This work was supported by the DFG (Deutsche Forschungsgemeinschaft, German Research Foundation) SFB 854 (Sonderforschungsbereich, collaborative research center). 
Thanks to Hans-Holger G&#228;rtner, Audiovisuelles Medienzentrum, Otto-von-Guericke University Magdeburg, Magdeburg, Germany, for technical support.

This study was performed with permission of the State of Saxony and Saxony-Anhalt, Regierungspraesidium Dresden/Halle, according to Section 8 of the German Law for animal protection (24D-9168.11-1/2008-24).
1 Cell Isolation
1.1 Preparation of Femur and Tibia
<ol>
	<li>Anesthetize the mouse using a 5% isoflurane concentration by vaporizing isoflurane in a closed bin. After the mouse has stopped moving for 3 sec, perform the cervical dislocation.</li>
	<li>Disinfect the hind limbs with ethanol (96%). Remove skin and muscles and separate the bones with a sterile scalpel.
	<ol>
		<li>Start with an inguinal skin incision, and extend the incision toward the medial malleolus and perform a circular dissection of the skin around the lower calf. Remove the skin of the legs completely by peeling it proximally.</li>
		<li>Detach the quadriceps muscle from the femur with a sharp scalpel, remove both the anterior peroneus and the gastrocnemius muscle groups and disarticulate the leg at the hip joint by locating and dissecting the ligaments.</li>
		<li>Start anteriorly and proceed around the joint by carefully rotating the leg and transecting the ligaments, thereby disarticulating the joint.</li>
	</ol>
	</li>
	<li>Wash femur and tibia with 96% ethanol for a minimum of 90 sec to guarantee aseptic cell preparation. Continue the washing process with sterile PBS to rinse off remaining ethanol. 
	Note: All subsequent steps must be sterile to avoid contamination.</li>
</ol>
1.2 Harvesting of Bone Marrow
<ol>
	<li>Cut the proximal and distal end of each bone with a pair of fine scissors to gain access to the femoral and tibial shafts. Be careful with this step, since these bones break very easily.</li>
	<li>Flush the bones with warm medium (M199 + 10% fetal calf serum (FCS), + 1% Penicillin/Streptomycin). Use a sterile 28-G needle, a 1 ml syringe, and between 10-15 ml medium per bone for rinsing.</li>
	<li>Hold the bone with a fine forceps and rinse one by one until it turns semi-translucent. Carefully apply pressure to the end of the syringe plunger in order to minimize cell stress.</li>
	<li>Filter the bone marrow through a 70 &#181;m nylon web and gather the filtrate. To extract the maximum quantity of bone marrow, rinse repeatedly from the distal and proximal ends.</li>
	<li>Rinse the sieve with PBS and gather the filtrate. Carefully dislodge debris and cellular conglomerates by gentle stirring and pipetting.</li>
</ol>
1.3 Cultivation
<ol>
	<li>Centrifuge the cell suspension at 250 x g for 10 min at RT. Discard the supernatant and resuspend the cells with approximately 25 ml of medium. Repeat once.</li>
	<li>Resuspend the cells in 6 ml of medium after the second washing step. Mix 50 &#181;l of the cell solution with 50 &#181;l of trypan blue. Count the cells in a counting chamber under a light microscope. Calculate the number of cells in the solution using this formula: 
	<img alt="Equation 1" fo:content-width="1.3in" src="/files/ftp_upload/52347/52347eq1.jpg" /></li>
	<li>Seed the cells on 6-well ultra-low-attachment surface plates to prevent permanent adhesion to the bottom of the plate. Use a concentration of 106 cells per ml with up to 6 ml per well.</li>
	<li>Supplement the suspension with 20 ng/ml M-CSF to promote cell differentiation.</li>
	<li>Culture the cells for 5 days at 37 &#176;C and 5% carbon dioxide and observe daily.</li>
</ol>
1.4 Harvesting of Cells
Note: These steps should be performed on ice. Proceed with either 1.4.1 or 1.4.2 accordingly.
<ol>
	<li>At this point, harvest the entire culture, including differentiated macrophages that will adhere to the culture-plates, even if they are ultra-low-attachment surface plates.
	<ol>
