus improved BDNF maturation and boosted adult hippocampal neurogenesis. By screening the miRNA mimics targeting the 5’UTR region of Cpe gene, we developed two agomirs that were capable of upregulating CPE expression. The two agomirs significantly rescued adult neurogenesis and cognition, showing multiple beneficial effects against the AD-associated pathologies in APP/PS1 mice. Of note, noninvasive approach via intranasal delivery of these agomirs improved the behavioral and neurocognitive functions of APP/PS1 mice.ConclusionsCPE may regulate adult hippocampal neurogenesis via the CPE–BDNF–TrkB signaling pathway. This study supports the prospect of developing miRNA agomirs targeting CPE as biopharmaceuticals to counteract aging- and disease-related neurological decline in human brains.

Long-Term Alterations in Motor Skills, Neurogenesis and Astrocyte Numbers following Transient Cerebral Ischemia in Mice.

Background and Objectives. Neurogenesis is an integral process in post-stroke recovery, involving the recruitment of proliferating neuroblasts from neurogenic niches of the mammal brain. However, the role of neurogenesis in the long-term restoration following ischemic stroke is fragmented. Post-stroke motor dysfunction includes challenges in the proper, coordinated use of hands and is present in roughly two-thirds of human patients. In this study, we investigated chronic behavioral and biochemical alterations after transient cerebral ischemia in adult male mice. Materials and Methods: Twelve-week-old C57BL/6N male mice were used, and fMCAo lasting 60 min was induced. At multiple timepoints after fMCAo induction, a single pellet reaching task was performed. Six months after the procedure, we immunohistochemically determined the number of proliferating neuroblasts (BrdU and DCX-positive) and the number of differentiated astrocytes (GFAP-positive) in both brain hemispheres. Results: The reaching ability of fMCAo mice was impaired from one month to six months after the induction of ischemia. Neuroblast proliferation was increased in the ipsilateral SVZ, whereas GFAP+ cell count was elevated in the hippocampal DG of both hemispheres of the fMCAo group mice. Conclusions: Our current report demonstrates the long-term effects of transient cerebral ischemia on mice functional parameters and neurogenesis progression. Our data demonstrate that transient cerebral ischemia promotes a long-lasting regenerative response in the ipsilateral brain hemisphere, specifically in the neurogenic SVZ and DG regions.

Spatio-temporal brain invasion pattern of Streptococcus pneumoniae and dynamic changes in the cellular environment in bacteremia-derived meningitis

Streptococcus pneumoniae (the pneumococcus) is the major cause of bacterial meningitis globally, and pneumococcal meningitis is associated with increased risk of long-term neurological sequelae. These include several sensorimotor functions that are controlled by specific brain regions which, during bacterial meningitis, are damaged by a neuroinflammatory response and the deleterious action of bacterial toxins in the brain. However, little is known about the invasion pattern of the pneumococcus into the brain. Using a bacteremia-derived meningitis mouse model, we combined 3D whole brain imaging with brain microdissection to show that all brain regions were equally affected during disease progression, with the presence of pneumococci closely associated to the microvasculature. In the hippocampus, the invasion provoked microglial activation, while the neurogenic niche showed increased proliferation and migration of neuroblasts. Our results indicate that, even before the outbreak of symptoms, the bacterial load throughout the brain is high and causes neuroinflammation and cell death, a pathological scenario which ultimately leads to a failing regeneration of new neurons.

Intron detention tightly regulates the stemness/differentiation switch in the adult neurogenic niche

The adult mammalian brain retains some capacity to replenish neurons and glia, holding promise for brain regeneration. Thus, understanding the mechanisms controlling adult neural stem cell (NSC) differentiation is crucial. Paradoxically, adult NSCs in the subependymal zone transcribe genes associated with both multipotency maintenance and neural differentiation, but the mechanism that prevents conflicts in fate decisions due to these opposing transcriptional programmes is unknown. Here we describe intron detention as such control mechanism. In NSCs, while multiple mRNAs from stemness genes are spliced and exported to the cytoplasm, transcripts from differentiation genes remain unspliced and detained in the nucleus, and the opposite is true under neural differentiation conditions. We also show that m6A methylation is the mechanism that releases intron detention and triggers nuclear export, enabling rapid and synchronized responses. m6A RNA methylation operates as an on/off switch for transcripts with antagonistic functions, tightly controlling the timing of NSCs commitment to differentiation.

