This work was supported by the CNRS (PICS 2012-2014 to E.G.) and by a grant from Regione Campania (L.R. n.5, 28.03.2002 to Giovanna Mottola). Filippo Conti is a fellow of the Scientific Cooperation Foundation &#39;&#39;Infectiopole Sud.&#39;&#39; Nicola Boucherit is a fellow of the French Ministry for Research and Technology. The funding sources had no role in the study design, data collection, data analysis, decision to publish, or manuscript preparation.

Ethics Statement
The protocol for animal handling was approved by our institutional Animal Ethics Committee &#34;Conseil Scientifique du Centre de Formation et de Recherche Experimental M&#233;dico-Chirurgical&#34; (CFREMC, Project permit 10-300122013 to Eric Ghigo) from Aix-Marseille University in accord with the rules of D&#233;cret N&#176; 87-848 of 10/19/1987. The experiments were performed at the Facult&#233; de M&#233;decine de la Timone (Experimentation permit number 13.385 to Eric Ghigo).
1. Material and Culture Media Preparation
<ol>
	<li>Sterilize two forceps, two scissors, two surgical blades, a mortar and a pestle.</li>
	<li>Obtain complete DMEM containing 10% fetal calf serum (FCS), 2 mM glutamine, 100 U/ml penicillin and 100 &#956;g/ml streptomycin .</li>
	<li>Dilute 10x PBS in sterile distillated water to obtain 1x PBS.</li>
	<li>Obtain ice-cold 1x PBS, ice-cold complete DMEM, complete DMEM warmed to 37 &#176;C.</li>
</ol>
2. Preparation of L929 Cell Supernatants
<ol>
	<li>Grow L929 cells to confluence (twenty 175 cm2 flasks) in complete DMEM at 37 &#176;C, 5% CO2.</li>
</ol>
Note: Granulocyte-macrophage colony stimulating factor (GM-CSF) is required to induce hematopoietic cell differentiation into macrophages12. L929 cells produce GM-CSF.
<ol start="2">
	<li>At confluence, replace culture media with fresh complete DMEM. Transfer flasks to 32 &#176;C, 5% CO2 for 10 days.</li>
	<li>Collect, pool and centrifuge the supernatants at 750 x g for 10 min. Discard cell pellets.</li>
	<li>Store supernatants in 15 ml tubes and store at -20 &#176;C.</li>
</ol>
3. Bone Marrow-derived Macrophage (BMDM) Preparation
<ol>
	<li>Sacrifice 1 mouse by cervical dislocation.
	<ol>
		<li>Use sterile surgical blades throughout the experiment. Disinfect the skin with 70% alcohol. Make an incision at the top of each hind leg and pull the skin down towards the foot to expose the muscle.</li>
		<li>Cut off the hind legs, remove the skin with sterile scissors and sterile forceps. Place legs within a sterile Petri dish (35/10 mm) containing sterile, ice-cold 1x PBS (5 ml).</li>
		<li>Remove the flesh and muscles that are adhering to the bones with sterile scissors and forceps.</li>
	</ol>
	</li>
	<li>Transfer the bones into a new, sterile Petri dish (35/10 mm) containing ice-cold, sterile 1x PBS (5 ml). Wash the bones two times with 5 ml ice-cold, sterile 1x PBS.</li>
	<li>Transfer the bone into a sterile mortar containing 5 ml ice-cold, sterile 1x PBS.</li>
	<li>Cut the tibia from the femur at the joint with sterile scissors. Smash the bones gently in a sterile mortar containing 5 ml ice-cold, sterile 1x PBS using a pestle.</li>
	<li>Collect the supernatant in ice-cold 15&#160;ml tubes. Repeat this step 3x.</li>
