This project was made possible by funding provided from the Children&#39;s Discovery Institute of Washington University and St. Louis Children&#39;s Hospital (CH-II-2015-462, CH-II-2017-628), Foundation of Barnes-Jewish Hospital (8038-88), and the NHLBI (R01 HL138466, R01 HL139714). K.J.L. is supported by NIH K08 HL123519 and Burroughs Welcome Fund (1014782).

The protocol presented has been approved by the Washington University in St. Louis Institutional Review Board (#201305086). All subjects provide informed consent before sample collection and the experiments are performed in accordance with the approved study protocol. The presented protocol is performed with the approval of the Institutional Animal Care and Use Committee at Washington University School of Medicine and follows the guidelines described in the NIH Guide for the Care and Use of Laboratory Animals.
1. Preparation of Human Cardiac Tissue Specimens
<ol>
	<li>Flush explanted hearts by cannulating the left and right coronary artery ostia and perfuse with 200 mL of cold saline.</li>
	<li>Flush LVAD apical cored tissues by cannulating an epicardial vessel and perfuse with 50 mL of cold saline.</li>
	<li>Dissect tissue specimen from the apical or lateral wall of the left ventricle in cold saline or HBSS using a sterile scissor.</li>
	<li>Carefully dissect out epicardial fat and chordae tendineae from the specimen using fine scissors.</li>
	<li>Dissect tissue chunks into pieces weighing approximately 200 mg with help of a sterile blade or scissors.</li>
</ol>
2. Preparation of Mouse Heart
<ol>
	<li>Euthanize the mouse by CO2 asphyxiation or cervical dislocation.</li>
	<li>Open the chest cavity with the help of sharp scissors. Use blunt hemostats to lift the heart upwards. Perfuse the heart with cold PBS using a 25 G needle attached to a 5 mL syringe. Perfuse until heart appears blanched in color.</li>
	<li>Remove the heart and place in a sterile Petri dish on ice.</li>
</ol>
3. Preparation of Single Cell Suspension
<ol>
	<li>Place human cardiac tissue chunks (~200 mg) or murine heart in a sterile Petri dish. Finely mince the tissue using a sterile blade or scissors.</li>
	<li>Set up the digestions:
	<ol>
		<li>Use a final digestion volume of 3 mL per human cardiac tissue chunk (200 mg) or per one murine heart. Final enzyme concentrations are as follows: Collagenase1 (450 U/mL), DNase1 (60 U/mL), Hyaluronidase (60 U/mL).</li>
		<li>For each digestion reaction add DMEM and all enzymes to a 15 mL conical tube. With the help of clean forceps, place the finely minced tissue into each reaction tube. Mix well by gentle vortexing.</li>
	</ol>
	</li>
	<li>Digest for 1 h at 37 &#176;C in a shaking incubator set to a low to medium agitation speed.</li>
	<li>After 1 h of digestion, take the tubes out from the incubator and place on ice. Set up 50 mL conical tubes with a 40 &#181;m cell strainer on top. Wet the filters with 2 mL of enzyme deactivating (ED) buffer.</li>
	<li>Deactivate the digestion enzymes by adding 8 mL of ED buffer to each digestion tube. Then pour the resulting 13 mL total mixture through the 40 &#181;m cell strainer into the 50 mL conical tubes. Transfer the samples back in fresh 15 mL conical tube. This enables optimal cell pelleting and minimizes cell loss during centrifugation.</li>
	<li>Spin the samples at 400 x g for 6 min (Centrifuge set at 4 &#176;C). Discard the supernatant leaving 0.5 mL of media. Resuspend the cell pellet by gentle pipetting and add 1 mL of ACK lysis buffer. Gently swirl the tube and incubate at room temperature for 5 min to perform red blood cell (RBC) lysis.</li>
	<li>After 5 min in ACK buffer, add 9 mL of DMEM to the sample. Put the lid back on to the tubes and gently invert the tubes to mix, and filter through a 40 &#181;m cell strainer. Collect the filtrate in 15 mL conical tubes.</li>
	<li>Centrifuge the tubes at 400 x g for 6 min and discard the supernatant.</li>
	<li>Add 1 mL of FACS buffer and resuspend the pellet. Then transfer in the cells in FACS buffer to a 1.5 mL microcentrifuge tube. Centrifuge again at 400 x g for 5 min. Discard the supernatant and resuspend the pellet in 100 &#181;L of FACS Buffer. A single cell suspension is now ready for antibody staining.</li>
</ol>
4. Antibody Staining
<ol>
	<li>A typical human antibody panel consists of the following antibodies: CD45-PercpCy5.5, CD14-PE, CD64-FITC, HLA-DR-APC/Cy7, CCR2-APC. Please refer to Table 1. Add all antibodies to the heart samples at 1:50 dilution and incubate for ~30-40 min at 4 &#176;C in the dark. Proceed to step 4.4 below.</li>
	<li>For stromal cells (endothelial cells, fibroblast, smooth muscle cells), add DRAQ5 (1 &#181;M final concentration) and CD45-percpCy5.5. Please refer to Table 1. Incubate for 30 min at 4 &#176;C in the dark. Proceed to step 4.4 below.</li>
	<li>For murine heart macrophages add the following antibodies: CD45-PercpCy5.5, CD64-APC, MHCII-APC/Cy7, CCR2-BV421, and Ly6G-FITC. Please refer to Table 2. Add all antibodies to the heart samples at 1:100 dilution and incubate for ~30-40 min at 4 &#176;C in the dark. Proceed to step 4.4 below.</li>
	<li>Wash the samples twice in FACS buffer. For each wash, add 1 mL of FACS buffer, gently vortex, and centrifuge at 400 x g for 5 min, resuspend in 350 &#181;L of FACS buffer and add DAPI (1 &#181;M, final concentration). Samples are now ready for FACS analysis/sorting.</li>
</ol>

