JMN acknowledges financial support from National Institute of General Medical Sciences (T32GM088129) and the National Institute of Dental &amp; Craniofacial Research (F31DE026682) both of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This project was also supported by the Cytometry and Cell Sorting Core at Baylor College of Medicine with funding from the NIH (P30 AI036211, P30 CA125123, and S10 RR024574) and the expert assistance of Joel M. Sederstrom.

All methods described here have been approved by the Institutional Animal Care and Use Committee (IACUC) of Baylor College of Medicine.
1. Tumor Harvest and Digestion
NOTE: The time required for harvest is ~3 - 5 min/tumor, and the time required for processing is ~1 h + 2 - 3 min/tumor.
<ol>
	<li>Euthanize mice by carbon dioxide inhalation and spray each mouse down with 70% ethanol before harvesting to prevent hair contamination. Surgically remove subcutaneous tumors from the mice and ensure that the tumors are free of any contaminating tissue (i.e., hair, skin, peritoneum, etc.). Place each tumor in 1.8 mL of base RPMI-1640 media without fetal bovine serum (FBS) in a 24-well plate. For larger harvests, keep plates cold on ice to preserve cellular viability. 
	NOTE: If sterility is required, all tumor dissections will need to be performed in a biosafety cabinet with sterile surgical tools (i.e., scissors, forceps, etc.), as well as any further steps. Tumors with the longest diameter between 0.5 -&#160;1 cm are optimal, and larger or smaller tumors will require scaling of reagents.</li>
	<li>Use scissors to cut the tumors into less than 1 mm3 pieces within each well.</li>
	<li>Prepare a 10x digestion cocktail by dissolving collagenase I at 10 mg/mL, collagenase IV at 2,500 U/mL, and DNase I at 200 U/mL in base RPMI-1640 media (without FBS). 
	NOTE: The digestion cocktail can be prepared a day in advance and stored at -20 &#176;C; however, prolonged storage is not recommended as enzymes will lose activity over time once dissolved.</li>
	<li>Add 200 &#181;L of 10x dissociation cocktail containing collagenase I, collagenase IV, and DNase I to each well with the 1 mm3 pieces.</li>
	<li>Allow the samples to digest for 1 h at 37 &#176;C while lightly shaking at 60 - 100 rpm using an orbital plate shaker. 
	NOTE: The elevation of temperature to 37 &#176;C during the enzymatic digestion may cause immune cell activation.</li>
	<li>After 1 h, neutralize the reaction by adding 1 mL of RPMI-1640 media supplemented with 5% FBS and 2 mM EDTA to each well.</li>
	<li>Pipette the tumor digestion and the remaining tumor pieces into a 40 &#181;m cell strainer seated on top of a 50 mL centrifuge tube. 
	NOTE: Cut the tip off of a 1 mL pipette tip for easier transfer of the tumor digestion to the strainer.</li>
	<li>Use a 10 mL syringe plunger to mechanically disaggregate the tumor pieces through the strainer. Periodically rinse the strainer with 2 mL of supplemented RPMI-1640 media (containing 5% FBS) and repeat until the cell strainer is clear of tumor. 
	NOTE: Approximately 4 - 10 mL of total media should be sufficient to adequately rinse the strainer of tumor. 
	NOTE: Place samples on ice until this step is completed for all samples to preserve cellular viability.</li>
	<li>Adjust each 50 mL centrifuge tube to the same volume using the supplemented RPMI-1640 media. 
	NOTE: The adjustment of volume is critical for centrifuge balancing. Skipping this step could result in centrifuge damage or personal injury.</li>
	<li>Centrifuge the cell suspensions (5 min, 805 x g, 4 &#176;C), discard the supernatants, and re-suspend in 2 mL of supplemented RPMI-1640 media. 
	NOTE: A cell aggregate may form following the centrifugation that is difficult to resuspend. Use a 5 mL serological pipette and mix rapidly to break it up before proceeding.</li>
</ol>
2. Separation of Immune and Tumor Cellular Fractions
NOTE: The time required for this step is approximately 1 h.
<ol>
	<li>Add 3 mL of density gradient medium to the bottom of a 15 mL centrifuge tube. Prepare and label enough tubes for each tumor.</li>
	<li>Layer the 2 mL of tumor cell suspension on top of the density gradient medium by pipetting slowly down the side of the tube to prevent mixing of the two layers.</li>
	<li>Carefully place the layered tubes in the centrifuge and spin for 20 min at 805 x g, 20 &#176;C, with no brake. 
	NOTE: It is extremely important to verify proper balancing and ensure that no brake is used during centrifugation. Any disruption of this process will result in layer mixing and the full sample recovery will be difficult.</li>
	<li>Carefully transfer the tumor infiltrating leukocyte (TIL) layer and the top media layer to a new 15 mL tube using a transfer pipette. Discard all remaining density gradient medium and resuspend the tumor pellet at the bottom of the tube in 2 mL of supplemented RPMI-1640. 
	NOTE: After centrifugation there will be four visible layers from the top to bottom which respectively correspond to: media, TILs, density gradient medium, and tumor cell pellet. See Figure 2A for an example of the various layers.</li>
	<li>Centrifuge both the TIL and tumor samples in separate tubes (5 min, 805 x g, 4 &#176;C) and discard the supernatant.</li>
	<li>Resuspend the TIL sample in 200 &#181;L and the tumor pellet in 2 mL of supplemented RPMI-1640 media. Keep on ice to preserve viability.</li>
</ol>
3. Plating and Staining
Note: The time required for plating is 30 s/tumor; the time required for surface staining is 1 h; the time required for intracellular staining is 40 min; the time required for flow cytometry analysis is 1 - 4 min/tumor.
<ol>
	<li>Prepare and label a 96-well U-bottom plate for each immune staining panel and an additional plate for cell counts. 
	NOTE: Typically, three plates are prepared in total: a lymphocyte-focused panel plate, a myeloid-focused panel plate, and a cell count plate.</li>
	<li>Aliquot the single-cell suspensions into each of the staining panel plates and a set volume into the count plate. 
	NOTE: The count plate is used to calculate the total number of cells added to each staining panel, thereby allowing accurate cell population counts. A flow cytometer with 96-well plate sampling and volumetric analysis capabilities can provide the number of cells per &#181;L in each sample, and therefore, calculate the number of cells added to each staining panel. Count plates can be acquired the following day after fixation overnight at 4 &#176;C, rinsing with FACs buffer (phosphate buffered saline (PBS) with 2% FBS), and resuspending in a set volume of FACs buffer.</li>
	<li>Wash the cells twice with 200 &#181;L of Dulbecco&#39;s phosphate buffered saline (DPBS) per sample by centrifuging (5 min, 805 x g, 4 &#176;C) and discarding the supernatant between each rinse to remove any free FBS.</li>
	<li>Add 50 &#181;L of Fc block, mix the samples using a multi-channel pipette, and incubate for 20 min at 4 &#176;C.</li>
	<li>Add 50 &#181;L of 2x concentrated extracellular targeting antibody and fixable viability stain mixture, mix using a multi-channel pipette, and incubate for 30 min in the dark at RT or 4 &#176;C. 
	NOTE: The exact staining conditions for the antibody depend on the manufacturer&#39;s instructions. All staining dilutions must be in DPBS, with no added FBS to prevent saturation of the fixable viability dye. Please see the Table of Materials/Equipment for the optimal dilutions of the staining panel used in this manuscript. Antibody and fixable viability staining solution is prepared at a 2x concentration to provide a final 1x staining concentration in 100 &#181;L of total staining volume when added to the Fc block.</li>
	<li>Wash the samples twice with FACs buffer by centrifuging (5 min, 805 x g, 4 &#176;C) and discarding the supernatants between each rinse.</li>
	<li>Resuspend in 200 &#181;L of 1x fixation/permeabilization solution and incubate overnight at 4 &#176;C protected from light. 
	NOTE: The experiment can be paused overnight at this point: keep samples at 4 &#176;C protected from light.</li>
	<li>The following day, centrifuge the plates (5 min, 805 x g, 4 &#176;C) and discard the supernatant.</li>
	<li>Rinse once with 200 &#181;L of 1x permeabilization buffer, centrifuge (5 min, 805 x g, 4 &#176;C), and discard the supernatant.</li>
	<li>Add 100 &#181;L of 1x concentrated intracellular antibody staining panel prepared in 1x permeabilization buffer and incubate for 30 min in the dark at RT or 4 &#176;C (this depends on staining recommendations from the manufacturer).</li>
	<li>Rinse once with 1x permeabilization buffer (5 min, 805 x g, 4 &#176;C), discard the supernatant, and rinse a second time with FACs buffer (PBS with 2% FBS).</li>
	<li>Resuspend the samples in 300 &#181;L of FACs buffer (PBS with 2% FBS), transfer the samples to flow cytometry tubes, and perform flow cytometry analysis.</li>
</ol>