	<li>Filter through a 70 &#956;m Nylon cell strainer to remove solid fragments. Centrifuge the filtrate at 450 x g for 10 min at 4 &#176;C.</li>
	<li>Gently discard the supernatant. Dissociate the pellet in 10 ml red blood cell lysis buffer for 30 sec. Add 20 ml ice-cold, complete DMEM.</li>
</ol>
Note: The aim of this step is to remove contaminating red blood cells; thus, this step must be performed within 2 min to avoid hematopoietic cell alteration by the red blood cell lysis buffer.
<ol start="8">
	<li>Centrifuge at 450 x g for 10 min at 4 &#176;C. Gently discard the supernatant. Dissociate the pellet in 20 ml complete DMEM that has been warmed to 37 &#176;C.</li>
	<li>Transfer the dissociated cells into 2 Petri dishes (100/20 mm). Incubate them for 4 hr at 37 &#176;C.</li>
	<li>Collect the supernatants in 50 ml tubes at room temperature. Discard the dishes that contain the resident macrophages.</li>
</ol>
Note: The objective of this step is to eliminate the resident bone marrow macrophages by their ability to adhere to culture-treated plastic. These resident macrophages may be used in other experiments.
<ol start="11">
	<li>Centrifuge the collected supernatants at 450 x g for 10 min at 4 &#176;C. Discard the supernatant.</li>
	<li>Dissociate gently the pellet in 10 ml complete DMEM containing 15% L929 cell supernatant. Filter the cells through a 40 &#956;m Nylon cell strainer.</li>
	<li>Recover the filtrate. Add the collected filtrate (10 ml) to 140 ml complete DMEM that has been supplemented with 15% L929 cell media.</li>
	<li>Distribute 10 ml of the cell suspension per Petri dish (15 Petri dishes, 100/20 mm). Incubate the cells at 37 &#176;C, 5% CO2.</li>
	<li>Grow cells for 3 days</li>
	<li>Add 10 ml complete DMEM that has been supplemented with 15% L929. Incubate cells for 4 additional days.</li>
</ol>
Note: Monitor cell growth periodically with an inverted microscope (steps 3.14-3.16). Adherent macrophages will be observed after 3 days of culture.
4. Harvesting BMDMs
<ol>
	<li>Remove the supernatant. Wash BMDMs 2 times with complete DMEM</li>
	<li>Add 5 ml complete DMEM that has been warmed to 37 &#176;C. Detach BMDMs by gently scraping with a rubber policeman.</li>
	<li>Collect BMDMs in 50 ml tubes and centrifuge at 450 x g for 10 min. Gently dissociate cell pellets in 20 ml complete DMEM.</li>
	<li>Count BMDMs in the presence of trypan blue (no more than 10% mortality should be observed).</li>
</ol>
Note: Generally, approximately 6-7.5 x 107 macrophages are obtained from 15 Petri dishes (100/20 mm) of macrophages. There are approximately 4-5 x 106 macrophages/Petri dish (100/20 mm).
<ol start="5">
	<li>Prepare BMDMs as required for the experiment. After 16 hr in complete media at 37 &#176;C, 5% CO2, macrophages will again adhere to the support.</li>
</ol>
5. Storing BMDMs
<ol>
	<li>Collect isolated BMDMs (step 4.3). Centrifuge at 450 x g for 10 min. Note: BMDMs may be frozen in liquid nitrogen.</li>
	<li>Resuspend cell pellets in freezing media consisting of 10% DMSO and 90% FCS at a final concentration of 4 x 106 cells/ml and pipette 1 ml into each ampoule.</li>
	<li>Freeze the cells at a cooling rate of 1 &#176;C/min. After 24 hr, transfer the ampoule to a liquid nitrogen container for long-term storage.</li>
</ol>

