Cell Types Of Nervous System Research Articles

Cervical spinal cord injury in a transgenic mouse expressing fluorophores in neurons, microglia, astrocytes, and oligodendrocytes

Spinal cord injury (SCI) most commonly occurs at cervical levels, and such injuries typically impair breathing. Reproducible cervical SCI models which facilitate high resolution evaluation of the tissue response to the injury will aide in the development and testing of therapeutics to improve respiratory function. These models can be evaluated by anatomical assessment of injury lesions. However, tissue processing using traditional immunohistochemistry is limited by the ability of antibodies to penetrate deep within the tissue sample. To address these issues, we studied the PRISM+ mouse, a genetically modified mouse with fluorophores tagging the four major cell types of the central nervous system endogenously express fluorophores, thereby eliminating the need for immunochemistry procedures. In the genetically modified mouse, neurons express YFP (512ex/529em), microglia express GFP (488ex/509em), astrocytes express DsRed (554ex/586em), and oligodendrocytes express CFP (435ex/485em). PRISM+ mice received a mid‐cervical (C3) dorsal‐lateral crush injury and tissues were harvested 3 days later. Initial histological evaluation of the injured spinal cords confirm an absence of neurons in the lesioned dorsal cord, as expected. However, YFP‐positive motor neurons were prominent in the ventral cord. The ipsilesional dorsal quadrant was clearly observed to have increased GFP‐positive microglial infiltration and lack of CFP‐positive oligodendrocytes. At this 3‐day post‐injury time point we detected no astroglial scar, and in fact there were fewer DsRed‐positive astrocytes in immediate vicinity of the lesion as compared to the rest of the spinal cord. Importantly, the fluorophores were robustly detected in all four cell types, and this enabled reliable and automated analysis of the histological sections. These data indicate that the Prism+ mouse provides a useful model for studying the histological response to SCI.Support or Funding InformationThis work was sponsored by T32‐HD043730 (MDS), 1F32NS095620‐01 (KS), SPARC OT2 OD023854 (DDF). 1 R01 NS080180‐01A1 (DDF), the University of Florida Preeminent Initiative, and by the Defense Advanced Research Projects Agency (DARPA) Microsystems Technology Office (MTO), under the auspices of Dr. Jack W. Judy (jack.judy@darpa.mil) and Dr. Doug Weber (Douglas.Weber@darpa.mil) as part of the Reliable Neural Technology Program, through the Space and Naval Warfare Systems Command (SPAWAR) Systems Center (SSC) Pacific grant No. N66001‐11‐1‐4013.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Controlling the Outgrowth and Functions of Neural Stem Cells: The Effect of Surface Topography.

Neural stem cells (NSCs) are self-renewing cells that generate the major cell types of the central nervous system, namely neurons, astrocytes and oligodendrocytes, during embryonic development and in the adult brain. NSCs reside in a complex niche where they are exposed to a plethora of signals, including both soluble and physical signals such as compressive and shear stresses, but also discontinuities and differences in morphology of the extracellular environment, termed as topographical features. Different approaches that incorporate artificial micro- and nano-scale surface topographical features have been developed aiming to recapitulate the in vivo NSC niche discontinuities and features, particularly for in vitro studies. The present review article aims at reviewing the existing body of literature on the use of artificial micro- and nano-topographical features to control NSCs orientation and differentiation into neuronal and/or neuroglial lineage. The different approaches on the study of the underlying mechanism of the topography-guided NSC responses are additionally revised and discussed.

Exploring the genetics and non-cell autonomous mechanisms underlying ALS/FTLD.