Evaluation of angiogenesis and microvascular remodeling in the subventricular zone of the brain of mice with experimental Alzheimer’s disease

BACKGROUND: Under the influence of external factors (learning), processes of microvasculature remodeling occur in the neurogenic niche to meet the metabolic needs of activated cells. However, it remains unclear how these mechanisms of brain plasticity are disrupted during neurodegeneration.
 AIM: To study the expression features of markers of angiogenesis and microvascular remodeling in the subventricular zone of the brain during training of animals, including against the background of the development of Alzheimer’s-type neurodegeneration in them.
 MATERIAL AND METHODS: The studies were carried out on C57BL/6 mice at the age of 8 months. Modeling of Alzheimer’s disease was carried out by intrahippocampal injection of 2 μl of a 1 mM solution of β-amyloid Aβ25-35. To assess cognitive deficits, a conditioned passive avoidance test using an aversive stimulus was used. The expression of LC3B, ZO1, VEGFR2, VEGFR3, CD146, ICAM2, Dll4, Tie2 in the subventricular zone per 100 DAPI-positive cells was assessed. The test results were processed using one-way ANOVA and Fisher's test, the Mann–Whitney U test, the results were considered significant at p 0.05.
 RESULTS: On the 9th day after the administration of β-amyloid, before the application of the aversive stimulus, an increase in the expression level of LC3 (7.95±5.83%, p=0.045), CD146 (18.35±0.01%, p=0.045) was recorded, as well as VEGFR3 (17.13±5.05%, p=0.045), which continued to increase after the presentation of the stimulus (26.61±0.01%, p=0.045). By the beginning of registration of cognitive impairment (38th day of the experiment), the expression level of VEGFR2 (20.61±2.8%, p=0.045) and ICAM2 (126.61±41.28%, p=0.045) increased, the content of Dll4 (29.66±8.72%, p=0.045) and Tie2 (36.39±7.8%, p=0.045) decreased in animals with experimental Alzheimer’s disease.
 CONCLUSION: An aversive stimulus stimulates microvascular remodeling mechanisms in the subventricular zone of the animal’s brain, but when exposed to β-amyloid, these processes are significantly disrupted.

Adult Neurogenesis of Teleost Fish Determines High Neuronal Plasticity and Regeneration.

Studying the properties of neural stem progenitor cells (NSPCs) in a fish model will provide new information about the organization of neurogenic niches containing embryonic and adult neural stem cells, reflecting their development, origin cell lines and proliferative dynamics. Currently, the molecular signatures of these populations in homeostasis and repair in the vertebrate forebrain are being intensively studied. Outside the telencephalon, the regenerative plasticity of NSPCs and their biological significance have not yet been practically studied. The impressive capacity of juvenile salmon to regenerate brain suggests that most NSPCs are likely multipotent, as they are capable of replacing virtually all cell lineages lost during injury, including neuroepithelial cells, radial glia, oligodendrocytes, and neurons. However, the unique regenerative profile of individual cell phenotypes in the diverse niches of brain stem cells remains unclear. Various types of neuronal precursors, as previously shown, are contained in sufficient numbers in different parts of the brain in juvenile Pacific salmon. This review article aims to provide an update on NSPCs in the brain of common models of zebrafish and other fish species, including Pacific salmon, and the involvement of these cells in homeostatic brain growth as well as reparative processes during the postraumatic period. Additionally, new data are presented on the participation of astrocytic glia in the functioning of neural circuits and animal behavior. Thus, from a molecular aspect, zebrafish radial glia cells are seen to be similar to mammalian astrocytes, and can therefore also be referred to as astroglia. However, a question exists as to if zebrafish astroglia cells interact functionally with neurons, in a similar way to their mammalian counterparts. Future studies of this fish will complement those on rodents and provide important information about the cellular and physiological processes underlying astroglial function that modulate neural activity and behavior in animals.