<ol>
	<li>Rutherford, M. S., Witsell, A., Schook, L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+generating+functionally+heterogeneous+macrophages:+chaos+revisited.">Mechanisms generating functionally heterogeneous macrophages: chaos revisited.</a> J. Leukocyte Biol. 53, 602-618 (1993).</li><li>Van Furth, R., Gallin, J. I., Goldstein, I. M., Snyderman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Inflammation: Basic Principles and Clinical Correlates. 112, 325-336 (1992).</li><li>Adams, D., Halmiton, T., Gallin, J. I., Goldstein, I. M., Snyderman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Inflammation: Basic Principles and Clinical Correlates. 112, 325-336 (1992).</li><li>Morris, L., Graham, C. F., Gordon, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophages+in+haemopoietic+and+other+tissues+of+the+developing+mouse+detected+by+the+monoclonal+antibody+F4/80.">Macrophages in haemopoietic and other tissues of the developing mouse detected by the monoclonal antibody F4/80.</a> Development. 112, 517-526 (1991).</li><li>Haas, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+phagosome:+compartment+with+a+license+to+kill.">The phagosome: compartment with a license to kill.</a> Traffic. 8, 311-330 (2007).</li><li>Underhill, D. M., Ozinsky, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phagocytosis+of+microbes:+complexity+in+action.">Phagocytosis of microbes: complexity in action.</a> Annu. Rev. Immunol. 20, 825-852 (2002).</li><li>Castagna, A., Polati, R., Bossi, A. M., Girelli, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monocyte/macrophage+proteomics:+recent+findings+and+biomedical+applications.">Monocyte/macrophage proteomics: recent findings and biomedical applications.</a> Expert Rev. Proteomics. 9, 201-215 (2012).</li><li>Benoit, M., Desnues, B., Mege, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macrophage+polarization+in+bacterial+infections.">Macrophage polarization in bacterial infections.</a> J. Immunol. 181, 3733-3739 (2008).</li><li>Barry, A. O., 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=Impaired+stimulation+of+p38alpha-MAPK/Vps41-HOPS+by+LPS+from+pathogenic+Coxiella+burnetii+prevents+trafficking+to+microbicidal+phagolysosomes.">Impaired stimulation of p38alpha-MAPK/Vps41-HOPS by LPS from pathogenic Coxiella burnetii prevents trafficking to microbicidal phagolysosomes.</a> Cell Host Microbe. 12, 751-763 (2012).</li><li>Henry, R. M., Hoppe, A. D., Joshi, N., Swanson, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+uniformity+of+phagosome+maturation+in+macrophages.">The uniformity of phagosome maturation in macrophages.</a> J. Cell Biol. 164, 185-194 (2004).</li><li>Sundaramurthy, V., 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=Integration+of+Chemical+and+RNAi+Multiparametric+Profiles+Identifies+Triggers+of+Intracellular+Mycobacterial+Killing.">Integration of Chemical and RNAi Multiparametric Profiles Identifies Triggers of Intracellular Mycobacterial Killing.</a> Cell Host Microbe. 13, 129-142 (2013).</li><li>Boltz-Nitulescu, G., 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=Differentiation+of+rat+bone+marrow+cells+into+macrophages+under+the+influence+of+mouse+L929+cell+supernatant.">Differentiation of rat bone marrow cells into macrophages under the influence of mouse L929 cell supernatant.</a> J. Leukocyte Biol. 41, 83-91 (1987).</li></ol>

