This work was supported by the University of Chicago Women's Board, the Wendy Will Case Fund, and the University of Chicago Comprehensive Cancer Center Support Grant (P30 CA014599). We would like to thank the Flow Cytometry Core at the University of Chicago for their help in setting up this experiment, and well as other members of the de Jong lab, particularly Leslie Pedraza and Sean McConnell.

All procedures with zebrafish have been approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Chicago. The University of Chicago is accredited by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC).
1. Generating and Isolating Fluorescently Labeled T-ALL Cells in Zebrafish
<ol>
	<li>Microinjection into syngeneic zebrafish embryos
	<ol>
		<li>Using commercially available kits, isolate circular rag2:c-myc and rag2:green fluorescent protein (rag2:GFP) plasmid DNA containing inverted terminal repeats recognized by tol2 transposase (see the Table of Materials for source of plasmid DNA)12 and elute the DNA in sterile water. 
		NOTE: GFP is used in this study, but any fluorescent protein will work.</li>
		<li>Prepare pCS2-transposase (tol2) RNA
		<ol>
			<li>Isolate tol2 plasmid DNA using commercially available kits (see the Table of Materials for the source of plasmid DNA)12 and elute the DNA in sterile water.</li>
			<li>Incubate 1 &#181;g of tol2 DNA at 37 &#176;C for 1 h with 5 units of NotI restriction enzyme in the appropriate buffer to linearize the plasmid. Heat-inactivate the NotI at 65 &#176;C for 20 min.</li>
			<li>Transcribe the tol2 RNA with SP6 RNA polymerase from the linearized DNA using a commercially available RNA transcription kit13. Store the RNA in single-use aliquots at -80 &#176;C.</li>
		</ol>
		</li>
		<li>Prepare the injection mix on ice by adding 250 ng of rag2:c-myc plasmid DNA, 250 ng of rag2:GFP plasmid DNA, 150 ng of tol2 RNA, and 0.5 &#181;L of phenol red. Adjust the volume to 10 &#181;L with nuclease-free water.</li>
		<li>Inject ~1 nL of injection mix into the cell of a one-cell stage syngeneic zebrafish embryo using a microinjector and needle pulled from a glass capillary tube, following previously established methods8,14. 
		NOTE: Syngeneic zebrafish generated by parthenogenesis15 are used here to eliminate genetic heterogeneity and immune rejection after transplantation. However, wildtype zebrafish or any desired strain can also be used.</li>
		<li>Remove dead, underdeveloped, or malformed embryos at 24 h and 48 h post-injection16.</li>
		<li>Place the injected fish on the fish system at 6 days post-injection and raise them according to standard protocol6.</li>
	</ol>
	</li>
	<li>Screening injected zebrafish and monitoring tumor growth
	<ol>
		<li>At 21 days post-injection, place a single injected larva in a droplet of embryo medium on a Petri dish and screen for GFP fluorescence using an epifluorescent microscope (excitation bandpass: 470/40, emission bandpass: 525/50)8. 
		NOTE: Zebrafish larvae that have integrated both rag2:c-myc and rag2:GFP will have a green fluorescent thymus (positive fish) and may already exhibit the expansion of malignant green fluorescent cells beyond the thymus. All fish with a GFP+ thymus will go on to develop a GFP+ T-ALL. The larvae that do not demonstrate integration of the plasmids will not have any green fluorescent cells (negative fish).</li>
		<li>Separate the negative fish (based on a lack of fluorescence) into a different tank and monitor the fish again at 28 and 35 days post-injection. At 28 and 35 days post-injection, anesthetize the fish with 0.02% buffered tricaine (MS-222) in fish system water prior to screening.</li>
		<li>Place each zebrafish larva that is positive for a fluorescently labeled thymus or a fluorescently labeled tumor in an individual tank for monitoring tumor growth three times a week.</li>
	</ol>
	</li>
	<li>Collection of fluorescently labeled T-ALL cells from the primary tumor fish
	<ol>
		<li>Prepare at least 20 mL of 10% heat-inactivated fetal bovine serum in 0.9x phosphate buffered saline (FBS/PBS).</li>
		<li>Add 1 mL of FBS/PBS to one vial of heparin sodium salt (300 units).</li>
		<li>Select fish bearing tumors in more than 50% of the body, or those fish having difficulty eating or swimming. Sacrifice the fish by overdosing them with tricaine or by ice water immersion. Confirm death by lack a of gill movement and heartbeat.</li>
		<li>Use a razor blade to remove the head of the fish.</li>
		<li>Wash the cavity of the fish with the heparin solution to remove excess red blood cells.
		<ol>
			<li>Using a pipette, inject 100 &#181;L of heparin solution (prepared in step 1.3.2) into the body cavity of the fish. Remove all liquid that spills out (it will contain blood cells) and pipette it into a 1.5 mL microcentrifuge tube.</li>
			<li>Use a fresh pipette tip to wash the body again. Perform at least three washes, or until the liquid that spills out appears free of blood.</li>
			<li>Discard all liquid from the washes in steps 1.3.5.1 and 1.3.5.2, as it will not be used in further analyses.</li>
		</ol>
		</li>
		<li>Collect the leukemia cells.
		<ol>
			<li>Inject 100 &#181;L of FBS/PBS into the body cavity of the fish.</li>