		<li>Harvest the entire culture by gentle pipetting and detaching with a solution of 4 &#176;C PBS, 0.5% bovine serum albumin (BSA) and 2 mM EDTA. Repeat until the plates are clear of remaining adherent cells - confirm under a microscope if unsure.</li>
	</ol>
	</li>
	<li>Alternatively, discard adherent macrophages by harvesting the supernatant with the cells in suspension, which predominantly contain monocytes.
	<ol>
		<li>Harvest the non-adherent cells with a solution of EDTA-free PBS and 0.5% BSA. Do not apply too much force in order to avoid dislodging mildly adherent macrophages.</li>
	</ol>
	</li>
</ol>
1.5 FACS-Analysis (Optional)
Note: It is possible to deplete the cell suspension of CD117+ stem- and progenitor cells by the use of MACS. Use manufacturer protocols for this procedure.
<ol>
	<li>Harvest the cells according to either steps 1.4.1 or 1.4.2.</li>
	<li>Centrifuge the cells at 250 x g for 10 min at 4 &#176;C and repeat this step again.</li>
	<li>Resuspend at least 250,000 cells in 300 &#181;l of FACS buffer per probe.</li>
	<li>Transfer cell solution onto a 96-well-plate (30 &#181;l per well).</li>
	<li>Centrifuge the cell suspension at 250 x g for 5 min at 4 &#176;C.</li>
	<li>Remove the supernatant and add 25 &#181;l of antibody to each well (use manufacturer dilution).</li>
	<li>Stain the cells with antibodies (following manufacturer protocols for cell phenotyping after steps 1.5.1-1.5.6. Commonly used markers for monocyte / macrophage identification include CD11b, F4/80 (Figure 3), CD115 (Figure 2), and Gr-1. 
	Note: For a further description of cell solutions, the use of markers like CD4, CD8a, CD11c, CD25, CD45, CD45R, CD62L, CD80, CD86, CD145, CD117, MHC&#8545;, Ly6C, Ly6G, and CD192 is recommended. Cellular characteristics were previously described12.</li>
	<li>Incubate the probes for 20 min at 4 &#176;C.</li>
	<li>Centrifuge the probes at 250 x g for 5 min at 4 &#176;C and resuspend with 200 &#181;l of FACS buffer. Repeat this step twice.</li>
	<li>Transfer the probes into FACS tubes and perform the FACS analysis12.</li>
	<li>Perform FACS analysis12 on day 0, 3 and 5 to analyze cell differentiation.</li>
</ol>
2. Tail Vein Injection
2.1 Preparation
<ol>
	<li>Warm the animals on a heating plate at 37 &#176;C for about 10 min. Observe the animals while warming to recognize signs of overheating.</li>
	<li>Resuspend the monocytes, isolated in steps 1.1- 1.4, in 150 &#181;l of NaCl, and load the cells into a 1 ml insulin syringe with a 30G needle. Lightly vortex the solution before loading the syringe to ensure all monocytes are injected. Always handle cells on ice to avoid heat-mediated attachment and activation of monocytes.</li>
</ol>
2.2 Restraining
<ol>
	<li>Avoid disturbing other mice in the cage when choosing a mouse for intravenous injection.</li>
	<li>Place the mouse into the restrainer. Avoid too much pressure and be careful with the hind limbs. (Figure 4) 
	Note: Alternatively, use general anesthesia to guarantee stress free handling of the animals.</li>
	<li>Ensure that the mouse has space for breathing before closing the restrainer.</li>
</ol>
2.3 Injection
<ol>
	<li>Disinfect the injection site with disinfection agent. Spray on the tail of the mouse and let stand for at least 1 min.</li>
	<li>Stop venous blood flow of the tail by applying gentle pressure to the lateral tail side above the injection site, for better visibility of the veins.</li>
	<li>Turn the tail 90 degrees, before injection. (Figure 5)</li>
	<li>Inject at a 45 degree angle. Inject slowly and no more than 5 &#181;l per g to avoid harming animals.</li>
	<li>If there is a blister, which is a sign of a failed injection, discontinue immediately and repeat the injection more proximally.</li>
	<li>Stop the bleeding at the injection side by applying gentle pressure for about 1 min.</li>
	<li>At the end of the procedure, open the retractor and place the mouse in its cage.</li>
	<li>Observe the mouse for 20 min to ensure that the animal was not harmed by the injection and sternal recumbency is maintained. Extend the time of observation until the mouse regains sufficient consciousness. Return the mouse to the company of other animals only after it has fully recovered.</li>
</ol>