There are no declared conflicts of interest.

The protocol described herein details a method to produce large numbers of BMDMs. BMDM are primary cells and have the biological function and properties of macrophages differentiated from monocytes because there are mature, in contrast to macrophage cell lines, which are immature. BMDMs may be used for genetic screening (RNAi), drug screening, functional studies, host-pathogen interaction studies and many other areas of investigation.
The procedure presented herein is very simple and does not ...

A significant aspect of macrophage function is their role in innate and adaptive immunity. Because of their capacity to phagocytose inert particles, bacteria or parasites, macrophages are a first line of defense against foreign invaders. Once internalized, microbes are degraded within phagolysosomes. Macrophages also send recruitment signals for and present antigens to other immune cells such as T lymphocytes. Macrophages are derived from monocytes. Monocytes arise in the bone marrow from myeloid stem cells and migrate to peripheral blood and various tissues where they differentiate into macrophages. It is estimated that a healthy adult mouse contains approximately 108 macrophages that are distributed throughout the body in various organs and tissues (Table 1)1,2. Macrophages display great phenotypic and functional diversity because of their ability to adapt to their microenvironment3,4. The most important macrophage property is their microbicidal activity, which is defined by their capacity to phagocytose microbes and destroy them. The phagocytic response is defined by the activation of complex signaling networks that are stimulated by microbial contact; thus, macrophages modulate gene expression appropriately in response to diverse stimuli. After phagocytosis, microbes are eliminated in a structure called the phagolysosome; however, many pathogenic microbes have developed strategies to subvert the microbicidal function of macrophages5. The diversity of subversion mechanisms that are utilized by different microbial species is a testament to the complexity of the phagocytic process6 and phagolysosome biogenesis. Infectious diseases are major human health problems, and numerous mechanisms and molecules participate in macrophage antimicrobial activities. Furthermore, the targets of the microbicidal properties that are hijacked by microbes remain unknown; thus, there is an explosion of interest in the evolutionary, genetic, and biochemical aspects of host-pathogen interactions that has renewed scientific attention regarding macrophages. Currently, the majority of the research in the field is done on macrophages cell lines, which differ from primary macrophages in the phagocytic activity, the cytokines production and the regulation of the oxidative burst. In addition, they are less suitable for microscopy. To investigate the interaction macrophages-pathogens it is recommended to use primary macrophages, such as Bone Marrow Derived Macrophages (BMDMs), which exhibit more physiological features. Moreover, it is possible to work on genetically modified BMDMs, because these macrophages might be isolated directly from transgenic mice and, with the availability of novel technologies such as lentiviral transfection, their gene expression profile can be altered by gene overexpression or RNA interference. Here, we describe a procedure to differentiate murine bone marrow into macrophages that will provide large numbers of macrophages in 7 days for various functional analyses such as proteomics7, transcriptomics8, intracellular trafficking studies9, dynamic studies10, genetic screens (RNAi) and drug screening11.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Material/Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco Life Technologies</td>
			<td>21969-035</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Calf Serum</td>
			<td>Gibco Life Technologies</td>
			<td>10270</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Gibco Life Technologies</td>
			<td>15070</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutamine</td>
			<td>Gibco Life Technologies</td>
			<td>25030-024</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS (10x)</td>
			<td>Lonza</td>
			<td>BEM515F</td>
			<td></td>
		</tr>
		<tr>
			<td>Red Blood Cell Lysis buffer</td>
			<td>Sigma</td>
			<td>R7757</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell strainer 70 &#956;m Nylon</td>
			<td>BD Falcon</td>
			<td>352350</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell strainer 40 &#956;m Nylon</td>
			<td>BD Falcon</td>
			<td>352340</td>
			<td></td>
		</tr>
		<tr>
			<td>50 ml tubes</td>
			<td>any supplier</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>15 ml tubes</td>
			<td>any supplier</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dishes (100/20 mm)</td>
			<td>any supplier</td>
			<td>n/a</td>
			<td>culture treated</td>
		</tr>
		<tr>
			<td>Petri dishes (35/10 mm)</td>
			<td>any supplier</td>
			<td>n/a</td>
			<td></td>
		</tr>
	</tbody>
</table>

bone marrow-derived macrophage production

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because of their powerful microbicidal activities. Macrophages are widely distributed throughout the body and are present in the lymphoid organs, liver, lungs, gastrointestinal tract, central nervous system, bone, and skin. Because of their repartition, they participate in a wide range of physiological and pathological processes. Macrophages are highly versatile cells that are able to recognize microenvironmental alterations and to maintain tissue homeostasis. Numerous pathogens have evolved mechanisms to use macrophages as Trojan horses to survive, replicate in, and infect both humans and animals and to propagate throughout the body. The recent explosion of interest in evolutionary, genetic, and biochemical aspects of host-pathogen interactions has renewed scientific attention regarding macrophages. Here, we describe a procedure to isolate and cultivate macrophages from murine bone marrow that will provide large numbers of macrophages for studying host-pathogen interactions as well as other processes.

The aim of this method was to easily obtain large numbers of macrophages in few days. The bone marrow cell preparation is illustrated in Figure 1. Bones from the hind leg were collected and smashed in a mortar. Once the resident macrophages were removed from the bone marrow cell preparation, bone marrow cells were incubated with GM-CSF (Day 0). After 3 days, the cells, which were round and nonadherent before culture, start to differentiate into macrophages and adhere (Figure 1A). Cytomet...

Watch this Scientific Journal Video about Bone Marrow-derived Macrophage Production at JoVE.com

Bone Marrow-derived Macrophage Production

Macrophages have long been recognized as a critical component of the innate and adaptive immune responses. The recent explosion of knowledge pertaining to evolutionary, genetic, and biochemical aspects of the interaction between macrophages and microbes has renewed scientific attention to macrophages. This article describes a method to differentiate macrophages from mouse bone marrow.

