The work was supported by the NIH R01 NS071039-01A1 research grant.

<ol>
	<li>Tremblay, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Role+of+Microglia+in+the+Healthy+Brain.">The Role of Microglia in the Healthy Brain.</a> J. Neurosci. 31, 16064-16069 (2011).</li><li>Graeber, M. B., Li, W., Rodriguez, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+microglia+in+CNS+inflammation.">Role of microglia in CNS inflammation.</a> FEBS Lett. , (2011).</li><li>Ponomarev, E. D., Shriver, L. P., Maresz, K., Dittel, B. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglial+cell+activation+and+proliferation+precedes+the+onset+of+CNS+autoimmunity.">Microglial cell activation and proliferation precedes the onset of CNS autoimmunity.</a> J. Neurosci. Res. 81, 374-389 (2005).</li><li>Perruisseau-Carrier, C., Jurga, M., Forraz, N., McGuckin, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=miRNAs+stem+cell+reprogramming+for+neuronal+induction+and+differentiation.">miRNAs stem cell reprogramming for neuronal induction and differentiation.</a> Mol. Neurobiol. 43, 215-227 (2011).</li><li>McCoy, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+miRNAs+in+cytokine+signaling.">The role of miRNAs in cytokine signaling.</a> Front Biosci. 17, 2161-2171 (2010).</li><li>He, M., Xu, Z., Ding, T., Kuang, D. M., Zheng, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA-155+regulates+inflammatory+cytokine+production+in+tumor-associated+macrophages+via+targeting+C/EBPbeta.">MicroRNA-155 regulates inflammatory cytokine production in tumor-associated macrophages via targeting C/EBPbeta.</a> Cell Mol. Immunol. 6, 343-352 (2009).</li><li>Ponomarev, E. D., Veremeyko, T., Barteneva, N., Krichevsky, A. M., Weiner, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA-124+promotes+microglia+quiescence+and+suppresses+EAE+by+deactivating+macrophages+via+the+C/EBP-alpha-PU.1+pathway.">MicroRNA-124 promotes microglia quiescence and suppresses EAE by deactivating macrophages via the C/EBP-alpha-PU.1 pathway.</a> Nat. Med. 17, 64-70 (2011).</li><li>Basu, S., Campbell, H. M., Dittel, B. N., Ray, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+Specific+Cell+Population+by+Fluorescence+Activated+Cell+Sorting+(FACS).">Purification of Specific Cell Population by Fluorescence Activated Cell Sorting (FACS).</a> J. Vis. Exp. (41), e1546-3791 (2010).</li><li>Gabriely, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA+21+promotes+glioma+invasion+by+targeting+matrix+metalloproteinase+regulators.">MicroRNA 21 promotes glioma invasion by targeting matrix metalloproteinase regulators.</a> Mol. Cell Biol. 28, 5369-5380 (2008).</li><li>Caffarelli, E., Filetici, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetic+regulation+in+cancer+development.">Epigenetic regulation in cancer development.</a> Front Biosci. 17, 2682-2694 (2011).</li><li>Cardona, A. E., Huang, D., Sasse, M. E., Ransohoff, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+murine+microglial+cells+for+RNA+analysis+or+flow+cytometry.">Isolation of murine microglial cells for RNA analysis or flow cytometry.</a> Nat. Protoc. 1, 1947-1951 (2006).</li><li>Gordon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+magnetic+separation+method+for+high-yield+isolation+of+pure+primary+microglia.">A simple magnetic separation method for high-yield isolation of pure primary microglia.</a> J. Neurosci. Methods. 194, 287-296 (2011).</li><li>Moltzahn, F., Hunkapiller, N., Mir, A. A., Imbar, T., Blelloch, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+Throughput+MicroRNA+Profiling:+Optimized+Multiplex+qRT-PCR+at+Nanoliter+Scale+on+the+Fluidigm+Dynamic+ArrayTM+IFCs.">High Throughput MicroRNA Profiling: Optimized Multiplex qRT-PCR at Nanoliter Scale on the Fluidigm Dynamic ArrayTM IFCs.</a> J. Vis. Exp. (54), e2552 (2011).</li></ol>

No conflicts of interest declared.