<ol>
	<li>Pinto, A. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+abundant+tissue+macrophage+population+in+the+adult+murine+heart+with+a+distinct+alternatively-activated+macrophage+profile.">An abundant tissue macrophage population in the adult murine heart with a distinct alternatively-activated macrophage profile.</a> PLoS One. 7 (5), e36814 (2012).</li><li>Hulsmans, 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=Macrophages+facilitate+electrical+conduction+in+the+heart.">Macrophages facilitate electrical conduction in the heart.</a> Cell. 169 (3), 510-522 (2017).</li><li>Hulsmans, 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=Cardiac+macrophages+promote+diastolic+dysfunction.">Cardiac macrophages promote diastolic dysfunction.</a> Journal of Experimental Medicine. 215 (2), 423-440 (2018).</li><li>Aurora, A. 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=Macrophages+are+required+for+neonatal+heart+regeneration.">Macrophages are required for neonatal heart regeneration.</a> Journal of Clinical Investigation. 124 (3), 1382-1392 (2014).</li><li>Lavine, K. 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=Distinct+macrophage+lineages+contribute+to+disparate+patterns+of+cardiac+recovery+and+remodeling+in+the+neonatal+and+adult+heart.">Distinct macrophage lineages contribute to disparate patterns of cardiac recovery and remodeling in the neonatal and adult heart.</a> Proceedings of the National Academy of Sciences of the United States of America. 111 (45), 16029-16034 (2014).</li><li>Epelman, S., 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=Embryonic+and+adult-derived+resident+cardiac+macrophages+are+maintained+through+distinct+mechanisms+at+steady+state+and+during+inflammation.">Embryonic and adult-derived resident cardiac macrophages are maintained through distinct mechanisms at steady state and during inflammation.</a> Immunity. 40 (1), 91-104 (2014).</li><li>Leid, 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=Primitive+embryonic+macrophages+are+required+for+coronary+development+and+maturation.">Primitive embryonic macrophages are required for coronary development and maturation.</a> Circulation Research. 118 (10), 1498-1511 (2016).</li><li>Bajpai, 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=The+human+heart+contains+distinct+macrophage+subsets+with+divergent+origins+and+functions.">The human heart contains distinct macrophage subsets with divergent origins and functions.</a> Nature Medicine. 24 (8), 1234-1245 (2018).</li><li>Dick, S. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-renewing+resident+cardiac+macrophages+limit+adverse+remodeling+following+myocardial+infarction.">Self-renewing resident cardiac macrophages limit adverse remodeling following myocardial infarction.</a> Nature Immunology. 20, 29-39 (2019).</li><li>Nahrendorf, 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=The+healing+myocardium+sequentially+mobilizes+two+monocyte+subsets+with+divergent+and+complementary+functions.">The healing myocardium sequentially mobilizes two monocyte subsets with divergent and complementary functions.</a> Journal of Experimental Medicine. 204 (12), 3037-3047 (2007).</li></ol>

Authors have nothing to disclose.