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because ...

bone-marrow-derived-macrophage-production

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Immunology and Infection

72.9K Views.  Aix-Marseille Université. Macrophages have long been recognized as a critical component of the innate and adaptive immune responses. The recent explosion of knowledge pertaining to evolutionary, genetic, and biochemical aspects of the interaction between macrophages and microbes has renewed scientific attention to macrophages. This article describes a method to differentiate macrophages from mouse bone marrow.

Video: Bone Marrow-derived Macrophage Production

Toxoplasma gondii Cyst Wall Formation in Activated Bone Marrow-derived Macrophages and Bradyzoite Conditions

Toxoplasma gondii is an obligate intracellular parasite that can invade any nucleated cell of warm-blooded animals. During infection, T. gondii disseminates as a fast replicating form called the tachyzoite. Tachyzoites convert into a slow-growing encysted form called the bradyzoite by a signaling process that is not well characterized. Within animals, bradyzoite cysts are found in the central nervous system and muscle tissue and represent the chronic stage of infection. Conversion to bradyzoites can be simulated in tissue culture by CO2 starvation, using medium with high a pH, or the addition of interferon gamma (IFN&gamma;). Bradyzoites are characterized by the presence of a cyst wall, to which the lectin Dolichos biflorus agglutinin (DBA) binds. Fluorescently labeled DBA is used to visualize the cyst wall in parasites grown in human foreskin fibroblasts (HFFs) that have been exposed to low CO2 and high pH medium. Similarly, parasites residing in murine bone marrow-derived macrophages (BMMs) display a cyst wall detectable by DBA after the BMMs are activated with IFN&gamma; and lipopolysaccharide (LPS). This protocol will demonstrate how to induce conversion of T. gondii to bradyzoites using a high pH growth medium with low CO2 and activation of BMMs. Host cells will be cultured on coverslips, infected with tachyzoites and either activated with addition of IFN&gamma; and LPS (BMMs) or exposed to a high pH growth medium (HFFs) for three days. Upon completion of infections, host cells will be fixed, permeabilized, and blocked. Cyst walls will be visualized using rhodamine DBA with fluorescence microscopy.

Toxoplasma gondii Cyst Wall Formation in Activated Bone Marrow-derived Macrophages and Bradyzoite Conditions

Toxoplasma gondii converts to a cyst form in response to environmental stresses, which can be mimicked in tissue culture models. This video demonstrates techniques to examine cyst wall formation by activating bone marrow-derived macrophages or changing growth medium pH in fibroblast cells.

Toxoplasma gondii is an obligate intracellular parasite that can invade any nucleated cell of warm-blooded animals. During infection, T. gondii ...

Generation and Labeling of Murine Bone Marrow-derived Dendritic Cells with Qdot Nanocrystals for Tracking Studies

Dendritic cells (DCs) are professional antigen presenting cells (APCs) found in peripheral tissues and in immunological organs such as thymus, bone marrow, spleen, lymph nodes and Peyer's patches 1-3. DCs present in peripheral tissues sample the organism for the presence of antigens, which they take up, process and present in their surface in the context of major histocompatibility molecules (MHC). Then, antigen-loaded DCs migrate to immunological organs where they present the processed antigen to T lymphocytes triggering specific immune responses. One way to evaluate the migratory capabilities of DCs is to label them with fluorescent dyes 4.
Herewith we demonstrate the use of Qdot fluorescent nanocrystals to label murine bone marrow-derived DC. The advantage of this labeling is that Qdot nanocrystals possess stable and long lasting fluorescence that make them ideal for detecting labeled cells in recovered tissues. To accomplish this, first cells will be recovered from murine bone marrows and cultured for 8 days in the presence of granulocyte macrophage-colony stimulating factor in order to induce DC differentiation. These cells will be then labeled with fluorescent Qdots by short in vitro incubation. Stained cells can be visualized with a fluorescent microscopy. Cells can be injected into experimental animals at this point or can be into mature cells upon in vitro incubation with inflammatory stimuli. In our hands, DC maturation did not determine loss of fluorescent signal nor does Qdot staining affect the biological properties of DCs. Upon injection, these cells can be identified in immune organs by fluorescent microscopy following typical dissection and fixation procedures.

