Name: isolation of mouse primary microglia by magnetic-activated cell sorting in animal models of demyelination
Uploaded: 2022-04-05T14:00:00
Description: Watch this Scientific Journal Video about Isolation of Mouse Primary Microglia by Magnetic-Activated Cell Sorting in Animal Models of Demyelination at JoVE.com

The study was supported by Tongji Hospital (HUST) Foundation for Excellent Young Scientist (Grant No. 2020YQ06).

All the animal procedures have been approved by the Institute of Animal Care Committee of Tongji Medical College, Huazhong University of Science and Technology, China.
1. Materials
<ol>
	<li>Prepare the following solutions before beginning the protocol.
	<ol>
		<li>Prepare the loading buffer by adding fetal bovine serum (FBS, 2%) to phosphate buffered saline (PBS).</li>
		<li>Add neutral red (NR) dye (final 1%) to PBS.</li>
	</ol>
	</li>
	<li>Prepare the following solutions ...

<ol>
	<li>Ginhoux, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fate+mapping+analysis+reveals+that+adult+microglia+derive+from+primitive+macrophages.">Fate mapping analysis reveals that adult microglia derive from primitive macrophages.</a> Science. 330 (6005), 841-845 (2010).</li><li>Schulz, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+lineage+of+myeloid+cells+independent+of+Myb+and+hematopoietic+stem+cells.">A lineage of myeloid cells independent of Myb and hematopoietic stem cells.</a> Science. 336 (6077), 86-90 (2012).</li><li>Paolicelli, R. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synaptic+pruning+by+microglia+is+necessary+for+normal+brain+development.">Synaptic pruning by microglia is necessary for normal brain development.</a> Science. 333 (6048), 1456-1458 (2011).</li><li>Squarzoni, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+modulate+wiring+of+the+embryonic+forebrain.">Microglia modulate wiring of the embryonic forebrain.</a> Cell Reports. 8 (5), 1271-1279 (2014).</li><li>Ueno, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Layer+V+cortical+neurons+require+microglial+support+for+survival+during+postnatal+development.">Layer V cortical neurons require microglial support for survival during postnatal development.</a> Nature Neuroscience. 16 (5), 543-551 (2013).</li><li>Cunningham, C. L., Mart&#237;nez-Cerde&#241;o, V., Noctor, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+regulate+the+number+of+neural+precursor+cells+in+the+developing+cerebral+cortex.">Microglia regulate the number of neural precursor cells in the developing cerebral cortex.</a> The Journal of Neuroscience: The Official Journal of the Society for Neuroscience. 33 (10), 4216-4233 (2013).</li><li>Colonna, M., Butovsky, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+function+in+the+central+nervous+system+during+health+and+neurodegeneration.">Microglia function in the central nervous system during health and neurodegeneration.</a> Annual Review of Immunology. 35, 441-468 (2017).</li><li>Benmamar-Badel, A., Owens, T., Wlodarczyk, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protective+microglial+subset+in+development,+aging,+and+disease:+Lessons+from+transcriptomic+studies.">Protective microglial subset in development, aging, and disease: Lessons from transcriptomic studies.</a> Frontiers in Immunology. 11, 430 (2020).</li><li>Y&#305;ld&#305;zhan, K., Naz&#305;ro&#287;lu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+and+its+role+in+neurodegenerative+diseases.">Microglia and its role in neurodegenerative diseases.</a> Journal of Cellular Neuroscience and Oxidative Stress. 11 (2), 861-873 (2019).</li><li>Gutmann, D. H., Kettenmann, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia/brain+macrophages+as+central+drivers+of+brain+tumor+pathobiology.">Microglia/brain macrophages as central drivers of brain tumor pathobiology.</a> Neuron. 104 (3), 442-449 (2019).</li><li>Hammond, T. R., Robinton, D., Stevens, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+and+the+brain:+Complementary+partners+in+development+and+disease.">Microglia and the brain: Complementary partners in development and disease.</a> Annual Review of Cell and Developmental Biology. 34, 523-544 (2018).</li><li>Menassa, D. A., Gomez-Nicola, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglial+dynamics+during+human+brain+development.">Microglial dynamics during human brain development.</a> Frontiers in Immunology. 9, 1014 (2018).