This work is supported by The National Natural Science Foundation of China (31971062, 31900326, and 31601022), The Natural Science Foundation of Jiangsu Province (BK20190043, BK20180838), Research Fund of State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University (KF-GN-202004). The Natural Science Foundation of the Jiangsu Higher Education Institutions of China (19KJB320003), The Livelihood and Technology Program of Suzhou City (SYS2019030), and The Research Innovation Program for College Graduates of Jiangsu Province (KYCX19-1981). This work is also supported by Tang Scholar of Soochow University.

This protocol was approved by the Animal Care and Use Committee of Cambridge-Suda Genomic Resource Center (CAM-SU) at Soochow University.
1. Intestinal Organoid Isolation and Culture
<ol>
	<li>Isolation of intestinal crypts and enteroid culture
	<ol>
		<li>Euthanize an 8-week-old wild-type mouse with CO2 inhalation. Use tissue forceps and fine iris scissors to dissect out approximately 8 cm of ileum.</li>
		<li>Flush out using a syringe with gavage feeding needle with about 40 mL of ice-cold Dulbecco&#39;s phosphate-buffered saline (DPBS), then cut lengthwise with scissors and open the ileum.</li>
		<li>Cut the ileum into small (0.5&#8722;1.0 cm) pieces. Place the pieces in 5 mL of sterile ice-cold DPBS in a 15 mL conical tube, then rock for 5 min on ice.</li>
		<li>Use a pipette controller to aspirate the DPBS and replace it with 10 mL of cold buffer 1 (2 mM EDTA in DPBS). Rock for 30 min on ice.</li>
		<li>Use the pipette controller to aspirate buffer 1 and replace with 10 mL of cold buffer 2 (54.9 mM D-sorbitol, 43.4 mM sucrose in DPBS). Shake for 2&#8722;3 min by hand (~80 shakes/min).</li>
		<li>Take a 20 &#181;L droplet of buffer 2 contents after shaking and inspect under a microscope.</li>
		<li>Filter buffer 2 contents with a 70 &#181;m sterile cell strainer, then collect the filtered buffer with a 50 mL conical tube.</li>
		<li>Pipette 20 &#181;L of filtrate onto the slide to count the crypts. Transfer a sufficient volume of buffer 2 from step 1.1.7 to ensure that there are ~500 crypts/well.</li>
		<li>Spin down at 150 x g for 10 min at 4 &#176;C. Once spinning is finished, carefully aspirate the supernatant.</li>
		<li>Suspend crypts in 50 &#181;L of basement membrane matrix (e.g., Matrigel) per 500 crypts, pipette up and down (being careful to avoid bubbles), then place a 50 &#181;L droplet of basement membrane matrix/crypt mix in the center of one well in a 24 well plate. Incubate for 30 min at 37 &#176;C to polymerize basement membrane matrix.</li>
		<li>After 30 min of polymerization, carefully add 600 &#181;L of minigut media (advanced Dulbecco&#39;s modified Eagle medium [DMEM]/F12, 2 mM L-alanine-L-glutamine, pen/strep [100 units/mL], 10 mM Hepes, N2 supplement [1:100], B27 supplement [1:50] with epidermal growth factor [EGF; 50 ng/mL], Noggin [100 ng/mL], R-spondin [500 ng/mL], and Y27632 [10 &#181;M]) to each well, then return the plate to the 37 &#176;C incubator. Observe under a microscope each day, and change the media every 2&#8722;3 days.</li>
	</ol>
	</li>
	<li>Enteroid passaging 
	NOTE: For long cultures, enteroids should be split approximately each week.
	<ol>
		<li>To passage the enteroids, place the tissue culture plate on ice. Aspirate the media and add 1 mL of cold DPBS to each well. Use a P1000 tip to pipette up and down until no solid basement membrane matrix chunks remain.</li>
		<li>Pass up and down once through a 1 mL insulin syringe (27 G) and into a 15 mL conical tube. Spin down for 5 min at 150 x g at 4 &#176;C.</li>
		<li>Use pipette to remove DPBS. Resuspend in 50 &#181;L of basement membrane matrix/well.</li>
		<li>Place the plate in a 37 &#176;C incubator for 30 min to allow basement membrane matrix to polymerize. Overlay each well with 600 &#181;L of ENR media (minigut media, 50 ng/mL EGF, 100 ng/mL Noggin, 500 ng/mL R-spondin), then return the plate to the incubator.</li>
	</ol>
	</li>
</ol>
2. Flow Cytometry Analysis of EdU-positive Cells in Enteroids
NOTE: Figure 1 shows the workflow for flow cytometry analysis of EdU-positive cells in enteroids.
<ol>
	<li>Incubation of enteroids with EdU
	<ol>
		<li>Grow enteroids from step 1.2.4 for 5&#8211;7 days. Passage enteroids into a new 24 well plate in a splitting ratio of 1:2. Add 600 &#181;L of ENR medium to each well. Incubate enteroids for 4&#8722;5 days in a 37 &#176;C incubator.</li>
		<li>Set the control group (untreated enteroids) and experimental group (enteroids treated with 5 ng/mL interleukin 22 [IL-22]). Prepare at least three replicates for each group.</li>