Dendritic cells uptake antigens and migrate towards immune organs to present processed antigens to T cells. Qdot nanocrystal labeling provides a long-lasting and stable fluorescent signal. This allows tracking of dendritic cells to different organs by fluorescent microscopy.

Dendritic cells (DCs) are professional antigen presenting cells (APCs) found in peripheral tissues and in immunological organs such as thymus, bone ...

Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic ...

Isolation and Intravenous Injection of Murine Bone Marrow Derived Monocytes

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of various fields in biomedical science. The method described below is a simple and effective way to isolate murine monocytes from heterogeneous bone marrow.
Bone marrow from the femur and tibia of Balb/c mice is harvested by flushing with phosphate buffered saline (PBS). Cell suspension is supplemented with macrophage-colony stimulating factor (M-CSF) and cultured on ultra-low attachment surfaces to avoid adhesion-triggered differentiation of monocytes. The properties and differentiation of monocytes are characterized at various intervals. Fluorescence activated cell sorting (FACS), with markers like CD11b, CD115, and F4/80, is used for phenotyping. At the end of cultivation, the suspension consists of 45%&#177; 12% monocytes. By removing adhesive macrophages, the purity can be raised up to 86%&#177; 6%. After the isolation, monocytes can be utilized in various ways, and one of the most effective and common methods for in vivo delivery is intravenous tail vein injection. 
This technique of isolation and application is important for mouse model studies, especially in the fields of inflammation or immunology. Monocytes can also be used therapeutically in mouse disease models.

Here we present a protocol that generates large amounts of murine monocytes from heterogeneous bone marrow for translational applications. In comparison to others, this new method helps reduce the number of sacrificed animals and lowers costs by avoiding expensive methods such as high gradient magnetic cell separation (MACS).

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of ...

Metabolic Characterization of Polarized M1 and M2 Bone Marrow-derived Macrophages Using Real-time Extracellular Flux Analysis

Specific metabolic pathways are increasingly being recognized as critical hallmarks of macrophage subsets. While LPS-induced classically activated M1 or M(LPS) macrophages are pro-inflammatory, IL-4 induces alternative macrophage activation and these so-called M2 or M(IL-4) support resolution of inflammation and wound healing. Recent evidence shows the crucial role of metabolic reprogramming in the regulation of M1 and M2 macrophage polarization. 
In this manuscript, an extracellular flux analyzer is applied to assess the metabolic characteristics of naive, M1 and M2 polarized mouse bone marrow-derived macrophages. This instrument uses pH and oxygen sensors to measure the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR), which can be related to glycolytic and mitochondrial oxidative metabolism. As such, both glycolysis and mitochondrial oxidative metabolism can be measured in real-time in one single assay.
Using this technique, we demonstrate here that inflammatory M1 macrophages display enhanced glycolytic metabolism and reduced mitochondrial activity. Conversely, anti-inflammatory M2 macrophages show high mitochondrial oxidative phosphorylation (OXPHOS) and are characterized by an enhanced spare respiratory capacity (SRC). 
The presented functional assay serves as a framework to investigate how particular cytokines, pharmacological compounds, gene knock outs or other interventions affect the macrophage&#8217;s metabolic phenotype and inflammatory status.

Metabolic reprogramming is a characteristic and prerequisite for M1 and M2 macrophage polarization. This manuscript describes an assay for the measurement of fundamental parameters of glycolysis and mitochondrial function in mouse bone marrow-derived macrophages. This tool can be applied to investigate how particular factors affect the macrophage&#8217;s metabolism and phenotype.

Specific metabolic pathways are increasingly being recognized as critical hallmarks of macrophage subsets. While LPS-induced classically activated M1 or ...