<ol>
	<li>Fouad, Y. A., Aanei, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Revisiting+the+hallmarks+of+cancer.">Revisiting the hallmarks of cancer.</a> American Journal of Cancer Research. 7 (5), 1016-1036 (2017).</li><li>Gajewski, T. F., Schreiber, H., Fu, Y. -. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Innate+and+adaptive+immune+cells+in+the+tumor+microenvironment.">Innate and adaptive immune cells in the tumor microenvironment.</a> Nature Immunology. 14 (10), 1014-1022 (2013).</li><li>Whiteside, T. 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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+murine+small+intestine+leukocyte+isolation+for+global+immune+phenotype+analysis.">Optimization of murine small intestine leukocyte isolation for global immune phenotype analysis.</a> Journal of Immunological Methods. 405, 97-108 (2014).</li><li>Casadevall, A., Fang, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rigorous+Science:+A+How-To+Guide.">Rigorous Science: A How-To Guide.</a> mBio. 7 (6), 01902-01916 (2016).</li><li>Yao, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CyTOF+supports+efficient+detection+of+immune+cell+subsets+from+small+samples.">CyTOF supports efficient detection of immune cell subsets from small samples.</a> Journal of Immunological Methods. 415, 1-5 (2014).</li><li>Kay, A. W., Strauss-Albee, D. M., Blish, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+Mass+Cytometry+(CyTOF)+for+Functional+and+Phenotypic+Analysis+of+Natural+Killer+Cells.">Application of Mass Cytometry (CyTOF) for Functional and Phenotypic Analysis of Natural Killer Cells.</a> Methods Mol. Biol. 1441, 13-26 (2016).</li><li>Pachynski, R. K., Scholz, A., Monnier, J., Butcher, E. C., Zabel, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+Tumor-infiltrating+Leukocyte+Subsets+in+a+Subcutaneous+Tumor+Model.">Evaluation of Tumor-infiltrating Leukocyte Subsets in a Subcutaneous Tumor Model.</a> Journal of Visualized Experiments. (98), (2015).</li></ol>

The authors have nothing to disclose.