			<li>Apply gentle pressure to the outside of the body of the fish with the pipette tip to squeeze/push out the tumor cells. 
			NOTE: If this step is performed using a dissecting microscope, the tumor cells spilling out of the body cavity will be evident.</li>
			<li>Collect the liquid and cells from each wash into a 1.5 mL microcentrifuge tube.</li>
			<li>Repeat steps 1.3.6.1-1.3.6.3 until most of the tumor cells are collected (usually 5-10 times). Collect all tumor cells into the same 1.5-mL microcentrifuge tube. Keep the cells at room temperature.</li>
		</ol>
		</li>
		<li>Mix the collected tumor cells from step 1.3.6 by gently pipetting them to dissociate the clumps of cells. Filter the cell suspension through a 40-&#181;m mesh filter. Wash the filter 1-2 times with 100 &#181;L of FBS/PBS. Keep the cells at room temperature.</li>
		<li>Mix 2 &#181;L of cell suspension with 18 &#181;L of trypan blue (0.4%, diluted 1:10 and filtered) in a new tube. Load 10 &#181;L on a hemocytometer and count the number of live (non-blue) fluorescent cells to calculate the number of isolated tumor cells. 
		NOTE: Non-blue GFP-negative cells are likely normal, non-malignant T-cells and should not be counted. At least 2 x 106 cells are required to stain the cells with Hoechst 33342.</li>
	</ol>
	</li>
</ol>
2. Staining the Fluorescently Labeled T-ALL Cells with Hoechst 33342 to Identify the Side Population
<ol>
	<li>Dilute Hoechst 33342 1:10 with nuclease-free H2O to make the 1 mg/mL working concentration. Store the dye at 4 &#176;C and in the dark.</li>
	<li>Prepare a 100-mM solution of verapamil by dissolving 49.1 mg in 1 mL of dimethyl sulfoxide (DMSO). 
	NOTE: Verapamil is an inhibitor of ABC transporters and is an important control for side population experiments. Adding verapamil to samples will inhibit the ability of the ABC transporters to efflux the Hoechst 33342 dye. Therefore, a true side population will disappear when verapamil is added to the sample.</li>
	<li>Set a water bath to 28 &#176;C.</li>
	<li>Prepare samples and controls in the dark by adding cells and solutions to fluorescence-activated cell sorter (FACS) tubes.
	<ol>
		<li>Prepare the samples by adding 106 cells, 15 &#181;L of 1 mg/mL Hoechst 33342, and 2.5 &#181;L of DMSO to a FACS tube. Adjust the volume to 1 mL with FBS/PBS.</li>
		<li>Prepare the controls by adding 106 cells, 15 &#181;L of 1 mg/mL Hoechst 33342, and 2.5 &#181;L of 100 mM verapamil to a FACS tube. Adjust the volume to 1 mL with FBS/PBS. 
		NOTE: A minimum of 106 cells/sample is recommended, but staining more cells is preferred, especially if the side population cells will be sorted for further analysis. Do not exceed 106 cells/mL, and maintain the Hoechst 33342 concentration at 15 &#181;g/mL. If 10 x 106 cells are stained, the total reaction volume is 10 mL.</li>
	</ol>
	</li>
	<li>Incubate in a 28 &#176;C water bath in the dark for 120 min.</li>
	<li>After the incubation, place the cells immediately on ice and keep them in the dark.</li>
	<li>Pellet the cells at 4 &#176;C for 6 min at 300 x g. Remove the supernatant. Wash with 1 mL of FBS/PBS.</li>
	<li>Pellet the cells at 4 &#176;C for 6 min at 300 x g. Remove the supernatant. Resuspend the cells in 1 mL of FBS/PBS.</li>
	<li>Keep at 4 &#176;C until cell sorting.</li>
	<li>15 min prior to cell sorting, add 2 &#181;L of propidium iodide (PI) stock (1 mg/mL) to each 1 mL of FBS/PBS (final concentration: 2 &#181;g/mL). Mix well.</li>
</ol>
3. Use FACS to Find the Side Population within the Fluorescently Labeled T-ALL Cell Population
<ol>
	<li>Analyze the stained zebrafish T-ALL cell suspensions on a cell sorter equipped with a UV laser for Hoechst 33342 dye excitation and a 488-nm laser for PI excitation and for the detection of the GFP+ T-ALL cells.</li>
	<li>Determine a gate for the live, GFP+ T-ALL cells.
	<ol>
		<li>Use forward scatter (FSC) and side scatter (SSC) area to gate out debris. 
		NOTE: FSC is used to distinguish cell size and SSC is used to distinguish the granularity of the cell.</li>
		<li>Use FSC and SSC width to discriminate doublets. 
		NOTE: There are three components identified by the flow cytometer detectors: area, height, and width. Area is typically used to measure the fluorescence of the cell. Width measures the time of flight and is twice as wide if two cells are clumped together.</li>
		<li>For live tumor cells, draw a gate around the cells positive for GFP and negative for PI using the appropriate detectors (e.g., FITC for GFP and PerCP Cy5-5 for PI).</li>
	</ol>
	</li>
	<li>In the live cell gate, measure the Hoechst 33342 fluorescence through the Hoechst Blue and Hoechst Red bandpass filters (450/50 and 670/30, respectively). 
	NOTE: The side population, if present, will be evident after this is set up. Importantly, the side population must disappear in the verapamil control in order for it to be considered a true side population.</li>
	<li>If sorting the side population cells for further experiments, use the large nozzle tip (100 &#181;m) and collect the cells into a FACS tube containing 3 mL of 100% FBS. Use a larger nozzle tip (100 &#181;m) instead of the smaller tip (70 &#181;m) to improve cell viability after sorting.</li>
</ol>