Although amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, was first described in 1874, a flurry of genetic discoveries in the last 10 years has markedly increased our understanding of this disease. These findings have not only enhanced our knowledge of mechanisms leading to ALS, but also have revealed that ALS shares many genetic causes with another neurodegenerative disease, frontotemporal lobar dementia (FTLD). In this review, we survey how recent genetic studies have bridged our mechanistic understanding of these two related diseases and how the genetics behind ALS and FTLD point to complex disorders, implicating non-neuronal cell types in disease pathophysiology. The involvement of non-neuronal cell types is consistent with a non-cell autonomous component in these diseases. This is further supported by studies that identified a critical role of immune-associated genes within ALS/FTLD and other neurodegenerative disorders. The molecular functions of these genes support an emerging concept that various non-autonomous functions are involved in neurodegeneration. Further insights into such a mechanism(s) will ultimately lead to a better understanding of potential routes of therapeutic intervention. Facts ALS and FTLD are severe neurodegenerative disorders on the same disease spectrum. Multiple cellular processes including dysregulation of RNA homeostasis, imbalance of proteostasis, contribute to ALS/FTLD pathogenesis. Aberrant function in non-neuronal cell types, including microglia, contributes to ALS/FTLD. Strong neuroimmune and neuroinflammatory components are associated with ALS/FTLD patients. Open Questions Why can patients with similar mutations have different disease manifestations, i.e., why do C9ORF72 mutations lead to motor neuron loss in some patients while others exhibit loss of neurons in the frontotemporal lobe? Do ALS causal mutations result in microglial dysfunction and contribute to ALS/FTLD pathology? How do microglia normally act to mitigate neurodegeneration in ALS/FTLD? To what extent do cellular signaling pathways mediate non-cell autonomous communications between distinct central nervous system (CNS) cell types during disease? Is it possible to therapeutically target specific cell types in the CNS?

Immune-related genetic enrichment in frontotemporal dementia: An analysis of genome-wide association studies.

BackgroundConverging evidence suggests that immune-mediated dysfunction plays an important role in the pathogenesis of frontotemporal dementia (FTD). Although genetic studies have shown that immune-associated loci are associated with increased FTD risk, a systematic investigation of genetic overlap between immune-mediated diseases and the spectrum of FTD-related disorders has not been performed.Methods and findingsUsing large genome-wide association studies (GWASs) (total n = 192,886 cases and controls) and recently developed tools to quantify genetic overlap/pleiotropy, we systematically identified single nucleotide polymorphisms (SNPs) jointly associated with FTD-related disorders—namely, FTD, corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), and amyotrophic lateral sclerosis (ALS)—and 1 or more immune-mediated diseases including Crohn disease, ulcerative colitis (UC), rheumatoid arthritis (RA), type 1 diabetes (T1D), celiac disease (CeD), and psoriasis. We found up to 270-fold genetic enrichment between FTD and RA, up to 160-fold genetic enrichment between FTD and UC, up to 180-fold genetic enrichment between FTD and T1D, and up to 175-fold genetic enrichment between FTD and CeD. In contrast, for CBD and PSP, only 1 of the 6 immune-mediated diseases produced genetic enrichment comparable to that seen for FTD, with up to 150-fold genetic enrichment between CBD and CeD and up to 180-fold enrichment between PSP and RA. Further, we found minimal enrichment between ALS and the immune-mediated diseases tested, with the highest levels of enrichment between ALS and RA (up to 20-fold). For FTD, at a conjunction false discovery rate < 0.05 and after excluding SNPs in linkage disequilibrium, we found that 8 of the 15 identified loci mapped to the human leukocyte antigen (HLA) region on Chromosome (Chr) 6. We also found novel candidate FTD susceptibility loci within LRRK2 (leucine rich repeat kinase 2), TBKBP1 (TBK1 binding protein 1), and PGBD5 (piggyBac transposable element derived 5). Functionally, we found that the expression of FTD–immune pleiotropic genes (particularly within the HLA region) is altered in postmortem brain tissue from patients with FTD and is enriched in microglia/macrophages compared to other central nervous system cell types. The main study limitation is that the results represent only clinically diagnosed individuals. Also, given the complex interconnectedness of the HLA region, we were not able to define the specific gene or genes on Chr 6 responsible for our pleiotropic signal.ConclusionsWe show immune-mediated genetic enrichment specifically in FTD, particularly within the HLA region. Our genetic results suggest that for a subset of patients, immune dysfunction may contribute to FTD risk. These findings have potential implications for clinical trials targeting immune dysfunction in patients with FTD.

Oncotic Cell Death in Stroke.