Murine Hind Limb Long Bone Dissection and Bone Marrow Isolation

Investigation of the bone and the bone marrow is critical in many research fields including basic bone biology, immunology, hematology, cancer metastasis, biomechanics, and stem cell biology. Despite the importance of the bone in healthy and pathologic states, however, it is a largely under-researched organ due to lack of specialized knowledge of bone dissection and bone marrow isolation. Mice are a common model organism to study effects on bone and bone marrow, necessitating a standardized and efficient method for long bone dissection and bone marrow isolation for processing of large experimental cohorts. We describe a straightforward dissection procedure for the removal of the femur and tibia that is suitable for downstream applications, including but not limited to histomorphologic analysis and strength testing. In addition, we outline a rapid procedure for isolation of bone marrow from the long bones via centrifugation with limited handling time, ideal for cell sorting, primary cell culture, or DNA, RNA, and protein extraction. The protocol is streamlined for rapid processing of samples to limit experimental error, and is standardized to minimize user-to-user variability.

Here we present a protocol for the dissection of hind limb long bones (femurs and tibiae) from the laboratory mouse. We further describe a rapid technique for bone marrow isolation from these bones that utilizes centrifugation for removal of bone marrow from the bone marrow space.

Investigation of the bone and the bone marrow is critical in many research fields including basic bone biology, immunology, hematology, cancer metastasis, ...

Visualizing Macrophage Extracellular Traps Using Confocal Microscopy

A primary method used to define the presence of neutrophil extracellular traps (NETs) is confocal microscopy. We have modified established confocal microscopy methods to visualize macrophage extracellular traps (METs). These extracellular traps are defined by the presence of extracellular chromatin with co-expression of other components such as granule proteases, citrullinated histones, and peptidyl arginase deiminase (PAD). The expression of METs is generally measured after exposure to a stimulus and compared to un-stimulated samples. Samples are also included for background and isotype control. Cells are analyzed using well-defined image analysis software. Confocal microscopy may be used to define the presence of METs both in vitro and in vivo in lung tissue.

Macrophage extracellular traps are a newly described entity. This article will concentrate on confocal microscopy methods and how they are visualized in vitro and in vivo from lung samples.

A primary method used to define the presence of neutrophil extracellular traps (NETs) is confocal microscopy. We have modified established confocal ...

Assessment of Antibody-based Drugs Effects on Murine Bone Marrow and Peritoneal Macrophage Activation

Macrophages are phagocytic innate immune cells, which initiate immune responses to pathogens and contribute to healing and tissue restitution. Macrophages are equally important in turning off inflammatory responses. We have shown that macrophages stimulated with intravenous immunoglobulin (IVIg) can produce high amounts of the anti-inflammatory cytokine, interleukin 10 (IL-10), and low levels of pro-inflammatory cytokines in response to bacterial lipopolysaccharides (LPS). IVIg is a polyvalent antibody, primarily immunoglobulin Gs (IgGs), pooled from the plasma of more than 1,000 blood donors. It is used to supplement antibodies in patients with immune deficiencies or to suppress immune responses in patients with autoimmune or inflammatory conditions. Infliximab, a therapeutic anti-tumor necrosis factor alpha (TNF&#945;) antibody, has also been shown to activate macrophages to produce IL-10 in response to inflammatory stimuli. IVIg and other antibody-based biologics can be tested to determine their effects on macrophage activation. This paper describes methods for derivation, stimulation, and assessment of murine bone marrow macrophages activated by antibodies in vitro and murine peritoneal macrophages activated with antibodies in vivo. Finally, we demonstrate the use of western blotting to determine the contribution of specific cell signaling pathways to anti-inflammatory macrophage activity. These protocols can be used with genetically modified mice, to determine the effect of a specific protein(s) on anti-inflammatory macrophage activation. These techniques can also be used to assess whether specific biologics may act by changing macrophages to an IL-10-producing anti-inflammatory activation state that reduces inflammatory responses in vivo. This can provide information on the role of macrophage activation in the efficacy of biologics during disease models in mice, and provide insight into a potential new mechanism of action in people. Conversely, this may caution against the use of specific antibody-based biologics to treat infectious disease, particularly if macrophages play an important role in host defense against that infection.