</li><li>Masuda, T., Sankowski, R., Staszewski, O., Prinz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+heterogeneity+in+the+single-cell+era.">Microglia heterogeneity in the single-cell era.</a> Cell Reports. 30 (5), 1271-1281 (2020).</li><li>Ni, M., Aschner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neonatal+rat+primary+microglia:+isolation,+culturing,+and+selected+applications.">Neonatal rat primary microglia: isolation, culturing, and selected applications.</a> Current Protocols in Toxicology. , (2010).</li><li>Yildizhan, K., Naziroglu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glutathione+depletion+and+parkinsonian+neurotoxin+MPP(+)-induced+TRPM2+channel+activation+play+central+roles+in+oxidative+cytotoxicity+and+inflammation+in+microglia.">Glutathione depletion and parkinsonian neurotoxin MPP(+)-induced TRPM2 channel activation play central roles in oxidative cytotoxicity and inflammation in microglia.</a> Molecular Neurobiology. 57 (8), 3508-3525 (2020).</li><li>Bohlen, C. J., Bennett, F. C., Bennett, 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=Isolation+and+culture+of+microglia.">Isolation and culture of microglia.</a> Current Protocols in Immunology. 125 (1), 70 (2019).</li><li>Bennett, M. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+tools+for+studying+microglia+in+the+mouse+and+human+CNS.">New tools for studying microglia in the mouse and human CNS.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (12), 1738-1746 (2016).</li><li>Gordon, R., et al. <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> Journal of Neuroscience Methods. 194 (2), 287-296 (2011).</li><li>Pan, J., Wan, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methodological+comparison+of+FACS+and+MACS+isolation+of+enriched+microglia+and+astrocytes+from+mouse+brain.">Methodological comparison of FACS and MACS isolation of enriched microglia and astrocytes from mouse brain.</a> Journal of Immunological Methods. 486, 112834 (2020).</li><li>Baydyuk, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracking+the+evolution+of+CNS+remyelinating+lesion+in+mice+with+neutral+red+dye.">Tracking the evolution of CNS remyelinating lesion in mice with neutral red dye.</a> Proceedings of the National Academy of Sciences of the United States of America. 116 (28), 14290-14299 (2019).</li><li>Sahel, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alteration+of+synaptic+connectivity+of+oligodendrocyte+precursor+cells+following+demyelination.">Alteration of synaptic connectivity of oligodendrocyte precursor cells following demyelination.</a> Frontiers in Cell Neuroscience. 9, 77 (2015).</li><li>Schroeter, C. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One+brain-all+cells:+A+comprehensive+protocol+to+isolate+all+principal+CNS-resident+cell+types+from+brain+and+spinal+cord+of+adult+healthy+and+EAE+mice.">One brain-all cells: A comprehensive protocol to isolate all principal CNS-resident cell types from brain and spinal cord of adult healthy and EAE mice.</a> Cells. 10 (3), 651 (2021).</li><li>Liu, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissociation+of+microdissected+mouse+brain+tissue+for+artifact+free+single-cell+RNA+sequencing.">Dissociation of microdissected mouse brain tissue for artifact free single-cell RNA sequencing.</a> STAR Protocols. 2 (2), 100590 (2021).</li><li>Marsh, S. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+cell+sequencing+reveals+glial+specific+responses+to+tissue+processing+&amp;+enzymatic+dissociation+in+mice+and+humans.">Single cell sequencing reveals glial specific responses to tissue processing &amp; enzymatic dissociation in mice and humans.</a> bioRxiv. , (2020).</li><li>Holt, L. M., Olsen, 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=Novel+applications+of+magnetic+cell+sorting+to+analyze+cell-type+specific+gene+and+protein+expression+in+the+central+nervous+system.">Novel applications of magnetic cell sorting to analyze cell-type specific gene and protein expression in the central nervous system.</a> PLoS One. 11 (2), 0150290 (2016).</li><li>He, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+sequencing+analysis+reveals+quiescent+microglia+isolation+methods+from+postnatal+mouse+brains+and+limitations+of+BV2+cells.">RNA sequencing analysis reveals quiescent microglia isolation methods from postnatal mouse brains and limitations of BV2 cells.</a> Journal of Neuroinflammation. 15 (1), 153 (2018).</li></ol>