The protocol allows for the extraction of various macrophage subsets from human myocardium. The protocol is simple and takes 3 to 4 hours to prepare single cell suspension ready for FACS analysis. Although the protocol is relatively simple to perform, there are certain technical aspects that need to be considered which will minimize variability. Firstly, working in timely fashion with human tissue is necessary for optimal cell viability. It is important to keep the tissue in cold saline/HBSS to minimize cell death. It is...

Macrophages represent the most abundant immune cell type in the heart, and they play significant roles in generating robust inflammatory and reparative responses following cardiac injury1,2,3,4. Previously, our group identified two major subsets of macrophages in the murine heart derived from distinct developmental origins5,6. Broadly, distinct populations of tissue resident cardiac macrophage subsets can be identified based on the cell surface expression of CCR2 (C-C motif chemokine receptor 2). CCR2- macrophages (cell surface expression: CCR2-MHCIIlow and CCR2-MHCIIhigh) are of embryonic origin (primitive and erythromyeloid lineages), able to self-renew, and represent a dominant population under homeostatic conditions. Resident CCR2+ macrophages are of definitive hematopoietic origin, are maintained through recruitment from circulating monocytes, and represent a minor population under homeostatic conditions. Functionally, CCR2- macrophages generate minimal inflammation and are critical for coronary development neonatal heart regeneration5,7. In contrast, CCR2+ macrophages initiate robust inflammatory responses following cardiac insults and contribute to collateral cardiomyocyte injury, adverse remodeling of the left ventricle, and heart failure progression8,9.
Recently, we have shown that the human myocardium also contains two distinct subsets of macrophages identified similarly as either CCR2- or CCR2+8. Gene expression and functional analyses revealed that human CCR2- and CCR2+ macrophages represent functionally divergent subsets and are functionally analogous to CCR2- and CCR2+ macrophages found in the mouse heart. Human CCR2- macrophages express robust levels of growth factors, including IGF1, PDGF, Cyr61, and HB-EGF. CCR2+ macrophages are enriched in chemokines and cytokines that promote inflammation, such as IL-1b, IL-6, CCL-2, CCL-7, and TNF-a. Stimulated CCR2+ macrophages secrete markedly higher levels of the inflammatory cytokine interleukin-1&#946; (IL-1&#946;) in culture. How these subsets differentially contribute to tissue repair and left ventricular (LV) remodeling in the context of cardiac injury remains an area of active research.
Flow-cytometry based analysis of macrophage heterogeneity in the mouse and human heart requires digesting the cardiac tissue and generating a single cell suspension followed by flow cytometric analysis or cell sorting for further downstream processes such as bulk RNA sequencing/single cell RNA sequencing or culturing the cells for functional assays. The original protocol for making a single cell suspension from murine hearts were first reported by Nahrendorf group in Nahrendorf et al. 200710. Our lab has adapted and modified the protocol to extract macrophages from the human myocardium. Using the same protocol but with slight modification in staining and gating scheme, CD45- stromal cells from the human myocardium can also be harvested. Presented here, in text and video, is a protocol that is performed routinely for the extraction of macrophages or stromal from the human myocardium.
Cardiac tissue specimens are obtained from adult patients with dilated cardiomyopathy (DCM: idiopathic or familial) or ischemic cardiomyopathy (ICM) undergoing left ventricular assist device (LVAD) implantation or cardiac transplantation. Explanted hearts or LVAD cores are intravascularly perfused with cold saline prior to starting the digestion procedure. It is important to note that &#34;quality&#34; of tissue specimen determined in terms of degree of scarring or adipose tissue infiltration can greatly affect the yield of macrophages. Heart specimens with large areas of scarring will have much lower cell yield and can pose serious technical limitation when desired downstream analysis methods require in vitro cell culturing.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15 mL Conocal Tubes</td>
			<td>Thermo Fisher</td>
			<td>14-959-53A</td>
			<td></td>
		</tr>
		<tr>
			<td>40 &#181;m Cell Strainers</td>
			<td>Thermo Fisher</td>
			<td>50-828-736</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Conical Tubes</td>
			<td>Thermo Fisher</td>
			<td>352098</td>
			<td></td>
		</tr>
		<tr>
			<td>ACK Lysis Buffer</td>
			<td>Gibco</td>
			<td>A10492-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma</td>
			<td>A2058</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase 1</td>
			<td>Sigma</td>
			<td>C0130-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Thermo Fisher</td>
			<td>D1306</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM 1x</td>
			<td>Gibco</td>
			<td>11965-084</td>
			<td></td>
		</tr>
		<tr>
			<td>DNAse 1</td>
			<td>Sigma</td>
			<td>D4527-20KU</td>
			<td></td>
		</tr>
		<tr>
			<td>DRAQ5</td>
			<td>Thermo Fisher</td>
			<td>62251</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA 0.5M pH 8</td>
			<td>Corning</td>
			<td>46-034-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Enzyme Deactivating Buffer</td>
			<td></td>
			<td></td>
			<td>490 mL HBSS, 10 mL FBS, 1 g BSA</td>
		</tr>
		<tr>
			<td>FACS Buffer</td>
			<td></td>
			<td></td>
			<td>976 mL PBS, 20 mL FBS, 4mL EDTA (0.5M)</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Gibco</td>
			<td>A3840201</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>VWR</td>
			<td>82027-406</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS 1x</td>
			<td>Gibco</td>
			<td>14175-079</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemostats</td>
			<td>VWR</td>
			<td>63042-052</td>
			<td></td>
		</tr>
		<tr>
			<td>Hyaluronidase type 1-s</td>
			<td>Sigma</td>
			<td>H3506-500MG</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS 1x</td>
			<td>Gibco</td>
			<td>14190-136</td>
			<td></td>
		</tr>
		<tr>
			<td>Petridishes</td>
			<td>Thermo Fisher</td>
			<td>172931</td>
			<td></td>
		</tr>
		<tr>
			<td>Razor Blade</td>
			<td>VWR</td>
			<td>55411-050</td>
			<td></td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>VWR</td>
			<td>82027-578</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of macrophage subsets and stromal cells from human and mouse myocardial specimens