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I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish:+a+model+system+for+the+study+of+human+disease.">Zebrafish: a model system for the study of human disease.</a> Curr Opin Genet Dev. 10 (3), 252-256 (2000).</li><li>White, R., Rose, K., Zon, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish+cancer:+the+state+of+the+art+and+the+path+forward.">Zebrafish cancer: the state of the art and the path forward.</a> Nat Rev Cancer. 13 (9), 624-636 (2013).</li><li>Kobayashi, I., 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=Characterization+and+localization+of+side+population+(SP)+cells+in+zebrafish+kidney+hematopoietic+tissue.">Characterization and localization of side population (SP) cells in zebrafish kidney hematopoietic tissue.</a> Blood. 111 (3), 1131-1137 (2008).</li><li>Tsinkalovsky, O., Vik-Mo, A. 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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=Clonal+evolution+enhances+leukemia-propagating+cell+frequency+in+T+cell+acute+lymphoblastic+leukemia+through+Akt/mTORC1+pathway+activation.">Clonal evolution enhances leukemia-propagating cell frequency in T cell acute lymphoblastic leukemia through Akt/mTORC1 pathway activation.</a> Cancer Cell. 25, 366-378 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+Methods+in+Cellular+and+Molecular+Biology.+Plasmid+Purification.">Basic Methods in Cellular and Molecular Biology. 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Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transplantable+tumor+lines+generated+in+clonal+zebrafish.">Transplantable tumor lines generated in clonal zebrafish.</a> Cancer Research. 66 (6), 3120-3125 (2006).</li><li>Westerfield, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Zebrafish Book: A Guide for the Laboratory Use of Zebrafish. , (1993).</li><li>Hirschmann-Jax, 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=A+distinct+"side+population"+of+cells+with+high+drug+efflux+capacity+in+human+tumor+cells.">A distinct "side population" of cells with high drug efflux capacity in human tumor cells.</a> Proc Natl Acad Sci. USA. 101 (39), 14228-14233 (2004).</li><li>Komuro, H., 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=Identification+of+side+population+cells+(stem-like+cell+population)+in+pediatric+solid+tumor+cell+lines.">Identification of side population cells (stem-like cell population) in pediatric solid tumor cell lines.</a> J Pediatr Surg. 42 (12), 2040-2045 (2007).</li><li>Moshaver, 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=Identification+of+a+small+subpopulation+of+candidate+leukemia-initiating+cells+in+the+side+population+of+patients+with+acute+myeloid+leukemia.">Identification of a small subpopulation of candidate leukemia-initiating cells in the side population of patients with acute myeloid leukemia.</a> Stem Cells. 26 (12), 3059-3067 (2008).</li></ol>

The authors have nothing to disclose.

The side population assay is highly sensitive; therefore, small changes to the protocol can result in a difficulty in detecting side population cells. First, the temperature during the staining step is specific to each animal/cell system. For mammalian systems, the side population assay is typically performed at 37 &#176;C2. When the zebrafish T-ALL cells were incubated at 37 &#176;C, many of the cells died, which made this incubation temperature unacceptable (data not shown). When Kobayashi and c...