		<li>Add EdU to the ENR medium to prepare EdU medium with a concentration of 50 &#956;M. Add 600 &#956;L of EdU medium to each well and incubate for 2 h in a 37 &#176;C incubator. Set one well of enteroids without EdU treatment as a negative control for background subtraction.</li>
	</ol>
	</li>
	<li>Harvesting of enteroids from basement membrane matrix
	<ol>
		<li>Use a pipette controller to aspirate EdU medium and wash 1x with DPBS. Add 1 mL of DPBS.</li>
		<li>Use P1000 pipette tip and pipette up and down until no solid basement membrane matrix chunks remain. Transfer to a 15 mL tube and spin down at 300 x g for 5 min. Discard the supernatant.</li>
		<li>Add 500 &#956;L of cell-dissociation enzymes (Table of Materials) and incubate for 15 min at 37 &#176;C. Use P200 pipette tip and pipette up and down to break enteroids into single cells.</li>
		<li>Add 3 mL of DMEM medium containing 10% fetal bovine serum (FBS) and repeatedly pipette with a P1000 pipette tip.</li>
		<li>Spin down at 300 x g for 5 min and aspirate the supernatant medium. Resuspend the cells with 1 mL of DPBS.</li>
	</ol>
	</li>
	<li>Fixation and permeabilization of cells
	<ol>
		<li>Transfer the cell suspension to a 1.5 mL tube, spin down at 300 x g for 5 min, and discard the supernatant.</li>
		<li>Resuspend cells with 1 mL of 4% paraformaldehyde (PFA), fix for 15 min at room temperature (RT), and spin down at 300 x g for 5 min. Aspirate the supernatant with a pipette tip, wash 1x with DPBS, and spin down to remove the supernatant.</li>
		<li>Resuspend cells with 1 mL of 0.5% nonionic surfactant. Incubate for 10 min at RT.</li>
		<li>Spin down at 300 x g for 5 min and aspirate the supernatant. Wash 1x with DPBS and spin down to remove the supernatant.</li>
	</ol>
	</li>
	<li>Detection of EdU
	<ol>
		<li>Prepare stock solutions for each component in advance: 1) working solution of the Alexa Fluor azide, 2) working solution of 1x EdU reaction buffer, and 3) 10x stock solution of EdU buffer additive.</li>
		<li>Prepare 1x EdU buffer additive by diluting the 10x solution 1:10 in deionized water. Prepare this solution fresh.</li>
		<li>Prepare reaction cocktail according to Table 1. 
		NOTE: Add the ingredients in the order listed in the table. Use the reaction cocktail within 15 min of preparation.</li>
		<li>Add 100 &#956;L of reaction cocktails to each 1.5 mL tube. Resuspend the cells, protect from light, incubate for 30 min at RT.</li>
		<li>Centrifuge at 300 x g for 5 min and aspirate the reaction solution with pipette tip gently.</li>
		<li>Add 0.5% nonionic surfactant penetrant to each tube to wash 1x at RT. Centrifuge at 300 x g for 5 min, aspirate the supernatant with pipette tip gently, and resuspend the cells in 1 mL of DPBS.</li>
	</ol>
	</li>
	<li>Analysis of cells by flow cytometry
	<ol>
		<li>Filter the resuspended cells with a 40 &#956;m strainer, then collect the filtered cells with a 15 mL conical tube. Perform FACS on-machine detection as soon as possible. 
		NOTE: If conditions are limited, the cell stained samples should be stored in the dark at 4 &#176;C and flow-tested within 3 days.</li>
		<li>Select the appropriate channel (according to the type of Alexa Fluor azide in the EdU kit; here, red channel) and voltage (here, ~150&#8211;350 V) for flow cytometry analysis.</li>
		<li>Gating strategy
		<ol>
			<li>Draw an FSC-A (x-axis) vs. SSC-A (y-axis) pseudocolor plot and distribute most of the cells to the visible range of the dot map by adjusting the voltage. Select the cell population (R1) and exclude the cell debris in the bottom left corner.</li>
			<li>From the R1 cell population, establish an FSC-A (x-axis) vs. FSC-H (y-axis) pseudocolor plot, and set the gate to select single cells (R2) to exclude cell clumps.</li>
			<li>From the R2 cell population, establish the fluorescence intensity (x-axis) vs. cell number (y-axis) plot, and use the negative control to set the gate. The region of the fluorescent signal is a positive cell region (R3). Compare the ratio of EdU-positive cells (R3) between the experimental and control groups.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
3. Flow Cytometry Analysis of PI-positive Cells in Enteroids
NOTE: Figure 2 shows the workflow for flow cytometry analysis of PI-positive cells in enteroids.
<ol>
	<li>Incubation of enteroid cells with PI
	<ol>
		<li>Grow enteroids from step 1.2.4 for 5&#8211;7 days. Passage enteroids into a new 24 well plate in a splitting ratio of 1:2. Add 600 &#181;L of ENR medium to each well. Incubate enteroids for 4&#8722;5 days in a 37 &#176;C incubator.</li>
		<li>Set the control group (untreated) and experimental group (IL-22 treated), using at least three replicates for each group.</li>