Macrophages represent the most heterogeneous and abundant immune cell populations in the heart and are central in driving inflammation and reparative responses after cardiac injury. How various subsets of macrophages orchestrate the immune responses after cardiac injury is an active area of research. Presented here is a simple protocol that our lab performs routinely, for the extraction of macrophages from mouse and human myocardium specimens obtained from healthy and diseased individuals. Briefly, this protocol involves enzymatic digestion of cardiac tissue to generate a single cell suspension, followed by antibody staining, and flow cytometry. This technique is suitable for functional assays performed on sorted cells as well as bulk and single cell RNA sequencing. A major advantage of this protocol is its simplicity, minimal day to day variation and wide applicability allowing investigation of macrophage heterogeneity across various mouse models and human disease entities.

The protocol described allows isolation of macrophages from mouse and human myocardium. Using the same protocol, but with a different staining and gating strategy, stromal cells can also be harvested from the human myocardium. FACS results presented here were acquired either on BD LSRII or BD FACS ARIA III platform. Compensation controls were generated from single color control samples from stained splenocytes. Figure 1 shows unprocessed and processed human L...

Watch this Scientific Journal Video about Isolation of Macrophage Subsets and Stromal Cells from Human and Mouse Myocardial Specimens at JoVE.com

Isolation of Macrophage Subsets and Stromal Cells from Human and Mouse Myocardial Specimens

Presented here is a protocol to isolate various subsets of macrophages and other non-immune cells from human and mouse myocardium by preparing a single cell suspension through enzymatic digestion. Gating schemes for flow cytometry based identification and characterization of isolated macrophages are also presented.

Macrophages represent the most heterogeneous and abundant immune cell populations in the heart and are central in driving inflammation and reparative ...

isolation-macrophage-subsets-stromal-cells-from-human-mouse

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Immunology and Infection

7.8K Views.  Washington University School of Medicine. Presented here is a protocol to isolate various subsets of macrophages and other non-immune cells from human and mouse myocardium by preparing a single cell suspension through enzymatic digestion. Gating schemes for flow cytometry based identification and characterization of isolated macrophages are also presented.