The side population assay capitalizes on the enhanced ability of certain cells within a tissue to efflux the DNA binding dye Hoechst 33342 due to high levels of the ATP binding cassette (ABC) transporter proteins on the cell membrane. The cells that efflux the Hoechst 33342 dye can be identified using dual wavelength flow cytometric analysis after the dye is excited by a UV laser. This assay was first used to identify murine hematopoietic stem cells (HSCs)1, but it has since been used to identify stem/progenitor cell populations in many tissues and cancers (reviewed in reference 2). However, not all populations of cells have a side population, and not all side populations are enriched for stem/progenitor cells.
The zebrafish is a powerful vertebrate genetic model system for studying human cancer3,4, with a number of advantages over traditional murine models of cancer. Zebrafish embryos are externally fertilized and are optically clear, facilitating transgenesis and the in vivo observation of pathologic processes, including cancer initiation and progression. To date, the side population assay to detect potential stem or progenitor cells has only been applied to the kidney marrow in zebrafish to identify HSCs, and not to any zebrafish cancer models5,6.
The zebrafish model of T-cell acute lymphoblastic leukemia (T-ALL) is morphologically and genetically similar to human T-ALL7,8,11. T-ALL is an aggressive malignancy that, in humans, accounts for 10-15% of pediatric and 25% of adult ALL cases9. While the treatment of T-ALL has improved, relapse is still common and is associated with a poor prognosis. T-ALL tumors are heterogeneous and contain many different tumor cell subpopulations, including leukemia initiating cells (LICs). LICs are defined by their ability to regrow the entire tumor from a single cell, and the frequency of LICs within a tumor cell population can be calculated by transplanting varying cell doses into recipients via a limiting dilution transplantation assay (LDA). While LDA experiments have been performed in zebrafish to calculate the frequency of LICs8,10,11, this determination is made in hindsight and does not allow for the prospective isolation of LICs. Therefore, a method to prospectively isolate a population enriched for cancer stem cell activity is lacking. Identifying and isolating side population cells from zebrafish T-ALLs is the first step towards addressing this deficiency.
The protocol presented here describes how to efficiently generate T-ALL tumors in zebrafish utilizing tol2-mediated transgenesis, harvest the T-ALL tumors cells, and stain them with Hoechst 33342 to identify the side population of cells. Future in vivo experiments with zebrafish T-ALL could include whether the side population cells are enriched for LICs or have other stem- or progenitor-like properties.

<table border="0" cellpadding="0" cellspacing="0" width="859">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Syngeneic zebrafish (CG2)</td>
			<td style="width:199px;"></td>
			<td style="width:208px;"></td>
			<td style="width:208px;">See Mizgireuv et al., 2006</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">rag2:c-myc plasmid</td>
			<td style="width:199px;"></td>
			<td style="width:208px;"></td>
			<td>Langenau Laboratory</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:245px;">rag2:GFP plasmid constructed in de Jong Lab</td>
			<td style="width:199px;"></td>
			<td style="width:208px;"></td>
			<td style="width:208px;">rag2 promoter from Langenau Laboratory</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">pCS2-transposase plasmid</td>
			<td style="width:199px;"></td>
			<td style="width:208px;"></td>
			<td>Chien Laboratory</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">NotI -HF restriction enzyme</td>
			<td style="width:199px;">New England Bio-Labs Inc.</td>
			<td>R3189S</td>
			<td>500 units in 25 &#181;L</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:245px;">mMessage Machine SP6 Transcription Kit</td>
			<td style="width:199px;">Ambion</td>
			<td style="width:208px;">Thermo Fisher Scientific - AM1340</td>
			<td>25 reactions</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">QIAGEN Plasmid Midi Kit</td>
			<td style="width:199px;">Qiagen, Inc.</td>
			<td style="width:208px;">12643</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">SteREO Discovery V8 Microscope</td>
			<td style="width:199px;">Carl Zeiss Microscopy</td>
			<td>495015-0008-000</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Digital microinjector</td>
			<td style="width:199px;">Tritech Research</td>
			<td>MINJ-D</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Brass straight-arm needle holder</td>
			<td style="width:199px;">Tritech Research</td>
			<td>MINJ-4</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Magnetic base and stand</td>
			<td style="width:199px;">Tritech Research</td>
			<td>MINJ-HBMB</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Micromanipulator</td>
			<td style="width:199px;">Narishige International</td>
			<td style="width:208px;">MN153</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Glass capillaries</td>
			<td style="width:199px;">Sutter Instrument Co.</td>
			<td style="width:208px;">B100-50-10</td>
			<td>10 cm without filament</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Flaming/Brown micropipette puller</td>
			<td style="width:199px;">Sutter Instrument Co.</td>
			<td style="width:208px;">P-97</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Microloader pipette tips</td>
			<td style="width:199px;">Eppendorf North America Inc.</td>
			<td>930001007</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Phenol Red solution</td>
			<td style="width:199px;">Sigma Life Science</td>
			<td style="width:208px;">P0290</td>
			<td>0.5% concentration 100 mL</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Plastic Transfer pipettes</td>
			<td style="width:199px;">Fisherbrand</td>
			<td>137119D</td>
			<td>graduated 7.5 mL bulb</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Tricaine methanesulfonate (MS-222)</td>
			<td style="width:199px;">Western Chemical, Inc.</td>
			<td style="width:208px;">Fisher Scientific - NC0342409</td>
			<td>100 g</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Fetal bovine serum (FBS)</td>
			<td style="width:199px;">HyClone Laboratories, Inc.</td>
			<td style="width:208px;">Fisher Scientific - SH3007103</td>
			<td>500 mL</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Phosphate-Buffered Saline (PBS)</td>
			<td style="width:199px;">Gibco by Life Technologies</td>
			<td style="width:208px;">1001-023</td>
			<td>pH 7.4 (1x) - 500 mL</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Heparin sodium salt</td>
			<td style="width:199px;">Sigma-Aldrich</td>
			<td style="width:208px;">2106</td>
			<td>15 - 300 unit vials</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">40 um mesh filter</td>
			<td style="width:199px;">Falcon Corning Brand</td>
			<td style="width:208px;">352340</td>
			<td>Case of 50</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Trypan blue</td>
			<td style="width:199px;">Sigma Life Science</td>
			<td style="width:208px;">T8154</td>
			<td>20 mL - Solution (0.4%)</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Hoechst 33342</td>
			<td style="width:199px;">Life Technologies</td>
			<td style="width:208px;">H3570</td>
			<td>10 mL</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Verapamil</td>
			<td style="width:199px;">Sigma Life Science</td>
			<td style="width:208px;">V4629</td>
			<td>1 g</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Dimethyl sulfoxide (DMSO)</td>
			<td style="width:199px;">Sigma Life Science</td>
			<td style="width:208px;">D8418</td>
			<td>100 mL</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">Propidium Iodide</td>
			<td style="width:199px;">Life Technologies</td>
			<td style="width:208px;">P3566</td>
			<td>10 mL</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">FACSAria Fusion cell sorter</td>
			<td style="width:199px;">BD Biosciences</td>
			<td style="width:208px;"></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">BD FACSDiva 8.0.1</td>
			<td style="width:199px;">BD Biosciences</td>
			<td style="width:208px;"></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:245px;">FlowJo v10.2</td>
			<td style="width:199px;">FlowJo, LLC</td>
			<td style="width:208px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of the side population in myc-induced t-cell acute lymphoblastic leukemia in zebrafish