<ol>
	<li>Herold, J., 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=Transplantation+of+monocytes:+a+novel+strategy+for+in+vivo+augmentation+of+collateral+vessel+growth.">Transplantation of monocytes: a novel strategy for in vivo augmentation of collateral vessel growth.</a> Hum Gene Ther. 15 (1), 1-12 (2004).</li><li>Herold, J., Tillmanns, H., Xing, Z., Strasser, R. H., Braun-Dullaeus, R. C. <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+transduction+of+monocytes:+promising+vehicles+for+therapeutic+arteriogenesis.">Isolation and transduction of monocytes: promising vehicles for therapeutic arteriogenesis.</a> Langenbecks Arch Surg. 391 (2), 72-82 (2006).</li><li>Francke, A., Weinert, S., Strasser, R. H., Braun-Dullaeus, R. C., Herold, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transplantation+of+bone+marrow+derived+monocytes:+a+novel+approach+for+augmentation+of+arteriogenesis+in+a+murine+model+of+femoral+artery+ligation.">Transplantation of bone marrow derived monocytes: a novel approach for augmentation of arteriogenesis in a murine model of femoral artery ligation.</a> American Journal Of Translational Research. 5 (2), 155-169 (2013).</li><li>Leon, 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=Dendritic+cell+differentiation+potential+of+mouse+monocytes:+monocytes+represent+immediate+precursors+of+CD8-+and+CD8++splenic+dendritic+cells.">Dendritic cell differentiation potential of mouse monocytes: monocytes represent immediate precursors of CD8- and CD8+ splenic dendritic cells.</a> Blood. 103 (7), 2668-2676 (2004).</li><li>Timmerman, J. M., Levy, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendritic+cell+vaccines+for+cancer+immunotherapy.">Dendritic cell vaccines for cancer immunotherapy.</a> Annu Rev Med. 50, 507-529 (1999).</li><li>Salem, 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=The+use+of+dendritic+cells+for+Peptide-based+vaccination+in+cancer+immunotherapy.">The use of dendritic cells for Peptide-based vaccination in cancer immunotherapy.</a> Methods Mol Biol. 1139, 479-503 (2014).</li><li>Timmerman, J. 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=Idiotype-pulsed+dendritic+cell+vaccination+for+B-cell+lymphoma:+clinical+and+immune+responses+in+35+patients.">Idiotype-pulsed dendritic cell vaccination for B-cell lymphoma: clinical and immune responses in 35 patients.</a> Blood. 99 (5), 1517-1526 (2002).</li><li>Berthold, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+human+monocytes+by+Ficoll+density+gradient+centrifugation.">Isolation of human monocytes by Ficoll density gradient centrifugation.</a> Blut. 43 (6), 367-371 (1981).</li><li>Houthuys, E., Movahedi, K., De Baetselier, P., Van Ginderachter, J. A., Brouckaert, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+the+isolation+and+purification+of+mouse+peripheral+blood+monocytes.">A method for the isolation and purification of mouse peripheral blood monocytes.</a> Journal Of Immunological Methods. 359 (1-2), 1-10 (2010).</li><li>Seeger, F. H., Tonn, T., Krzossok, N., Zeiher, A. M., Dimmeler, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+isolation+procedures+matter:+a+comparison+of+different+isolation+protocols+of+bone+marrow+mononuclear+cells+used+for+cell+therapy+in+patients+with+acute+myocardial+infarction.">Cell isolation procedures matter: a comparison of different isolation protocols of bone marrow mononuclear cells used for cell therapy in patients with acute myocardial infarction.</a> European Heart Journal. 28 (6), 766-772 (2007).</li><li>Auffray, 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=CX3CR1++CD115++CD135++common+macrophage/DC+precursors+and+the+role+of+CX3CR1+in+their+response+to+inflammation.">CX3CR1+ CD115+ CD135+ common macrophage/DC precursors and the role of CX3CR1 in their response to inflammation.</a> The Journal Of Experimental Medicine. 206 (3), 595-606 (2009).</li><li>Francke, A., Herold, J., Weinert, S., Strasser, R. H., Braun-Dullaeus, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+mature+murine+monocytes+from+heterogeneous+bone+marrow+and+description+of+their+properties.">Generation of mature murine monocytes from heterogeneous bone marrow and description of their properties.</a> J. Histochem. Cytochem. 59 (9), 813-825 (2011).</li><li>Sneider, E. B., Nowicki, P. T., Messina, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regenerative+medicine+in+the+treatment+of+peripheral+arterial+disease.">Regenerative medicine in the treatment of peripheral arterial disease.</a> Journal Of Cellular Biochemistry. 108 (4), 753-761 (2009).</li><li>Van Royen, N., Piek, J. J., Schaper, W., Fulton, W. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+critical+review+of+clinical+arteriogenesis+research.">A critical review of clinical arteriogenesis research.</a> J Am Coll Cardiol. 55 (1), 17-25 (2009).</li><li>Lawall, H., Bramlage, P., Amann, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Treatment+of+peripheral+arterial+disease+using+stem+and+progenitor+cell+therapy.">Treatment of peripheral arterial disease using stem and progenitor cell therapy.</a> J Vasc Surg. 53 (2), 445-453 (2011).</li><li>Herold, J., 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=Tetanus+toxoid-pulsed+monocyte+vaccination+for+augmentation+of+collateral+vessel+growth.">Tetanus toxoid-pulsed monocyte vaccination for augmentation of collateral vessel growth.</a> Journal of the American Heart Association. 3 (2), e000611 (2014).</li></ol>