The TIME is composed of diverse and complex cellular components and molecules. Recent evidence suggests that accurate characterization of this environment can provide a better understanding of treatment success or failure, and can even help identify mechanisms of therapeutic resistance. For example, increasing intratumoral levels of various immunosuppressive cells (i.e., MDSCs, T regulatory cells, etc.) can mitigate effector immune responses and abrogate immunotherapeutic effects. On the other hand, the...

The suppressive TIME has recently been recognized as a hallmark of cancer, and is known to play a significant role in the development, progression, and protection of solid tumor cancers as well as mitigate their susceptibility to immunotherapy1. The TIME is composed of numerous cellular subsets and phenotypes, all of which provide critical insight into the immunologic state of the tumor. These immunologic subsets can be further stratified into cells of lymphocyte or myeloid origin, which together constitute the majority of the innate and adaptive immune responses2,3. Recent advances in the field of cancer immunotherapy have demonstrated that immunotherapeutic strategies (i.e., immune checkpoint inhibitors, chimeric antigen receptor T-cells, etc.) have the potential to induce durable cancer regressions; however, they remain relatively ineffective in solid tumor cancers4,5. Numerous groups have shown the critical hurdle that the TIME can play on treatment success6,7, and thus, there remains a need to accurately evaluate new immunotherapies in the pre-clinical setting specifically focusing on their ability to modulate or overcome the TIME8.
Current efforts to characterize the TIME typically utilize either microscopy or flow cytometry along with antibody labeling strategies to identify immune cellular subsets and their features9,10. These two strategies provide uniquely different information, as microscopy allows spatial appreciation of cellular subsets and flow cytometry provides high throughput and broader quantification of cellular changes. Despite the recent improvements in fluorescent multiplex immunohistochemistry optimizing spectral imaging systems, which now can support up to 7 parameters, limited panel size makes broad level immune profiling difficult and thus this technique is often reserved for more focused analyses. As a result, flow cytometry remains one of the most widely used immune profiling techniques. Despite its widespread use in TIME characterization, the methods used for processing and staining are quite variable. Most often protocols utilize a tumor dissociating enzyme (i.e., collagenases, DNase, etc.) and manual dissociation methods to achieve single-cell suspensions, followed by antibody staining and analysis7. Despite the benefits of each method, numerous groups have shown the extensive variability that can be induced through these techniques11. This makes cross-study comparisons of tumor microenvironment profiling extremely difficult, even when assessing the same murine tumor model. Furthermore, these methods provide limited potential to assess tumor cellular and tumor immune infiltrate components independently, since both components are interspersed after digestion. Sample quantity then limits multi-panel staining and analysis, which becomes a major issue when attempting to characterize rare immunologic subsets (i.e., tumor-specific T-cells)12. More recent techniques such as mass cytometry, or cytometry by time of flight (CyTOF), allow high-dimensional phenotypic analysis of cellular subsets with some systems supporting panel designs of greater than 42 independent parameters13. Despite the tremendous power of CyTOF technology in immune profiling, it remains limited because of the expense, analysis expertise, and the access to the equipment. In addition, many CyTOF protocols recommend purification of immune subsets to improve signal-to-noise ratios14, and thus we suggest that our enrichment method could be used upstream of CyTOF analysis to improve data quality.
Herein we describe a tumor microenvironment digestion and analysis method that incorporates tumor immune infiltrate separation. The purpose of this method is to allow independent high-throughput profiling of the tumor immune infiltrate and tumor cellular fractions for broader characterization of the tumor microenvironment. Using this method, we further demonstrate the importance of performing whole tumor analysis, as a subcutaneous solid tumor model was found to have significant spatial immunologic heterogeneity. Overall, this method can more accurately and consistently compare between samples because it enriches for immune cellular subsets within the tumor and allows for independent profiling of tumor cell and immune fractions of a tumor.