		<li>Add PI to the ENR medium to prepare PI medium with a concentration of 3 &#956;M.</li>
		<li>Add 600 &#956;L of PI medium to each well and incubate for 30 min in a 37 &#176;C incubator. Set one well of enteroids without PI treatment as a negative control for background subtraction.</li>
	</ol>
	</li>
	<li>Harvest enteroids from basement membrane matrix following steps 2.2.1&#8722;2.2.5.</li>
	<li>Analysis of cells by flow cytometry
	<ol>
		<li>Filter the resuspended cells with a 40 &#956;m strainer and collect the filtered cells with a 15 mL conical tube.</li>
		<li>Perform FACS on-machine detection as soon as possible. 
		NOTE: If conditions are limited, the cell stained samples should be stored in the dark at 4 &#176;C and flow-tested within 3 days.</li>
		<li>Select the appropriate channel (here, red channel) and voltage (here, ~150&#8211;350 V) for flow cytometry analysis.</li>
		<li>Use the same gating strategy as described in section 2.5.3.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Odenwald, M. A., Turner, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+intestinal+epithelial+barrier:+a+therapeutic+target.">The intestinal epithelial barrier: a therapeutic target.</a> Nature reviews. Gastroenterology &amp; Hepatology. 14 (1), 9-21 (2017).</li><li>Buckley, A., Turner, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+Biology+of+Tight+Junction+Barrier+Regulation+and+Mucosal+Disease.">Cell Biology of Tight Junction Barrier Regulation and Mucosal Disease.</a> Cold Spring Harbor Perspectives in Biology. 10 (1), (2018).</li><li>Gehart, H., Clevers, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tales+from+the+crypt:+new+insights+into+intestinal+stem+cells.">Tales from the crypt: new insights into intestinal stem cells.</a> Nature reviews. Gastroenterology &amp; Hepatology. 16 (1), 19-34 (2019).</li><li>Vancamelbeke, M., Vermeire, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+intestinal+barrier:+a+fundamental+role+in+health+and+disease.">The intestinal barrier: a fundamental role in health and disease.</a> Expert Review of Gastroenterology &amp; Hepatology. 11 (9), 821-834 (2017).</li><li>Garcia-Carbonell, R., Yao, S. J., Das, S., Guma, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dysregulation+of+Intestinal+Epithelial+Cell+RIPK+Pathways+Promotes+Chronic+Inflammation+in+the+IBD+Gut.">Dysregulation of Intestinal Epithelial Cell RIPK Pathways Promotes Chronic Inflammation in the IBD Gut.</a> Frontiers in Immunology. 10, 1094 (2019).</li><li>Li, B. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Vitro+and+In+Vivo+Approaches+to+Determine+Intestinal+Epithelial+Cell+Permeability.">In Vitro and In Vivo Approaches to Determine Intestinal Epithelial Cell Permeability.</a> Journal of Visualized Experiments. (140), e57032 (2018).</li><li>Turner, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intestinal+mucosal+barrier+function+in+health+and+disease.">Intestinal mucosal barrier function in health and disease.</a> Nature Reviews Immunology. 9 (11), 799-809 (2009).</li><li>Graham, W. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+MLCK1+diversion+reverses+barrier+loss+to+restore+mucosal+homeostasis.">Intracellular MLCK1 diversion reverses barrier loss to restore mucosal homeostasis.</a> Nature Medicine. 25 (4), 690-700 (2019).</li><li>Sato, T., 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=Single+Lgr5+stem+cells+build+crypt-villus+structures+in+vitro+without+a+mesenchymal+niche.">Single Lgr5 stem cells build crypt-villus structures in vitro without a mesenchymal niche.</a> Nature. 459 (7244), 262-265 (2009).</li><li>Sato, T., Clevers, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growing+self-organizing+mini-guts+from+a+single+intestinal+stem+cell:+mechanism+and+applications.">Growing self-organizing mini-guts from a single intestinal stem cell: mechanism and applications.</a> Science. 340 (6137), 1190-1194 (2013).</li><li>Friedrich, M., Pohin, M., Powrie, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytokine+Networks+in+the+Pathophysiology+of+Inflammatory+Bowel+Disease.">Cytokine Networks in the Pathophysiology of Inflammatory Bowel Disease.</a> Immunity. 50 (4), 992-1006 (2019).</li><li>Zha, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interleukin+22+Expands+Transit-Amplifying+Cells+While+Depleting+Lgr5+Stem+Cells+via+Inhibition+of+Wnt+and+Notch+Signaling.">Interleukin 22 Expands Transit-Amplifying Cells While Depleting Lgr5 Stem Cells via Inhibition of Wnt and Notch Signaling.</a> Cellular and Molecular Gastroenterology and Hepatology. 7 (2), 255-274 (2019).</li></ol>