Recently significant interest was given to microglia and involvement of these cells in many pathologies associated with neuroinflammation and neurodegeneration. In addition, the role of microRNAs in the differentiation of immune and cancer cells has dramatically grown over the last several years5,10. We have previously reported the role of miR-124 in the maintenance of non-activated or resting phenotype of microglia in normal CNS7, but the role of the other types of microRNAs in microglia phenotype ...

<table><tbody><tr><td> 1X PBS</td><td>GIBCO</td><td>14190</td><td>Can be prepared from dry components in the laboratory, pH: 7.2-7.4</td></tr><tr><td> 10X PBS</td><td>Thermo Scientific</td><td>SH30258.02</td><td>Can be prepared from dry components in the laboratory, pH: 7.2-7.4</td></tr><tr><td>DMEM; FBS</td><td>GBCO</td><td>11965; 10438</td><td></td></tr><tr><td>miRVana kit</td><td>Invitrogen</td><td>AM1561</td><td></td></tr><tr><td> Percoll</td><td>Sigma</td><td>P4937-500 ml</td><td>100 ml of 100% Percoll is prepared by mixing 10 ml of 10X PBS and 90 ml of Percoll from Sigma. 50 ml of 70% Percoll is prepared by mixing of 35 ml of 100% Percoll and 15 ml of DMEM 50 ml of 40% Percoll is prepared by mixing 20 ml of 100% Percoll and 30 ml of 1X PBS</td></tr><tr><td>MOG&lt;sub&gt;35-55&lt;/sub&gt; peptide</td><td>AnaSpec Inc</td><td>60130-5</td><td></td></tr><tr><td>CFA</td><td>DIFCO</td><td>263810</td><td></td></tr><tr><td>Pertussis Toxin</td><td>Sigma</td><td>P7208</td><td></td></tr><tr><td>FcR blocking antibodies</td><td>BD Biosciences</td><td>553142</td><td>Clone 2.4G2</td></tr><tr><td> Anti-CD11b&lt;sup&gt;-&lt;/sup&gt;PE mAb</td><td>BD Biosciences</td><td>553311</td><td>Can be used with different fluorophores (e.g. AF488)</td></tr><tr><td> Anti-CD45-APC-Cy7 mABs</td><td>Biolegend</td><td>103116</td><td>Can be used with different fluorophores (e.g. APC)</td></tr><tr><td>Paraformaldehyde (16%)</td><td>EMS Inc</td><td>15710</td><td>Dilute 1:15 in 1X PBS</td></tr><tr><td>15% TBE-Urea Gel</td><td>Life Technologies Inc.</td><td>EC68855BOX</td><td></td></tr><tr><td>TaqMan MicroRNA Reverse Transcription Kit</td><td>Life Technologies Inc</td><td>4366596</td><td></td></tr><tr><td>TaqMan Universal PCR Master Mix</td><td>Life Technologies Inc</td><td>4304437</td><td></td></tr><tr><td>TaqMan MicroRNA Assays mmu-miR-124a</td><td>Life Technologies Inc</td><td>4427975 ID 001182</td><td></td></tr><tr><td>TaqMan MicroRNA Assays snoRNA-55</td><td>Life Technologies Inc</td><td>4427975 ID 001228</td><td></td></tr><tr><td>Nuclease-free water</td><td>Life Technologies Inc</td><td>AM9937</td><td>Nuclease-free water</td></tr><tr><td> 384-well clear optical reaction plate</td><td>Life Technologies Inc.</td><td>4309849</td><td>Can be substituted with other plates (e.g. 96 well plate) in different real-time PCR instruments</td></tr><tr><td>Dounce homogenizer (15 ml)</td><td>Wheaton Science Products.</td><td>358044</td><td> Teflon/glass</td></tr><tr><td>40 &amp;mu; nylon cell strainer</td><td>Falcon</td><td>352340</td><td></td></tr><tr><td>Big centrifuge</td><td>Sorval</td><td>RT 6000B</td><td>Rotor diameter 18.5 cm</td></tr><tr><td>Small centrifuge</td><td>Eppendorf</td><td>5415 R</td><td>Rotor diameter 6.5 cm</td></tr><tr><td>Real-time PCR Instrument</td><td>Life Technologies Inc.</td><td>AB 7900 HT</td><td>Can be substituted with other instruments</td></tr><tr><td>Flow cytometer</td><td>BD Biosciencess</td><td>LSR II</td><td>Can be substituted with other instruments</td></tr><tr><td>FACS</td><td>BD Biosciences</td><td>FACSAria</td><td>Can be substituted with other instruments</td></tr><tr><td>Nanodrop spectrophotometer</td><td>Thermo Scientific</td><td>Nanodrop 1000</td><td></td></tr></tbody></table>