Video: Isolation of Macrophage Subsets and Stromal Cells from Human and Mouse Myocardial Specimens

Isolation of Mouse Peritoneal Cavity Cells

The peritoneal cavity is a membrane-bound and fluid-filled abdominal cavity of mammals, which contains the liver, spleen, most of the gastro-intestinal tract and other viscera. It harbors a number of immune cells including macrophages, B cells and T cells. The presence of a high number of na&iuml;ve macrophages in the peritoneal cavity makes it a preferred site for the collection of na&iuml;ve tissue resident macrophages (1). The peritoneal cavity is also important to the study of B cells because of the presence of a unique peritoneal cavity-resident B cell subset known as B1 cells in addition to conventional B2 cells. B1 cells are subdivided into B1a and B1b cells, which can be distinguished by the surface expression of CD11b and CD5. B1 cells are an important source of natural IgM providing early protection from a variety of pathogens (2-4). These cells are autoreactive in nature (5), but how they are controlled to prevent autoimmunity is still not understood completely. On the contrary, CD5+ B1a cells possess some regulatory properties by virtue of their IL-10 producing capacity (6). Therefore, peritoneal cavity B1 cells are an interesting cell population to study because of their diverse function and many unaddressed questions associated with their development and regulation. The isolation of peritoneal cavity resident immune cells is tricky because of the lack of a defined structure inside the peritoneal cavity. Our protocol will describe a procedure for obtaining viable immune cells from the peritoneal cavity of mice, which then can be used for phenotypic analysis by flow cytometry and for different biochemical and immunological assays.

The peritoneal cavity in mammals contains different immune cell populations crucial for innate immune responses. An efficient isolation method is required for biochemical and functional analyses of these cells. Here we provide a comprehensive method for the isolation of peritoneal cavity cells in the mouse.

The peritoneal cavity is a membrane-bound and fluid-filled abdominal cavity of mammals, which contains the liver, spleen, most of the gastro-intestinal ...

Isolation of Mouse Lung Dendritic Cells

Lung dendritic cells (DC) play a fundamental role in sensing invading pathogens 1,2 as well as in the control of tolerogenic responses 3 in the respiratory tract. At least three main subsets of lung dendritic cells have been described in mice: conventional DC (cDC) 4, plasmacytoid DC (pDC) 5 and the IFN-producing killer DC (IKDC) 6,7. The cDC subset is the most prominent DC subset in the lung 8. 
The common marker known to identify DC subsets is CD11c, a type I transmembrane integrin (&beta;2) that is also expressed on monocytes, macrophages, neutrophils and some B cells 9. In some tissues, using CD11c as a marker to identify mouse DC is valid, as in spleen, where most CD11c+ cells represent the cDC subset which expresses high levels of the major histocompatibility complex class II (MHC-II). However, the lung is a more heterogeneous tissue where beside DC subsets, there is a high percentage of a distinct cell population that expresses high levels of CD11c bout low levels of MHC-II. Based on its characterization and mostly on its expression of F4&#47;80, an splenic macrophage marker, the CD11chiMHC-IIlo lung cell population has been identified as pulmonary macrophages 10 and more recently, as a potential DC precursor 11. 
In contrast to mouse pDC, the study of the specific role of cDC in the pulmonary immune response has been limited due to the lack of a specific marker that could help in the isolation of these cells. Therefore, in this work, we describe a procedure to isolate highly purified mouse lung cDC. The isolation of pulmonary DC subsets represents a very useful tool to gain insights into the function of these cells in response to respiratory pathogens as well as environmental factors that can trigger the host immune response in the lung.

A highly purified preparation of mouse lung dendritic cells is described. Specific emphasis is given to the isolation of conventional dendritic cell subset.

Lung dendritic cells (DC) play a fundamental role in sensing invading pathogens 1,2 as well as in the control of tolerogenic responses 3 in the ...