The protocol proposes a method to isolate microglia around the demyelinating lesions, which can help study the functional characteristics of microglia in inflammatory demyelinating diseases. Microglia captured using CD11b beads exhibit high purity and viability. Critical steps in the protocol include the precise localization of foci and optimal microglial purification. In protocol step 2.1, it is necessary to inject the NR solution 2 h before sacrificing the mouse to ensure that the lesions can be accurately displayed<su...

Microglia originate from yolk-sac progenitors, which reach the embryonic brain very early and participate in the development of the CNS1,2. For instance, they are involved in synaptic pruning3 and regulating axonal growth4. They secrete factors that promote neuronal survival and help neuronal localization5. At the same time, they are involved in removing abnormal cells and apoptotic cells to ensure normal brain development6. In addition, as the immune-competent cells of the brain, microglia continually surveil the brain parenchyma to clear dead cells, dysfunctional synapses, and cellular debris7. It has been demonstrated that microglial activation plays an important role in a variety of diseases, including inflammatory demyelinating diseases, neurodegenerative diseases, and brain tumors. Activated microglia in multiple sclerosis (MS) contribute to the differentiation of oligodendrocyte precursor cells (OPCs) and regeneration of myelin by engulfing myelin debris8.
In Alzheimer&#39;s disease (AD), accumulation of amyloid beta (A&#946;) activates microglia, which affects the phagocytic and inflammatory functions of microglia9. Activated microglia in the glioma tissue, called glioma-associated microglia (GAM), can regulate the progression of glioma and ultimately affect the prognosis of patients10. The activation profoundly alters the microglial transcriptome, resulting in morphological changes, expression of immune receptors, increased phagocytic activity, and enhanced cytokine secretion11. There are different subsets of activated microglia in neurodegenerative diseases such as disease-associated microglia (DAM), activated response microglia (ARM), and microglial neurodegenerative phenotype (MGnD)8.
Similarly, multiple dynamic functional subsets of microglia also coexist in the brain in inflammatory demyelinating diseases12. Understanding the heterogeneity between different subsets of microglia is essential to investigate the pathogenesis of inflammatory demyelinating diseases and to find their potential therapeutic strategies. The heterogeneity of microglia mainly depends on the molecular specificity8. It is essential to describe the molecular alterations of microglia accurately for the study of the heterogeneity. Advances in single-cell RNA-sequencing (RNA-seq) technology have enabled the identification of the molecular characteristics of activated microglia in pathological conditions13. Therefore, the ability to isolate cell populations is critical for further investigation of these target cells under specific conditions.
Studies performed to understand the characteristics and functions of microglia are usually in vitro studies, since it has been found that large numbers of primary microglia can be prepared and cultured from mouse pup brains (1-3 days old), which attach to the culture flasks and grow on the plastic surface with other mixed glial cells. Subsequently, pure microglia can be isolated based on the different adhesiveness of mixed glial cells14,15. However, this method can only isolate microglia from the perinatal brain and takes several weeks. Potential variables in cell culture may influence microglial characteristics such as molecular expression16. Moreover, microglia isolated by these methods can only participate in in vitro experiments by simulating the conditions of CNS diseases and cannot represent the characteristics and functions of microglia in in vivo disease states. Therefore, it is necessary to develop methods for isolating microglia from the adult mouse brain.