detection of micrornas in microglia by real-time pcr in normal cns and during neuroinflammation

Microglia are cells of the myeloid lineage that reside in the central nervous system (CNS)1. These cells play an important role in pathologies of many diseases associated with neuroinflammation such as multiple sclerosis (MS)2. Microglia in a normal CNS express macrophage marker CD11b and exhibit a resting phenotype by expressing low levels of activation markers such as CD45. During pathological events in the CNS, microglia become activated as determined by upregulation of CD45 and other markers3. The factors that affect microglia phenotype and functions in the CNS are not well studied. MicroRNAs (miRNAs) are a growing family of conserved molecules (~22 nucleotides long) that are involved in many normal physiological processes such as cell growth and differentiation4 and pathologies such as inflammation5. MiRNAs downregulate the expression of certain target genes by binding complementary sequences of their mRNAs and play an important role in the activation of innate immune cells including macrophages6 and microglia7. In order to investigate miRNA-mediated pathways that define the microglial phenotype, biological function, and to distinguish microglia from other types of macrophages, it is important to quantitatively assess the expression of particular microRNAs in distinct subsets of CNS-resident microglia. Common methods for measuring the expression of miRNAs in the CNS include quantitative PCR from whole neuronal tissue and in situ hybridization. However, quantitative PCR from whole tissue homogenate does not allow the assessment of the expression of miRNA in microglia, which represent only 5-15% of the cells of neuronal tissue. Hybridization in situ allows the assessment of the expression of microRNA in specific cell types in the tissue sections, but this method is not entirely quantitative. In this report we describe a quantitative and sensitive method for the detection of miRNA by real-time PCR in microglia isolated from normal CNS or during neuroinflammation using experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. The described method will be useful to measure the level of expression of microRNAs in microglia in normal CNS or during neuroinflammation associated with various pathologies including MS, stroke, traumatic injury, Alzheimer's disease and brain tumors.

Watch this Scientific Journal Video about Detection of MicroRNAs in Microglia by Real-time PCR in Normal CNS and During Neuroinflammation at JoVE.com

Detection of MicroRNAs in Microglia by Real-time PCR in Normal CNS and During Neuroinflammation

Microglia are resident macrophages that provide the first line of defense and immune surveillance of the central nervous system. MicroRNAs are regulatory molecules that play an important role in many physiological processes including activation and differentiation of macrophages. In this article, we describe the method for measurement of microRNAs in microglia.

Microglia are cells of the myeloid lineage that reside in the central nervous system (CNS)1. These cells play an important role in pathologies of many ...

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Universidad de Cartagena UDEC

Research

JoVE Journal

Immunology and Infection

19.3K Views.  Harvard Medical School. Microglia are resident macrophages that provide the first line of defense and immune surveillance of the central nervous system. MicroRNAs are regulatory molecules that play an important role in many physiological processes including activation and differentiation of macrophages. In this article, we describe the method for measurement of microRNAs in microglia.

Video: Detection of MicroRNAs in Microglia by Real-time PCR in Normal CNS and During Neuroinflammation

Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates

Isolation of microglia from CNS tissue is a powerful investigative tool used to study microglial biology ex vivo. The present method details a procedure for isolation of microglia from neonatal murine cortices by mechanical agitation with a rotary shaker. This microglia isolation method yields highly pure cortical microglia that exhibit morphological and functional characteristics indicative of quiescent microglia in normal, nonpathological conditions in vivo. This procedure also preserves the microglial immunophenotype and biochemical functionality as demonstrated by the induction of morphological changes, nuclear translocation of the p65 subunit of NF-&#954;B (p65), and secretion of the hallmark proinflammatory cytokine, tumor necrosis factor-&#945; (TNF-&#945;), upon lipopolysaccharide (LPS) and Pam3CSK4 (Pam) challenges. Therefore, the present isolation procedure preserves the immunophenotype of both quiescent and activated microglia, providing an experimental method of investigating microglia biology in ex vivo conditions.