The authors declare that they have no competing financial interests.

We describe a simple and cost-effective method to isolate large amounts of murine monocytes from bone marrow. In comparison to other protocols using peripheral blood, which obtain monocyte yields5 of 1.4 x106, we are able to obtain higher yields of 11 x 106 &#177; 3 x 106 monocytes from a single donor mouse.
When considering challenges with this method, it is important to mention the potential for contamination when working under non-sterile conditio...

The isolation of monocytes is important and critical for many in vitro and in vivo studies. These cells are targets for diseases such as peripheral arterial disease, coronary heart disease, or other ischemic diseases, since collateral vessel growth is strongly driven by local inflammation. Inflammatory responses include endothelial activation and local recruitment of leukocytes, mainly monocytes, which then mature to macrophages and create a highly arteriogenic environment by secreting multiple growth factors to induce the remodeling of an arteriole into a functional collateral artery1-3. Monocytes also mature to dendritic cells, which are frequently used for immunological studies4,5 and cancer research6,7.
Problematic in the approach for monocyte isolation from peripheral blood8 is the high number of donor animals needed to produce a sufficient amount of monocytes for most analyses. Former protocols describe methods such as density gradient centrifugation and cell depletion via MACS9 when isolating monocytes; however, these techniques can alter the characteristics and functionality of monocytes which can lead to difficulties in interpretation10,11. Moreover, these methods are difficult and can reduce experimental reproducibility.
Our aim with this protocol is to provide a simple and cost effective method to generate large amounts of bone marrow-derived monocytes. Due to the high cell yield of 11 x 106 &#177; 3 x 106 cells obtained by this protocol, we can substantially reduce the number of mice required during the isolation of bone marrow-derived monocytes. The procedure can be completed within a minimal amount of time, and without using expensive and complicated techniques as referenced above. Here, we extract monocytes from native bone marrow suspension of donor mice, cultivate the suspension on ultralow attachment plates, and supplement the solution with 20 ng/ml M-CFS. On day 5 of incubation, cells are harvested and characterized to confirm functional and phenotypic properties.
For experiments in the field of arteriogenesis, intravenous transplantation of these bone marrow-derived monocytes into mice is an effective method of systemic drug delivery, which can be combined with femoral artery ligation in common peripheral arterial disease models.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>6-well-ultra-low-attachment plate</td>
			<td>Corning Incorporated, NY, USA</td>
			<td></td>
			<td>6-well-ultra-low-attachment plate, with cap, sterile</td>
		</tr>
		<tr>
			<td>8- 12 week old, male, balb/c mice&#160;</td>
			<td>Charles River, Sulzfeld, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>96-well-plate</td>
			<td>Greiner bio one GmbH, Frickenhausen, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Blue dead cell stain</td>
			<td>Life technologies GmbH, Darmstadt, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine serum albumine</td>
			<td>GE Healthcare, Freiburg, Germany</td>
			<td></td>
			<td>Fraction V, pH 7,0</td>
		</tr>
		<tr>
			<td>Canules</td>
			<td>B. Braun, Melsungen AG, Melsungen, Germany</td>
			<td></td>
			<td>28G, 30G</td>
		</tr>
		<tr>
			<td>CD115</td>
			<td>eBioscience, San Diego, USA</td>
			<td>12-1152</td>
			<td></td>
		</tr>
		<tr>
			<td>CD11b</td>
			<td>eBioscience, San Diego, USA</td>
			<td>53-0112</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture dish</td>
			<td>Greiner Bio-One GmbH, Frickenhausen, Germany</td>
			<td></td>
			<td>With cap, steril</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Beckman Coulter GmbH, Krefeld, Germany</td>
			<td></td>
			<td>Allegra&#174; X-15R centrifuge</td>
		</tr>
		<tr>
			<td>Depilatory cream</td>
			<td>Veet, Mannheim, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Disinfection agent</td>
			<td>Sch&#252;lke&#38;Mayr GmbH, Norderstedt, Germany</td>
			<td></td>
			<td>Kodan Tinktur forte</td>
		</tr>
		<tr>
			<td>Disposable scalpel No.10&#160;</td>
			<td>Feather safety razor Co.Ltd, Osaka, Japan&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol 96%&#160;</td>