Abstract 2776: Exploring the differences between brain tumor initiating cell extracellular vesicles and secreted factors that influence the tumor microenvironment

Abstract Glioblastoma (GBM) is the most common and lethal primary brain tumor in adults. Within the tumor, there is a subtype of cells deemed brain tumor initiating cells (BTICs), which contribute to tumor progression, therapy resistance, and tumoral heterogeneity. The tumor microenvironment, surrounding tumors, contains an ecosystem of cells in which BTICs can interact with and further promote tumor progression. In the lateral wall of the lateral ventricles, the neurogenic niche of the subventricular zone (SVZ), contains neural progenitor cells (NPCs) that self-renew and generate highly migratory neuroblasts. Interestingly, GBM tumors proximal to the SVZ are more proliferative, migratory, and negatively impact the survival of patients. We have previously observed that the presence of GBM induces reciprocal changes to the SVZ altering its neurogenic capacity and resulting in a more proliferative tumor. BTICs share similar self-renewal capacity to NPCs and may exert intercellular communication resulting in increased malignancy features. The mechanisms of intercellular communication, present in the SVZ include paracrine, autocrine, direct cell contact, gap junctions, nanotubes, and more recently extracellular vesicles (EVs). However, the exact mechanisms of how BTICs communicate with NPCs is not well understood. EVs are a heterogenous group of cell-derived membranous structures that serve as means of intercellular communication, allowing for cells to exchange proteins, lipids, RNA, and other genetic material. Cancer cells release higher amounts of EVs than non-malignant cells, and these EVs help communicate with other nearby cells, leading to promotion of tumorigenesis. We have observed that BTICs-derived EVs increase the proliferation of human NPCs, while altering their morphology and expression of stem cell markers. These effects are not observed when NPCs are treated with vesicle-free BTIC-derived secreted factors. To investigate the distinctions between BTIC secreted factors and protein cargo contained in BTIC-EVs, we employ the proximity protein labelling system, TurboID, and express this system in BTIC-EVs. The overarching goal of this project is to characterize BTIC-derived EV cargo to identify proteins that modify the GBM tumor microenvironment. We hypothesize that the phenotype of non-cancer NPCs is altered by distinct protein cargo contained in BTIC-derived EVs. The results of these experiments will help us to elucidate what BTIC-specific EV cargo impacts the tumor microenvironment, with the potential of revealing therapeutic targets for GBM. Citation Format: Marissa Russo, Maria Jose Ulloa Navas, Emily Norton-Ramos, Alfredo Quiñones Hinojosa, Hugo Guerrero Cazares. Exploring the differences between brain tumor initiating cell extracellular vesicles and secreted factors that influence the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2776.

Tamoxifen exerts direct and microglia-mediated effects preventing neuroinflammatory changes in the adult mouse hippocampal neurogenic niche.

Tamoxifen-inducible systems are widely used in research to control Cre-mediated gene deletion in genetically modified animals. Beyond Cre activation, tamoxifen also exerts off-target effects, whose consequences are still poorly addressed. Here, we investigated the impact of tamoxifen on lipopolysaccharide (LPS)-induced neuroinflammatory responses, focusing on the neurogenic activity in the adult mouse dentate gyrus. We demonstrated that a four-day LPS treatment led to an increase in microglia, astrocytes and radial glial cells with concomitant reduction of newborn neurons. These effects were counteracted by a two-day tamoxifen pre-treatment. Through selective microglia depletion, we elucidated that both LPS and tamoxifen influenced astrogliogenesis via microglia mediated mechanisms, while the effects on neurogenesis persisted even in a microglia-depleted environment. Notably, changes in radial glial cells resulted from a combination of microglia-dependent and -independent mechanisms. Overall, our data reveal that tamoxifen treatment per se does not alter the balance between adult neurogenesis and astrogliogenesis but does modulate cellular responses to inflammatory stimuli exerting a protective role within the adult hippocampal neurogenic niche.

Hippocampal neurodegeneration induces transient endogenous regeneration and long-term exhaustion of the neurogenic niche.