The authors have nothing to disclose.

This protocol details the steps necessary for the culture of enteroids in vitro and quantification of EdU- and PI-positive cells in the enteroids by flow cytometry. There are several advantages of this strategy. First, EdU labelling is used to detect proliferating cells in enteroids. Compared with traditional BrdU assay, EdU labelling method is faster, more sensitive, and more accurate. EdU is very similar to thymine (T), which replaces thymine in DNA synthesis during cell division. Compared to the BrdU antibody, EdU is ...

A fundamental function of intestinal epithelial cells is to protect the entry of luminal contents such as pathogenic bacteria and toxins1,2. To perform such a function, intestinal stem cells continuously proliferate and differentiate into a variety of epithelial cells, including enterocytes and secretory cells, which form a barrier by forming tight connections3. The rapid renewal of intestinal epithelial cells requires strict coordination of cell proliferation, cell differentiation, and cell death4,5. Reduced cell proliferation or excessive cell death leads to epithelial damage and compromised barrier function1,6. Dysfunction of intestinal barrier has been associated with inflammatory bowel diseases7,8.
A method to culture intestinal crypts has been previously developed. Using this technique, isolated mouse crypts grow into intestinal organoids (enteroids), which have crypt-villus like structures and contain all intestinal epithelial cell lineage9,10. 5-Ethynyl-2'-deoxyuridine (EdU) is a thymidine analog that is capable of replacing thymine (T) in DNA that is undergoing replication during cell proliferation. The proliferative cells can be quickly and accurately labeled by EdU staining. Propidium iodide (PI) is an analog of ethidium bromide that releases red fluorescence upon insertion into double-stranded DNA. PI specifically detects dead cells, since it only passes through the damaged cell membrane.
In this protocol, we first describe how to isolate crypts from the murine small intestine then culture them as enteroids in vitro. We then describe how to analyze the proliferative and dead cells in enteroids by EdU and PI incorporation and flow cytometry.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15 ml centrifuge tube</td>
			<td>Corning</td>
			<td>430791</td>
			<td></td>
		</tr>
		<tr>
			<td>22 G gavage needle</td>
			<td>VWR</td>
			<td>20068-608</td>
			<td></td>
		</tr>
		<tr>
			<td>24-well plate</td>
			<td>Nunc</td>
			<td>142475</td>
			<td></td>
		</tr>
		<tr>
			<td>40 mm sterile cell strainer</td>
			<td>BD</td>
			<td>352340</td>
			<td></td>
		</tr>
		<tr>
			<td>50 ml centrifuge tube</td>
			<td>Corning</td>
			<td>430829</td>
			<td></td>
		</tr>
		<tr>
			<td>70 mm sterile cell strainer</td>
			<td>BD</td>
			<td>352350</td>
			<td></td>
		</tr>
		<tr>
			<td>Advanced DMEM/F-12</td>
			<td>GIBCO</td>
			<td>12634010</td>
			<td></td>
		</tr>
		<tr>
			<td>Attune NxT Acoustic Focusing Cytometer</td>
			<td>Invitrogen</td>
			<td>A24863</td>
			<td></td>
		</tr>
		<tr>
			<td>B-27 Supplement</td>
			<td>GIBCO</td>
			<td>17504044</td>
			<td></td>
		</tr>
		<tr>
			<td>Buffer 1</td>
			<td></td>
			<td></td>
			<td>2 mM EDTA in DPBS</td>
		</tr>
		<tr>
			<td>Buffer 2</td>
			<td></td>
			<td></td>
			<td>54.9 mM D-sorbitol, 43.4 mM sucrose in DPBS</td>
		</tr>
		<tr>
			<td>C57/B6 mice</td>
			<td>Nanjing Biomedical Research Institute of Nanjing University</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cell-dissociation enzymes (TrypLE)</td>
			<td>Life technologies</td>
			<td>12605-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5424</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5424R</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5810R</td>
			<td></td>
		</tr>
		<tr>
			<td>Click-iT Plus EdU Alexa Fluor 594 Imaging Kit</td>
			<td>Life technologies</td>
			<td>C10639</td>
			<td></td>
		</tr>
		<tr>
			<td>CO2 incubator</td>
			<td>Panasonic</td>
			<td>MCO-18AC</td>
			<td></td>
		</tr>
		<tr>
			<td>DPBS</td>
			<td>GIBCO</td>
			<td>14190144</td>
			<td></td>
		</tr>
		<tr>
			<td>D-sorbitol</td>
			<td>BBI</td>
			<td>SB0491</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>BBI</td>
			<td>EB0185</td>
			<td></td>
		</tr>
		<tr>
			<td>ENR media</td>
			<td></td>
			<td></td>
			<td>Minigut media, 50 ng/ml EGF, 100 ng/ml Noggin, 500 ng/ml R-spondin</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Gibco</td>
			<td>10270-106</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Iris Scissors</td>
			<td>Tansoole</td>
			<td>2037454</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence microscope</td>
			<td>Olympus</td>
			<td>FV1000</td>
			<td></td>
		</tr>
		<tr>
			<td>GlutaMAX Supplement</td>
			<td>GIBCO</td>
			<td>35050-061</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat Serum</td>
			<td>Life technologies</td>
			<td>16210-064</td>
			<td></td>
		</tr>
		<tr>
			<td>HDMEM</td>
			<td>Hyclone</td>
			<td>SH30243.01B</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma</td>
			<td>H4034</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>Corning</td>
			<td>356231</td>
			<td></td>
		</tr>
		<tr>
			<td>Minigut media</td>
			<td></td>
			<td></td>
			<td>Advanced DMEM/F12, 2 mM Glutamax, Penn/Strep (100 units/ml), 10 mM Hepes, N2 supplement (1:100), B27 supplement (1:50)</td>
		</tr>
		<tr>
			<td>N2 supplement</td>
			<td>R&#38;D</td>
			<td>AR009</td>
			<td></td>
		</tr>
		<tr>
			<td>Nonionic surfactant (Triton X)</td>
			<td>BBI</td>
			<td>TB0198-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Operating Scissor (12.5 cm)</td>
			<td>Tansoole</td>
			<td>2025785</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde (PFA)</td>
			<td>sigma</td>
			<td>158127-500g</td>
			<td></td>
		</tr>
		<tr>
			<td>Penn/Strep</td>
			<td>Invitrogen</td>
			<td>15140-148</td>
			<td></td>
		</tr>
		<tr>
			<td>Phase contrast microscope</td>
			<td>Nikon</td>
			<td>TS1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Propidium iodide</td>
			<td>Sigma</td>
			<td>P4170-25MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant EGF</td>
			<td>PeproTech</td>
			<td>315-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Mouse Noggin</td>
			<td>PeproTech</td>
			<td>250-38</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Mouse R-Spondin 1</td>
			<td>R&#38;D</td>
			<td>3474-RS-050</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Murine IL-22</td>
			<td>PeproTech</td>
			<td>210-22-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>BBI</td>
			<td>SB0498</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Forceps</td>
			<td>Tansoole</td>
			<td>2026704</td>
			<td></td>
		</tr>
		<tr>
			<td>Y-27632 2HC1</td>
			<td>Selleck</td>
			<td>S1049</td>
			<td></td>
		</tr>
	</tbody>
</table>

