This work was supported by grants from Agence Nationale pour la Recherche (ANR-12-MALZ-0003-02-P2X7RAD), Association France Alzheimer and Bpifrance. Our laboratory is also supported by Inserm, CNRS, Universit&#233; Pierre et Marie-Curie and the program &#34;Investissements d&#39;avenir&#34; ANR-10-IAIHU-06 (IHU-A-ICM).&#160;We would like to thank the assistance of the CELIS cell culture core facility.

All methods described here have been approved by the Institutional Animal Care and Use Committee at the ICM Institute and by the Darwin French Ethic Animal Committee, and are covered under the protocol 01407.02.
1. Preparation
<ol>
	<li>Prepare the digestion cocktail in a 1.5 mL tube by combining the following for each mouse: 1 mL Phosphate Buffered Saline (PBS); 123 &#181;L digestion enzyme (see table of materials) at 13 wunsch/mL (stock solution), final concentration 1.6 wunsch/mL; and 5 &#181;L DNase I (see table of materials) at 100 mg/mL (stock solution), final concentration 0.5 mg/mL.</li>
</ol>
2. Perfusion and Dissection
<ol>
	<li>Euthanize the mice with a lethal dose of pentobarbital (100 &#181;L at 400 mg/mL).</li>
	<li>Place the animal in supine position and wet the body with 70% ethanol.</li>
	<li>Cut the ventral skin with fine scissors just below the xyphoid process to expose the thoracic cavity.</li>
	<li>Make an incision in the diaphragm and cut the lateral aspects of the rib cage with fine scissorsin a caudal to rostral direction to expose the heart (and avoid cutting other organs). Identify the left ventricle (LV) and the right atrium (RA).</li>
	<li>Insert a butterfly catheter with a 25 G needle inside the LV. Make an incision on the RA with fine scissors and at the beginning of blood flow, start perfusion at 10 mL/min flow rate through the LV with 20 mL PBS to remove cells and blood from vessels; successful perfusion is noted by the blanching of the lungs and the liver as blood is displaced.</li>
	<li>Decapitate the animal with medium scissors. Dissect the spinal column with fine scissors and separate it from the body by excising the abdominal wall musculature on the ventral side of the spinal column and by cutting the vertebral column at the base of the tail.</li>
	<li>Insert a 10 mL syringe containing PBS and a mounted 200 &#181;L pipette tip into the lumbar side of the spinal column and flush the spinal cord on the cervical side. 
	NOTE: The 200 &#181;L pipette tip is cut with scissors at its widest end (approximately 1 cm) and tightly inserted on a 10 mL syringe previously filled with PBS.</li>
	<li>Remove the skin above the skull and use forceps to expose the brain. Insert a scissor blade at the base of the skull and cut the cranium following the sagittal suture. Insert small forceps into the cut and gently lift the skull. Dissect the brain from the mouse head and remove the olfactory bulb and cerebellum.</li>
	<li>Collect the brain and spinal cord in a 1.5 mL tube containing 1.128 mL PBS with digestion cocktail (from step 1.1).</li>
</ol>
3. Cell Dissociation
<ol>
	<li>Finely cut the brain and spinal cord in the 1.5 mL tube (step 2.9) into 1-2 mm3 pieces with small scissors (Figure 1).</li>
	<li>Incubate the 1.5 mL tube containing the minced tissues for 30 min in an incubator at 37 &#176;C with 5% CO2. 
	NOTE: Prepare the density gradient at this step.</li>
	<li>Add 20 &#181;L 0.5 M EDTA (stock solution), final concentration 10 mM, to the 1.5 mL tube to stop the enzymatic reaction.</li>
	<li>Gently make a cell suspension by pipetting up and down with a 5 mL pipette.</li>
	<li>Pass the cell suspension through a nylon mesh (70 &#181;m pore size) in a 50 mL tube using the plunger of a 10 mL syringe.</li>
	<li>Wash the nylon mesh with 20 mL 5% Fetal Bovine Serum (FBS)-PBS.</li>