Heterogeneous cell populations, from either healthy or malignant tissues, may contain a population of cells characterized by a differential ability to efflux the DNA-binding dye Hoechst 33342. This "side population" of cells can be identified using flow cytometric methods after the Hoechst 33342 dye is excited by an ultraviolet (UV) laser. The side population of many cell types contains stem- or progenitor-like cells. However, not all cell types have an identifiable side population. Danio rerio, zebrafish, have a robust in vivo model of T-cell acute lymphoblastic leukemia (T-ALL), but whether these zebrafish T-ALLs have a side population is unknown. The method described here outlines how to isolate the side population cells in zebrafish T-ALL. To begin, the T-ALL in zebrafish is generated via the microinjection of tol2 plasmids into one-cell stage embryos. Once the tumors have grown to a stage at which they expand into more than half of the animal's body, the T-ALL cells can be harvested. The cells are then stained with Hoechst 33342 and examined by flow cytometry for side population cells. This method has broad applications in zebrafish T-ALL research. While there are no known cell surface markers in zebrafish that confirm whether these side population cells are cancer stem cell-like, in vivo functional transplantation assays are possible. Furthermore, single-cell transcriptomics could be applied to identify the genetic features of these side population cells.

To efficiently generate fluorescent myc-induced T-ALL tumors in zebrafish, circular DNA constructs flanked by tol2 transposase sites can be co-injected with tol2 RNA. Previous studies from the injection of linearized DNA into zebrafish embryos report a 5% transgenesis rate8. With the protocol adjusted to include tol2-mediated transgenesis, transgenesis rates ranging from 10-44% can be observed (Table 1).
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Watch this Scientific Journal Video about Isolation of the Side Population in Myc-induced T-cell Acute Lymphoblastic Leukemia in Zebrafish at JoVE.com

Isolation of the Side Population in Myc-induced T-cell Acute Lymphoblastic Leukemia in Zebrafish

Here, we describe a technique to isolate the side population cells from a zebrafish model of myc-induced T-cell acute lymphoblastic leukemia (T-ALL). This side population assay is highly sensitive and is described for zebrafish T-ALL, but it may be applicable to other malignant and non-malignant zebrafish cell types.

Heterogeneous cell populations, from either healthy or malignant tissues, may contain a population of cells characterized by a differential ability to ...

isolation-side-population-myc-induced-t-cell-acute-lymphoblastic

Research

JoVE Journal

Immunology and Infection

6.5K Views.  The University of Chicago. Here, we describe a technique to isolate the side population cells from a zebrafish model of myc-induced T-cell acute lymphoblastic leukemia (T-ALL). This side population assay is highly sensitive and is described for zebrafish T-ALL, but it may be applicable to other malignant and non-malignant zebrafish cell types.