<table border="0" cellpadding="0" cellspacing="0" style="width:615px;" width="615">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">6 to 12 week old male C57BL/6 mice</td>
			<td style="width:113px;">Jackson Laboratory&#160;</td>
			<td style="width:119px;">N/A</td>
			<td style="width:167px;">Mice used in our tumor studies</td>
		</tr>
		<tr height="81">
			<td height="81" style="height:81px;width:216px;">MEER Murine Syngeneic Cancer Cell line</td>
			<td style="width:113px;">Acquired from collaborator&#160;</td>
			<td style="width:119px;">N/A</td>
			<td style="width:167px;">E6/E7 HPV antigen expressing murine tonsillar epithelial cancer cell line&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">70% isopropyl alcohol&#160;</td>
			<td style="width:113px;">EMD Milipore&#160;</td>
			<td style="width:119px;">PX1840</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Murine surgical tool kit</td>
			<td style="width:113px;">World Precision Instruments</td>
			<td style="width:119px;">MOUSEKIT</td>
			<td style="width:167px;">Primarily only need scissors, tweezers, and a scalpel.&#160;</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">24-well plate&#160;</td>
			<td style="width:113px;">Denville Scientific Inc.</td>
			<td style="width:119px;">T1024</td>
			<td style="width:167px;">Or any 24-well flat bottom plate.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">RPMI-1640 media</td>
			<td style="width:113px;">Sigma-Aldrich</td>
			<td style="width:119px;">R0883</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Collagenase I&#160;</td>
			<td style="width:113px;">EMD Milipore</td>
			<td style="width:119px;">234153</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Collagenase IV</td>
			<td style="width:113px;">Worthington Biochemical Corporation</td>
			<td style="width:119px;">LS004189</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DNase I&#160;</td>
			<td style="width:113px;">Sigma-Aldrich</td>
			<td style="width:119px;">11284932001</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">Low Speed Orbital Shaker</td>
			<td style="width:113px;">BioExpress (supplier: Genemate)&#160;</td>
			<td style="width:119px;">S-3200-LS</td>
			<td style="width:167px;">Or any orbital shaker.&#160;</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Thermoregulating incubator</td>
			<td style="width:113px;">Fisher Scientific</td>
			<td style="width:119px;">13-255-27</td>
			<td style="width:167px;">Or any other thermo-regulated incubator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">FBS</td>
			<td style="width:113px;">Sigma-Aldrich</td>
			<td style="width:119px;">F8192</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">EDTA</td>
			<td style="width:113px;">AMRESCO</td>
			<td style="width:119px;">E177</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">1 mL Pipette and tips</td>
			<td style="width:113px;">Eppendorf</td>
			<td style="width:119px;">13-690-032</td>
			<td style="width:167px;">Or any other pipette and tips</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">40 um Cell Strainers</td>
			<td style="width:113px;">Fisher Scientific</td>
			<td style="width:119px;">22363547</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">50 mL Centrifuge Tubes</td>
			<td style="width:113px;">Denville Scientific Inc.</td>
			<td style="width:119px;">C1062-P</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">15 mL Conical Tubes</td>
			<td style="width:113px;">Denville Scientific Inc.</td>
			<td style="width:119px;">C1012</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">10 mL Luer-Lok Syringe without needles</td>
			<td style="width:113px;">BD</td>
			<td style="width:119px;">309604</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Lymphoprep Density Gradient Medium</td>
			<td style="width:113px;">STEMCELL Technologies</td>
			<td style="width:119px;">7811</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Transfer Pipettes</td>
			<td style="width:113px;">Denville Scientific Inc.</td>
			<td style="width:119px;">P7212</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">96-well U-bottom plates</td>
			<td style="width:113px;">Denville Scientific Inc.</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DPBS</td>
			<td style="width:113px;">Sigma Aldrich&#160;</td>
			<td style="width:119px;">D8573</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">FoxP3 Transcription Factor Staining Buffer Set&#160;</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">00-5523-00</td>
			<td style="width:167px;">Fix/Permeabilization Buffer and Permeabilization Buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Thermoregulated Centrifuge</td>
			<td style="width:113px;">Eppendorf&#160;</td>
			<td style="width:119px;">5810 R</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Attune NxT Flow Cytometer</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">N/A</td>
			<td style="width:167px;">For 96-well cell volumetric counting&#160;</td>
		</tr>
		<tr height="62">
			<td height="62" style="height:62px;width:216px;">Purified Rat Anti-Mouse CD16/CD32 (Mouse BD Fc Block)&#160;Clone 2.4G2&#160;</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">553141</td>
			<td style="width:167px;">Fc Block</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">LIVE/DEAD Fixable Blue Dead Cell Stain Kit, for UV excitation</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">L34962</td>
			<td style="width:167px;">Fixable viability stain</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">CD45 Monoclonal Antibody (30-F11), APC-eFluor 780</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">47-0451-80</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">TCR beta Monoclonal Antibody (H57-597), APC</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">17-5961-82</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">CD8-&#945; Antibody (KT15), PE</td>
			<td style="width:113px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-53473&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">CD4 Monoclonal Antibody (GK1.5), PE-Cyanine5</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">15-0041-81</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">MHC Class II (I-A/I-E) Monoclonal Antibody (M5/114.15.2), Alexa Fluor 700</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">56-5321-82</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">CD11c Monoclonal Antibody (N418), PE-Cyanine5</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">15-0114-82</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">F4/80 Monoclonal Antibody (BM8), eFluor 450</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">48-4801-80</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">CD11b Monoclonal Antibody (M1/70), APC</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">17-0112-81</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Ly-6G (Gr-1) Monoclonal Antibody (RB6-8C5), PE</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">12-5931-82</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="61">
			<td height="61" style="height:61px;width:216px;">CD274 (PD-L1, B7-H1) Monoclonal Antibody (MIH5), PE-Cyanine7</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">25-5982-80</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">CD273 (B7-DC) Monoclonal Antibody (122), PerCP-eFluor 710</td>
			<td style="width:113px;">ThermoFisher Scientific</td>
			<td style="width:119px;">46-9972-82</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">Ki-67 Monoclonal Antibody (B56), BV711</td>
			<td style="width:113px;">BD Biosciences</td>
			<td style="width:119px;">563755</td>
			<td style="width:167px;"></td>
		</tr>
	</tbody>
</table>

enrichment and characterization of the tumor immune and non-immune microenvironments in established subcutaneous murine tumors