The hippocampal dentate gyrus, responds to diverse pathological stimuli through neurogenesis. This phenomenon, observed following brain injury or neurodegeneration, is postulated to contribute to neuronal repair and functional recovery, thereby presenting an avenue for endogenous neuronal restoration. This study investigated the extent of regenerative response in hippocampal neurogenesis by leveraging the well-established kainic acid-induced status epilepticus model in vivo. In our study, we observed the activation and proliferation of neuronal progenitors or neural stem cell (NSC) and their subsequent migration to the injury sites following the seizure. At the injury sites, new neurons (Tuj1+BrdU+ and NeuN+BrdU+) have been generated indicating regenerative and reparative roles of the progenitor cells. We further detected whether this transient neurogenic burst, which might be a response towards an attempt to repair the brain, is associated with persistent long-term exhaustion of the dentate progenitor cells and impairment of adult neurogenesis marked by downregulation of Ki67, HoPX, and Sox2 with BrdU+ cell in the later part of life. Our studies suggest that the adult brain has the constitutive endogenous regenerative potential for brain repair to restore the damaged neurons, meanwhile, in the long term, it accelerates the depletion of the finite NSC pool in the hippocampal neurogenic niche by changing its proliferative and neurogenic capacity. A thorough understanding of the impact of modulating adult neurogenesis will eventually be required to design novel therapeutics to stimulate or assist brain repair while simultaneously preventing the adverse effects of early robust neurogenesis on the proliferative potential of endogenous neuronal progenitors.

RNA-Seq time-course analysis of neural precursor cell transcriptome in response to herpes simplex Virus-1 infection

The neurogenic niches within the central nervous system serve as essential reservoirs for neural precursor cells (NPCs), playing a crucial role in neurogenesis. However, these NPCs are particularly vulnerable to infection by the herpes simplex virus 1 (HSV-1). In the present study, we investigated the changes in the transcriptome of NPCs in response to HSV-1 infection using bulk RNA-Seq, compared to those of uninfected samples, at different time points post infection and in the presence or absence of antivirals. The results showed that NPCs upon HSV-1 infection undergo a significant dysregulation of genes playing a crucial role in aspects of neurogenesis, including genes affecting NPC proliferation, migration, and differentiation. Our analysis revealed that the CREB signaling, which plays a crucial role in the regulation of neurogenesis and memory consolidation, was the most consistantly downregulated pathway, even in the presence of antivirals. Additionally, cholesterol biosynthesis was significantly downregulated in HSV-1-infected NPCs. The findings from this study, for the first time, offer insights into the intricate molecular mechanisms that underlie the neurogenesis impairment associated with HSV-1 infection.

DNA methylation-altered genes in the rat hippocampal neurogenic niche after continuous exposure to amorphous curcumin

Rat offspring who are exposed to an amorphous formula of curcumin (CUR) from the embryonic stage have anti-anxiety-like behaviors, enhanced fear extinction learning, and increased synaptic plasticity in the hippocampal dentate gyrus (DG). In the present study, we investigated the links between genes with altered methylation status in the neurogenic niche and enhanced neural functions after CUR exposure. We conducted methylation and RNA sequencing analyses of the DG of CUR-exposed rat offspring on day 77 after delivery. Methylation status and transcript levels of candidate genes were validated using methylation-sensitive high-resolution melting and real-time reverse-transcription PCR, respectively. In the CUR group, we confirmed the hypermethylation and downregulation of Gpr150, Mmp23, Rprml, and Pcdh8 as well as the hypomethylation and upregulation of Ppm1j, Fam222a, and Opn3. Immunohistochemically, reprimo-like+ hilar cells and protocadherin-8+ granule cells were decreased and opsin-3+ hilar cells were increased by CUR exposure. Both reprimo-like and opsin-3 were partially expressed on subpopulations of glutamic acid decarboxylase 67+ γ-aminobutyric acid-ergic interneurons. Furthermore, the transcript levels of genes involved in protocadherin-8-mediated N-cadherin endocytosis were altered with CUR exposure; this was accompanied by Ctnnb1 and Syp upregulation and Mapk14, Map2k3, and Grip1 downregulation, suggesting that CUR-induced enhanced synaptic plasticity is associated with cell adhesion. Together, our results indicate that functionally different genes have altered methylation and expression in different neuronal populations of the hippocampal neurogenic niche, thus enhancing synaptic plasticity after CUR exposure.