One key to successful investigation of microglial biology is the preservation of microglial immunofunction ex vivo during isolation from CNS tissue. Isolating microglia via rotary shaking results in highly pure and immunofunctional cell cultures as assessed by fluorescent imaging, immunocytochemistry, and ELISA following microglia activation with the proinflammatory stimuli lipopolysaccharide (LPS) and Pam3CSK4 (Pam).

Isolation of microglia from CNS tissue is a powerful investigative tool used to study microglial biology ex vivo. The present method details a procedure ...

Cerebrospinal Fluid MicroRNA Profiling Using Quantitative Real Time PCR

MicroRNAs (miRNAs) constitute a potent layer of gene regulation by guiding RISC to target sites located on mRNAs and, consequently, by modulating their translational repression. Changes in miRNA expression have been shown to be involved in the development of all major complex diseases. Furthermore, recent findings showed that miRNAs can be secreted to the extracellular environment and enter the bloodstream and other body fluids where they can circulate with high stability. The function of such circulating miRNAs remains largely elusive, but systematic high throughput approaches, such as miRNA profiling arrays, have lead to the identification of miRNA signatures in several pathological conditions, including neurodegenerative disorders and several types of cancers. In this context, the identification of miRNA expression profile in the cerebrospinal fluid, as reported in our recent study, makes miRNAs attractive candidates for biomarker analysis.
There are several tools available for profiling microRNAs, such as microarrays, quantitative real-time PCR (qPCR), and deep sequencing. Here, we describe a sensitive method to profile microRNAs in cerebrospinal fluids by quantitative real-time PCR. We used the Exiqon microRNA ready-to-use PCR human panels I and II V2.R, which allows detection of 742 unique human microRNAs. We performed the arrays in triplicate runs and we processed and analyzed data using the GenEx Professional 5 software.
Using this protocol, we have successfully profiled microRNAs in various types of cell lines and primary cells, CSF, plasma, and formalin-fixed paraffin-embedded tissues.

We describe a protocol of real time PCR to profile microRNAs in the cerebrospinal fluid (CSF). With the exception of RNA extraction protocols, the procedure can be extended to RNA extracted from other body fluids, cultured cells, or tissue specimens.

MicroRNAs (miRNAs) constitute a potent layer of gene regulation by guiding RISC to target sites located on mRNAs and, consequently, by modulating their ...

Medicine

In Vivo Dynamics of Retinal Microglial Activation During Neurodegeneration: Confocal Ophthalmoscopic Imaging and Cell Morphometry in Mouse Glaucoma

Microglia, which are CNS-resident neuroimmune cells, transform their morphology and size in response to CNS damage, switching to an activated state with distinct functions and gene expression profiles. The roles of microglial activation in health, injury and disease remain incompletely understood due to their dynamic and complex regulation in response to changes in their microenvironment. Thus, it is critical to non-invasively monitor and analyze changes in microglial activation over time in the intact organism. In vivo studies of microglial activation have been delayed by technical limitations to tracking microglial behavior without altering the CNS environment. This has been particularly challenging during chronic neurodegeneration, where long-term changes must be tracked. The retina, a CNS organ amenable to non-invasive live imaging, offers a powerful system to visualize and characterize the dynamics of microglia activation during chronic disorders.
This protocol outlines methods for long-term, in vivo imaging of retinal microglia, using confocal ophthalmoscopy (cSLO) and CX3CR1GFP/+ reporter mice, to visualize microglia with cellular resolution. Also, we describe methods to quantify monthly changes in cell activation and density in large cell subsets (200-300 cells per retina). We confirm the use of somal area as a useful metric for live tracking of microglial activation in the retina by applying automated threshold-based morphometric analysis of in vivo images. We use these live image acquisition and analyses strategies to monitor the dynamic changes in microglial activation and microgliosis during early stages of retinal neurodegeneration in a mouse model of chronic glaucoma. This approach should be useful to investigate the contributions of microglia to neuronal and axonal decline in chronic CNS disorders that affect the retina and optic nerve.