Isolation and Characterization of Dendritic Cells and Macrophages from the Mouse Intestine

Within the intestine reside unique populations of innate and adaptive immune cells that are involved in promoting tolerance towards commensal flora and food antigens while concomitantly remaining poised to mount inflammatory responses toward invasive pathogens1,2. Antigen presenting cells, particularly DCs and macrophages, play critical roles in maintaining intestinal immune homeostasis via their ability to sense and appropriately respond to the microbiota3-14. Efficient isolation of intestinal DCs and macrophages is a critical step in characterizing the phenotype and function of these cells. While many effective methods of isolating intestinal immune cells, including DCs and macrophages, have been described6,10,15-24, many rely upon long digestions times that may negatively influence cell surface antigen expression, cell viability, and/or cell yield. Here, we detail a methodology for the rapid isolation of large numbers of viable, intestinal DCs and macrophages. Phenotypic characterization of intestinal DCs and macrophages is carried out by directly staining isolated intestinal cells with specific fluorescence-labeled monoclonal antibodies for multi-color flow cytometric analysis. Furthermore, highly pure DC and macrophage populations are isolated for functional studies utilizing CD11c and CD11b magnetic-activated cell sorting beads followed by cell sorting.

Here, we detail a methodology for the rapid isolation of mouse intestinal dendritic cells (DCs) and macrophages. Phenotypic characterization of intestinal DCs and macrophages is performed using multi-color flow cytometric analysis while magnetic bead enrichment followed by cell sorting is used to yield highly pure populations for functional studies.

Within the intestine reside unique populations of innate and adaptive immune cells that are involved in promoting tolerance towards commensal flora and ...

Isolation of Precursor B-cell Subsets from Umbilical Cord Blood

Umbilical cord blood is highly enriched for hematopoietic progenitor cells at different lineage commitment stages. We have developed a protocol for isolating precursor B-cells at four different stages of differentiation. Because genes are expressed and epigenetic modifications occur in a tissue specific manner, it is vital to discriminate between tissues and cell types in order to be able to identify alterations in the genome and the epigenome that may lead to the development of disease. This method can be adapted to any type of cell present in umbilical cord blood at any stage of differentiation.	
This method comprises 4 main steps. First, mononuclear cells are separated by density centrifugation. Second, B-cells are enriched using biotin conjugated antibodies that recognize and remove non B-cells from the mononuclear cells. Third the B-cells are fluorescently labeled with cell surface protein antibodies specific to individual stages of B-cell development. Finally, the fluorescently labeled cells are sorted and individual populations are recovered. The recovered cells are of sufficient quantity and quality to be utilized in downstream nucleic acid assays.

Here we describe a protocol for isolating subsets of precursor B-cells from umbilical cord blood. A sufficient quantity and quality of nucleic acids may be extracted from the cells and used in subsequent assays utilizing DNA or RNA.

Umbilical cord blood is highly enriched for hematopoietic progenitor cells at different lineage commitment stages. We have developed a protocol for ...

Isolation of Myeloid Dendritic Cells and Epithelial Cells from Human Thymus

In this protocol we provide a method to isolate dendritic cells (DC) and epithelial cells (TEC) from the human thymus. DC and TEC are the major antigen presenting cell (APC) types found in a normal thymus and it is well established that they play distinct roles during thymic selection. These cells are localized in distinct microenvironments in the thymus and each APC type makes up only a minor population of cells. To further understand the biology of these cell types, characterization of these cell populations is highly desirable but due to their low frequency, isolation of any of these cell types requires an efficient and reproducible procedure. This protocol details a method to obtain cells suitable for characterization of diverse cellular properties. Thymic tissue is mechanically disrupted and after different steps of enzymatic digestion, the resulting cell suspension is enriched using a Percoll density centrifugation step. For isolation of myeloid DC (CD11c+), cells from the low-density fraction (LDF) are immunoselected by magnetic cell sorting. Enrichment of TEC populations (mTEC, cTEC) is achieved by depletion of hematopoietic (CD45hi) cells from the low-density Percoll cell fraction allowing their subsequent isolation via fluorescence activated cell sorting (FACS) using specific cell markers. The isolated cells can be used for different downstream applications.

This protocol details a method to isolate antigen presenting cells from human thymus via different steps of enzymatic digestion of the tissue followed by density centrifugation of the single cell suspension and finally magnetic and/or FACS sorting of the cell populations of interest.

In this protocol we provide a method to isolate dendritic cells (DC) and epithelial cells (TEC) from the human thymus. DC and TEC are the major antigen ...