The tumor immune microenvironment (TIME) has recently been recognized as a critical mediator of treatment response in solid tumors, especially for immunotherapies. Recent clinical advances in immunotherapy highlight the need for reproducible methods to accurately and thoroughly characterize the tumor and its associated immune infiltrate. Tumor enzymatic digestion and flow cytometric analysis allow broad characterization of numerous immune cell subsets and phenotypes; however, depth of analysis is often limited by fluorophore restrictions on panel design and the need to acquire large tumor samples to observe rare immune populations of interest. Thus, we have developed an effective and high throughput method for separating and enriching the tumor immune infiltrate from the non-immune tumor components. The described tumor digestion and centrifugal density-based separation technique allows separate characterization of tumor and tumor immune infiltrate fractions and preserves cellular viability, and thus, provides a broad characterization of the tumor immunologic state. This method was used to characterize the extensive spatial immune heterogeneity in solid tumors, which further demonstrates the need for consistent whole tumor immunologic profiling techniques. Overall, this method provides an effective and adaptable technique for the immunologic characterization of subcutaneous solid murine tumors; as such, this tool can be used to better characterize the tumoral immunologic features and in the preclinical evaluation of novel immunotherapeutic strategies.

Our results demonstrate the significant benefit of TIL separation from non-immune tumor components, as explained in the protocol. Additionally, using the described method we demonstrate the significant immunologic heterogeneity of established solid tumors.
A significant problem with many tumor dissociation techniques is the loss of sample viability, most often as a result of harsh digestion conditions (i.e., elevated te...

Watch this Scientific Journal Video about Enrichment and Characterization of the Tumor Immune and Non-immune Microenvironments in Established Subcutaneous Murine Tumors at JoVE.com

Enrichment and Characterization of the Tumor Immune and Non-immune Microenvironments in Established Subcutaneous Murine Tumors

Here we describe a method to separate and enrich components of the tumor immune and non-immune microenvironment in established subcutaneous tumors. This technique allows for the separate analysis of tumor immune infiltrate and non-immune tumor fractions which can permit comprehensive characterization of the tumor immune microenvironment.

The tumor immune microenvironment (TIME) has recently been recognized as a critical mediator of treatment response in solid tumors, especially for ...

enrichment-characterization-tumor-immune-non-immune-microenvironments

Research

JoVE Journal

Cancer Research

9.5K Views.  Baylor College of Medicine. Here we describe a method to separate and enrich components of the tumor immune and non-immune microenvironment in established subcutaneous tumors. This technique allows for the separate analysis of tumor immune infiltrate and non-immune tumor fractions which can permit comprehensive characterization of the tumor immune microenvironment.

Video: Enrichment and Characterization of the Tumor Immune and Non-immune Microenvironments in Established Subcutaneous Murine Tumors

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the context of a whole organism. Sophisticated techniques to generate genetic mosaics facilitate induction of visually marked, genetically defined clones surrounded by normal tissue. The clones can be analyzed through diverse molecular, cellular and omics approaches. This study describes how to generate fluorescently labeled clonal tumors of varying malignancy in the eye/antennal imaginal discs (EAD) of Drosophila larvae using the Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. It describes procedures how to recover the mosaic EAD and brain from the larvae and how to process them for simultaneous imaging of fluorescent transgenic reporters and antibody staining. To facilitate molecular characterization of the mosaic tissue, we describe a protocol for isolation of total RNA from the EAD. The dissection procedure is suitable to recover EAD and brains from any larval stage. The fixation and staining protocol for imaginal discs works with a number of transgenic reporters and antibodies that recognize Drosophila proteins. The protocol for RNA isolation can be applied to various larval organs, whole larvae, and adult flies. Total RNA can be used for profiling of gene expression changes using candidate or genome-wide approaches. Finally, we detail a method for quantifying invasiveness of the clonal tumors. Although this method has limited use, its underlying concept is broadly applicable to other quantitative studies where cognitive bias must be avoided.

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

This protocol demonstrates how to generate fluorescently marked, genetically defined clonal tumors in the Drosophila eye/antennal imaginal discs (EAD). It describes how to dissect the EAD and brain from the third instar larvae and how to process them to visualize and quantify gene expression changes and tumor invasiveness.

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the ...