In Vivo Dynamics of Retinal Microglial Activation During Neurodegeneration: Confocal Ophthalmoscopic Imaging and Cell Morphometry in Mouse Glaucoma

Microglia activation and microgliosis are key responses to chronic neurodegeneration. Here, we present methods for in vivo, long-term visualization of retinal CX3CR1-GFP+ microglial cells by confocal ophthalmoscopy, and for threshold and morphometric analyses to identify and quantify their activation. We monitor microglial changes during early stages of age-related glaucoma.

Microglia, which are CNS-resident neuroimmune cells, transform their morphology and size in response to CNS damage, switching to an activated state with ...

Microglia as a Surrogate Biosensor to Determine Nanoparticle Neurotoxicity

Nanoparticles found in air pollutants can alter neurotransmitter profiles, increase neuroinflammation, and alter brain function. Therefore, the assay described here will aid in elucidating the role of microglia in neuroinflammation and neurodegenerative diseases. The use of microglia, resident immune cells of the brain, as a surrogate biosensor provides novel insight into how inflammatory responses mediate neuronal insults. Here, we utilize an immortalized murine microglial cell line, designated BV2, and describe a method for nanoparticle exposure using silver nanoparticles (AgNPs) as a standard. We describe how to expose microglia to nanoparticles, how to remove nanoparticles from supernatant, and how to use supernatant from activated microglia to determine toxicity, using hypothalamic cell survival as a measure. Following AgNP exposure, BV2 microglial activation was validated using a tumor necrosis factor alpha (TNF-&#945;) enzyme linked immunosorbent assay (ELISA). The supernatant was filtered to remove the AgNP and to allow cytokines and other secreted factors to remain in the conditioned media. Hypothalamic cells were then exposed to supernatant from AgNP activated microglia and survival of neurons was determined using a resazurin-based fluorescent assay. This technique is useful for utilizing microglia as a surrogate biomarker of neuroinflammation and determining the effect of neuroinflammation on other cell types.

Microglia (immune cells of the brain), are used as a surrogate biosensor to determine how nanoparticles influence neurotoxicity. We describe a series of experiments designed to assay microglial response to nanoparticles and exposure of hypothalamic neurons to supernatant from activated microglia to determine neurotoxicity.

Nanoparticles found in air pollutants can alter neurotransmitter profiles, increase neuroinflammation, and alter brain function. Therefore, the assay ...

Neuroscience

Rapid and Refined CD11b Magnetic Isolation of Primary Microglia with Enhanced Purity and Versatility

Microglia are the primary responders to central nervous system insults; however, much remains unknown about their role in regulating neuroinflammation. Microglia are mesodermal cells that function similarly to macrophages in surveying inflammatory stress. The classical (M1-type) and alternative (M2-type) activations of macrophages have also been extended to microglia in an effort to better understand the underlying interplay these phenotypes have in neuroinflammatory conditions such as Parkinson&#39;s, Alzheimer&#39;s, and Huntington&#39;s Diseases. In vitro experimentation utilizing primary microglia offers rapid and reliable results that may be extended to the in vivo environment. Although this is a clear advantage over in vivo experimentation, isolating microglia while achieving adequate yields of optimal purity has been a challenge. Common methods currently in use either suffer from low recovery, low purity, or both. Herein, we demonstrate a refinement of the column-free CD11b magnetic separation method that achieves a high cell recovery and enhanced purity in half the amount of time. We propose this optimized method as a highly useful model of primary microglial isolation for the purposes of studying neuroinflammation and neurodegeneration.

Here, we present a protocol to isolate microglia from postnatal mouse pups (day 1) for in vitro experimentation. This improvised method of isolation generates both high yield and purity, a significant advantage over alternate methods that allows broad range experimentation for the purposes of elucidating microglial biology.

Microglia are the primary responders to central nervous system insults; however, much remains unknown about their role in regulating neuroinflammation. ...