Exploring the Intricacies of Neurogenic Niches: Unraveling the Anatomy and Neural Microenvironments.

Neurogenesis is the process of forming new neurons from neural stem cells (NSCs). In adults, this process takes place in specific areas of the brain, known as neurogenic niches. These regions have unique anatomical features that have been studied in animal models and in the human brain; however, there are differences between these models that need to be addressed. The most studied areas are the subventricular zone, the lateral and latero-dorsal walls of the lateral ventricles, and the dentate gyrus of the hippocampus (Hp), which are known as the canonical areas. Other, less-studied niches, such as the hypothalamus, the cerebellum, and the amygdala, are known as non-canonical areas. Anatomy occupies a relevant place in adult neurogenesis, in which the tissue architecture and cellular location are necessities for the interaction and release of diverse molecules that allow this phenomenon. The cell arrangement within the niche and the location of the niche itself are of particular relevance to the state in which the NSCs are found. Consequently, the majority of previous discoveries have been related to pathology. While many studies are based on animal models, discoveries related to neurogenesis in humans have also been made; however, in this case, opinions vary, leading to extensive controversy in recent years. In this review, we address the anatomical characteristics of the different brain regions to better understand their relationships within neurogenesis.

Epigenetic regulation of microglia and neurons by proinflammatory signaling following adolescent intermittent ethanol (AIE) exposure and in human AUD.

Adolescent alcohol drinking is linked to high rates of adult alcohol problems and alcohol use disorder (AUD). The Neurobiology of Alcohol Drinking in Adulthood (NADIA) consortium adolescent intermittent ethanol (AIE) models adolescent binge drinking, followed by abstinent maturation to adulthood to determine the persistent AIE changes in neurobiology and behavior. AIE increases adult alcohol drinking and preference, increases anxiety and reward seeking, and disrupts sleep and cognition, all risks for AUD. In addition, AIE induces changes in neuroimmune gene expression in neurons and glia that alter neurocircuitry and behavior. HMGB1 is a unique neuroimmune signal released from neurons and glia by ethanol that activates multiple proinflammatory receptors, including Toll-like receptors (TLRs), that spread proinflammatory gene induction. HMGB1 expression is increased by AIE in rat brain and in post-mortem human AUD brain, where it correlates with lifetime alcohol consumption. HMGB1 activation of TLR increase TLR expression. Human AUD brain and rat brain following AIE show increases in multiple TLRs. Brain regional differences in neurotransmitters and cell types impact ethanol responses and neuroimmune gene induction. Microglia are monocyte-like cells that provide trophic and synaptic functions, that ethanol proinflammatory signals sensitize or "prime" during repeated drinking cycles, impacting neurocircuitry. Neurocircuits are differently impacted dependent upon neuronal-glial signaling. Acetylcholine is an anti-inflammatory neurotransmitter. AIE increases HMGB1-TLR4 signaling in forebrain, reducing cholinergic neurons by silencing multiple cholinergic defining genes through upregulation of RE-1 silencing factor (REST), a transcription inhibitor known to regulate neuronal differentiation. HMGB1 REST induction reduces cholinergic neurons in basal forebrain and cholinergic innervation of hippocampus. Adult brain hippocampal neurogenesis is regulated by a neurogenic niche formed from multiple cells. In vivo AIE and in vitro studies find ethanol increases HMGB1-TLR4 signaling and other proinflammatory signaling as well as reducing trophic factors, NGF, and BDNF, coincident with loss of the cholinergic synapse marker vChAT. These changes in gene expression-transcriptomes result in reduced adult neurogenesis. Excitingly, HMGB1 antagonists, anti-inflammatories, and epigenetic modifiers like histone deacetylase inhibitors restore trophic the neurogenesis. These findings suggest anti-inflammatory and epigenetic drugs should be considered for AUD therapy and may provide long-lasting reversal of psychopathology.

Constitutive cell proliferation and neurogenesis in the organum vasculosum lamina terminalis and subfornical organ of adult rats.