A Murine Orthotopic Bladder Tumor Model and Tumor Detection System

This protocol describes the generation of bladder tumors in female C57BL/6J mice using the murine bladder cancer cell line MB49, which has been modified to secrete human Prostate Specific Antigen (PSA), and the procedure for the confirmation of tumor implantation. In brief, mice are anesthetized using injectable drugs and are made to lay in the dorsal position. Urine is vacated from the bladder and 50 &#181;L of poly-L-lysine (PLL) is slowly instilled at a rate of 10 &#181;L/20 s using a 24 G IV catheter. It is left in the bladder for 20 min by stoppering the catheter. The catheter is removed and PLL is vacated by gentle pressure on the bladder. This is followed by instillation of the murine bladder cancer cell line (1 x 105 cells/50 &#181;L) at a rate of 10 &#181;L/20 s. The catheter is stoppered to prevent premature evacuation. After 1 h, the mice are revived with a reversal drug, and the bladder is vacated. The slow instillation rate is important, as it reduces vesico-ureteral reflux, which can cause tumors to occur in the upper urinary tract and in the kidneys. The cell line should be well re-suspended to reduce clumping of cells, as this can lead to uneven tumor sizes after implantation.
This technique induces tumors with high efficiency. Tumor growth is monitored by urinary PSA secretion. PSA marker monitoring is more reliable than ultrasound or fluorescence imaging for the detection of the presence of tumors in the bladder. Tumors in mice generally reach a maximum size that negatively impacts health by about 3 - 4 weeks if left untreated. By monitoring tumor growth, it is possible to differentiate mice that were cured from those that were not successfully implanted with tumors. With only end-point analysis, the latter may be mistakenly assumed to have been cured by therapy.

This protocol describes the generation of murine orthotopic bladder tumors in female C57BL/6J mice and the monitoring of tumor growth.

This protocol describes the generation of bladder tumors in female C57BL/6J mice using the murine bladder cancer cell line MB49, which has been modified ...

Ex Vivo Imaging of Resident CD8 T Lymphocytes in Human Lung Tumor Slices Using Confocal Microscopy

CD8 T cell are key players in the fight against cancer. In order for CD8 T cells to kill tumor cells they need to enter into the tumor, migrate within the tumor microenvironment and respond adequately to tumor antigens. The recent development of improved imaging approaches, such as 2-photon microscopy, and the use of powerful mouse tumor models have shed light on some of the mechanisms that regulate anti-tumor T cell activities. Whereas such systems have provided valuable insights, they do not always predict human responses. In human, our knowledge in the field mainly comes from a description of fixed tumor samples from human patients, as well as in vitro studies. However, in vitro models lack the complex three-dimensional tumor milieu and, therefore, are incomplete approximations of in vivo T cell activities. Fresh slices made from explanted tissue represent a complex multi-cellular tumor environment that can act as an important link between co-cultured studies and animal models. Originally set up in murine lymph nodes1 and previously described in a JoVE article2, this approach has now been transposed to human tumors to examine the dynamics of both plated3&#160;as well as resident&#160;T cells4.
Here, a protocol for the preparation of human lung tumor slices, immunostaining of resident CD8 T and tumor cells, and tracking of CD8 T lymphocytes within the tumor microenvironment using confocal microscopy is described. This system is uniquely placed to screen for novel immunotherapy agents favoring T cell migration in tumors.

Ex Vivo Imaging of Resident CD8 T Lymphocytes in Human Lung Tumor Slices Using Confocal Microscopy

This protocol describes a method to image resident tumor-infiltrating CD8 T cells labeled with fluorescently coupled antibodies within human lung tumor slices. This technique permits real-time analyses of CD8 T cell migration using confocal microscopy.

CD8 T cell are key players in the fight against cancer. In order for CD8 T cells to kill tumor cells they need to enter into the tumor, migrate within the ...

Transplantation of Zebrafish Pediatric Brain Tumors into Immune-competent Hosts for Long-term Study of Tumor Cell Behavior and Drug Response

Tumor cell transplantation is an important technique to define the mechanisms controlling cancer cell growth, migration, and host response, as well as to assess potential patient response to therapy. Current methods largely depend on using syngeneic or immune-compromised animals to avoid rejection of the tumor graft. Such methods require the use of specific genetic strains that often prevent the analysis of immune-tumor cell interactions and/or are limited to specific genetic backgrounds. An alternative method in zebrafish takes advantage of an incompletely developed immune system in the embryonic brain before 3 days, where tumor cells are transplanted for use in short-term assays (i.e., 3 to 10 days). However, these methods cause host lethality, which prevents the long-term study of tumor cell behavior and drug response. This protocol describes a simple and efficient method for the long-term orthotopic transplantation of zebrafish brain tumor tissue into the fourth ventricle of a 2-day-old immune-competent zebrafish. This method allows: 1) long-term study of tumor cell behaviors, such as invasion and dissemination; 2) durable tumor response to drugs; and 3) re-transplantation of tumors for the study of tumor evolution and/or the impact of different host genetic backgrounds. In summary, this technique allows cancer researchers to assess engraftment, invasion, and growth at distant sites, as well as to perform chemical screens and cell competition assays over many months. This protocol can be extended to studies of other tumor types and can be used to elucidate mechanisms of chemoresistance and metastasis.

The transplantation of cancer cells is an important tool for the identification of cancer mechanisms and therapeutic responses. Current techniques depend on immune-incompetent animals. Here, we describe a method to transplant zebrafish tumor cells into immune-competent embryos for the long-term analysis of tumor cell behavior and in vivo drug responses.

Tumor cell transplantation is an important technique to define the mechanisms controlling cancer cell growth, migration, and host response, as well as to ...