Video: Isolation of the Side Population in Myc-induced T-cell Acute Lymphoblastic Leukemia in Zebrafish

Retroviral Transduction of T-cell Receptors in Mouse T-cells

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen presenting cells (APCs)1. This recognition leads to the activation of T-cells and a series of functional outcomes (e.g. cytokine production, killing of the target cells). Understanding the functional role of TCRs is critical to harness the power of the immune system to treat a variety of immunology related diseases (e.g. cancer or autoimmunity).
It is convenient to study TCRs in mouse models, which can be accomplished in several ways. Making TCR transgenic mouse models is costly and time-consuming and currently there are only a limited number of them available2-4. Alternatively, mice with antigen-specific T-cells can be generated by bone marrow chimera. This method also takes several weeks and requires expertise5. Retroviral transduction of TCRs into in vitro activated mouse T-cells is a quick and relatively easy method to obtain T-cells of desired peptide-MHC specificity. Antigen-specific T-cells can be generated in one week and used in any downstream applications. Studying transduced T-cells also has direct application to human immunotherapy, as adoptive transfer of human T-cells transduced with antigen-specific TCRs is an emerging strategy for cancer treatment6.
Here we present a protocol to retrovirally transduce TCRs into in vitro activated mouse T-cells. Both human and mouse TCR genes can be used. Retroviruses carrying specific TCR genes are generated and used to infect mouse T-cells activated with anti-CD3 and anti-CD28 antibodies. After in vitro expansion, transduced T-cells are analyzed by flow cytometry.

We present a protocol to produce antigen-specific mouse T-cells using retroviral transduction

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen ...

Genotypic Inference of HIV-1 Tropism Using Population-based Sequencing of V3

Background: Prior to receiving a drug from CCR5-antagonist class in HIV therapy, a patient must undergo an HIV tropism test to confirm that his or her viral population uses the CCR5 coreceptor for cellular entry, and not an alternative coreceptor. One approach to tropism testing is to examine the sequence of the V3 region of the HIV envelope, which interacts with the coreceptor.
Methods: Viral RNA is extracted from blood plasma. The V3 region is amplified in triplicate with nested reverse transcriptase-PCR. The amplifications are then sequenced and analyzed using the software, RE_Call. Sequences are then submitted to a bioinformatic algorithm such as geno2pheno to infer viral tropism from the V3 region. Sequences are inferred to be non-R5 if their geno2pheno false positive rate falls below 5.75%. If any one of the three sequences from a sample is inferred to be non-R5, the patient is unlikely to respond to a CCR5-antagonist.

HIV tropism can be inferred from the V3 region of the viral envelope. V3 is PCR amplified in triplicate using nested RT-PCR, sequenced, and interpreted using bioinformatic software. Samples with with 1 or more sequence(s) with low g2P scores are classified as non-R5 virus.

Background: Prior to receiving a drug from CCR5-antagonist class in HIV therapy, a patient must undergo an HIV tropism test to confirm that his or her ...

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological deficiencies. GVHD is caused by mature alloreactive T cells present in the bone marrow graft that are infused into the recipient and cause damage to host organs. However, in mice, T cells must be added to the bone marrow inoculum to cause GVHD. Although extensive work has been done to characterize T cell responses post transplant, bioluminescent imaging technology is a non-invasive method to monitor T cell trafficking patterns in vivo. 
Following lethal irradiation, recipient mice are transplanted with bone marrow cells and splenocytes from donor mice. T cell subsets from L2G85.B6 (transgenic mice that constitutively express luciferase) are included in the transplant. By only transplanting certain T cell subsets, one is able to track specific T cell subsets in vivo, and based on their location, develop hypotheses regarding the role of specific T cell subsets in promoting GVHD at various time points. At predetermined intervals post transplant, recipient mice are imaged using a Xenogen IVIS CCD camera. Light intensity can be quantified using Living Image software to generate a pseudo-color image based on photon intensity (red = high intensity, violet = low intensity). 
Between 4-7 days post transplant, recipient mice begin to show clinical signs of GVHD. Cooke et al.1 developed a scoring system to quantitate disease progression based on the recipient mice fur texture, skin integrity, activity, weight loss, and posture. Mice are scored daily, and euthanized when they become moribund. Recipient mice generally become moribund 20-30 days post transplant. 
Murine models are valuable tools for studying the immunology of GVHD. Selectively transplanting particular T cell subsets allows for careful identification of the roles each subset plays. Non-invasively tracking T cell responses in vivo adds another layer of value to murine GVHD models.

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Murine bone marrow transplantation is a widely used technique to study immunological mechanisms governing graft-versus-host disease in humans. The ability to monitor T cell trafficking patterns in vivo allows for detailed analysis of the development and perpetuation of T cell responses during graft-versus-host disease.