Neurogenesis continues throughout adulthood in the subventricular zone, hippocampal subgranular zone, and the hypothalamic median eminence (ME) and the adjacent medio-basal hypothalamus. The ME is one of the circumventricular organs (CVO), which are specialized brain areas characterized by an incomplete blood-brain barrier and, thus, are involved in mediating communication between the central nervous system and the periphery. Additional CVOs include the organum vasculosum laminae terminalis (OVLT) and the subfornical organs (SFO). Previous studies have demonstrated that the ME contains neural stem cells (NSCs) capable of generating new neurons and glia in the adult brain. However, it remains unclear whether the OVLT and SFO also contain proliferating cells, the identity of these cells, and their ability to differentiate into mature neurons. Here we show that glial and mural subtypes exhibit NSC characteristics, expressing the endogenous mitotic maker Ki67, and incorporating the exogenous mitotic marker BrdU in the OVLT and SFO of adult rats. Glial cells constitutively proliferating in the SFO comprise NG2 glia, while in the OVLT, both NG2 glia and tanycytes appear to constitute the NSC pool. Furthermore, pericytes, which are mural cells associated with capillaries, also contribute to the pool of cells constitutively proliferating in the OVLT and SFO of adult rats. In addition to these glial and mural cells, a fraction of NSCs containing proliferation markers Ki67 and BrdU also expresses the early postmitotic neuronal marker doublecortin, suggesting that these CVOs comprise newborn neurons. Notably, these neurons can differentiate and express the mature neuronal marker NeuN. These findings establish the sensory CVOs OVLT and SFO as additional neurogenic niches, where the generation of new neurons and glia persists in the adult brain.

Single-Nucleus RNA-Seq Characterizes the Cell Types Along the Neuronal Lineage in the Adult Human Subependymal Zone and Reveals Reduced Oligodendrocyte Progenitor Abundance with Age.

The subependymal zone (SEZ), also known as the subventricular zone (SVZ), constitutes a neurogenic niche that persists during postnatal life. In humans, the neurogenic potential of the SEZ declines after the first year of life. However, studies discovering markers of stem and progenitor cells highlight the neurogenic capacity of progenitors in the adult human SEZ, with increased neurogenic activity occurring under pathological conditions. In the present study, the complete cellular niche of the adult human SEZ was characterized by single-nucleus RNA sequencing, and compared between four youth (age 16-22) and four middle-aged adults (age 44-53). We identified 11 cellular clusters including clusters expressing marker genes for neural stem cells (NSCs), neuroblasts, immature neurons, and oligodendrocyte progenitor cells. The relative abundance of NSC and neuroblast clusters did not differ between the two age groups, indicating that the pool of SEZ NSCs does not decline in this age range. The relative abundance of oligodendrocyte progenitors and microglia decreased in middle-age, indicating that the cellular composition of human SEZ is remodeled between youth and adulthood. The expression of genes related to nervous system development was higher across different cell types, including NSCs, in youth as compared with middle-age. These transcriptional changes suggest ongoing central nervous system plasticity in the SEZ in youth, which declined in middle-age.

Postnatal Zika virus infection leads to morphological and cellular alterations within the neurogenic niche.

The Zika virus received significant attention in 2016, following a declaration by the World Health Organization of an epidemic in the Americas, in which infections were associated with microcephaly. Indeed, prenatal Zika virus infection is detrimental to fetal neural stem cells and can cause premature cell loss and neurodevelopmental abnormalities in newborn infants, collectively described as congenital Zika syndrome. Contrastingly, much less is known about how neonatal infection affects the development of the newborn nervous system. Here, we investigated the development of the dentate gyrus of wild-type mice following intracranial injection of the virus at birth (postnatal day 0). Through this approach, we found that Zika virus infection affected the development of neurogenic regions within the dentate gyrus and caused reactive gliosis, cell death and a decrease in cell proliferation. Such infection also altered volumetric features of the postnatal dentate gyrus. Thus, we found that Zika virus exposure to newborn mice is detrimental to the subgranular zone of the dentate gyrus. These observations offer insight into the cellular mechanisms that underlie the neurological features of congenital Zika syndrome in children.