Target Cell Pre-enrichment and Whole Genome Amplification for Single Cell Downstream Characterization

Rare target cells can be isolated from a high background of non-target cells using antibodies specific for surface proteins of target cells. A recently developed method uses a medical wire functionalized with anti-epithelial cell adhesion molecule (EpCAM) antibodies for in vivo isolation of circulating tumor cells (CTCs)1. A patient-matched cohort in non-metastatic prostate cancer showed that the in vivo isolation technique resulted in a higher percentage of patients positive for CTCs as well as higher CTC counts as compared to the current gold standard in CTC enumeration. As cells cannot be recovered from current medical devices, a new functionalized wire (referred to as Device) was manufactured allowing capture and subsequent detachment of cells by enzymatic treatment. Cells are allowed to attach to the Device, visualized on a microscope and detached using enzymatic treatment. Recovered cells are cytocentrifuged onto membrane-coated slides and harvested individually by means of laser microdissection or micromanipulation. Single-cell samples are then subjected to single-cell whole genome amplification allowing multiple downstream analysis including screening and target-specific approaches. The procedure of isolation and recovery yields high quality DNA from single cells and does not impair subsequent whole genome amplification (WGA). A single cell&#39;s amplified DNA can be forwarded to screening and/or targeted analysis such as array comparative genome hybridization (array-CGH) or sequencing. The device allows ex vivo isolation from artificial rare cell samples (i.e. 500 target cells spiked into 5 mL of peripheral blood). Whereas detachment rates of cells are acceptable (50 - 90%), the recovery rate of detached cells onto slides spans a wide range dependent on the cell line used (&#60;10 - &#62;50%) and needs some further attention. This device is not cleared for the use in patients.

This protocol is to recover and prepare rare target cells from a mixture with non-target background cells for molecular genetic characterization at the single-cell level. DNA quality is equal to non-treated single cells and allows for single-cell application (both screening based and targeted analysis).

Rare target cells can be isolated from a high background of non-target cells using antibodies specific for surface proteins of target cells. A recently ...

A Method to Define the Effects of Environmental Enrichment on Colon Microbiome Biodiversity in a Mouse Colon Tumor Model

Several recent studies have illustrated the beneficial effects of living in an enriched environment on improving human disease. In mice, environmental enrichment (EE) reduces tumorigenesis by activating the mouse immune system, or affects tumor bearing animal survival by stimulating the wound repair response, including improved microbiome diversity, in the tumor microenvironment. Provided here is a detailed procedure to assess the effects of environmental enrichment on the biodiversity of the microbiome in a mouse colon tumor model. Precautions regarding animal breeding and considerations for animal genotype and mouse colony integration are described, all of which ultimately affect microbial biodiversity. Heeding these precautions may allow more uniform microbiome transmission, and consequently will alleviate non-treatment dependent effects that can confound study findings. Further, in this procedure, microbiota changes are characterized using 16S rDNA sequencing of DNA isolated from stool collected from the distal colon following long-term environmental enrichment. Gut microbiota imbalance is associated with the pathogenesis of inflammatory bowel disease and colon cancer, but also of obesity and diabetes among others. Importantly, this protocol for EE and microbiome analysis can be utilized to study the role of microbiome pathogenesis across a variety of diseases where robust mouse models exist that can recapitulate human disease.

Environmental Enrichment (EE) is an animal housing environment that is used to reveal mechanisms that underlie the connections between lifestyle, stress, and disease. This protocol describes a procedure that uses a mouse model of colon tumorigenesis and EE to specifically define alterations in microbiota biodiversity that may impact animal mortality.

Several recent studies have illustrated the beneficial effects of living in an enriched environment on improving human disease. In mice, environmental ...

Digital Polymerase Chain Reaction Assay for the Genetic Variation in a Sporadic Familial Adenomatous Polyposis Patient Using the Chip-in-a-tube Format

The quantitative analysis of human genetic variation is crucial for understanding the molecular characteristics of serious medical conditions, such as tumors. Because digital polymerase chain reactions (PCR) enable the precise quantification of DNA copy number variants, they are becoming an essential tool for detecting rare genetic variations, such as drug-resistant mutations. It is expected that molecular diagnoses using digital PCR (dPCR) will be available in clinical practice in the near future; thus, how to efficiently conduct dPCR with human genetic material is a hot topic. Here, we introduce a method to detect Adenomatous polyposis coli (APC) somatic mosaicism using dPCR with the chip-in-a-tube format, which allows eight dPCR reactions to be simultaneously conducted. Care should be taken when filling and sealing the reaction mixture on the chips. This article demonstrates how to avoid the over- and underestimation of positive partitions. Furthermore, we present a simple procedure for collecting the dPCR product from the partitions on the chips, which can then be used to confirm the specific amplification. We hope that this methods report will help promote the dPCR with the chip-in-a-tube method in genetic research.

Digital polymerase chain reaction (PCR) is a useful tool for the high-sensitivity detection of single nucleotide variants and DNA copy number variants. Here, we demonstrate key considerations for measuring rare variants in the human genome using digital PCR with the chip-in-a-tube format.

The quantitative analysis of human genetic variation is crucial for understanding the molecular characteristics of serious medical conditions, such as ...