quantification of proliferative and dead cells in enteroids

The intestinal epithelium acts as a barrier that prevents luminal contents, such as pathogenic microbiota and toxins, from entering the rest of the body. Epithelial barrier function requires the integrity of intestinal epithelial cells. While epithelial cell proliferation maintains a continuous layer of cells that forms a barrier, epithelial damage leads to barrier dysfunction. As a result, luminal contents can across the intestinal barrier via an unrestricted pathway. Dysfunction of intestinal barrier has been associated with many intestinal diseases, such as inflammatory bowel disease. Isolated mouse intestinal crypts can be cultured and maintained as crypt-villus-like structures, which are termed intestinal organoids or &ldquo;enteroids&rdquo;. Enteroids are ideal to study the proliferation and cell death of intestinal epithelial cells in vitro. In this protocol, we describe a simple method to quantify the number of proliferative and dead cells in cultured enteroids. 5-ethynyl-2&rsquo;-deoxyuridine (EdU) and propidium iodide are used to label proliferating and dead cells in enteroids, and the proportion of proliferating and dead cells are then analyzed by flow cytometry. This is a useful tool to test the effects of drug treatment on intestinal epithelial cell proliferation and cell survival.

Small intestinal crypts were isolated and cultured as enteroids in basement membrane matrix. Enteroids started to form buds 2 days after isolation. On day 6, enteroids had many buds with lots of debris (dead cells) in the lumen. Enteroids were ready to be passaged at this stage (Figure 3).
Numerous studies have shown that inflammatory cytokines are essential for the maintenance of intestinal epithelial homeostasis. Abnormal expression of inflammatory cytokines is ...

Watch this Scientific Journal Video about Quantification of Proliferative and Dead Cells in Enteroids at JoVE.com

Quantification of Proliferative and Dead Cells in Enteroids

The presented protocol uses flow cytometry to quantify the number of proliferating and dead cells in cultured mouse enteroids. This method is helpful to evaluate the effects of drug treatment on organoid proliferation and survival.

The intestinal epithelium acts as a barrier that prevents luminal contents, such as pathogenic microbiota and toxins, from entering the rest of the body. ...

quantification-of-proliferative-and-dead-cells-in-enteroids

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Biology

8.3K Views.  The First Affiliated Hospital of Soochow University. The presented protocol uses flow cytometry to quantify the number of proliferating and dead cells in cultured mouse enteroids. This method is helpful to evaluate the effects of drug treatment on organoid proliferation and survival.