Isolation of Region-specific Microglia from One Adult Mouse Brain Hemisphere for Deep Single-cell RNA Sequencing

As resident macrophages in the central nervous system, microglia actively control brain development and homeostasis, and their dysfunctions may drive human diseases. Considerable advances have been made to uncover the molecular signatures of homeostatic microglia as well as alterations of their gene expression in response to environmental stimuli. With the advent and maturation of single-cell genomic methodologies, it is increasingly recognized that heterogenous microglia may underlie the diverse roles they play in different developmental and pathological conditions. Further dissection of such heterogeneity can be achieved through efficient isolation of microglia from a given region of interest, followed by sensitive profiling of individual cells. Here, we provide a detailed protocol for the rapid isolation of microglia from different brain regions in a single adult mouse brain hemisphere. We also demonstrate how to use these sorted microglia for plate-based deep single-cell RNA sequencing. We discuss the adaptability of this method to other scenarios and provide guidelines for improving the system to accommodate large-scale studies.

We provide a protocol for isolation of microglia from different dissected regions of an adult mouse brain hemisphere, followed by semi-automated library preparation for deep single-cell RNA sequencing of full-length transcriptomes. This method will help to elucidate functional heterogeneity of microglia in health and disease.

As resident macrophages in the central nervous system, microglia actively control brain development and homeostasis, and their dysfunctions may drive ...

Magnetic Isolation of Microglial Cells from Neonate Mouse for Primary Cell Cultures

Microglia, as brain resident macrophages, are fundamental to several functions, including response to environmental stress and brain homeostasis. Microglia can adopt a large spectrum of activation phenotypes. Moreover, microglia that endorse pro-inflammatory phenotype is associated with both neurodevelopmental and neurodegenerative disorders. In vitro studies are widely used in research to evaluate potential therapeutic strategies in specific cell types. In this context studying microglial activation and neuroinflammation in vitro using primary microglial cultures is more relevant than microglial cell lines or stem-cell-derived microglia. However, the use of some primary cultures might suffer from a lack of reproducibility. This protocol proposes a reproducible and relevant method of magnetically isolating microglia from neonate pups. Microglial activation using several stimuli after 4 h and 24 h by mRNA expression quantification and a Cy3-bead phagocytic assay is demonstrated here. The current work is expected to provide an easily reproducible technique for isolating physiologically relevant microglia from juvenile developmental stages.

Primary microglia cultures are commonly used to evaluate new anti-inflammatory molecules. The present protocol describes a reproducible and relevant method to magnetically isolate microglia from neonate pups.

Microglia, as brain resident macrophages, are fundamental to several functions, including response to environmental stress and brain homeostasis. ...

In Vivo Chronic Two-Photon Imaging of Microglia in the Mouse Hippocampus

Microglia, the only immune cells resident in the brain, actively participate in neural circuit maintenance by modifying synapses and neuronal excitability. Recent studies have revealed the differential gene expression and functional heterogeneity of microglia in different brain regions. The unique functions of the hippocampal neural network in learning and memory may be associated with the active roles of microglia in synapse remodeling. However, inflammatory responses induced by surgical procedures have been problematic in the two-photon microscopic analysis of hippocampal microglia. Here, a method is presented that enables the chronic observation of microglia in all layers of the hippocampal CA1 through an imaging window. This method allows the analysis of morphological changes in microglial processes for more than 1 month. Long-term and high-resolution imaging of the resting microglia requires minimally invasive surgical procedures, appropriate objective lens selection, and optimized imaging techniques. The transient inflammatory response of hippocampal microglia may prevent imaging immediately after surgery, but the microglia restore their quiescent morphology within a few weeks. Furthermore, imaging neurons simultaneously with microglia allows us to analyze the interactions of multiple cell types in the hippocampus. This technique may provide essential information about microglial function in the hippocampus.

In Vivo Chronic Two-Photon Imaging of Microglia in the Mouse Hippocampus

This paper describes a method for chronic in vivo observation of the resting microglia in the mouse hippocampal CA1 using precisely controlled surgery and two-photon microscopy.

Microglia, the only immune cells resident in the brain, actively participate in neural circuit maintenance by modifying synapses and neuronal ...

