Name: genetic engineering of primary mouse intestinal organoids using magnetic nanoparticle transduction viral vectors for frozen sectioning
Uploaded: 2019-05-10T12:30:00
Description: Watch this Scientific Journal Video about Genetic Engineering of Primary Mouse Intestinal Organoids Using Magnetic Nanoparticle Transduction Viral Vectors for Frozen Sectioning at JoVE.com

This work was supported by grants from the National Institute of Health (R01DK102943, R03CA182679, R03CA191621), the Maryland Stem Cell Research Fund (2015-MSCRFE-1759, 2017-MSCRFD-3934), the American Lung Association, the Allegheny Health Network - Johns Hopkins Research Fund and the Hopkins Digestive Diseases Basic Research Core Center.

This protocol was approved by the Johns Hopkins Medical Institutions Animal Care and Use Committee (IACUC). This protocol is modified from a previously published methods10,11,12,13.
1. Preparation of Reagents
<ol>
	<li>Prepare fresh 293T medium several hours in advance and warm to 37 &#176;C in a water bath for at least 10 min before use (Table 1)....

<ol>
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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=TIGAR+is+required+for+efficient+intestinal+regeneration+and+tumorigenesis.">TIGAR is required for efficient intestinal regeneration and tumorigenesis.</a> Dev Cell. 25 (5), 463-477 (2013).</li><li>Xian, L., 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=HMGA1+amplifies+Wnt+signalling+and+expands+the+intestinal+stem+cell+compartment+and+Paneth+cell+niche.">HMGA1 amplifies Wnt signalling and expands the intestinal stem cell compartment and Paneth cell niche.</a> Nature Comm. , (2017).</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>Koo, B. K., 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=Controlled+gene+expression+in+primary+Lgr5+organoid+cultures.">Controlled gene expression in primary Lgr5 organoid cultures.</a> Nature Methods. 9 (1), 81-83 (2012).</li><li>Kabiri, Z., 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=Stroma+provides+an+intestinal+stem+cell+niche+in+the+absence+of+epithelial+Wnts.">Stroma provides an intestinal stem cell niche in the absence of epithelial Wnts.</a> Development. 141, 2206-2215 (2014).</li><li>Boj, S. F., 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=Organoid+models+of+human+and+mouse+ductal+pancreatic+cancer.">Organoid models of human and mouse ductal pancreatic cancer.</a> Cell. 160 (1-2), 324-338 (2015).</li><li>Boj, S. F., 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=Forskolin-induced+Swelling+in+Intestinal+Organoids:+An+In+Vitro+Assay+for+Assessing+Drug+Response+in+Cystic+Fibrosis+Patients.">Forskolin-induced Swelling in Intestinal Organoids: An In Vitro Assay for Assessing Drug Response in Cystic Fibrosis Patients.</a> J Vis Exp. (120), (2017).</li><li>Mu&#241;oz, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Lgr5+intestinal+stem+cell+signature:+robust+expression+of+proposed+quiescent+'+4'+cellmarkers.">The Lgr5 intestinal stem cell signature: robust expression of proposed quiescent '+4' cellmarkers.</a> EMBO J. 31 (14), 3079-3091 (2012).</li><li>Schwank, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+repair+of+CFTR+by+CRISPR/Cas9+in+intestinal+stem+cell+organoids+of+cystic+fibrosis+patients.">Functional repair of CFTR by CRISPR/Cas9 in intestinal stem cell organoids of cystic fibrosis patients.</a> Cell Stem Cell. 13 (6), 653-658 (2014).</li><li>Andersson-Rolf, A., Fink, J., Mustata, R. C., Koo, B. 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(90), e51765 (2014).</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=Primary+mouse+small+intestinal+epithelial+cell+cultures.">Primary mouse small intestinal epithelial cell cultures.</a> Methods Mol Biol. 945, 319-328 (2013).</li><li>Ye, Z., Yu, X., Cheng, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lentiviral+gene+transduction+of+mouse+and+human+stem+cells.">Lentiviral gene transduction of mouse and human stem cells.</a> Methods Mol Biol. 430, 243-253 (2008).</li><li>Cheung, K. J., Gabrielson, E., Werb, Z., Ewald, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collective+invasion+in+breast+cancer+requires+a+conserved+basal+epithelial+program.">Collective invasion in breast cancer requires a conserved basal epithelial program.</a> Cell. 155 (7), 1639-1651 (2013).</li><li>Tesfaye, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+High-Mobility+Group+A1+gene+up-regulates+Cyclooxygenase-2+expression+in+uterine+tumorigenesis.">The High-Mobility Group A1 gene up-regulates Cyclooxygenase-2 expression in uterine tumorigenesis.</a> Cancer Res. 67 (9), 3998-4004 (2007).</li><li>Haim, 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=Synchronized+infection+of+cell+cultures+by+magnetically+controlled+virus.">Synchronized infection of cell cultures by magnetically controlled virus.</a> J. 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Primary culture of adult intestinal epithelium as organoids provides a powerful tool to study molecular mechanisms involved in stem cell function, intestinal epithelial homeostasis, and pathology1,2,3,4. Although CRISPR/Cas9 technology can be used to genetically engineer organoids9, it is limited by the need for extensive screening and selection based on sequence analysi...