Fluorescence-activated cell sorting (FACS) and magnetic separation are two widely used methods, although they have their own different limitations16,17,18,19. Their respective advantages and disadvantages will be contrasted in the discussion section. The maturation of MACS technology offers the possibility to rapidly purify cells. Huang et al. have developed a convenient method to label demyelinating lesions in brains20. Combining these two technical approaches, we propose a rapid and efficient columnar CD11b magnetic separation protocol, providing a step-by-step description to isolate microglia around demyelinating lesions in adult mouse brains and preserve the molecular characteristics of microglia. The focal demyelinating lesions were caused by the stereotactic injection of 2 &#181;L of lysolecithin solution (1% LPC in 0.9% NaCl) in the corpus callosum 3 days before starting the protocol21. This protocol lays the foundation to perform the next step in in vitro experiments. Moreover, this protocol saves time and remains feasible for widespread use in various experiments.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1.5 mL Micro Centrifuge Tubes</td>
			<td>BIOFIL</td>
			<td>CFT001015</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Centrifuge Tubes</td>
			<td>BIOFIL</td>
			<td>CFT011150</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Centrifuge Tubes</td>
			<td>BIOFIL</td>
			<td>CFT011500</td>
			<td></td>
		</tr>
		<tr>
			<td>70 &#181;m Filter</td>
			<td>Miltenyi Biotec</td>
			<td>130-095-823</td>
			<td></td>
		</tr>
		<tr>
			<td>Adult Brain Dissociation Kit, mouse and rat</td>
			<td>Miltenyi Biotec</td>
			<td>130-107-677</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6J Mice</td>
			<td>SJA Labs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CD11b (Microglia) Beads, human and mouse</td>
			<td>Miltenyi Biotec</td>
			<td>130-093-634</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>BOSTER</td>
			<td>PYG0001</td>
			<td></td>
		</tr>
		<tr>
			<td>FlowJo</td>
			<td>BD Biosciences</td>
			<td>V10</td>
			<td></td>
		</tr>
		<tr>
			<td>MACS MultiStand</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-303</td>
			<td></td>
		</tr>
		<tr>
			<td>MiniMACS Separator</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-102</td>
			<td></td>
		</tr>
		<tr>
			<td>MS columns</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-201</td>
			<td></td>
		</tr>
		<tr>
			<td>Neutral Red</td>
			<td>Sigma-Aldrich</td>
			<td>1013690025</td>
			<td></td>
		</tr>
		<tr>
			<td>NovoCyte Flow Cytometer</td>
			<td>Agilent</td>
			<td></td>
			<td>A system consisting of various parts</td>
		</tr>
		<tr>
			<td>NovoExpress</td>
			<td>Agilent</td>
			<td>1.4.1</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>BOSTER</td>
			<td>PYG0021</td>
			<td></td>
		</tr>
		<tr>
			<td>Pentobarbital</td>
			<td>Sigma-Aldrich</td>
			<td>P-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>MshOt</td>
			<td>MZ62</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of mouse primary microglia by magnetic-activated cell sorting in animal models of demyelination

Microglia, the resident innate immune cells in the brain, are the primary responders to inflammation or injury in the central nervous system (CNS). Microglia can be divided into resting state and activated state and can rapidly change state in response to the microenvironment of the brain. Microglia will be activated under different pathological conditions and exhibit different phenotypes. In addition, there are many different subgroups of activated microglia and great heterogeneity between different subgroups. The heterogeneity mainly depends on the molecular specificity of microglia. Studies have revealed that microglia will be activated and play an important role in the pathological process of inflammatory demyelination. To better understand the characteristics of microglia in inflammatory demyelinating diseases such as multiple sclerosis and neuromyelitis optica spectrum disorder, we propose a perilesional primary microglial sorting protocol. This protocol utilizes columnar magnetic-activated cell sorting (MACS) to obtain highly purified primary microglia and preserve the molecular characteristics of microglia to investigate the potential effects of microglia in inflammatory demyelinating diseases.