Antibody-based drugs have revolutionized treatment for inflammatory diseases. In addition to having direct effects on specific targets, antibodies can activate macrophages to become anti-inflammatory. This protocol describes how anti-inflammatory macrophage activation can be assessed in vitro, using mouse bone marrow macrophages, and in vivo, using peritoneal macrophages.

Macrophages are phagocytic innate immune cells, which initiate immune responses to pathogens and contribute to healing and tissue restitution. Macrophages ...

Detection of Inflammasome Activation and Pyroptotic Cell Death in Murine Bone Marrow-derived Macrophages

Inflammasomes are innate immune signaling platforms that are required for the successful control of many pathogenic organisms, but also promote inflammatory and autoinflammatory diseases. Inflammasomes are activated by cytosolic pattern recognition receptors, including members of the NOD-like receptor (NLR) family. These receptors oligomerize upon the detection of microbial or damage-associated stimuli. Subsequent recruitment of the adaptor protein ASC forms a microscopically visible inflammasome complex, which activates caspase-1 through proximity-induced auto-activation. Following the activation, caspase-1 cleaves pro-IL-1&#946; and pro-IL-18, leading to the activation and secretion of these pro-inflammatory cytokines. Caspase-1 also mediates the inflammatory form of cell death termed pyroptosis, which features the loss of membrane integrity and cell lysis. Caspase-1 cleaves gasdermin D, releasing the N-terminal fragment which forms plasma membrane pores, leading to osmotic lysis.
In vitro, the activation of caspase-1 can be determined by labeling bone marrow-derived macrophages with the caspase-1 activity probe FAM-YVAD-FMK and by labeling the cells with antibodies against the adaptor protein ASC. This technique allows the identification of inflammasome formation and caspase-1 activation in individual cells using fluorescence microscopy. Pyroptotic cell death can be detected by measuring the release of cytosolic lactate dehydrogenase into the medium. This procedure is simple, cost effective and performed in a 96-well plate format, allowing adaptation for screening. In this manuscript, we show that activation of the NLRP3 inflammasome by nigericin leads to the co-localization of the adaptor protein ASC and active caspase-1, leading to pyroptosis.

We describe the detection of NLRP3 inflammasome activation on cellular basis using fluorescence microscopy and staining for active caspase-1 and the adaptor, ASC. A lactate dehydrogenase release assay is presented to detect pyroptotic lysis on a population basis. These techniques can be adapted to study many aspects of inflammasome biology.

Inflammasomes are innate immune signaling platforms that are required for the successful control of many pathogenic organisms, but also promote ...

An In Vivo Mouse Model to Measure Na&#239;ve CD4 T Cell Activation, Proliferation and Th1 Differentiation Induced by Bone Marrow-derived Dendritic Cells

Quantification of na&#239;ve CD4 T cell activation, proliferation, and differentiation to T helper 1 (Th1) cells is a useful way to assess the role played by T cells in an immune response. This protocol describes the in vitro differentiation of bone marrow (BM) progenitors to obtain granulocyte macrophage colony-stimulating factor (GM-CSF) derived-dendritic cells (DCs). The protocol also describes the adoptive transfer of ovalbumin peptide (OVAp)-loaded GM-CSF-derived DCs and na&#239;ve CD4 T cells from OTII transgenic mice in order to analyze the in vivo activation, proliferation, and Th1 differentiation of the transferred CD4 T cells. This protocol circumvents the limitation of purely in vivo methods imposed by the inability to specifically manipulate or select the studied cell population. Moreover, this protocol allows studies in an in vivo environment, thus avoiding alterations to functional factors that may occur in vitro and including the influence of cell types and other factors only found in intact organs. The protocol is a useful tool for generating changes in DCs and T cells that modify adaptive immune responses, potentially providing important results to understand the origin or development of numerous immune associated diseases.

Here, we present a protocol for the in vivo determination of na&#239;ve CD4 T cell (T cell) activation, proliferation, and Th1 differentiation induced by GM-CSF bone marrow (BM)-derived dendritic cells (DCs). In addition, this protocol describes BM and T-cell isolation, DC generation, and DC and T-cell adoptive transfer.

Quantification of na&#239;ve CD4 T cell activation, proliferation, and differentiation to T helper 1 (Th1) cells is a useful way to assess the role played ...