The Vestibular Nuclei: A Cerebral Reservoir of Stem Cells Involved in Balance Function in Normal and Pathological Conditions.

In this review, we explore the intriguing realm of neurogenesis in the vestibular nuclei-a critical brainstem region governing balance and spatial orientation. We retrace almost 20 years of research into vestibular neurogenesis, from its discovery in the feline model in 2007 to the recent discovery of a vestibular neural stem cell niche. We explore the reasons why neurogenesis is important in the vestibular nuclei and the triggers for activating the vestibular neurogenic niche. We develop the symbiotic relationship between neurogenesis and gliogenesis to promote vestibular compensation. Finally, we examine the potential impact of reactive neurogenesis on vestibular compensation, highlighting its role in restoring balance through various mechanisms.

An easy and cost-effective method for the isolation and culturing of neural stem/progenitor cells from the subventricular (SVZ) and dentate gyrus (DG) of adult mouse brain

BackgroundIsolation of adult Neural Stem/Progenitor Cells (NSPCs) from their neurogenic niches, is a prerequisite for studies involving culturing of NSPCs as neurospheres or attached monolayers in vitro. The currently available protocols involve the use of multiple animals and expensive reagents to establish the NSPCs culture. New methodThis unit describes a method to isolate and culture NSPCs from the two neurogenic niches in the mouse brain, the Subventricular Zone (SVZ) and Dentate gyrus (DG)/subgranular zone (SGZ), in an easy and cost-effective manner. ResultsNSPCs from SVZ and DG regions of adult mouse brains were isolated and cultured up to passage 15 without losing their stem/progenitor characteristics. These NSPCs could be differentiated into neurons, astrocytes, and oligodendrocytes, revealing its trilineage potential. Comparison with existing methodsThis protocol eliminates the need for multiple animals as well as the use of many expensive reagents mentioned in previous protocols, adding to the cost-effectiveness of experiments. In addition, we have effectively reduced the number of steps involved in isolation and propagation, thereby minimizing the chances of contamination. ConclusionOur simplified protocol for the isolation and culturing of adult NSPCs from the SVZ and DG demonstrates a cost-effective and efficient alternative to existing methods, reducing the need for sacrificing many animals and the usage of expensive reagents. This method permits the long-term maintenance of NSPCs' stem/progenitor characteristics and their effective differentiation into the major types of cells in the brain, making it a valuable resource for researchers in the field. Basic protocolIsolation and Culturing of Neural Stem/Progenitor cells from the Sub ventricular Zone and the Dentate Gyrus of the adult mouse brain. Support protocol 1Cryopreservation, and revival of frozen NSPCs. Support protocol 2Preparation of adherent monolayer cultures of neural stem/progenitor cells for the differentiation into multiple lineages Support protocol 3Differentiation of NSPCs to neuronal and glial lineages Support protocol 4Characterization of differentiated cells by immunocytochemistry

SOX2 and SOX9 Expression in Developing Postnatal Opossum (Monodelphis domestica) Cortex.

(1) Background: Central nervous system (CNS) development is characterized by dynamic changes in cell proliferation and differentiation. Key regulators of these transitions are the transcription factors such as SOX2 and SOX9. SOX2 is involved in the maintenance of progenitor cell state and neural stem cell multipotency, while SOX9, expressed in neurogenic niches, plays an important role in neuron/glia switch with predominant expression in astrocytes in the adult brain. (2) Methods: To validate SOX2 and SOX9 expression patterns in developing opossum (Monodelphis domestica) cortex, we used immunohistochemistry (IHC) and the isotropic fractionator method on fixed cortical tissue from comparable postnatal ages, as well as dissociated primary neuronal cultures. (3) Results: Neurons positive for both neuronal (TUJ1 or NeuN) and stem cell (SOX2) markers were identified, and their presence was confirmed with all methods and postnatal age groups (P4-6, P6-18, and P30) analyzed. SOX9 showed exclusive staining in non-neuronal cells, and it was coexpressed with SOX2. (4) Conclusions: The persistence of SOX2 expression in developing cortical neurons of M. domestica during the first postnatal month implies the functional role of SOX2 during neuronal differentiation and maturation, which was not previously reported in opossums.