Simultaneous Imaging of Microglial Dynamics and Neuronal Activity in Awake Mice

Since brain functions are under the continuous influence of the signals derived from peripheral tissues, it is critical to elucidate how glial cells in the brain sense various biological conditions in the periphery and transmit the signals to neurons. Microglia, immune cells in the brain, are involved in synaptic development and plasticity. Therefore, the contribution of microglia to neural circuit construction in response to the internal state of the body should be tested critically by intravital imaging of the relationship between microglial dynamics and neuronal activity.
Here, we describe a technique for the simultaneous imaging of microglial dynamics and neuronal activity in awake mice. Adeno-associated virus encoding R-CaMP, a gene-encoded calcium indicator of red fluorescence protein, was injected into layer 2/3 of the primary visual cortex in CX3CR1-EGFP transgenic mice expressing EGFP in microglia. After viral injection, a cranial window was installed onto the brain surface of the injected region. In vivo two-photon imaging in awake mice 4 weeks after the surgery demonstrated that neural activity and microglial dynamics could be recorded simultaneously at the sub-second temporal resolution. This technique can uncover the coordination between microglial dynamics and neuronal activity, with the former responding to peripheral immunological states and the latter encoding the internal brain states.

Here, we describe a protocol combining adeno-associated virus injection with cranial window implantation for simultaneous imaging of microglial dynamics and neuronal activity in awake mice.

Since brain functions are under the continuous influence of the signals derived from peripheral tissues, it is critical to elucidate how glial cells in ...

Isolation of Hypothalamic Microglia from Mice Using MACS for In Vitro Assays

Isolation of Hypothalamic Microglia from Freshly Perfused Adult Mouse Brain by Magnetic-Activated Cell Sorting

Microglia, as the resident macrophages of the brain, are essential for maintaining brain homeostasis. They shape neuronal circuits during development, survey their environment for debris or dead cells, as well as respond to infection and injury in the brain, among many other functions. However, their important role in neurodevelopment and synaptic plasticity and pathophysiology has not been fully defined, highlighting the need for further investigation. To gain a more comprehensive understanding of the role of microglia in these processes, we need to isolate microglia and characterize them genetically, metabolically, and functionally. However, the isolation of microglia from adult mice, especially from small brain structures, is challenging as they represent a small percentage of the total brain cells, and the yield of isolated microglia is often too low. Here, the magnetic isolation of microglia using CD11b+ microbeads allows us to sort microglial cells from the hypothalamus of a freshly perfused adult mouse brain. The current method allows us to achieve relatively high purity and yield in a short period while maintaining cell viability.

Author Spotlight: Investigating the Impact of Nutrition on Mouse Brain Function and Metabolic Disorders 

We describe a protocol for isolating microglial cells from the mouse hypothalamus (or equivalent small brain structures) using magnetically activated cell sorting (MACS), in a relatively short time. The MACS-sorted hypothalamic microglia can be used for ex vivo analysis and can be plated to perform in vitro assays.

Microglia, as the resident macrophages of the brain, are essential for maintaining brain homeostasis. They shape neuronal circuits during development, ...

Detection of MicroRNAs in Microglia by Real-time PCR in Normal CNS and During Neuroinflammation

Summary

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Chapters in this video

Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates

Cerebrospinal Fluid MicroRNA Profiling Using Quantitative Real Time PCR

In Vivo Dynamics of Retinal Microglial Activation During Neurodegeneration: Confocal Ophthalmoscopic Imaging and Cell Morphometry in Mouse Glaucoma

Microglia as a Surrogate Biosensor to Determine Nanoparticle Neurotoxicity

Rapid and Refined CD11b Magnetic Isolation of Primary Microglia with Enhanced Purity and Versatility

Isolation of Region-specific Microglia from One Adult Mouse Brain Hemisphere for Deep Single-cell RNA Sequencing

Magnetic Isolation of Microglial Cells from Neonate Mouse for Primary Cell Cultures

In Vivo Chronic Two-Photon Imaging of Microglia in the Mouse Hippocampus

Simultaneous Imaging of Microglial Dynamics and Neuronal Activity in Awake Mice

Isolation of Hypothalamic Microglia from Freshly Perfused Adult Mouse Brain by Magnetic-Activated Cell Sorting