	<li>Centrifuge for 7 min (300 x g) at room temperature (18 &#176;C). Discard the supernatant by aspiration and proceed to the next step. Be extremely careful when removing the supernatant; do not disturb the pellet, which can easily be aspirated by the aspirating pipette.</li>
</ol>
4. Density Gradient
<ol>
	<li>Prepare a stock solution of the density gradient medium by adding the appropriate amount of 10x PBS to the density gradient medium. 
	NOTE: Add one part 10X PBS to nine parts density gradient medium.</li>
	<li>Dilute the stock density gradient medium with 1x PBS for the different percentages as described in Table 1.</li>
	<li>Resuspend the pellet (from step 3.7) with 4 mL 30% density gradient medium and transfer to a 15 mL tube.</li>
	<li>Place a Pasteur pipette in the bottom of the 15 mL tube and slowly underlay 4 mL of 37% density gradient medium.</li>
	<li>Add 4 mL of 70% density gradient medium, as described above.</li>
	<li>Centrifuge the gradient for 40 min (800 x g) at room temperature (18 &#176;C). Ensure that the centrifuge stops with minimal or no brake so that the interphase is not disturbed. 
	NOTE: The tube will appear stratified. The cells layered at the 70% - 37% density gradient interface are the mononucleated immune cells (microglia and macrophage subpopulations); the upper levels are cell debris and myelin, respectively (Figure 2).</li>
	<li>Using a transfer pipette, gently remove the layer of myelin.</li>
	<li>Collect 3-4 mL of the 70-37% density gradient interphase containing the macrophage subpopulations cells into a clean 15 mL tube.</li>
	<li>Wash the cells 3x with PBS, total volume of 15 mL. Make sure that the density gradient medium containing the cells is diluted at least three times with PBS, and to centrifuge for 7 min (500 x g, 4 &#176;C) with the brake &#34;on&#34;.</li>
	<li>Resuspend the cell pellet with 1 mL PBS for cell labeling or for other functional assays.</li>
</ol>
5. Cell Labeling for Flow Cytometry
<ol>
	<li>Transfer the cells (step 4.10) into a flow cytometry tube.</li>
	<li>Add 1 &#181;L of fixable dead cell stain reagent to each cell sample obtained in step 4.10. Incubate for 30 min on ice, protected from light.</li>
	<li>Wash the cells once with 2 mL PBS and centrifuge for 5 min (300 x g, 4 &#176;C).</li>
	<li>Remove the supernatant, and resuspend the cell pellet with 400 &#181;L PBS 1% BSA, 0.1% azide.</li>
	<li>Add 1 &#181;g CD16/CD32 antibodies to 100 &#181;L of the cells to block the Fc receptors. Incubate 10-15 min on ice, protected from light.</li>
	<li>Prepare the primary antibody mix in PBS 1% BSA, 0.1% azide or PBS 1% BSA, 0.1% azide, 0.25% saponin, for cell permeabilization for intracellular staining.</li>
	<li>Add 100 &#181;L of primary antibodies mix (2x) and incubate for 30 min on ice, protected from light. 
	NOTE: All antibodies should be titrated prior to conducting the experiment to ensure optimal results.</li>
	<li>Wash the cells with 2 mL PBS and centrifuge for 5 min (300 x g, 4 &#176;C). Repeat this step three times.</li>
	<li>Add 100 &#181;L of a secondary antibody if the primary antibodies are not directly conjugated to a fluorophore, and incubate for 30 min on ice, protected from light.</li>
	<li>Wash the cells with 2 mL PBS and centrifuge for 5 min at 300 x g at 4 &#176;C). Repeat this step three times.</li>
	<li>Fix the cells with 100 &#181;L 1% PFA for 15 min at room temperature, protected from light. 
	NOTE: Caution: PFA is toxic. Use in a fume hood and wear personal protective equipment.</li>
	<li>Wash the cells with 2 mL PBS and centrifuge for 5 min at 300 x g at 4 &#176;C. Repeat this step three times.</li>
	<li>Resuspend the cell pellet with 200 &#181;L PBS and proceed to flow cytometry acquisition and analysis. Follow the gating strategy in Figure 3.</li>
</ol>