Oncotic cell death or oncosis represents a major mechanism of cell death in ischaemic stroke, occurring in many central nervous system (CNS) cell types including neurons, glia and vascular endothelial cells. In stroke, energy depletion causes ionic pump failure and disrupts ionic homeostasis. Imbalance between the influx of Na+ and Cl- ions and the efflux of K+ ions through various channel proteins and transporters creates a transmembrane osmotic gradient, with ensuing movement of water into the cells, resulting in cell swelling and oncosis. Oncosis is a key mediator of cerebral oedema in ischaemic stroke, contributing directly through cytotoxic oedema, and indirectly through vasogenic oedema by causing vascular endothelial cell death and disruption of the blood-brain barrier (BBB). Hence, inhibition of uncontrolled ionic flux represents a novel and powerful strategy in achieving neuroprotection in stroke. In this review, we provide an overview of oncotic cell death in the pathology of stroke. Importantly, we summarised the therapeutically significant pathways of water, Na+, Cl- and K+ movement across cell membranes in the CNS and their respective roles in the pathobiology of stroke.

The Importance of Non-neuronal Cell Types in hiPSC-Based Disease Modeling and Drug Screening.

Current applications of human induced pluripotent stem cell (hiPSC) technologies in patient-specific models of neurodegenerative and neuropsychiatric disorders tend to focus on neuronal phenotypes. Here, we review recent efforts toward advancing hiPSCs toward non-neuronal cell types of the central nervous system (CNS) and highlight their potential use for the development of more complex in vitro models of neurodevelopment and disease. We present evidence from previous works in both rodents and humans of the importance of these cell types (oligodendrocytes, microglia, astrocytes) in neurological disease and highlight new hiPSC-based models that have sought to explore these relationships in vitro. Lastly, we summarize efforts toward conducting high-throughput screening experiments with hiPSCs and propose methods by which new screening platforms could be designed to better capture complex relationships between neural cell populations in health and disease.

A multiplexable TALE-based binary expression system for in vivo cellular interaction studies

Binary expression systems have revolutionised genetic research by enabling delivery of loss-of-function and gain-of-function transgenes with precise spatial-temporal resolution in vivo. However, at present, each existing platform relies on a defined exogenous transcription activator capable of binding a unique recognition sequence. Consequently, none of these technologies alone can be used to simultaneously target different tissues or cell types in the same organism. Here, we report a modular system based on programmable transcription activator-like effector (TALE) proteins, which enables parallel expression of multiple transgenes in spatially distinct tissues in vivo. Using endogenous enhancers coupled to TALE drivers, we demonstrate multiplexed orthogonal activation of several transgenes carrying cognate variable activating sequences (VAS) in distinct neighbouring cell types of the Drosophila central nervous system. Since the number of combinatorial TALE–VAS pairs is virtually unlimited, this platform provides an experimental framework for highly complex genetic manipulation studies in vivo.

Laser-captured microglia in the Alzheimer's and Parkinson's brain reveal unique regional expression profiles and suggest a potential role for hepatitis B in the Alzheimer's brain

Expression array data from dozens of laboratories, including our own, show significant changes in expression of many genes in Alzheimer's disease (AD) patients compared with normal controls. These data typically rely on brain homogenates, and information about transcripts specific to microglia and other central nervous system (CNS) cell types, which far outnumber microglia-specific transcripts, is lost. We therefore used single-cell laser capture methods to assess the full range of microglia-specific expression changes that occur in different brain regions (substantia nigra and hippocampus CA1) and disease states (AD, Parkinson's disease, and normal controls). Two novel pathways, neuronal repair and viral processing were identified. Based on KEGG analysis (Kyoto Encyclopedia of Genes and Genomes, a collection of biological pathways), one of the most significant viruses was hepatitis B virus (HBV) (false discovery rate < 0.00000001). Immunohistochemical analysis using HBV-core antibody in HBV-positive control, amnestic mild cognitive impairment, and HBV-positive AD cases show increased HBV immunoreactivity as disease pathology increases. These results are the first, to our knowledge, to show regional differences in human microglia. In addition, these data reveal new functions for microglia and suggest a novel risk factor for AD.