Video: Quantification of Proliferative and Dead Cells in Enteroids

Quantification of &gamma;H2AX Foci in Response to Ionising Radiation

DNA double-strand breaks (DSBs), which are induced by either endogenous metabolic processes or by exogenous sources, are one of the most critical DNA lesions with respect to survival and preservation of genomic integrity. An early response to the induction of DSBs is phosphorylation of the H2A histone variant, H2AX, at the serine-139 residue, in the highly conserved C-terminal SQEY motif, forming &gamma;H2AX1. Following induction of DSBs, H2AX is rapidly phosphorylated by the phosphatidyl-inosito 3-kinase (PIKK) family of proteins, ataxia telangiectasia mutated (ATM), DNA-protein kinase catalytic subunit and ATM and RAD3-related (ATR)2. Typically, only a few base-pairs (bp) are implicated in a DSB, however, there is significant signal amplification, given the importance of chromatin modifications in DNA damage signalling and repair. Phosphorylation of H2AX mediated predominantly by ATM spreads to adjacent areas of chromatin, affecting approximately 0.03% of total cellular H2AX per DSB2,3. This corresponds to phosphorylation of approximately 2000 H2AX molecules spanning ~2 Mbp regions of chromatin surrounding the site of the DSB and results in the formation of discrete &gamma;H2AX foci which can be easily visualized and quantitated by immunofluorescence microscopy2. The loss of &gamma;H2AX at DSB reflects repair, however, there is some controversy as to what defines complete repair of DSBs; it has been proposed that rejoining of both strands of DNA is adequate however, it has also been suggested that re-instatement of the original chromatin state of compaction is necessary4-8. The disappearence of &gamma;H2AX involves at least in part, dephosphorylation by phosphatases, phosphatase 2A and phosphatase 4C5,6. Further, removal of &gamma;H2AX by redistribution involving histone exchange with H2A.Z has been implicated7,8. Importantly, the quantitative analysis of &gamma;H2AX foci has led to a wide range of applications in medical and nuclear research. Here, we demonstrate the most commonly used immunofluorescence method for evaluation of initial DNA damage by detection and quantitation of &gamma;H2AX foci in &gamma;-irradiated adherent human keratinocytes9.

Quantification of &amp;#947;H2AX Foci in Response to Ionising Radiation

Quantification of DNA double-strand streaks using &gamma;H2AX formation as a molecular marker has become an invaluable tool in radiation biology. Here we demonstrate the use of an immunofluorescence assay for quantification of &gamma;H2AX foci after exposure of cells to radiation.

DNA double-strand breaks (DSBs), which are induced by either endogenous metabolic processes or by exogenous sources, are one of the most critical DNA ...

Induction and Analysis of Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is essential for proper morphogenesis during development. Misregulation of this process has been implicated as a key event in fibrosis and the progression of carcinomas to a metastatic state. Understanding the processes that underlie EMT is imperative for the early diagnosis and clinical control of these disease states. Reliable induction of EMT in vitro is a useful tool for drug discovery as well as to identify common gene expression signatures for diagnostic purposes. Here we demonstrate a straightforward method for the induction of EMT in a variety of cell types. Methods for the analysis of cells pre- and post-EMT induction by immunocytochemistry are also included. Additionally, we demonstrate the effectiveness of this method through antibody-based array analysis and migration/invasion assays.

A straightforward method is described for the induction of epithelial to mesenchymal transition (EMT) in a variety of cell types. Methods for the analysis of cells in EMT states by immunocytochemistry are included.

Epithelial  to mesenchymal transition (EMT) is essential for proper morphogenesis during  development. Misregulation of this  process has been implicated ...

Temporal Quantification of MAPK Induced Expression in Single Yeast Cells

The quantification of gene expression at the single cell level uncovers novel regulatory mechanisms obscured in measurements performed at the population level. Two methods based on microscopy and flow cytometry are presented to demonstrate how such data can be acquired. The expression of a fluorescent reporter induced upon activation of the high osmolarity glycerol MAPK pathway in yeast is used as an example. The specific advantages of each method are highlighted. Flow cytometry measures a large number of cells (10,000) and provides a direct measure of the dynamics of protein expression independent of the slow maturation kinetics of the fluorescent protein. Imaging of living cells by microscopy is by contrast limited to the measurement of the matured form of the reporter in fewer cells. However, the data sets generated by this technique can be extremely rich thanks to the combinations of multiple reporters and to the spatial and temporal information obtained from individual cells. The combination of these two measurement methods can deliver new insights on the regulation of protein expression by signaling pathways.

Two complementary methods based on flow cytometry and microscopy are presented which enable the quantification, at the single cell level, of the dynamics of gene expression induced by the activation of a MAPK pathway in yeast.

The quantification of gene expression at the  single cell level uncovers novel regulatory mechanisms obscured in measurements  performed at the population ...