Microglia isolated using CD11b beads have high purity 
Microglial cells around the lesions in demyelination mouse models were isolated using the above-mentioned protocol and tested by flow cytometry. Cells are fluorescently labeled with CD11b-fluorescein isothiocyanate (FITC) and CD45-allophycocyanin (APC) to determine microglia in flow cytometry according to the manufacturer&#39;s instructions. There are multiple literatures demonstrating that CD11b and CD45 antibodies are enough to check for the p...

Watch this Scientific Journal Video about Isolation of Mouse Primary Microglia by Magnetic-Activated Cell Sorting in Animal Models of Demyelination at JoVE.com

Isolation of Mouse Primary Microglia by Magnetic-Activated Cell Sorting in Animal Models of Demyelination

Here, we present a protocol to isolate and purify primary microglia in animal models of demyelinating diseases, utilizing columnar magnetic-activated cell sorting.

Microglia, the resident innate immune cells in the brain, are the primary responders to inflammation or injury in the central nervous system (CNS). ...

This protocol helps to isolate microglia from the microdissected demyelination lesions of the adult mouse brain to study the microglial characteristics in vivo. This technique saves time and has lower requirements for both experimenters and equipments. This method helps to isolate microglia from the animal's brain, especially those microdissected tissues in various disease states.Begin by microdissecting the lesions labeled by neutral dye around the corpus callosum under a stereomicroscope. Centrifuge the dissected tissue at 300 times g for 30 seconds to collect the sample at the bottom of the tube. Preheat enzyme mix one and enzyme mix two to 37 degrees Celsius in an incubator.Then, add 1, 950 microliters of preheated enzyme mix one to one sample, and digest in an incubator at 37 degrees Celsius for five minutes. Add 30 microliters of preheated enzyme mix two, and mix gently. After digestion, add four milliliters of cold PBS to the tube, and shake gently.Centrifuge the tissue samples at 300 times g for 10 minutes at four degrees Celsius, and aspirate the supernatant slowly and completely. Resuspend the cell pellet gently with 1, 550 microliters of cold PBS. Add 450 microliters of the cold solution for debris removal, and mix them well.Use a 1, 000-microliter pipette to overlay the mixture very slowly, and gently with two milliliters of cold PBS. Centrifuge the mixture, and then look for the three layers. Use a 1, 000-microliter pipette to completely aspirate the two top layers, and fill the tube up to five milliliters with cold loading buffer.Gently invert the tube three times. Next, after centrifugation and aspiration of the supernatant, resuspend the cell pellet with 90 microliters of loading buffer, and add 10 microliters of CD11b beads. Mix well, and incubate for 15 minutes at four degrees Celsius.After the incubation, add one milliliter of the loading buffer, and wash the cells by gently pipetting the liquid up and down with a 1, 000-microliter pipette. Centrifuge the cells at 300 times g for 10 minutes at four degrees Celsius, and aspirate the supernatant completely to remove the unbound beads. Resuspend the cells in 500 microliters of the loading buffer, and place the MS column with its separator for positive selection in the magnetic field.Rinse the column with 500 microliters of the loading buffer to protect the cells and ensure the efficiency of magnetic sorting based on the manufacturer's protocol. Apply the cell suspension onto the MS column, and discard the flow-through containing the unlabeled cells. Add 500 microliters of the loading buffer to wash the column, and remove it from the separator.Place the column on a 15-milliliter centrifuge tube, and add one milliliter of the loading buffer into the column. Finally, push the plunger to the bottom of the column to flush out the magnetically labeled cells. A schematic representation of the gating strategy used in flow cytometry analysis of microglia isolated from demyelination lesions of adult mice before and after the magnetic-activated cell sorting is shown here.The graphical images represent the forward scatter height and side scatter height for selecting cells, forward scatter area and forward scatter height for selecting single cells, and CD11b-FITC and CD45-APC for selecting the myeloid cells and microglia. The proportion of microglia has increased significantly after the magnetic-activated cell sorting. The graphical image represents the gating strategy used in flow cytometry analysis for living and dead single cells after the magnetic-activated cell sorting.Here, 7-aminoactinomycin D and side scatter height have been used to select the living cells. While attempting this procedure, remember to precisely microdissect the demyelinating lesions under a stereomicroscope based on the neutral red markings.