Increased Neuronal Differentiation of Neural Progenitor Cells Derived from Phosphovimentin-Deficient Mice

Vimentin is an intermediate filament (also known as nanofilament) protein expressed in several cell types of the central nervous system, including astrocytes and neural stem/progenitor cells. Mutation of the vimentin serine sites that are phosphorylated during mitosis (VIMSA/SA) leads to cytokinetic failures in fibroblasts and lens epithelial cells, resulting in chromosomal instability and increased expression of cell senescence markers. In this study, we investigated morphology, proliferative capacity, and motility of VIMSA/SA astrocytes, and their effect on the differentiation of neural stem/progenitor cells. VIMSA/SA astrocytes expressed less vimentin and more GFAP but showed a well-developed intermediate filament network, exhibited normal cell morphology, proliferation, and motility in an in vitro wound closing assay. Interestingly, we found a two- to fourfold increased neuronal differentiation of VIMSA/SA neurosphere cells, both in a standard 2D and in Bioactive3D cell culture systems, and determined that this effect was neurosphere cell autonomous and not dependent on cocultured astrocytes. Using BrdU in vivo labeling to assess neural stem/progenitor cell proliferation and differentiation in the hippocampus of adult mice, one of the two major adult neurogenic regions, we found a modest increase (by 8%) in the fraction of newly born and surviving neurons. Thus, mutation of the serine sites phosphorylated in vimentin during mitosis alters intermediate filament protein expression but has no effect on astrocyte morphology or proliferation, and leads to increased neuronal differentiation of neural progenitor cells.

Systemic Inflammation as a Driver of Brain Injury: the Astrocyte as an Emerging Player.

Severe systemic inflammation has strong effects on brain functions, promoting permanent neurocognitive dysfunction and high mortality rates. Additionally, hippocampal damage seems to be directly involved in this process and astrocytes play an important role in neuroinflammation and in the neuroimmune response. However, the contribution of the astrocytes to the pathology of acute brain dysfunction is not well understood. Recently, our group established a protocol for obtaining astrocyte cultures from mature brain to allow the characterization of these cells and their functions under pathologic conditions. The present study was designed to characterize astrocyte function after acute systemic inflammation induced by cecal ligation and perforation (CLP). Hippocampal astrocyte cultures from CLP animals presented increased levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, IL-18, and cyclooxygenase-2 and decreased levels of IL-10. This proinflammatory profile was accompanied by an increase in Toll-like receptor (TLR)2 mRNA expression levels and no change either in TLR4 or in vascular endothelial growth factor (VEGF) gene expression. These alterations were associated with increased expressions of p21, nuclear factor kappa B (NFκB), and inducible nitric oxide synthase (iNOS) in astrocytes from CLP animals. The same parameters were also evaluated in whole hippocampal tissue, but differences in this profile were found compared to hippocampal astrocyte cultures from CLP, reflecting an interaction between other central nervous system cell types, which may mask specific astrocytic changes. These results improve our understanding of the mechanisms by which astrocytes react against systemic inflammation, and suggest these cells to be potential targets for therapeutic modulation.

Acid Ceramidase Deficiency in Mice Results in a Broad Range of Central Nervous System Abnormalities

Farber disease is a rare autosomal recessive disorder caused by acid ceramidase deficiency that usually presents as early-onset progressive visceral and neurologic disease. To understand the neurologic abnormality, we investigated behavioral, biochemical, and cellular abnormalities in the central nervous system of Asah1P361R/P361R mice, which serve as a model of Farber disease. Behaviorally, the mutant mice had reduced voluntary locomotion and exploration, increased thigmotaxis, abnormal spectra of basic behavioral activities, impaired muscle grip strength, and defects in motor coordination. A few mutant mice developed hydrocephalus. Mass spectrometry revealed elevations of ceramides, hydroxy-ceramides, dihydroceramides, sphingosine, dihexosylceramides, and monosialodihexosylganglioside in the brain. The highest accumulation was in hydroxy-ceramides. Storage compound distribution was analyzed by mass spectrometry imaging and morphologic analyses and revealed involvement of a wide range of central nervous system cell types (eg,neurons, endothelial cells, and choroid plexus cells), most notably microglia and/or macrophages. Coalescing and mostly perivascular granuloma-like accumulations of storage-laden CD68+ microglia and/or macrophages were seen as early as 3 weeks of age and located preferentially in white matter, periventricular zones, and meninges. Neurodegeneration was also evident in specific cerebral areas in late disease. Overall, our central nervous system studies in Asah1P361R/P361R mice substantially extend the understanding of human Farber disease and suggest that this model can be used to advance therapeutic approaches for this currently untreatable disorder.

Glycoconjugates reveal diversity of human neural stem cells (hNSCs) derived from human induced pluripotent stem cells (hiPSCs).