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The authors have nothing to disclose

It has been demonstrated that the microglia and MDM have different functions and phenotypes in the CNS, and thus the identification and the analysis of these macrophage subpopulations are essential in order to better understand neurological diseases9,18,25. Flow cytometry analysis using two markers (CD11b and CD45) allows for the distinction between each subpopulation (Figure 3C). This strategy was ...

The microglia are the parenchymal tissue-resident macrophages of the central nervous system (CNS). They play two key functional roles: immune defense and maintenance of the CNS homeostasis. In contrast to the MDM, which are renewed continually from the hematopoietic stem cells in the bone marrow, the microglial cells differentiate from primitive hematopoietic progenitor cells originating in the yolk sac (YS) that colonized the brain during embryonic development1,2,3. In rodents, the transcription factor Myb plays a crucial role in the development of all bone marrow derived monocytes and macrophages, but for YS derived microglia, this factor is dispensable and differentiation remains dependent on the transcription factor PU.14.
In the healthy CNS, microglia are dynamic cells that constantly sample their environment, scanning and surveying for invading pathogens or tissue damage5. The detection of such signals initiates a pathway to resolve the injury. The microglia rapidly switch from a ramified morphology to an amoeboid one, which is followed by phagocytosis and release of various mediators, such as pro- or anti-inflammatory cytokines. Thus, depending on their microenvironment, activated microglia can acquire a spectrum of distinct priming states6.
The microglia profoundly impact the development and progression of many neurological disorders. In the rodent models of Alzheimer&#39;s disease (AD)7, Amyotrophic Lateral Sclerosis (ALS)8, Multiple Sclerosis (MS)9 or Parkinson disease (PD)10, the microglia are shown to play a dual role, either inducing detrimental neurotoxicity or acting in a neuroprotective manner, which is dependent on the specific disease, the disease stage, and whether the disease was influenced by the systemic immune compartment7,8,9,10,11. Most of the CNS lesions observed in the diseases cited above contain a heterogeneous population of myeloid cells, including not only parenchymal microglia, but also perivascular and meningeal macrophages, as well as CNS-infiltrating MDM. These cell types may differentially contribute to the pathophysiologic mechanisms related to injury and repair7,12,13,14,15. The current challenge for investigators who are studying these disease models is to establish whether the peripheral monocytes and macrophages infiltrate the CNS and if so, to distinguish the resident microglia from these cells. Indeed, the microglial cells are very plastic; when they are activated, the microglia re-express markers that are usually expressed by peripheral monocytes and macrophages. The issue, therefore, relies on identifying markers that can distinguish the resident microglia from the infiltrating monocytes and macrophages.
The discrimination of these populations on brain slices by immunohistological applications is limited due to the lack of specific antibodies. However, flow cytometry analysis is an efficient technique to assess the expression of several markers and to distinguish cell populations (for example, lymphocytes, macrophages/MDM CD11b+CD45high, and microglia CD11b+CD45med), as well as cell subpopulations16,17,18. This protocol describes the procedures for isolating the mononuclear cells from the mouse CNS in neurologic disease models by using an optimized, enzymatic tissue dissociation and a density gradient centrifugation; as well as, a method for differentiating the microglia and MDM populations in the CNS by using flow cytometry.
Another approach is to eliminate the myelin and purify the cells by using magnetic beads conjugated to specific antibodies19,20,21. Myelin removal using anti-myelin magnetic beads is more expensive and affects the viability and the yield of isolated cells22. This step and the following immunomagnetic separation of the microglia, limit further studies of specific immune cell populations21,22.
These procedures provide an easy way to study the macrophage subpopulations in disease development, and to determine the drug effects or gene modifications on macrophage phenotypes and activation states.