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Research

JoVE Journal

Neuroscience

Mouse Models of Periventricular Leukomalacia

We describe a protocol for establishing mouse models of periventricular leukomalacia (PVL). PVL is the predominant form of brain injury in premature infants and the most common antecedent of cerebral palsy. PVL is characterized by periventricular white matter damage with prominent oligodendroglial injury. Hypoxia/ischemia with or without systemic infection/inflammation are the primary causes of PVL. We use P6 mice to create models of neonatal brain injury by the induction of hypoxia/ischemia with or without systemic infection/inflammation with unilateral carotid ligation followed by exposure to hypoxia with or without injection of the endotoxin lipopolysaccharide (LPS). Immunohistochemistry of myelin basic protein (MBP) or O1 and electron microscopic examination show prominent myelin loss in cerebral white matter with additional damage to the hippocampus and thalamus. Establishment of mouse models of PVL will greatly facilitate the study of disease pathogenesis using available transgenic mouse strains, conduction of drug trials in a relatively high throughput manner to identify candidate therapeutic agents, and testing of stem cell transplantation using immunodeficiency mouse strains.

We established mouse models of periventricular leukomalacia (PVL), the predominant brain injury in premature infants characterized by periventricular white matter lesions. Hypoxia/ischemia with/without systemic infection are the primary causes of PVL. Unilateral carotid ligation and hypoxia exposure with/without lipopolysaccharide injection creates PVL-like lesions in P6 mice.

We describe a protocol for establishing mouse models of periventricular leukomalacia (PVL). PVL is the predominant form of brain injury in premature ...

Olfactory Assays for Mouse Models of Neurodegenerative Disease

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process and may be a useful behavioral marker for early detection. Earlier detection in neurodegenerative disease is a major goal in the field because this is when neuroprotective therapies have the best potential to be effective. Therefore, in preclinical studies testing novel neuroprotective strategies in rodent models of neurodegenerative disease, olfactory assessment could be highly useful in determining therapeutic potential of compounds and translation to the clinic. In the present study we describe a battery of olfactory assays that are useful in measuring olfactory function in mice. The tests presented in this study were chosen because they measure olfaction abilities in mice related to food odors, social odors, and non-social odors. These tests have proven useful in characterizing novel genetic mouse models of Parkinson&#8217;s disease as well as in testing potential disease-modifying therapies.

Impairment in olfactory function is a common feature in many neurodegenerative disorders including Parkinson, Alzheimer, and Huntington diseases. In the present article, we describe a set of tests for assessing olfaction discrimination and detection in mice that can be used to measure olfactory abilities in mouse models of neurodegenerative diseases.

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process ...

Experimental Demyelination and Remyelination of Murine Spinal Cord by Focal Injection of Lysolecithin

Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system characterized by plaque formation containing lost oligodendrocytes, myelin, axons, and neurons. Remyelination is an endogenous repair mechanism whereby new myelin is produced subsequent to proliferation, recruitment, and differentiation of oligodendrocyte precursor cells into myelin-forming oligodendrocytes, and is necessary to protect axons from further damage. Currently, all therapeutics for the treatment of multiple sclerosis target the aberrant immune component of the disease, which reduce inflammatory relapses but do not prevent progression to irreversible neurological decline. It is therefore imperative that remyelination-promoting strategies be developed which may delay disease progression and perhaps reverse neurological symptoms. Several animal models of demyelination exist, including experimental autoimmune encephalomyelitis and curprizone; however, there are limitations in their use for studying remyelination. A more robust approach is the focal injection of toxins into the central nervous system, including the detergent lysolecithin into the spinal cord white matter of rodents. In this protocol, we demonstrate that the surgical procedure involved in injecting lysolecithin into the ventral white matter of mice is fast, cost-effective, and requires no additional materials than those commercially available. This procedure is important not only for studying the normal events involved in the remyelination process, but also as a pre-clinical tool for screening candidate remyelination-promoting therapeutics.