Neural stem cells (NSCs) have the ability to self-renew and to differentiate into various cell types of the central nervous system. This potential can be recapitulated by human induced pluripotent stem cells (hiPSCs) in vitro. The differentiation capacity of hiPSCs is characterized by several stages with distinct morphologies and the expression of various marker molecules. We used the monoclonal antibodies (mAbs) 487LeX, 5750LeX and 473HD to analyze the expression pattern of particular carbohydrate motifs as potential markers at six differentiation stages of hiPSCs. Mouse ESCs were used as a comparison. At the pluripotent stage, 487LeX-, 5750LeX- and 473HD-related glycans were differently expressed. Later, cells of the three germ layers in embryoid bodies (hEBs) and, even after neuralization of hEBs, subpopulations of cells were labeled with these surface antibodies. At the human rosette-stage of NSCs (hR-NSC), LeX- and 473HD-related epitopes showed antibody-specific expression patterns. We also found evidence that these surface antibodies could be used to distinguish the hR-NSCs from the hSR-NSCs stages. Characterization of hNSCsFGF-2/EGF derived from hSR-NSCs revealed that both LeX antibodies and the 473HD antibody labeled subpopulations of hNSCsFGF-2/EGF. Finally, we identified potential LeX carrier molecules that were spatiotemporally regulated in early and late stages of differentiation. Our study provides new insights into the regulation of glycoconjugates during early human stem cell development. The mAbs 487LeX, 5750LeX and 473HD are promising tools for identifying distinct stages during neural differentiation.

Dynamism of an Astrocyte In Vivo: Perspectives on Identity and Function.

Astrocytes are an abundant and evolutionarily conserved central nervous system cell type. Despite decades of evidence that astrocytes are integral to neural circuit function, it seems as though astrocytic and neuronal biology continue to advance in parallel to each other, to the detriment of both. Recent advances in molecular biology and optical imaging are being applied to astrocytes in new and exciting ways but without fully considering their unique biology. From this perspective, we explore the reasons that astrocytes remain enigmatic, arguing that their responses to neuronal and environmental cues shape form and function in dynamic ways. Here, we provide a roadmap for future experiments to explore the nature of astrocytes in situ.

Equol, a Dietary Daidzein Gut Metabolite Attenuates Microglial Activation and Potentiates Neuroprotection In Vitro.

Estrogen deficiency has been well characterized in inflammatory disorders including neuroinflammation. Daidzein, a dietary alternative phytoestrogen found in soy (Glycine max) as primary isoflavones, possess anti-inflammatory activity, but the effect of its active metabolite Equol (7-hydroxy-3-(4′-hydroxyphenyl)-chroman) has not been well established. In this study, we investigated the anti-neuroinflammatory and neuroprotective effect of Equol in vitro. To evaluate the potential effects of Equol, three major types of central nervous system (CNS) cells, including microglia (BV-2), astrocytes (C6), and neurons (N2a), were used. Effects of Equol on the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), Mitogen activated protein kinase (MAPK) signaling proteins, and apoptosis-related proteins were measured by western blot analysis. Equol inhibited the lipopolysaccharide (LPS)-induced TLR4 activation, MAPK activation, NF-kB-mediated transcription of inflammatory mediators, production of nitric oxide (NO), release of prostaglandin E2 (PGE-2), secretion of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), in Lipopolysaccharide (LPS)-activated murine microglia cells. Additionally, Equol protects neurons from neuroinflammatory injury mediated by LPS-activated microglia through downregulation of neuronal apoptosis, increased neurite outgrowth in N2a cell and neurotrophins like nerve growth factor (NGF) production through astrocytes further supporting its neuroprotective potential. These findings provide novel insight into the anti-neuroinflammatory effects of Equol on microglial cells, which may have clinical significance in cases of neurodegeneration.