<table border="0" cellpadding="0" cellspacing="0" width="908">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">5-month-old Mice</td>
			<td style="width:223px;">Janvier</td>
			<td style="width:119px;">C57BL/6J</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Liberase TL Research Grade</td>
			<td style="width:223px;">Sigma-Aldrich</td>
			<td style="width:119px;">5401020001</td>
			<td>Digestion enzyme</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Deoxyribonuclease I from bovine pancreas</td>
			<td style="width:223px;">Sigma-Aldrich</td>
			<td style="width:119px;">DN25</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Percoll</td>
			<td style="width:223px;">GE Healthcare Life Sciences</td>
			<td style="width:119px;">17-0891-01&#160;</td>
			<td>Density gradient medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Cell Strainer size 70 &#181;m Nylon</td>
			<td style="width:223px;">Corning</td>
			<td style="width:119px;">731751</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Venofix 25G</td>
			<td style="width:223px;">BRAUN</td>
			<td style="width:119px;">4056370</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Piston syringe 10 mL</td>
			<td style="width:223px;">Terumo</td>
			<td style="width:119px;">SS+10ES1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Pasteur pipette 230 mm</td>
			<td style="width:223px;">Dustcher</td>
			<td style="width:119px;">20420</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">1,5 mL&#160; tube</td>
			<td style="width:223px;">Eppendorf</td>
			<td style="width:119px;">0030 123.328</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">15 mL&#160; tube</td>
			<td style="width:223px;">TPP</td>
			<td style="width:119px;">91015</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">50 mL&#160; tube</td>
			<td style="width:223px;">TPP</td>
			<td style="width:119px;">91050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">5 mL polystyrene round bottom tube</td>
			<td style="width:223px;">BD Falcon</td>
			<td style="width:119px;">352054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">D-PBS (1X) without Ca2+/Mg2+</td>
			<td style="width:223px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">14190-094</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">D-PBS (10X) without Ca2+/Mg2+</td>
			<td style="width:223px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">14200-067</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Fetal bovine serum</td>
			<td style="width:223px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">10270-106</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">EDTA</td>
			<td style="width:223px;">Sigma-Aldrich</td>
			<td style="width:119px;">E4884</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Bovine Serum Albumin solution 30%</td>
			<td style="width:223px;">Sigma-Aldrich</td>
			<td style="width:119px;">A7284</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Paraformaldehyde 32% Solution</td>
			<td style="width:223px;">Electron Microscopy Sciences</td>
			<td style="width:119px;">15714-S</td>
			<td>Caution -Toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Saponin</td>
			<td style="width:223px;">Sigma-Aldrich</td>
			<td style="width:119px;">S2002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Sodium Azide</td>
			<td style="width:223px;">Sigma-Aldrich</td>
			<td style="width:119px;">47036</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">PerCPCy5.5 Rat anti-mouse CD11b (clone M1/70)</td>
			<td style="width:223px;">eBioscience</td>
			<td style="width:119px;">45-0112</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Rat IgG2b K Isotype Control PerCP-Cyanine5.5</td>
			<td style="width:223px;">eBioscience</td>
			<td style="width:119px;">45-4031&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">BV421 Rat anti-mouse CD45 (clone 30-F11)</td>
			<td style="width:223px;">BD Biosciences</td>
			<td style="width:119px;">563890</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">BV421 Rat IgG2b, &#954; Isotype Control RUO</td>
			<td style="width:223px;">BD Biosciences</td>
			<td style="width:119px;">562603</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Rabbit anti-mouse TMEM119 (clone28-3)</td>
			<td style="width:223px;">Abcam</td>
			<td style="width:119px;">ab209064</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">AlexaFluor 647 Donkey anti-rabbit IgG</td>
			<td>Life Technologies</td>
			<td>A31573</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Anti-Mouse CD16/CD32 Purified</td>
			<td style="width:223px;">eBioscience</td>
			<td style="width:119px;">14-0161</td>
			<td>Mouse Fc Block</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Fixable Dead Cell Stain Kits</td>
			<td style="width:223px;">Invitrogen</td>
			<td style="width:119px;">L34969</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Mouse CCR2 APC-conjugated Antibody</td>
			<td style="width:223px;">R&#38;D</td>
			<td style="width:119px;">FAB5538A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Rat IgG2B APC-conjugated Isotype Control</td>
			<td style="width:223px;">R&#38;D</td>
			<td style="width:119px;">IC013A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Mouse CX3CR1 PE-conjugated Antibody</td>
			<td style="width:223px;">R&#38;D</td>
			<td style="width:119px;">FAB5825P</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Goat IgG PE-conjugated Antibody</td>
			<td style="width:223px;">R&#38;D</td>
			<td style="width:119px;">IC108P</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Centrifuge</td>
			<td style="width:223px;">Eppendorf</td>
			<td style="width:119px;">5804R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Cell analyzer</td>
			<td style="width:223px;">BD Biosciences</td>
			<td style="width:119px;">BD FACSVERSE</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Data Analysis Software</td>
			<td style="width:223px;">FlowJo LLC</td>
			<td style="width:119px;">FlowJo</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Fine scissors</td>
			<td style="width:223px;">F.S.T</td>
			<td style="width:119px;">14090-11</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Standard Pattern Forceps</td>
			<td style="width:223px;">F.S.T</td>
			<td style="width:119px;">11000-13</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Mayo Scissors</td>
			<td style="width:223px;">F.S.T</td>
			<td style="width:119px;">14010-15</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:399px;">Dumont #5 Forceps</td>
			<td style="width:223px;">F.S.T</td>
			<td style="width:119px;">11251-20</td>
			<td></td>
		</tr>
	</tbody>
</table>

analysis of microglia and monocyte-derived macrophages from the central nervous system by flow cytometry