Quantification of Orofacial Phenotypes in Xenopus

Xenopus has become an important tool for dissecting the mechanisms governing craniofacial development and defects. A method to quantify orofacial development will allow for more rigorous analysis of orofacial phenotypes upon abrogation with substances that can genetically or molecularly manipulate gene expression or protein function. Using two dimensional images of the embryonic heads, traditional size dimensions-such as orofacial width, height and area- are measured. In addition, a roundness measure of the embryonic mouth opening is used to describe the shape of the mouth. Geometric morphometrics of these two dimensional images is also performed to provide a more sophisticated view of changes in the shape of the orofacial region. Landmarks are assigned to specific points in the orofacial region and coordinates are created. A principle component analysis is used to reduce landmark coordinates to principle components that then discriminate the treatment groups. These results are displayed as a scatter plot in which individuals with similar orofacial shapes cluster together. It is also useful to perform a discriminant function analysis, which statistically compares the positions of the landmarks between two treatment groups. This analysis is displayed on a transformation grid where changes in landmark position are viewed as vectors. A grid is superimposed on these vectors so that a warping pattern is displayed to show where significant landmark positions have changed. Shape changes in the discriminant function analysis are based on a statistical measure, and therefore can be evaluated by a p-value. This analysis is simple and accessible, requiring only a stereoscope and freeware software, and thus will be a valuable research and teaching resource.

Quantification of Orofacial Phenotypes in Xenopus

A method to quantify the orofacial size and shape of Xenopus laevis embryos has been developed. In this protocol, traditional size measurements are combined with geometric morphometrics to allow for more sophisticated analyses of orofacial development and defects.

Xenopus has become an important tool for dissecting the mechanisms governing craniofacial development and defects. A method to quantify orofacial ...

High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications

Plant cells are surrounded by a cell wall, the composition of which determines their final size and shape. The cell wall is composed of a complex matrix containing polysaccharides that include cellulose microfibrils that form both crystalline structures and cellulose chains of amorphous organization. The orientation of the cellulose fibers and their concentrations dictate the mechanical properties of the cell. Several methods are used to determine the levels of crystalline cellulose, each bringing both advantages and limitations. Some can distinguish the proportion of crystalline regions within the total cellulose. However, they are limited to whole-organ analyses that are deficient in spatiotemporal information. Others relying on live imaging, are limited by the use of imprecise dyes. Here, we report a sensitive polarized light-based system for specific quantification of relative light retardance, representing crystalline cellulose accumulation in cross sections of Arabidopsis thaliana roots. In this method, the cellular resolution and anatomical data are maintained, enabling direct comparisons between the different tissues composing the growing root. This approach opens a new analytical dimension, shedding light on the link between cell wall composition, cellular behavior and whole-organ growth.

High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications

Crystalline cellulose is an important constituent of the plant cell wall. However, its quantification at a cellular resolution is technically challenging. Here, we report the use of polarized light technology and root cross sections to obtain information of cell wall composition at a spatiotemporal resolution.

Plant cells are surrounded by a cell wall, the composition of which determines their final size and shape. The cell wall is composed of a complex matrix ...

Nephrotoxin Microinjection in Zebrafish to Model Acute Kidney Injury

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid decline in renal function and development of the clinical syndrome known as acute kidney injury (AKI). Pharmacological agents used to treat medical circumstances ranging from bacterial infection to cancer, when administered individually or in combination with other drugs, can initiate AKI. Zebrafish are a useful animal model to study the chemical effects on renal function in vivo, as they form an embryonic kidney comprised of nephron functional units that are conserved with higher vertebrates, including humans. Further, zebrafish can be utilized to perform genetic and chemical screens, which provide opportunities to elucidate the cellular and molecular facets of AKI and develop therapeutic strategies such as the identification of nephroprotective molecules. Here, we demonstrate how microinjection into the zebrafish embryo can be utilized as a paradigm for nephrotoxin studies.

Renal injuries incurred from nephrotoxins, which include drugs ranging from antibiotics to chemotherapeutics, can result in complex disorders whose pathogenesis remains incompletely understood. This protocol demonstrates how zebrafish can be used for disease modeling of these conditions, which can be applied to the identification of renoprotective measures.

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid ...

Observation and Quantification of Mating Behavior in the Pinewood Nematode, Bursaphelenchus xylophilus

A method for observing and quantifying the mating behavior of the pinewood nematode, Bursaphelenchus xylophilus, was established under a stereomicroscope. To improve the mating efficiency of B. Xylophilus and to increase the chances of mating observation, virgin adults were cultured and used for the investigation. Eggs were obtained by keeping the nematodes in water and allowing the females to lay eggs for 10 min. The second-stage juveniles (J2) were synchronized by incubating the eggs for 24 h at 25 &#176;C in the dark, and the early J4 were obtained by culturing the J2 with grey mold, Botrytis cinerea, for another 52 h. At this time point, most J4 nematodes could be clearly distinguished as being male or female using their genital morphology. The male and female J4 were collected and cultured separately in two different Petri dishes for 24 h to get virgin adult nematodes. A virgin male and a virgin female were paired in a drop of water in the well of a concave slide. The mating behavior was filmed with a video recorder under a stereomicroscope. The whole period of the mating process was 82.8 &#177;3.91 min (mean &#177;SE) and could be divided into 4 different phases: searching, contacting, copulating, and lingering. The mean minutes of duration were 21.8 &#177; 2.0, 28.0 &#177; 1.9, 25.8 &#177; 0.7 and 7.2 &#177; 0.5, respectively. Eleven sub-behaviors were described: cruising, approaching, encountering, touching, hooping, locating, attaching, ejaculating, separating, quiescence, and roaming. Interestingly, obvious intra-sexual competition was observed when one female was grouped with 3 males or one male with 3 females. This protocol is useful and valuable, not only in investigating the mating behavior of B. xylophilus, but also in acting as a reference for ethological studies of other nematodes.