The ability to culture mouse or human crypts cells as three dimensional (3D) organoids from the small intestines or colon over prolonged time periods provided a major breakthrough because these cultures display defining features of intestinal epithelium in vivo1,2,3. Organoids derived from primary crypts are capable of self-renewal and self-organization, exhibiting cellular functions similar to their tissues of origin. Indeed, organoids recapitulate not only the structural organization of crypts in vivo, but also many molecular features, thus providing useful tools to study normal biology and disease states. To illustrate, organoid studies have revealed novel molecular pathways involved in tissue regeneration1,2,3,4,5 as well as drugs that could enhance function in pathologic settings6,7.
The study of intestinal stem cells is of particular interest because the intestinal lining is among the most highly regenerative mammalian tissues, renewing itself every 3-5 days to protect the organism from bacteria, toxins, and other pathogens within the intestinal lumens. Intestinal stem cells (ISCs) are responsible for this remarkable regenerative capability and thus provide a unique paradigm for studying adult stem cell function1,2. Lineage-tracing experiments in mice demonstrated that isolated Lgr5-positive stem cells can be cultured to generate 3D organoids or &#39;mini-guts&#39; in vitro where they closely mirror their in vivo counterparts. Organoid cultures can also be derived from intestinal crypt cell isolates comprised of progenitors, ISCs, and Paneth cells, the latter of which constitute the epithelial niche cells in vivo. In fact, organoid culture from primary intestinal crypt cells has evolved into a relatively routine technique that is easy to implement in most laboratories using widely available reagents. This model is also amenable to quantitative analysis of gene expression by RNA-sequencing (RNA-Seq) and proteins by mass spectrometry, immunohistochemistry, or immunofluorescent staining2,4,8. In addition, functional genetics can be studied using gain-of-function (gene overexpression or expression of an activating mutant gene) or loss-of-function (gene silencing or expression of a loss-of-function mutant) approaches2.
Importantly, low efficiency and high toxicity of standard plasmid DNA or viral transduction protocols with polybrene remain a major hurdle in the field. Although CRISPR/Cas9 technology allows for precise genome editing, this approach requires time-consuming selection followed by sequence validation9. Here, we present a viral transduction protocol for primary intestinal organoids that optimizes delivery of viral particles by conjugation to magnetic nanoparticles and application of a magnetic field. Key modifications to prior protocols4,5,10,11,12,13 and recommendations to enhance efficiency are provided. We also describe an approach to generate frozen sections from intact organoids cultured in 3D matrigel (henceforth referred to as basement membrane matrix or matrix) for further analysis with immunohistochemistry or immunofluorescent staining.