Numerous studies have demonstrated the role of immune cells, in particular macrophages, in central nervous system (CNS) pathologies. There are two main macrophage populations in the CNS: (i) the microglia, which are the resident macrophages of the CNS and are derived from yolk sac progenitors during embryogenesis, and (ii) the monocyte-derived macrophages (MDM), which can infiltrate the CNS during disease and are derived from bone marrow progenitors. The roles of each macrophage subpopulation differ depending on the pathology being studied. Furthermore, there is no consensus on the histological markers or the distinguishing criteria used for these macrophage subpopulations. However, the analysis of the expression profiles of the CD11b and CD45 markers by flow cytometry allows us to distinguish the microglia (CD11b+CD45med) from the MDM (CD11b+CD45high). In this protocol, we show that the density gradient centrifugation and the flow cytometry analysis can be used to characterize these CNS macrophage subpopulations, and to study several markers of interest expressed by these cells as we recently published. Thus, this technique can further our understanding of the role of macrophages in mouse models of neurological diseases and can also be used to evaluate drug effects on these cells.

After the density gradient centrifugation and antibody staining, the cells were acquired on a flow cytometer and analyzed using a morphological gating strategy as follows. A first gate was defined in the dot plot Forward-Scattered-Area (FSC-A) versus Forward-Scattered-Height (FSC-H) to discriminate single cells from doublets (Figure 3A). The single cells were then gated on FSC-A versusSide-Scattered-Area (SSC-A) dot plots to exclude cell deb...

Watch this Scientific Journal Video about Analysis of Microglia and Monocyte-derived Macrophages from the Central Nervous System by Flow Cytometry at JoVE.com

Analysis of Microglia and Monocyte-derived Macrophages from the Central Nervous System by Flow Cytometry

This protocol provides an analysis of the macrophage subpopulations in the adult mouse central nervous system by flow cytometry and is helpful for the study of multiple markers expressed by these cells.

Numerous studies have demonstrated the role of immune cells, in particular macrophages, in central nervous system (CNS) pathologies. There are two main ...

analysis-microglia-monocyte-derived-macrophages-from-central-nervous

Research

JoVE Journal

Immunology and Infection

23.5K Views.  Inserm U 1227, CNRS UMR 7225. This protocol provides an analysis of the macrophage subpopulations in the adult mouse central nervous system by flow cytometry and is helpful for the study of multiple markers expressed by these cells.

Video: Analysis of Microglia and Monocyte-derived Macrophages from the Central Nervous System by Flow Cytometry

Culturing Microglia from the Neonatal and Adult Central Nervous System

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and pathological processes such as CNS maturation in development, multiple sclerosis, and spinal cord injury. Microglia can be activated and recruited to action by neuronal injury or stimulation, such as axonal damage seen in MS or ischemic brain trauma resulting from stroke. These immunocompetent members of the CNS are also thought to have roles in synaptic plasticity under non-pathological conditions. We employ protocols for culturing microglia from the neonatal and adult tissues that are aimed to maximize the viable cell numbers while minimizing confounding variables, such as the presence of other CNS cell types and cell culture debris. We utilize large and easily discernable CNS components (e.g. cortex, spinal cord segments), which makes the entire process feasible and reproducible. The use of adult cells is a suitable alternative to the use of neonatal brain microglia, as many pathologies studied mainly affect the postnatal spinal cord. These culture systems are also useful for directly testing the effect of compounds that may either inhibit or promote microglial activation. Since microglial activation can shape the outcomes of disease in the adult CNS, there is a need for in vitro systems in which neonatal and adult microglia can be cultured and studied.

We outline methods for the efficient and quick isolation/culture of viable microglia from the neonatal cerebral cortex and adult spinal cord. The dissection and plating of cortical microglia can be accomplished within 90 minutes, with the subsequent microglial harvest taking place ~ 10 days following the initial dissection.

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and ...

Culture of Macrophage Colony-stimulating Factor Differentiated Human Monocyte-derived Macrophages

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation of experiments, fresh or frozen monocytes are cultured in flasks for 1 week with M-CSF to induce their differentiation into macrophages. Then, the macrophages can be harvested and seeded into culture wells at required cell densities for carrying out experiments. The use of defined numbers of macrophages rather than defined numbers of monocytes to initiate macrophage cultures for experiments yields macrophage cultures in which the desired cell density can be more consistently attained. Use of cryopreserved monocytes reduces dependency on donor availability and produces more homogeneous macrophage cultures.