Rab32 connects ER stress to mitochondrial defects in multiple sclerosis

BackgroundEndoplasmic reticulum (ER) stress is a hallmark of neurodegenerative diseases such as multiple sclerosis (MS). However, this physiological mechanism has multiple manifestations that range from impaired clearance of unfolded proteins to altered mitochondrial dynamics and apoptosis. While connections between the triggering of the unfolded protein response (UPR) and downstream mitochondrial dysfunction are poorly understood, the membranous contacts between the ER and mitochondria, called the mitochondria-associated membrane (MAM), could provide a functional link between these two mechanisms. Therefore, we investigated whether the guanosine triphosphatase (GTPase) Rab32, a known regulator of the MAM, mitochondrial dynamics, and apoptosis, could be associated with ER stress as well as mitochondrial dysfunction.MethodsWe assessed Rab32 expression in MS patient and experimental autoimmune encephalomyelitis (EAE) tissue, via observation of mitochondria in primary neurons and via monitoring of survival of neuronal cells upon increased Rab32 expression.ResultsWe found that the induction of Rab32 and other MAM proteins correlates with ER stress proteins in MS brain, as well as in EAE, and occurs in multiple central nervous system (CNS) cell types. We identify Rab32, known to increase in response to acute brain inflammation, as a novel unfolded protein response (UPR) target. High Rab32 expression shortens neurite length, alters mitochondria morphology, and accelerates apoptosis/necroptosis of human primary neurons and cell lines.ConclusionsER stress is strongly associated with Rab32 upregulation in the progression of MS, leading to mitochondrial dysfunction and neuronal death.

SOD1 Lysine 123 Acetylation in the Adult Central Nervous System.

Superoxide dismutase 1 (SOD1) knockout (Sod1−/−) mice exhibit an accelerated aging phenotype. In humans, SOD1 mutations are linked to familial amyotrophic lateral sclerosis (ALS), and post-translational modification (PTM) of wild-type SOD1 has been associated with sporadic ALS. Reversible acetylation regulates many enzymes and proteomic studies have identified SOD1 acetylation at lysine 123 (K123). The function and distribution of K123-acetylated SOD1 (Ac-K123 SOD1) in the nervous system is unknown. Here, we generated polyclonal rabbit antibodies against Ac-K123 SOD1. Sod1 deletion in Sod1−/− mice, K123 mutation or preabsorption with Ac-K123 peptide all abolished antibody binding. Using immunohistochemistry, we assessed Ac-K123 SOD1 distribution in the normal adult mouse nervous system. In the cerebellum, Ac-K123 SOD1 staining was prominent in cell bodies of the granular cell layer (GCL) and Purkinje cell dendrites and interneurons of the molecular cell layer. In the hippocampus, Ac-K123 SOD1 staining was strong in the fimbria, subiculum, pyramidal cells and Schaffer collateral fibers of the cornus ammonis field 1 (CA1) region and granule and neuronal progenitor cells of the dentate gyrus. In addition, labeling was observed in the choroid plexus (CP) and the ependyma of the brain ventricles and central canal of the spinal cord. In the olfactory bulb, Ac-K123 SOD1 staining was prominent in axons of sensory neurons, in cell bodies of interneurons and neurites of the mitral and tufted cells. In the retina, labeling was strong in the retinal ganglion cell layer (RGCL) and axons of retinal ganglion cells (RGCs), the inner nuclear layer (INL) and cone photoreceptors of the outer nuclear layer (ONL). In summary, our findings describe Ac-K123 SOD1 distribution to distinct regions and cell types of the normal nervous system.

Human Neural Stem Cell Transplantation Rescues Cognitive Defects in APP/PS1 Model of Alzheimer’s Disease by Enhancing Neuronal Connectivity and Metabolic Activity

Alzheimer’s disease (AD), the most frequent type of dementia, is featured by Aβ pathology, neural degeneration and cognitive decline. To date, there is no cure for this disease. Neural stem cell (NSC) transplantation provides new promise for treating AD. Many studies report that intra-hippocampal transplantation of murine NSCs improved cognition in rodents with AD by alleviating neurodegeneration via neuronal complement or replacement. However, few reports examined the potential of human NSC transplantation for AD. In this study, we implanted human brain-derived NSCs (hNSCs) into bilateral hippocampus of an amyloid precursor protein (APP)/presenilin 1 (PS1) transgenic (Tg) mouse model of AD to test the effects of hNSC transplantation on Alzheimer’s behavior and neuropathology. Six weeks later, transplanted hNSCs engrafted into the brains of AD mice, migrated dispersedly in broad brain regions, and some of them differentiated into neural cell types of central nervous system (CNS). The hNSC transplantation restored the recognition, learning and memory deficits but not anxiety tasks in AD mice. Although Aβ plaques were not significantly reduced, the neuronal, synaptic and nerve fiber density was significantly increased in the frontal cortex and hippocampus of hNSC-treated AD mice, suggesting of improved neuronal connectivity in AD brains after hNSC transplantation. Ultrastructural analysis confirmed that synapses and nerve fibers maintained relatively well-structured shapes in these mice. Furthermore, in vivo magnetic resonance spectroscopy (MRS) showed that hNSC-treated mice had notably increased levels of N-acetylaspartate (NAA) and Glu in the frontal cortex and hippocampus, suggesting that neuronal metabolic activity was improved in AD brains after hNSC transplantation. These results suggest that transplanted hNSCs rescued Alzheimer’s cognition by enhancing neuronal connectivity and metabolic activity through a compensation mechanism in APP/PS1 mice. This study provides preclinical evidence that hNSC transplantation can be a possible and feasible strategy for treating patients with AD.