Demyelinating diseases can be modeled in animals by focal application of lysolecithin into the CNS. A single injection of lysolecithin into mouse spinal cord produces a lesion that spontaneously repairs over time. The goal is to study factors involved in de- and remyelination, and to test agents for enhancing repair.

Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system characterized by plaque formation containing lost ...

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. ...

Characterization and Isolation of Mouse Primary Microglia by Density Gradient Centrifugation

Microglia, the resident immune cells in the brain, are the first responders to inflammation or injury in the central nervous system. Recent research has revealed microglia to be dynamic, capable of assuming both pro-inflammatory and anti-inflammatory phenotypes. Both M1 (pro-inflammatory) and M2 (pro-reparative) phenotypes play an important role in neuroinflammatory conditions such as perinatal brain injury, and exhibit differing functions in response to certain environmental stimuli. The modulation of microglial activation has been noted to confer neuroprotection thus suggesting microglia may have therapeutic potential in brain injury. However, more research is required to better understand the role of microglia in disease, and this protocol facilitates that. The protocol described below combines a density gradient centrifugation process to reduce cellular debris, with magnetic separation, producing a highly pure sample of primary microglial cells that can be used for in vitro experimentation, without the need for 2-3 weeks culturing. Additionally, the characterization steps yield robust functional data about microglia, aiding studies to better our understanding of the polarization and priming of these cells, which has strong implications in the field of regenerative medicine.

A protocol for the isolation of primary microglia from murine brains is presented. This technique aids in furthering the current understanding of neurological conditions. Density gradient centrifugation and magnetic separation are combined to produce sufficient yield of a highly pure sample. Furthermore, we outline the steps for characterization of microglia.

Microglia, the resident immune cells in the brain, are the first responders to inflammation or injury in the central nervous system. Recent research has ...

Rapid and Specific Immunomagnetic Isolation of Mouse Primary Oligodendrocytes

The efficient and robust isolation and culture of primary oligodendrocytes (OLs) is a valuable tool for the in vitro study of the development of oligodendroglia as well as the biology of demyelinating diseases such as multiple sclerosis and Pelizaeus-Merzbacher-like disease (PMLD). Here, we present a simple and efficient selection method for the immunomagnetic isolation of stage three O4+ preoligodendrocytes cells from neonatal mice pups. Since immature OL constitute more than 80% of the rodent-brain white matter at postnatal day 7 (P7) this isolation method not only ensures high cellular yield, but also the specific isolation of OLs already committed to the oligodendroglial lineage, decreasing the possibility of isolating contaminating cells such as astrocytes and other cells from the mouse brain. This method is a modification of the techniques reported previously, and provides oligodendrocyte preparation purity above 80% in about 4 h.

We describe the immunomagnetic isolation of primary mouse oligodendrocytes, which allows the rapid and specific isolation of the cells for in vitro culture.

The efficient and robust isolation and culture of primary oligodendrocytes (OLs) is a valuable tool for the in vitro study of the development of ...

Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing neuronal dysfunction which eventually leads to cognitive decline. Hyperphosphorylated tau aggregates in the neuron are believed to cause most of the pathology associated with AD. These aggregates are assumed to be released into the extracellular compartment and taken up by adjacent healthy neurons where they induce further tau aggregation. This &#34;prion-like&#34; spreading can be interrupted by antibodies capable of binding and &#34;neutralizing&#34; extracellular tau aggregates as shown in preclinical mouse models of AD. One of the proposed mechanisms by which therapeutic antibodies reduce pathology is antibody-mediated uptake and clearance of pathological aggregated forms of tau by microglia. Here, we describe a quantitative cell-based assay to assess tau uptake by microglia. This assay uses the mouse microglial cell line BV-2, allows for high specificity, low variability and medium throughput. Data generated with this assay can contribute to a better characterization of anti-tau antibody effector functions.