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. The protocol utilizes cryopreservation of monocytes coupled with their bulk differentiation into macrophages. Then harvested macrophages can then be seeded into culture wells at required cell densities for carrying out experiments.

A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation ...

Characterization of Human Monocyte-derived Dendritic Cells by Imaging Flow Cytometry: A Comparison between Two Monocyte Isolation Protocols

Dendritic cells (DCs) are antigen presenting cells of the immune system that play a crucial role in lymphocyte responses, host defense mechanisms, and pathogenesis of inflammation. Isolation and study of DCs have been important in biological research because of their distinctive features. Although they are essential key mediators of the immune system, DCs are very rare in blood, accounting for approximately 0.1 - 1% of total blood mononuclear cells. Therefore, alternatives for isolation methods rely on the differentiation of DCs from monocytes isolated from peripheral blood mononuclear cells (PBMCs). The utilization of proper isolation techniques that combine simplicity, affordability, high purity, and high yield of cells is imperative to consider. In the current study, two distinct methods for the generation of DCs will be compared. Monocytes were selected by adherence or negatively enriched using magnetic separation procedure followed by differentiation into DCs with IL-4 and GM-CSF. Monocyte and MDDC viability, proliferation, and phenotype were assessed using viability dyes, MTT assay, and CD11c/ CD14 surface marker analysis by imaging flow cytometry. Although the magnetic separation method yielded a significant higher percentage of monocytes with higher proliferative capacity when compared to the adhesion method, the findings have demonstrated the ability of both techniques to simultaneously generate monocytes that are capable of proliferating and differentiating into viable CD11c+ MDDCs after seven days in culture. Both methods yielded &gt; 70% CD11c+ MDDCs. Therefore, our results provide insights that contribute to the development of reliable methods for isolation and characterization of human DCs.

This study compares two different methods of human monocyte isolation for obtaining in vitro dendritic cells (DCs). Monocytes are selected by adherence or negatively enriched by magnetic separation. Monocyte yield and viability along with MDDC viability, proliferation and CD11c/CD14 surface marker expression will be compared between both methods.

Dendritic cells (DCs) are antigen presenting cells of the immune system that play a crucial role in lymphocyte responses, host defense mechanisms, and ...

Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry

There is increasing evidence suggesting the important role of inflammation and, subsequently, macrophages in the development and progression of renal disease. Macrophages are heterogeneous cells that have been implicated in kidney injury. Macrophages may be classified into two different phenotypes: classically activated macrophages (M1 macrophages), that release pro-inflammatory cytokines and promote fibrosis; and alternatively activated macrophages (M2 macrophages) that are associated with immunoregulatory and tissue-remodeling functions. These macrophage phenotypes need to be discriminated and analyzed to determine their contribution to renal injury. However, there are scarce studies reporting consistent phenotypic and functional information about macrophage subtypes in inflammatory renal disease models, especially in rats. This fact may be related to the limited macrophage markers used in rats, contrary to mice. Therefore, novel strategies are necessary to quantify and characterize the renal content of these infiltrating cells in a reliable way. This manuscript details a protocol for kidney digestion and further phenotypic and quantitative analysis of macrophages from rat kidneys by flow cytometry. Briefly, kidneys were incubated with collagenase and total macrophages were identified according to the dual presence of CD45 (leukocytes common antigen) and CD68 (PAN macrophage marker) in live cells.This was followed by surface staining of CD86 (M1 marker) and CD163 (M2 marker). Rat peritoneal macrophages were used as positive control for macrophage marker detection by flow cytometry. Our protocol resulted in low cellular mortality and allowed characterization of different intracellular and surface protein markers, thus limiting the loss of cellular integrity observed in other protocols. Moreover, this procedure allows the use of macrophages for further techniques, including cell sorting and mRNA or protein expression studies, among others.

This manuscript describes a detailed protocol for phenotypic and quantitative analysis of resident macrophages from rat kidneys by flow cytometry. The resulting stained cells can be also used for other applications, including cell sorting, gene expression analysis or functional studies, thus increasing the information obtained in the experimental model.

There is increasing evidence suggesting the important role of inflammation and, subsequently, macrophages in the development and progression of renal ...