			<td>Otto Fischar GmbH und Co KG, Saarbr&#252;cken, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Extraction unit Pipetus</td>
			<td>Hirschmann Laborger&#228;te GmbH &#38; Co.KG, Eberstadt, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>F4/80</td>
			<td>AbD Serotec, D&#252;sseldorf, Germany</td>
			<td>MCA497APC</td>
			<td></td>
		</tr>
		<tr>
			<td>FACS buffer&#160;</td>
			<td>Manufactured by our group with single components</td>
			<td></td>
			<td>PBS, 0,5% BSA, 0,1% NaN3</td>
		</tr>
		<tr>
			<td>FACS device</td>
			<td>Becton, Dickinson and Company, Franklyn Lakes, New Jersey, USA</td>
			<td></td>
			<td>BD FACS Canto II</td>
		</tr>
		<tr>
			<td>FACS tubes&#160;&#160;&#160;&#160;</td>
			<td>Becton, Dickinson and Company, Franklyn Lakes, New Jersey, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon&#174; pipette</td>
			<td>Becton Dickenson Labware, NY, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal calf serum</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fine forceps</td>
			<td>Rubis, Stabio, Switzerland</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gloves</td>
			<td>R&#246;sner-Matby Meditrade GmbH, Kiefersfelden, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gr1</td>
			<td>eBioscience, San Diego, USA</td>
			<td>53-5931</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating plate&#160;</td>
			<td>Labotect GmbH, G&#246;ttingen, Germany&#160;</td>
			<td></td>
			<td>Hot Plate 062</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Ewald Innovationstechnik GmbH, Bad Nenndorf, Germany</td>
			<td></td>
			<td>Incu safe</td>
		</tr>
		<tr>
			<td>Isofluran</td>
			<td>Baxter Deutschland GmbH, Unterschlei&#223;heim, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Light microscope</td>
			<td>Carl Zeiss SMT GmbH, Oberkochen, Germany</td>
			<td></td>
			<td>Axiovert 40 &#176;C</td>
		</tr>
		<tr>
			<td>Macrophage-Colony Stimulating Factor</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/srp3110?lang=de&amp;region=DE">SRP3110&#160;</a></td>
			<td></td>
		</tr>
		<tr>
			<td>Mechanical shaker</td>
			<td>IKA, Staufen, Germany</td>
			<td></td>
			<td>ms2 minishaker</td>
		</tr>
		<tr>
			<td>Medium 199</td>
			<td>PAA Laboratories GmbH, Pasching, Austria</td>
			<td></td>
			<td>Warm in 37 &#176;C water bath before use</td>
		</tr>
		<tr>
			<td>Micro test tubes</td>
			<td>Eppendorf AG, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microbiological work bench</td>
			<td>Thermo Electron, LED GmbH, Langenselbold, Germany</td>
			<td></td>
			<td>Hera safe</td>
		</tr>
		<tr>
			<td>Monocyte wash buffer&#160;</td>
			<td>Manufactured by our group with single components</td>
			<td></td>
			<td>PBS, 0,5% BSA, 2mM EDTA</td>
		</tr>
		<tr>
			<td>Mouse restrainer</td>
			<td>Various</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Berlin Chemie AG, Berlin, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NaN3 (sodium acide)</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Neubauer counting chamber</td>
			<td>Paul Marienfeld GmbH und Co.KG, Lauda-K&#246;nigshofen, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon cellsieve</td>
			<td>Becton, Dickinson and Company, Franklyn Lakes, New Jersey, USA</td>
			<td></td>
			<td>Cell strainer, 70 &#181;m mesh size</td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline</td>
			<td>Life technologies GmbH, Darmstadt, Germany</td>
			<td></td>
			<td>pH 7.4, sterile</td>
		</tr>
		<tr>
			<td>Pipettes</td>
			<td>Eppendorf AG, Hamburg, Germany</td>
			<td></td>
			<td>10&#181;L/100&#181;L/200&#181;L/1000&#181;L</td>
		</tr>
		<tr>
			<td>Pipetting heads</td>
			<td>Eppendorf AG, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipette</td>
			<td>Greiner Bio-One GmbH, Frickenhausen, Germany</td>
			<td></td>
			<td>Cellstar 5 ml, 10 ml</td>
		</tr>
		<tr>
			<td>Suction unit</td>
			<td>Integra bioscience, Fernwald, Germany</td>
			<td></td>
			<td>Vacusafe comfort</td>
		</tr>
		<tr>
			<td>Surgical scissors</td>
			<td>Word Precision Instruments, Inc., Sarasota, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe</td>
			<td>B. Braun, Melsungen AG, Melsungen, Germany</td>
			<td></td>
			<td>1mL Omnifix&#174; -F insuline syringe</td>
		</tr>
		<tr>
			<td>Tubes with cap</td>
			<td>Greiner bio one GmbH, Frickenhausen, Germany</td>
			<td></td>
			<td>15mL/50mL Cellstar tubes</td>
		</tr>
		<tr>
			<td>Warm water bath</td>
			<td>Julabo Labortechnik GmbH, Seelbach, Germany</td>
			<td></td>
			<td>Julabo SW22</td>
		</tr>
	</tbody>
</table>