Here we describe a cell-based assay to quantitatively assess tau uptake by microglia with the aim of creating an investigational tool to better characterize the mechanisms of action of anti-tau antibodies.

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing ...

Primary Cell Culture of Purified GABAergic or Glutamatergic Neurons Established through Fluorescence-activated Cell Sorting

The overall goal of this protocol is to generate purified neuronal cultures derived from either GABAergic or glutamatergic neurons. Purified neurons can be cultured in defined media for 16 days in vitro and are amenable to any analyses typically performed on dissociated cultures, including electrophysiological, morphological and survival analyses. The major advantage of these cultures is that specific cell types can be selectively studied in the absence of complex external influences, such as those arising from glial cells or other neuron types. When planning experiments with purified cells, however, it is important to note that neurons strongly depend on glia-conditioned media for their growth and survival. In addition, glutamatergic neurons further depend on glia-secreted factors for the establishment of synaptic transmission. We therefore also describe a method for co-culturing neurons and glial cells in a non-contact arrangement. Using these methods, we have identified major differences between the development of GABAergic and glutamatergic neuronal networks. Thus, studying cultures of purified neurons has great potential for furthering our understanding of how the nervous system develops and functions. Moreover, purified cultures may be useful for investigating the direct action of pharmacological agents, growth factors or for exploring the consequences of genetic manipulations on specific cell types. As more and more transgenic animals become available, labeling additional specific cell types of interest, we expect that the protocols described here will grow in their applicability and potential.

This protocol describes a cell sorting based method for the purification and culture of fluorescent GABAergic or glutamatergic neurons from the neocortex and hippocampus of postnatal mice or rats.

The overall goal of this protocol is to generate purified neuronal cultures derived from either GABAergic or glutamatergic neurons. Purified neurons can ...

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 ...

A Behavioral Screen for Heat-Induced Seizures in Mouse Models of Epilepsy

Transgenic mouse models have proved to be powerful tools in studying various aspects of human neurological disorders, including epilepsy. The SCN1A-associated genetic epilepsies comprise a wide spectrum of seizure disorders with incomplete penetrance and clinical variability. SCN1A mutations can result in a large variety of seizure phenotype ranging from simple, self-limited fever-associated febrile seizures (FS), moderate-level genetic epilepsy with febrile seizures plus (GEFS+) to more severe Dravet Syndrome (DS). Although FS are commonly seen in children below 6-7 years of age who do not have genetic epilepsy, FS in GEFS+ patients continue to occur into adulthood. Traditionally, experimental FS have been induced in mice by exposing the animal to a stream of dry air or heating lamps, and the rate of change in body temperature is often not well controlled. Here, we describe a custom-built heating chamber, with a plexiglass front, that is fitted with a digital temperature controller and a heater-equipped electric fan, which can send heated forced air into the test arena in a temperature-controlled manner. The body temperature of a mouse placed in the chamber, monitored through a rectal probe, can be increased to 40-42 &#176;C in a reproducible manner by increasing the temperature inside the chamber. Continual visual monitoring of the animals during the heating period demonstrates induction of heat-induced seizures in mice carrying an FS mutation at a body temperature that does not elicit behavioral seizures in wild-type litter mates. Animals can be easily removed from the chamber and placed on a cooling pad to rapidly return body temperature to normal. This method provides for a simple, rapid, and reproducible screening protocol for the occurrence of heat-induced seizures in epilepsy mouse models.

The goal of the method is to screen for hyperthermia or heat-induced seizures in mouse models. The protocol describes the use of a custom-built chamber with continuous monitoring of the body temperature to determine whether elevated body temperature leads to seizures.