Isolation, Characterization, and Purification of Macrophages from Tissues Affected by Obesity-related Inflammation

Obesity promotes a chronic inflammatory state that is largely mediated by tissue-resident macrophages as well as monocyte-derived macrophages. Diet-induced obesity (DIO) is a valuable model in studying the role of macrophage heterogeneity; however, adequate macrophage isolations are difficult to acquire from inflamed tissues. In this protocol, we outline the isolation steps and necessary troubleshooting guidelines derived from our studies for obtaining a suitable population of tissue-resident macrophages from mice following 18 weeks of high-fat (HFD) or high-fat/high-cholesterol (HFHCD) diet intervention. This protocol focuses on three hallmark tissues studied in obesity and atherosclerosis including the liver, white adipose tissues (WAT), and the aorta. We highlight how dualistic usage of flow cytometry can achieve a new dimension of isolation and characterization of tissue-resident macrophages. A fundamental section of this protocol addresses the intricacies underlying tissue-specific enzymatic digestions and macrophage isolation, and subsequent cell-surface antibody staining for flow cytometric analysis. This protocol addresses existing complexities underlying fluorescent-activated cell sorting (FACS) and presents clarifications to these complexities so as to obtain broad range characterization from adequately sorted cell populations. Alternate enrichment methods are included for sorting cells, such as the dense liver, allowing for flexibility and time management when working with FACS. In brief, this protocol aids the researcher to evaluate macrophage heterogeneity from a multitude of inflamed tissues in a given study and provides insightful troubleshooting tips that have been successful for favorable cellular isolation and characterization of immune cells in DIO-mediated inflammation.

This protocol allows a researcher to isolate and characterize tissue-resident macrophages in various hallmark inflamed tissues extracted from diet-induced models of metabolic disorders.

Obesity promotes a chronic inflammatory state that is largely mediated by tissue-resident macrophages as well as monocyte-derived macrophages. ...

Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages

Alveolar macrophages are terminally differentiated, lung-resident macrophages of prenatal origin. Alveolar macrophages are unique in their long life and their important role in lung development and function, as well as their lung-localized responses to infection and inflammation. To date, no unified method for identification, isolation, and handling of alveolar macrophages from humans and mice exists. Such a method is needed for studies on these important innate immune cells in various experimental settings. The method described here, which can be easily adopted by any laboratory, is a simplified approach to harvesting alveolar macrophages from bronchoalveolar lavage fluid or from lung tissue and maintaining them in vitro. Because alveolar macrophages primarily occur as adherent cells in the alveoli, the focus of this method is on dislodging them prior to harvest and identification. The lung is a highly vascularized organ, and various cell types of myeloid and lymphoid origin inhabit, interact, and are influenced by the lung microenvironment. By using the set of surface markers described here, researchers can easily and unambiguously distinguish alveolar macrophages from other leukocytes, and purify them for downstream applications. The culture method developed herein supports both human and mouse alveolar macrophages for in vitro growth, and is compatible with cellular and molecular studies.

Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages

This communication describes methodologies for isolation and culture of alveolar macrophages from humans and murine models for experimental purposes.

Alveolar macrophages are terminally differentiated, lung-resident macrophages of prenatal origin. Alveolar macrophages are unique in their long life and ...

Characterization of Human Monocyte Subsets by Whole Blood Flow Cytometry Analysis

Monocytes are key contributors in various inflammatory disorders and alterations to these cells, including their subset proportions and functions, can have pathological significance. An ideal method for examining alterations to monocytes is whole blood flow cytometry as the minimal handling of samples by this method limits artifactual cell activation. However, many different approaches are taken to gate the monocyte subsets leading to inconsistent identification of the subsets between studies. Here we demonstrate a method using whole blood flow cytometry to identify and characterize human monocyte subsets (classical, intermediate, and non-classical). We outline how to prepare the blood samples for flow cytometry, gate the subsets (ensure contaminating cells have been removed), and determine monocyte subset expression of surface markers &#8212; in this example M1 and M2 markers. This protocol can be extended to other studies that require a standard gating method for assessing monocyte subset proportions and monocyte subset expression of other functional markers.

Here we present a protocol for characterizing monocyte subsets by whole blood flow cytometry. This includes outlining how to gate the subsets and assess their expression of surface markers and giving an example of the assessment of the expression of M1 (inflammatory) and M2 markers (anti-inflammatory).

Monocytes are key contributors in various inflammatory disorders and alterations to these cells, including their subset proportions and functions, can ...