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological ...

Real-time Live Imaging of T-cell Signaling Complex Formation

Protection against infectious diseases is mediated by the immune system 1,2. T lymphocytes are the master coordinators of the immune system, regulating the activation and responses of multiple immune cells 3,4. T-cell activation is dependent on the recognition of specific antigens displayed by antigen presenting cells (APCs). The T-cell antigen receptor (TCR) is specific to each T-cell clone and determines antigen specificity 5. The binding of the TCR to the antigen induces the phosphorylation of components of the TCR complex. In order to promote T-cell activation, this signal must be transduced from the membrane to the cytoplasm and the nucleus, initiating various crucial responses such as recruitment of signaling proteins to the TCR;APC site (the immune synapse), their molecular activation, cytoskeletal rearrangement, elevation of intracellular calcium concentration, and changes in gene expression 6,7. The correct initiation and termination of activating signals is crucial for appropriate T-cell responses. The activity of signaling proteins is dependent on the formation and termination of protein-protein interactions, post translational modifications such as protein phosphorylation, formation of protein complexes, protein ubiquitylation and the recruitment of proteins to various cellular sites 8. Understanding the inner workings of the T-cell activation process is crucial for both immunological research and clinical applications.
Various assays have been developed in order to investigate protein-protein interactions; however, biochemical assays, such as the widely used co-immunoprecipitation method, do not allow protein location to be discerned, thus precluding the observation of valuable insights into the dynamics of cellular mechanisms. Additionally, these bulk assays usually combine proteins from many different cells that might be at different stages of the investigated cellular process. This can have a detrimental effect on temporal resolution. The use of real-time imaging of live cells allows both the spatial tracking of proteins and the ability to temporally distinguish between signaling events, thus shedding light on the dynamics of the process 9,10. We present a method of real-time imaging of signaling-complex formation during T-cell activation. Primary T-cells or T-cell lines, such as Jurkat, are transfected with plasmids encoding for proteins of interest fused to monomeric fluorescent proteins, preventing non-physiological oligomerization 11. Live T cells are dropped over a coverslip pre-coated with T-cell activating antibody 8,9, which binds to the CD3/TCR complex, inducing T-cell activation while overcoming the need for specific activating antigens. Activated cells are constantly imaged with the use of confocal microscopy. Imaging data are analyzed to yield quantitative results, such as the colocalization coefficient of the signaling proteins.

We describe a live-cell imaging method that provides insight into protein dynamics during the T-cell activation process. We demonstrate the combined usage of the T-cell spreading assay, confocal microscopy and imaging analysis to yield quantitative results to follow signaling complex formation throughout T-cell activation.

Protection against infectious diseases is mediated by the immune system 1,2. T lymphocytes are the master coordinators of the immune system, regulating ...

Culturing Microglia from the Neonatal and Adult Central Nervous System

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

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

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

The Use of Fluorescent Target Arrays for Assessment of T Cell Responses In vivo

The ability to monitor T cell responses in vivo is important for the development of our understanding of the immune response and the design of immunotherapies. Here we describe the use of fluorescent target array (FTA) technology, which utilizes vital dyes such as carboxyfluorescein succinimidyl ester (CFSE), violet laser excitable dyes (CellTrace Violet: CTV) and red laser excitable dyes (Cell Proliferation Dye eFluor 670: CPD) to combinatorially label mouse lymphocytes into &#62;250 discernable fluorescent cell clusters. Cell clusters within these FTAs can be pulsed with major histocompatibility (MHC) class-I and MHC class-II binding peptides and thereby act as target cells for CD8+ and CD4+ T cells, respectively. These FTA cells remain viable and fully functional, and can therefore be administered into mice to allow assessment of CD8+ T cell-mediated killing of FTA target cells and CD4+ T cell-meditated help of FTA B cell target cells in real time in vivo by flow cytometry. Since &#62;250 target cells can be assessed at once, the technique allows the monitoring of T cell responses against several antigen epitopes at several concentrations and in multiple replicates. As such, the technique can measure T cell responses at both a quantitative (e.g.&#160;the cumulative magnitude of the response) and a qualitative (e.g.&#160;functional avidity and epitope-cross reactivity of the response) level. Herein, we describe how these FTAs are constructed and give an example of how they can be applied to assess T cell responses induced by a recombinant pox virus vaccine.

The Use of Fluorescent Target Arrays for Assessment of T Cell Responses In vivo

The ability to monitor T cell responses in detail in vivo is important for the development of our understanding of the immune response. Here we describe the use of fluorescent target arrays (FTAs) in an in vivo T cell assay that assesses &#62;250 parameters simultaneously by flow cytometry.

The ability to monitor T cell responses in vivo is important for the development of our understanding of the immune response and the design of ...