Isolation of Murine Lymph Node Stromal Cells

Secondary lymphoid organs including lymph nodes are composed of stromal cells that provide a structural environment for homeostasis, activation and differentiation of lymphocytes. Various stromal cell subsets have been identified by the expression of the adhesion molecule CD31 and glycoprotein podoplanin (gp38), T zone reticular cells or fibroblastic reticular cells, lymphatic endothelial cells, blood endothelial cells and FRC-like pericytes within the double negative cell population. For all populations different functions are described including, separation and lining of different compartments, attraction of and interaction with different cell types, filtration of the draining fluidics and contraction of the lymphatic vessels. In the last years, different groups have described an additional role of stromal cells in orchestrating and regulating cytotoxic T cell responses potentially dangerous for the host. 
Lymph nodes are complex structures with many different cell types and therefore require a appropriate procedure for isolation of the desired cell populations. Currently, protocols for the isolation of lymph node stromal cells rely on enzymatic digestion with varying incubation times; however, stromal cells and their surface molecules are sensitive to these enzymes, which results in loss of surface marker expression and cell death. Here a short enzymatic digestion protocol combined with automated mechanical disruption to obtain viable single cells suspension of lymph node stromal cells maintaining their surface molecule expression is proposed.

Isolation of lymph node stromal cells is a multistep procedure including enzymatic digestion and mechanical disaggregation to obtain fibroblastic reticular cells, lymphatic and blood endothelial cells. In the described procedure, a short digestion is combined with automated mechanical disaggregation to minimize surface marker degradation of viable lymph node stromal cells.

Secondary lymphoid organs including lymph nodes are composed of stromal cells that provide a structural environment for homeostasis, activation and ...

Analyzing the Effects of Stromal Cells on the Recruitment of Leukocytes from Flow

Stromal cells regulate the recruitment of circulating leukocytes during inflammation through cross-talk with neighboring endothelial cells. Here we describe two in vitro &#8220;vascular&#8221; models for studying the recruitment of circulating neutrophils from flow by inflamed endothelial cells. A major advantage of these models is the ability to analyze each step in the leukocyte adhesion cascade in order, as would occur in vivo. We also describe how both models can be adapted to study the role of stromal cells, in this case mesenchymal stem cells (MSC), in regulating leukocyte recruitment.
Primary endothelial cells were cultured alone or together with human MSC in direct contact on Ibidi microslides or on opposite sides of a Transwell filter for 24 hr. Cultures were stimulated with tumor necrosis factor alpha (TNF&#945;) for 4 hr and incorporated into a flow-based adhesion assay. A bolus of neutrophils was perfused over the endothelium for 4 min. The capture of flowing neutrophils and their interactions with the endothelium was visualized by phase-contrast microscopy.
In both models, cytokine-stimulation increased endothelial recruitment of flowing neutrophils in a dose-dependent manner. Analysis of the behavior of recruited neutrophils showed a dose-dependent decrease in rolling and a dose-dependent increase in transmigration through the endothelium. In co-culture, MSC suppressed neutrophil adhesion to TNF&#945;-stimulated endothelium.
Our flow based-adhesion models mimic the initial phases of leukocyte recruitment from the circulation. In addition to leukocytes, they can be used to examine the recruitment of other cell types, such as therapeutically administered MSC or circulating tumor cells. Our multi-layered co-culture models have shown that MSC communicate with endothelium to modify their response to pro-inflammatory cytokines, altering the recruitment of neutrophils. Further research using such models is required to fully understand how stromal cells from different tissues and conditions (inflammatory disorders or cancer) influence the recruitment of leukocytes during inflammation.

The ability of inflamed endothelium to recruit leukocytes from flow is regulated by mesenchymal stromal cells. We describe two in vitro models incorporating primary human cells that can be used to assess neutrophil recruitment from flow and examine the role that mesenchymal stromal cells play in regulating this process.

Stromal cells regulate the recruitment of circulating leukocytes during inflammation through cross-talk with neighboring endothelial cells. Here we ...