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.

The cell solution extracted from the murine bone marrow consists of various cell types. The major cell types are lymphocytes, granulocytes and monocytes. Cell types can be estimated by size and granularity, which is shown in Figure 1 for both native suspensions and cells harvested after 5 days of differentiation. Note the shifting cellular composition during cultivation. However, accurate classification of populations must rely on distinctive expression of cellular markers.
Th...

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Isolation and Intravenous Injection of Murine Bone Marrow Derived Monocytes

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 ...

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Immunology and Infection

23.5K Views.  Otto von Guericke University Magdeburg. 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).

Video: Isolation and Intravenous Injection of Murine Bone Marrow Derived Monocytes

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 ...

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.

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 ...

Tracking Mouse Bone Marrow Monocytes In Vivo

Real time multiphoton imaging provides a great opportunity to study cell trafficking and cell-to-cell interactions in their physiological 3-dimensionnal environment. Biological activities of immune cells mainly rely on their motility capacities. Blood monocytes have short half-life in the bloodstream; they originate in the bone marrow and are constitutively released from it. In inflammatory condition, this process is enhanced, leading to blood monocytosis and subsequent infiltration of the peripheral inflammatory tissues. Identifying the biomechanical events controlling monocyte trafficking from the bone marrow towards the vascular network is an important step to understand monocyte physiopathological relevance. We performed in vivo time-lapse imaging by two-photon microscopy of the skull bone marrow of the Csf1r-Gal4VP16/UAS-ECFP (MacBlue) mouse. The MacBlue mouse expresses the fluorescent reporters enhanced cyan fluorescent protein (ECFP) under the control of a myeloid specific promoter 1, in combination with vascular network labelling. We describe how this approach enables the tracking of individual medullar monocytes in real time to further quantify the migratory behaviour within the bone marrow parenchyma and the vasculature, as well as cell-to-cell interactions. This approach provides novel insights into the biology of the bone marrow monocyte subsets and allows to further address how these cells can be influenced in specific pathological conditions.