An Ex vivo Model of an Oligodendrocyte-directed T-Cell Attack in Acute Brain Slices

Death of oligodendrocytes accompanied by destruction of neurons and axons are typical histopathological findings in cortical and subcortical grey matter lesions in inflammatory demyelinating disorders like multiple sclerosis (MS). In these disorders, mainly CD8+ T-cells of putative specificity for myelin- and oligodendrocyte-related antigens are found, so that neuronal apoptosis in grey matter lesions may be a collateral effect of these cells. Different types of animal models are established to study the underlying mechanisms of the mentioned pathophysiological processes. However, although they mimic some aspects of MS, it is impossible to dissect the exact mechanism and time course of &#8216;&#8216;collateral&#8217;&#8217; neuronal cell death. To address this course, here we show a protocol to study the mechanisms and time response of neuronal damage following an oligodendrocyte-directed CD8+ T cell attack. To target only the myelin sheath and the oligodendrocytes, in vitro activated oligodendrocyte-specific CD8+ T-cells are transferred into acutely isolated brain slices. After a defined incubation period, myelin and neuronal damage can be analysed in different regions of interest. Potential applications and limitations of this model will be discussed.

An Ex vivo Model of an Oligodendrocyte-directed T-Cell Attack in Acute Brain Slices

To address mechanisms of demyelination and neuronal apoptosis in cortical lesions of inflammatory demyelinating disorders, different animal models are used. We here describe an ex vivo approach by using oligodendrocyte-specific CD8+ T-cells on brain slices, resulting in oligodendroglial and neuronal death. Potential applications and limitations of the model are discussed.

Death of oligodendrocytes accompanied by destruction of neurons and axons are typical histopathological findings in cortical and subcortical grey matter ...

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&#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 ...

Imaging CD4 T Cell Interstitial Migration in the Inflamed Dermis

The ability of CD4 T cells to carry out effector functions is dependent upon the rapid and efficient migration of these cells in inflamed peripheral tissues through an as-yet undefined mechanism. The application of multiphoton microscopy to the study of the immune system provides a tool to measure the dynamics of immune responses within intact tissues. Here we present a protocol for non-invasive intravital multiphoton imaging of CD4 T cells in the inflamed mouse ear dermis. Use of a custom imaging platform and a venous catheter allows for the visualization of CD4 T cell dynamics in the dermal interstitium, with the ability to interrogate these cells in real-time via the addition of blocking antibodies to key molecular components involved in motility. This system provides advantages over both in vitro models and surgically invasive imaging procedures. Understanding the pathways used by CD4 T cells for motility may ultimately provide insight into the basic function of CD4 T cells as well as the pathogenesis of both autoimmune diseases and pathology from chronic infections.

The mechanisms that govern the interstitial motility of CD4 effector T cells at sites of inflammation are relatively unknown. We present a non-invasive approach to visualize and manipulate in vitro-primed CD4 T cells in the inflamed ear dermis, allowing for study of the dynamic behavior of these cells in situ.

The ability of CD4 T cells to carry out effector functions is dependent upon the rapid and efficient migration of these cells in inflamed peripheral ...

Neutrophil Isolation and Analysis to Determine their Role in Lymphoma Cell Sensitivity to Therapeutic Agents

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of inflammation. They are key players in the innate immune system and play major roles in cancer biology. Neutrophils have been proposed as key mediators of malignant transformation, tumor progression, angiogenesis and in the modulation of the antitumor immunity; through their release of soluble factors or their interaction with tumor cells. To characterize the specific functions of neutrophils, a fast and reliable method is coveted for in vitro isolation of neutrophils from human blood. Here, a density gradient separation method is demonstrated to isolate neutrophils as well as mononuclear cells from the blood. The procedure consists of layering the density gradient solution such as Ficoll carefully above the diluted blood obtained from patients diagnosed with chronic lymphocytic leukemia (CLL), followed by centrifugation, isolation of mononuclear layer, separation of neutrophils from RBCsby dextran then lysis of residual erythrocytes. This method has been shown to isolate neutrophils &#8805; 90 % pure. To mimic the tumor microenvironment, 3-dimensional (3D) experiments were performed using basement membrane matrix such as Matrigel. Given the short half-life of neutrophils in vitro, 3D experiments with fresh human neutrophils cannot be performed. For this reason promyelocytic HL60 cells are differentiated along the granulocytic pathway using the differentiation inducers dimethyl sulfoxide (DMSO) and retinoic acid (RA). The aim of our experiments is to study the role of neutrophils on the sensitivity of lymphoma cells to anti-lymphoma agents. However these methods can be generalized to study the interactions of neutrophils or neutrophil-like cells with a large range of cell types in different situations.

Neutrophils are the most abundant type of white blood cells. The isolation of neutrophils from human blood by density gradient separation method and the differentiation of human promyelocytic (HL60) cells along the granulocytic pathway are described here; to test their role on sensitivity of lymphoma cells to anti-lymphoma agents.