Neural organoids for disease phenotyping, drug screening and developmental biology studies

Human induced pluripotent stem cells (hiPSCs) can theoretically yield limitless supplies of cells fated to any cell type that comprise the human organism, making them a new tool by which to potentially overcome caveats in current biomedical research. In vitro derivation of central nervous system (CNS) cell types has the potential to provide material for drug discovery and validation, safety and toxicity assays, cell replacement therapy and the elucidation of previously unknown disease mechanisms. However, current two-dimensional (2D) CNS differentiation protocols do not faithfully recapitulate the spatial organization of heterogeneous tissue, nor the cell-cell interactions, cell-extracellular matrix interactions, or specific physiological functions generated within complex tissue such as the brain. In an effort to overcome 2D protocol limitations, there have been advancements in deriving highly complicated 3D neural organoid structures. Herein we provide a synopsis of the derivation and application of neural organoids and discuss recent advancements and remaining challenges on the full potential of this novel technological platform.

Dehydroabietic acid cytotoxicity in goldfish radial glial cells in vitro

Dehydroabietic acid (DHAA) is a resin acid present in aquatic environments shown to induce cellular and molecular damage in aquatic animals. In this study, the cytotoxicity of DHAA on primary cultured goldfish radial glial cells (RGCs), an important component of the central nervous system, was evaluated. Here, it is reported that a concentration of 20mg/L DHAA affected cellular morphology and expression of genes involved in RGC steroidogenesis and metabolism. Higher concentration exposures of DHAA (40mg/L) lead to RGC death based on a lactate dehydrogenase leakage assay. Together, these data have implications in understanding the effects of DHAA on an integral central nervous system cell type important for neurogenesis, steroidogenesis and structural support. Due to the continuous presence of DHAA into water systems, results from this study provide indications as to the potential impacts of DHAA and demonstrate the importance of this class of chemicals on aquatic organisms.

Novel allele-dependent role for APOE in controlling the rate of synapse pruning by astrocytes

The strongest genetic risk factor influencing susceptibility to late-onset Alzheimer's disease (AD) is apolipoprotein E (APOE) genotype. APOE has three common isoforms in humans, E2, E3, and E4. The presence of two copies of the E4 allele increases risk by ∼12-fold whereas E2 allele is associated with an ∼twofold decreased risk for AD. These data put APOE central to AD pathophysiology, but it is not yet clear how APOE alleles modify AD risk. Recently we found that astrocytes, a major central nervous system cell type that produces APOE, are highly phagocytic and participate in normal synapse pruning and turnover. Here, we report a novel role for APOE in controlling the phagocytic capacity of astrocytes that is highly dependent on APOE isoform. APOE2 enhances the rate of phagocytosis of synapses by astrocytes, whereas APO4 decreases it. We also found that the amount of C1q protein accumulation in hippocampus, which may represent the accumulation of senescent synapses with enhanced vulnerability to complement-mediated degeneration, is highly dependent on APOE alleles: C1q accumulation was significantly reduced in APOE2 knock-in (KI) animals and was significantly increased in APOE4 KI animals compared with APOE3 KI animals. These studies reveal a novel allele-dependent role for APOE in regulating the rate of synapse pruning by astrocytes. They also suggest the hypothesis that AD susceptibility of APOE4 may originate in part from defective phagocytic capacity of astrocytes which accelerates the rate of accumulation of C1q-coated senescent synapses, enhancing synaptic vulnerability to classical-complement-cascade mediated neurodegeneration.