Mouse Na&#239;ve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets

Antigen inexperienced (na&#239;ve) CD4+ T cells undergo expansion and differentiation to effector subsets at the time of T cell receptor (TCR) recognition of cognate antigen presented on MHC class II. The cytokine signals present in the environment at the time of TCR activation are a major factor in determining the effector fate of a na&#239;ve CD4+ T cell. Although the cytokine environment during na&#239;ve T cell activation may be complex and involve both redundant and opposing signals in vivo, the addition of various cytokine combinations during naive CD4+ T cell activation in vitro can readily promote the establishment of effector T helper lineages with hallmark cytokine and transcription factor expression. Such differentiation experiments are commonly used as a first step for the evaluation of targets believed to promote or inhibit the development of certain CD4+ T helper subsets. The addition of mediators, such as signaling agonists, antagonists, or other cytokines, during the differentiation process can also be used to study the influence of a particular target on T cell differentiation. Here, we describe a basic protocol for the isolation of na&#239;ve T cells from mouse and the subsequent steps necessary for polarizing na&#239;ve cells to various T helper effector lineages in vitro.

Mouse Na&amp;#239;ve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets

Na&#239;ve CD4+ T cells polarize to various subsets depending on the environment at the time of activation. The differentiation of na&#239;ve CD4+ T cells to various effector subsets can be achieved in vitro through the addition of T cell receptor stimuli and specific cytokine signals.

Antigen inexperienced (na&#239;ve) CD4+ T cells undergo expansion and differentiation to effector subsets at the time of T cell receptor (TCR) recognition ...

Isolation and Flow Cytometric Analysis of Immune Cells from the Ischemic Mouse Brain

Ischemic stroke initiates a robust inflammatory response that starts in the intravascular compartment and involves rapid activation of brain resident cells. A key mechanism of this inflammatory response is the migration of circulating immune cells to the ischemic brain facilitated by chemokine release and increased endothelial adhesion molecule expression. Brain-invading leukocytes are well-known contributing to early-stage secondary ischemic injury, but their significance for the termination of inflammation and later brain repair has only recently been noticed.
Here, a simple protocol for the efficient isolation of immune cells from the ischemic mouse brain is provided. After transcardial perfusion, brain hemispheres are dissected and mechanically dissociated. Enzymatic digestion with Liberase&#160;is followed by density gradient (such as Percoll) centrifugation to remove myelin and cell debris. One major advantage of this protocol is the single-layer density gradient procedure which does not require time-consuming preparation of gradients and can be reliably performed. The approach yields highly reproducible cell counts per brain hemisphere and allows for measuring several flow cytometry panels in one biological replicate. Phenotypic characterization and quantification of brain-invading leukocytes after experimental stroke may contribute to a better understanding of their multifaceted roles in ischemic injury and repair.

Inflammation plays a central role in the pathogenesis of ischemic stroke. Increasing evidence suggests that it acts as a double-edged sword which exacerbates early brain injury, but also contributes to later repair. This protocol describes the isolation of immune cells from the ischemic brain and their subsequent flow cytometric phenotyping.

Ischemic stroke initiates a robust inflammatory response that starts in the intravascular compartment and involves rapid activation of brain resident ...

An Efficient and High Yield Method for Isolation of Mouse Dendritic Cell Subsets

Dendritic cells (DCs) are professional antigen-presenting cells primarily responsible for acquiring, processing and presenting antigens on antigen presenting molecules to initiate T-cell-mediated immunity. Dendritic cells can be separated into several phenotypically and functionally heterogeneous subsets. Three important subsets of splenic dendritic cells are plasmacytoid, CD8&#945;Pos and CD8&#945;Neg cells. The plasmacytoid DCs are natural producers of type I interferon and are important for anti-viral T cell immunity. The CD8&#945;Neg DC subset is specialized for MHC class II antigen presentation and is centrally involved in priming CD4 T cells. The CD8&#945;Pos DCs are primarily responsible for cross-presentation of exogenous antigens and CD8 T cell priming. The CD8&#945;Pos DCs have been demonstrated to be most efficient at the presentation of glycolipid antigens by CD1d molecules to a specialized T cell population known as invariant natural killer T (iNKT) cells. Administration of Flt-3 ligand increases the frequency of migration of dendritic cell progenitors from bone marrow, ultimately resulting in expansion of dendritic cells in peripheral lymphoid organs in murine models. We have adapted this model to purify large numbers of functional dendritic cells for use in cell transfer experiments to compare in vivo proficiency of different DC subsets.

Distinct dendritic cell subsets exist as rare populations in lymphoid organs, and therefore are challenging to isolate in sufficient numbers and purity for immunological experiments. Here we describe a high efficiency, high yield method for isolation of all of the currently known major subsets of mouse splenic dendritic cells.