Murine Model of Metastatic Liver Tumors in the Setting of Ischemia Reperfusion Injury

Liver ischemia and reperfusion (I/R) injury, a common clinical challenge, remains an inevitable pathophysiological process that has been shown to induce multiple tissue and organ damage. Despite recent advances and therapeutic approaches, the overall morbidity has remained unsatisfactory especially in patients with underlying parenchymal abnormalities. In the context of aggressive cancer growth and metastasis, surgical I/R is suspected to be the promoter regulating tumor recurrence. This article aims to describe a clinically relevant murine model of liver I/R and colorectal liver metastasis. In doing so, we aim to assist other investigators in establishing and perfecting this model for their routine research practice to better understand the effects of liver I/R on promoting liver metastases.

We describe in detail a clinically relevant colorectal cancer liver metastases (CRLM) tumor model and the influence of liver ischemia reperfusion (I/R) in tumor growth and metastasis. This model can help to better understand the mechanisms underlying surgery-induced promotion of liver metastatic growth.

Liver ischemia and reperfusion (I/R) injury, a common clinical challenge, remains an inevitable pathophysiological process that has been shown to induce ...

Establishment and Characterization of Small Bowel Neuroendocrine Tumor Spheroids

Small bowel neuroendocrine tumors (SBNETs) are rare cancers originating from enterochromaffin cells of the gut. Research in this field has been limited because very few patient derived SBNET cell lines have been generated. Well-differentiated SBNET cells are slow growing and are hard to propagate. The few cell lines that have been established are not readily available, and after time in culture may not continue to express characteristics of NET cells. Generating new cell lines could take many years since SBNET cells have a long doubling time and many enrichment steps are needed in order to eliminate the rapidly dividing cancer-associated fibroblasts. To overcome these limitations, we have developed a protocol to culture SBNET cells from surgically removed tumors as spheroids in extracellular matrix (ECM). The ECM forms a 3-dimensional matrix that encapsulates SBNET cells and mimics the tumor micro-environment for allowing SBNET cells to grow. Here, we characterized the growth rate of SBNET spheroids and described methods to identify SBNET markers using immunofluorescence microscopy and immunohistochemistry to confirm that the spheroids are neuroendocrine tumor cells. In addition, we used SBNET spheroids for testing the cytotoxicity of rapamycin.

Neuroendocrine tumors (NETs) originate from neuroendocrine cells of the neural crest. They are slow growing and challenging to culture. We present an alternative strategy to grow NETs from the small bowel by culturing them as spheroids. These spheroids have small bowel NET markers and can be used for drug testing.

Small bowel neuroendocrine tumors (SBNETs) are rare cancers originating from enterochromaffin cells of the gut. Research in this field has been limited ...

Generation of Orthotopic Pancreatic Tumors and Ex vivo Characterization of Tumor-Infiltrating T Cell Cytotoxicity

In vivo models of pancreatic cancer provide invaluable tools for studying disease dynamics, immune infiltration and new therapeutic strategies. The orthotopic murine model can be performed on large cohorts of immunocompetent mice simultaneously, is relatively inexpensive and preserves the cognate tissue microenvironment. The quantification of T cell infiltration and cytotoxic activity within orthotopic tumors provides a useful indicator of an antitumoral response.
This protocol describes the methodology for surgical generation of orthotopic pancreatic tumors by injection of a low number of syngeneic tumor cells resuspended in 5 &#181;L basement membrane directly into the pancreas. Mice bearing orthotopic tumors take approximately 30 days to reach endpoint, at which point tumors can be harvested and processed for characterization of tumor-infiltrating T cell activity. Rapid enzymatic digestion using collagenase and DNase allows a single-cell suspension to be extracted from tumors. The viability and cell surface markers of immune cells extracted from the tumor are preserved; therefore, it is appropriate for multiple downstream applications, including flow-assisted cell sorting of immune cells for culture or RNA extraction, flow cytometry analysis of immune cell populations. Here, we describe the ex vivo stimulation of T cell populations for intracellular cytokine quantification (IFN&#947; and TNF&#945;) and degranulation activity (CD107a) as a measure of overall cytotoxicity. Whole-tumor digests were stimulated with phorbol myristate acetate and ionomycin for 5 h, in the presence of anti-CD107a antibody in order to upregulate cytokine production and degranulation. The addition of brefeldin A and monensin for the final 4 h was performed to block extracellular transport and maximize cytokine detection. Extra- and intra-cellular staining of cells was then performed for flow cytometry analysis, where the proportion of IFN&#947;+, TNF&#945;+ and CD107a+ CD4+ and CD8+ T cells was quantified.
This method provides a starting base to perform comprehensive analysis of the tumor microenvironment.

Generation of Orthotopic Pancreatic Tumors and Ex vivo Characterization of Tumor-Infiltrating T Cell Cytotoxicity

This protocol describes the surgical generation of orthotopic pancreatic tumors and the rapid digestion of freshly isolated murine pancreatic tumors. Following digestion, viable immune cell populations can be used for further downstream analysis, including ex vivo stimulation of T cells for intracellular cytokine detection by flow cytometry.

In vivo models of pancreatic cancer provide invaluable tools for studying disease dynamics, immune infiltration and new therapeutic strategies. The ...