Flow Cytometric Analysis of Lymphocyte Infiltration in Central Nervous System during Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) caused by the combination of environmental factors and susceptible genetic background. Experimental autoimmune encephalomyelitis (EAE) is a typical disease model of MS widely used for investigating the pathogenesis in which T lymphocytes specific for myelin antigens initiate an inflammatory reaction in CNS. It is very important to assess how lymphocytes in the CNS regulate the development of disease. However, the approach for measuring the quantity and quality of infiltrated lymphocytes in the CNS is very limited due to the difficulties in isolating and detecting infiltrated lymphocytes from the brain. This manuscript presents a protocol for that is useful for the isolation, identification, and characterization of infiltrated lymphocytes from the CNS and will be helpful for our understanding of how lymphocytes are involved in the development of the CNS autoimmune disease.

This manuscript presents a protocol to induce active experimental autoimmune encephalomyelitis (EAE) in mice. A method for the isolation and characterization of the infiltrated lymphocytes in the central nervous system (CNS) is also presented to show how lymphocytes are involved in the development of CNS autoimmune disease.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) caused by the combination of environmental factors and susceptible ...

Isolating Central Nervous System Tissues and Associated Meninges for the Downstream Analysis of Immune cells

The central nervous system (CNS) is comprised of the brain and spinal cord and is enveloped by the meninges, membranous layers serving as a barrier between the periphery and the CNS. The CNS is an immunologically specialized site, and in steady state conditions, immune privilege is most evident in the CNS parenchyma. In contrast, the meninges harbor a diverse array of resident cells, including innate and adaptive immune cells. During inflammatory conditions triggered by CNS injury, autoimmunity, infection, or even neurodegeneration, peripherally derived immune cells may enter the parenchyma and take up residence within the meninges. These cells are thought to perform both beneficial and detrimental actions during CNS disease pathogenesis. Despite this knowledge, the meninges are often overlooked when analyzing the CNS compartment, because conventional CNS tissue extraction methods omit the meningeal layers. This protocol presents two distinct methods for the rapid isolation of murine CNS tissues (i.e., brain, spinal cord, and meninges) that are suitable for downstream analysis via single-cell techniques, immunohistochemistry, and in situ hybridization methods. The described methods provide a comprehensive analysis of CNS tissues, ideal for assessing the phenotype, function, and localization of cells occupying the CNS compartment under homeostatic conditions and during disease pathogenesis.

This paper presents two optimized protocols for examining resident and peripherally derived immune cells within the central nervous system, including the brain, spinal cord, and meninges. Each of these protocols helps to ascertain the function and composition of the cells occupying these compartments under steady state and inflammatory conditions.

The central nervous system (CNS) is comprised of the brain and spinal cord and is enveloped by the meninges, membranous layers serving as a barrier ...

Isolation of Mouse Kidney-Resident CD8+ T cells for Flow Cytometry Analysis

Tissue-resident memory T cell (TRM) is a rapidly expanding field of immunology research. Isolating T cells from various non-lymphoid tissues is one of the key steps to investigate TRMs. There are slight variations in lymphocyte isolation protocols for different organs. Kidney is an essential non-lymphoid organ with numerous immune cell infiltration especially after pathogen exposure or autoimmune activation. In recent years, multiple labs including our own have started characterizing kidney resident CD8+ T cells in various physiological and pathological settings in both mouse and human. Due to the abundance of T lymphocytes, kidney represents an attractive model organ to study TRMs in non-mucosal or non-barrier tissues. Here, we will describe a protocol commonly used in TRM-focused labs to isolate CD8+ T cells from mouse kidneys following systemic viral infection. Briefly, using an acute lymphocytic choriomeningitis virus (LCMV) infection model in C57BL/6 mice, we demonstrate intravascular CD8+ T cell labeling, enzymatic digestion, and density gradient centrifugation to isolate and enrich lymphocytes from mouse kidneys to make samples ready for the subsequent flow cytometry analysis.

Isolation of Mouse Kidney-Resident CD8+ T cells for Flow Cytometry Analysis

Following viral infection, kidney harbors a relatively large number of CD8+ T cells and offers an opportunity to study non-mucosal TRM cells. Here, we describe a protocol to isolate mouse kidney lymphocytes for flow cytometry analysis.

Tissue-resident memory T cell (TRM) is a rapidly expanding field of immunology research. Isolating T cells from various non-lymphoid tissues is one of the ...