Observation and Quantification of Mating Behavior in the Pinewood Nematode, Bursaphelenchus xylophilus

A protocol for investigating the mating behavior of the pinewood nematode, Bursaphelenchus xylophilus, is presented. Behavioral features of B. xylophilus are described in the mating process.

A method for observing and quantifying the mating behavior of the pinewood nematode, Bursaphelenchus xylophilus, was established under a stereomicroscope. ...

A Graphical User Interface for Software-assisted Tracking of Protein Concentration in Dynamic Cellular Protrusions

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex signaling mechanisms underlying filopodial initiation, elongation and subsequent stabilization or retraction, it is crucial to determine the spatio-temporal protein activity in these dynamic structures. To analyze protein function in filopodia, we recently developed a semi-automated tracking algorithm that adapts to filopodial shape-changes, thus allowing parallel analysis of protrusion dynamics and relative protein concentration along the whole filopodial length. Here, we present a detailed step-by-step protocol for optimized cell handling, image acquisition and software analysis. We further provide instructions for the use of optional features during image analysis and data representation, as well as troubleshooting guidelines for all critical steps along the way. Finally, we also include a comparison of the described image analysis software with other programs available for filopodia quantification. Together, the presented protocol provides a framework for accurate analysis of protein dynamics in filopodial protrusions using image analysis software.

We present a software solution for semi-automated tracking of relative protein concentration along the length of dynamic cellular protrusions.

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex ...

In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells

J-domain proteins (JDPs) form the largest and the most diverse co-chaperone family in eukaryotic cells. Recent findings show that specific members of the JDP family could form transient heterocomplexes in eukaryotes to fine-tune substrate selection for the 70 kDa heat shock protein (Hsp70) chaperone-based protein disaggregases. The JDP complexes target acute/chronic stress induced aggregated proteins and presumably help assemble the disaggregases by recruiting multiple Hsp70s to the surface of protein aggregates. The extent of the protein quality control (PQC) network formed by these physically interacting JDPs remains largely uncharacterized in vivo. Here, we describe a microscopy-based in situ protein interaction assay named the proximity ligation assay (PLA), which is able to robustly capture&#160;these transiently formed chaperone complexes in distinct cellular compartments of eukaryotic cells. Our work expands the employment of PLA from human cells to yeast (Saccharomyces cerevisiae) and bacteria (Escherichia coli), thus rendering an important tool to monitor the dynamics of transiently formed protein assemblies in both prokaryotic and eukaryotic cells.

Cognate J-domain proteins cooperate with the Hsp70 chaperone to assist in a myriad of biological processes ranging from protein folding to degradation. Here, we describe an in situ proximity ligation assay, which allows the monitoring of these transiently formed chaperone machineries in bacterial, yeast and human cells.

J-domain proteins (JDPs) form the largest and the most diverse co-chaperone family in eukaryotic cells. Recent findings show that specific members of the ...

Automating Aggregate Quantification in Caenorhabditis elegans

A rise in the prevalence of neurodegenerative protein conformational diseases (PCDs) has fostered a great interest in this subject over the years. This increased attention has called for the diversification and improvement of animal models capable of reproducing disease phenotypes observed in humans with PCDs. Though murine models have proven invaluable, they are expensive and are associated with laborious, low-throughput methods. Use of the Caenorhabditis elegans nematode model to study PCDs has been justified by its relative ease of maintenance, low cost, and rapid generation time, which allow for high-throughput applications. Additionally, high conservation between the C. elegans and human genomes makes this model an invaluable discovery tool. Nematodes that express fluorescently tagged tissue-specific polyglutamine (polyQ) tracts exhibit age- and polyQ length-dependent aggregation characterized by fluorescent foci. Such reporters are often employed as proxies to monitor changes in proteostasis across tissues. Manual aggregate quantification is time-consuming, limiting experimental throughput. Furthermore, manual foci quantification can introduce bias, as aggregate identification can be highly subjective. Herein, a protocol consisting of worm culturing, image acquisition, and data processing was standardized to support high-throughput aggregate quantification using C. elegans that express intestine-specific polyQ. By implementing a C. elegans-based image processing pipeline using CellProfiler, an image analysis software, this method has been optimized to separate and identify individual worms and enumerate their respective aggregates. Though the concept of automation is not entirely unique, the need to standardize such procedures for reproducibility, elimination of bias from manual counting, and increase throughput is high. It is anticipated that these methods can drastically simplify the screening process of large bacterial, genomic, or drug libraries using the C. elegans model.

Automating Aggregate Quantification in Caenorhabditis elegans

The following protocol describes the development and optimization of a high-throughput workflow for worm culturing, fluorescence imaging, and automated image processing to quantify polyglutamine aggregates as an assessment of changes in proteostasis.

A rise in the prevalence of neurodegenerative protein conformational diseases (PCDs) has fostered a great interest in this subject over the years. This ...