Tracking Mouse Bone Marrow Monocytes In Vivo

Monocytes are key regulators of innate immunity and play a critical role in the renewal of the peripheral mononuclear phagocytic system and in case of inflammation. This manuscript describes the procedure of real time imaging of the mouse calvaria bone marrow to study the monocyte mobilisation mechanism.

Real time multiphoton imaging provides a great opportunity to study cell trafficking and cell-to-cell interactions in their physiological 3-dimensionnal ...

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, ...

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 ...

Identification and Isolation of Oligopotent and Lineage-committed Myeloid Progenitors from Mouse Bone Marrow

Myeloid progenitors that yield neutrophils, monocytes and dendritic cells (DCs) can be identified in and isolated from the bone marrow of mice for hematological and immunological analyses. For example, studies of the cellular and molecular properties of myeloid progenitor populations can reveal mechanisms underlying leukemic transformation, or demonstrate how the immune system responds to pathogen exposure. Previously described flow cytometry strategies for myeloid progenitor identification have enabled significant advances in many fields, but the fractions they identify are very heterogeneous. The most commonly used gating strategies define bone marrow fractions that are enriched for the desired populations, but also contain large numbers of &#34;contaminating&#34; progenitors. Our recent studies have resolved much of this heterogeneity, and the protocol we present here permits the isolation of 6 subpopulations of oligopotent and lineage-committed myeloid progenitors from 2 previously described bone marrow fractions. The protocol describes 3 stages: 1) isolation of bone marrow cells, 2) enrichment for hematopoietic progenitors by magnetic-activated cell sorting (lineage depletion by MACS), and 3) identification of myeloid progenitor subsets by flow cytometry (including fluorescence-activated cell sorting, FACS, if desired). This approach permits progenitor quantification and isolation for a variety of in vitro and in vivo applications, and has already yielded novel insight into pathways and mechanisms of neutrophil, monocyte, and DC differentiation.

We demonstrate how to identify and isolate 6 subsets of myeloid progenitors from murine bone marrow using a combination of magnetic and fluorescence sorting (MACS and FACS). This protocol can be used for in vitro culture assays (methylcellulose or liquid cultures), in vivo adoptive transfer experiments, and RNA/protein analyses.

Myeloid progenitors that yield neutrophils, monocytes and dendritic cells (DCs) can be identified in and isolated from the bone marrow of mice for ...

Isolation of Lamina Propria Mononuclear Cells from Murine Colon Using Collagenase E

The intestine is the home to the largest number of immune cells in the body. The small and large intestinal immune systems police exposure to exogenous antigens and modulate responses to potent microbially derived immune stimuli. For this reason, the intestine is a major target site of immune dysregulation and inflammation in many diseases including but, not limited to inflammatory bowel diseases such as Crohn&#8217;s disease and ulcerative colitis, graft-versus-host disease (GVHD) after bone marrow transplantation (BMT), and many allergic and infectious conditions. Murine models of gastrointestinal inflammation and colitis are heavily used to study GI complications and to pre-clinically optimize strategies for prevention and treatment. Data gleaned from these models via isolation and phenotypic analysis of immune cells from the intestine is critical to further immune understanding that can be applied to ameliorate gastrointestinal and systemic inflammatory disorders. This report describes a highly effective protocol for the isolation of mononuclear cells (MNC) from the colon using a mixed silica-based density gradient interface. This method reproducibly isolates a significant number of viable leukocytes while minimizing contaminating debris, allowing subsequent immune phenotyping by flow cytometry or other methods.

The goal of this protocol is to isolate mononuclear cells that reside in the lamina propria of the colon by enzymatic digestion of the tissue using collagenase. This protocol allows for the efficient isolation of mononuclear cells resulting in a single cell suspension which in turn can be used for robust immunophenotyping.

The intestine is the home to the largest number of immune cells in the body. The small and large intestinal immune systems police exposure to exogenous ...