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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

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.

Abstract

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.

Introduction

Microglia are the central nervous system resident macrophage-like cells derived from erythropoietic precursors of the yolk sac that migrate to the neuroepithelium during early embryonic development1. Apart from their immunity functions, they also play a significant role during neurodevelopment, particularly for synaptogenesis, neuronal homeostasis, and myelination2. In adulthood, microglia develop long cellular processes to scan the environment continuously. In case of homeostasis ruptures such as brain injury or brain disease, microglia can change their morphological appearance to adopt an amoeboid shape, migrate to the....

Protocol

The protocol was approved, and all the animals were handled according to the institutional guidelines of Institut National de la Santé et de la Recherche Scientifique (Inserm, France). Magnetic isolation of microglia from the brains of 24 OF1 mouse pups (both male and female) at P8, divided into 6-well, 12-well, or 96-well plates, are presented. The experimental work was performed under a hood to maintain sterile conditions.

1. Preparation of sterile solutions for isolation and cel.......

Representative Results

Microglia is the CNS resident macrophage that gets activated when exposed to environmental challenges (trauma, toxic molecules, inflammation )4,5,6,34 (Figure 3A). In vitro studies on microglia are commonly used to evaluate cell-autonomous mechanisms related to those environmental challenges and characterize activation state after pharmacological or g.......

Discussion

The current work presents a primary microglial cell culture using magnetically sorted CD11b+ cells. In addition to the microglial functional evaluation (RT-qPCR and phagocytic assays), microglial culture purity was also determined.

Classical microglia cell cultures are commonly generated from P1 or P2 rodent neonate brain and co-culture with astrocytes for at least 10 days. Microglia are then separated mechanically using an orbital shaker. The method to isolate and culture microglia in vit.......

Acknowledgements

Figures were created using BioRender. Research is funded by Inserm, Université de Paris, Horizon 2020 (PREMSTEM-874721), Fondation de France, Fondation ARSEP, Fondation pour la Recherche sur le Cerveau, Fondation Grace de Monaco, and an additional grant from Investissement d'Avenir -ANR-11-INBS-0011-NeurATRIS and Investissement d'Avenir -ANR-17-EURE-001-EUR G.E.N.E.

....

Materials

NameCompanyCatalog NumberComments
Anti mouse ACSA-2 PE Vio 615Miltenyi Biotec130-116-246
Anti mouse CD11b BV421Sony Biotechnology1106255
Anti mouse CD45 BV510Sony Biotechnology1115690
Anti mouse CX3CR1 PE Cy7Sony Biotechnology1345075
Anti mouse NeuN PEMilli-MarkFCMAB317PE
anti mouse O4 Vio Bright B515Miltenyi Biotec130-120-016
BD Cytofix/Cytoperm permeabilization kitBD Biosciences554655
Bovine Serum AlbuminMiltenyi Biotec130-091-376
CD11b (Microglia) MicroBeads, h, mMiltenyi Biotec130-093-634
Confocal microscopeLeica TCS SP8
D-PBS (10x)Thermo Scientific14200067
EDTASigma-AldrichE1644
Falcon Cell culture 12-well plate, flat bottom + lidDutscher353043
Falcon Cell culture 96-well plate, flat bottom + lidDutscher353072
Falcon tubes 50 mLDutscher352098
Fc blocking reagent (Mouse CD16/32)BD Biosciences553142
Fluorescence microscopeNikon ECLIPSE TE300
gentleMACS C Tubes (4 x 25 tubes)Miltenyi Biotec130-096-334
gentleMACS Octo Dissociator with HeatersMiltenyi Biotec130-096-427
Hanks' Balanced Salt Solution (HBSS) +CaCl2 +MgCl2 10xThermo Scientific14065049
Hanks' Balanced Salt Solution (HBSS) -CaCl2 -MgCl2 10xThermo Scientific14185045
iQ SYBR Green SupermixBio-rad1725006CUST
Iscript c-DNA synthesisBio-rad1708890
Latex beads, amine-modified polystyrene, fluorescent redSigma-AldrichL2776-1mL
Lipopolysaccharides (LPS) from Escherichia coli O55:B5Sigma-AldrichL2880
Macrophage-SFM serum-free mediumThermo Scientific12065074
MACS BSA Stock SolutionMiltenyi Biotec130-091-376
MACS SmartStrainers (70 μm), 4 x 25 pcsMiltenyi Biotec130-110-916
Mouse IgG1 PEMilliporeMABC002H
Mouse IgG2a PE Cy7Sony Biotechnology2601265
Mouse IL1 betaMiltenyi Biotec130-101-684
Multi-24 Column BlocksMiltenyi Biotec130-095-691
MultiMACS Cell24 SeparatorMiltenyi Biotec
Neural Tissue Dissociation Kit - PapainMiltenyi Biotec130-092-628
Nucleocounter NC-200Chemometec
Nucleospin RNA Plus XSMacherey Nagel740990.5
Nun EZFlip Top Conical Centrifuge TubesThermo Scientific362694
OPTILUX Petri dish - 100 x 20 mmDutscher353003
Pénicilline-streptomycine (10 000 U/mL)Thermo Scientific15140122
Rat IgG2b, k BV421BD Biosciences562603
Rat IgG2b, k BV510Sony Biotechnology2603230
REA control (S) PE vio 615Miltenyi Biotec130-104-616
REA control (S) Vio Bright B515Miltenyi Biotec130-113-445
Recombinant Mouse IFN-gamma ProteinR&D System485-MI
Recombinant Mouse IL-10 ProteinR&D System417-ML
Recombinant Mouse IL-4 ProteinR&D System404-ML
RIPA BufferSigma-AldrichR0278
Viability probe (FVS780)BD Biosciences565388

References

  1. Kierdorf, K., et al. Microglia emerge from erythromyeloid precursors via Pu.1- and Irf8-dependent pathways. Nature Neuroscience. 16 (3), 273-280 (2013).
  2. Wright-Jin, E. C., Gutmann, D. H. Microglia as dynamic c....

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