<table>
	<tbody>
		<tr>
			<td>DMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>11965092</td>
			<td>Base medium for 293T cells</td>
		</tr>
		<tr>
			<td>DMEM/F12+</td>
			<td>Thermo Fisher Scientific</td>
			<td>12634010</td>
			<td>Base medium for organoid culture medium and organoid digestion buffer</td>
		</tr>
		<tr>
			<td>OPTI-MEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>11058021</td>
			<td>Virus plasmids transfection medium</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Corning</td>
			<td>35-011-CV</td>
			<td>Component of virus collection medium and 293T medium</td>
		</tr>
		<tr>
			<td>Pen/Strep</td>
			<td>Thermo Fisher Scientific</td>
			<td>15140122</td>
			<td>Component of organoid culture medium and crypt dissociation buffer</td>
		</tr>
		<tr>
			<td>PBS (without Ca2+, Mg2+)</td>
			<td>Thermo Fisher Scientific</td>
			<td>10010049</td>
			<td>A wash buffer and component of crypt dissociation buffer</td>
		</tr>
		<tr>
			<td>Mem-NEAA</td>
			<td>Thermo Fisher Scientific</td>
			<td>11140050</td>
			<td>Component of organoid culture medium</td>
		</tr>
		<tr>
			<td>GlutamaxII</td>
			<td>Thermo Fisher Scientific</td>
			<td>35050061</td>
			<td>Component of organoid culture medium</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Thermo Fisher Scientific</td>
			<td>15630080</td>
			<td>Component of organoid culture medium</td>
		</tr>
		<tr>
			<td>EGF</td>
			<td>Millipore Sigma</td>
			<td>E9644</td>
			<td>Component of organoid culture medium</td>
		</tr>
		<tr>
			<td>Noggin</td>
			<td>Peprotech</td>
			<td>250-38 B</td>
			<td>Component of organoid culture medium</td>
		</tr>
		<tr>
			<td>R-spondin</td>
			<td>R&#38;D</td>
			<td>7150-RS-025/CF</td>
			<td>Component of organoid culture medium</td>
		</tr>
		<tr>
			<td>Human recombinant insulin</td>
			<td>Millipore Sigma</td>
			<td>I9278-5ml</td>
			<td>Component of organoid culture medium</td>
		</tr>
		<tr>
			<td>Nicotinamide</td>
			<td>Millipore Sigma</td>
			<td>N3376-100G</td>
			<td>Component of Transduction medium</td>
		</tr>
		<tr>
			<td>Wnt3A</td>
			<td>R&#38;D</td>
			<td>5036-WN-010</td>
			<td>Component of Transduction medium</td>
		</tr>
		<tr>
			<td>Y27632</td>
			<td>Millipore Sigma</td>
			<td>Y0503-1MG</td>
			<td>Component of Transduction medium</td>
		</tr>
		<tr>
			<td>0.5M EDTA</td>
			<td>Thermo Fisher Scientific</td>
			<td>15575020</td>
			<td>Component of Crypts dissociation buffer</td>
		</tr>
		<tr>
			<td>DTT (dithiothreitol)</td>
			<td>Thermo Fisher Scientific</td>
			<td>R0861</td>
			<td>Component of Crypts dissociation buffer</td>
		</tr>
		<tr>
			<td>Dispase I</td>
			<td>Millipore Sigma</td>
			<td>D4818-2MG</td>
			<td>Component of organoid digestion buffer</td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>Millipore Sigma</td>
			<td>11284932001</td>
			<td>Component of organoid digestion buffer</td>
		</tr>
		<tr>
			<td>matrigel(Growth factor reduced)</td>
			<td>Corning</td>
			<td>356231</td>
			<td>Used as a matrix to embed organoids</td>
		</tr>
		<tr>
			<td>Opti-MEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>31985070</td>
			<td>Medium for transfection in viral production</td>
		</tr>
		<tr>
			<td>ViralMag R/L</td>
			<td>Oz Biosiences</td>
			<td>RL40200</td>
			<td>Magnetic particles of viral transduction</td>
		</tr>
		<tr>
			<td>Magnetic plate</td>
			<td>Oz Biosiences</td>
			<td>MF10000</td>
			<td>Magnetic plate to facilitate viral transduction</td>
		</tr>
		<tr>
			<td>Lipofectamine 2000</td>
			<td>Thermo Fisher Scientific</td>
			<td>11668019</td>
			<td>Transfection agent in viral production</td>
		</tr>
		<tr>
			<td>Poly-D-Lysine</td>
			<td>Millipore Sigma</td>
			<td>A-003-E</td>
			<td>Coating for plates before seeding 293T cells</td>
		</tr>
		<tr>
			<td>4% Formaldehyde Solution</td>
			<td>Boster</td>
			<td>AR1068</td>
			<td>Solution to fix organoids</td>
		</tr>
		<tr>
			<td>O.C.T embedding compound</td>
			<td>Thermo Fisher Scientific</td>
			<td>4583S</td>
			<td>For embedding of the the organoids</td>
		</tr>
		<tr>
			<td>5 mL Falcon polystyrene tubes</td>
			<td>Corning</td>
			<td>352054</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Falcon Tubes</td>
			<td>Sarstedt</td>
			<td>62.547.100</td>
			<td></td>
		</tr>
		<tr>
			<td>Orbitron rotator II Rocker Shaker</td>
			<td>Boekel Scientific</td>
			<td>260250</td>
			<td></td>
		</tr>
		<tr>
			<td>Olympus Inverted microscop CK30</td>
			<td>Olympus</td>
			<td>CK30</td>
			<td>for scanning and counting crypts</td>
		</tr>
		<tr>
			<td>Zeiss Axiovert 200 inverted fluorescence</td>
			<td>Nikon</td>
			<td>Axiovert 200</td>
			<td>for viewing fluorescence in the crypts</td>
		</tr>
		<tr>
			<td>Amicon Ultra-15 Centrifugal Filter unit with Ultracel-100 membrane</td>
			<td>Milipore Sigma</td>
			<td>UFC910024</td>
			<td>For concentrating viruses</td>
		</tr>
		<tr>
			<td>pluriStrainer 20 &#181;m (Cell Strainer)</td>
			<td>pluriSelect</td>
			<td>SKU 43-50020</td>
			<td>For preparing organoid fragments</td>
		</tr>
		<tr>
			<td>Falcon Cell Strainer</td>
			<td>Fisher Scientific</td>
			<td>352340</td>
			<td>For preparing cyrpts of similar size after crypt isolation</td>
		</tr>
		<tr>
			<td>Greiner CELLSTAR&#160;multiwell culture plates 48 wells (TC treated with lid)</td>
			<td>Millipore Sigma</td>
			<td>M8937-100EA</td>
			<td>ForD2:D37+D16:D37g organoid fragments</td>
		</tr>
		<tr>
			<td>Animal strain: C57BL/6J</td>
			<td>Jackson Lab</td>
			<td>#000664</td>
			<td>For organoid culture</td>
		</tr>
	</tbody>
</table>

genetic engineering of primary mouse intestinal organoids using magnetic nanoparticle transduction viral vectors for frozen sectioning

Intestinal organoid cultures provide a unique opportunity to investigate intestinal stem cell and crypt biology in vitro, although efficient approaches to manipulate gene expression in organoids have made limited progress in this arena. While CRISPR/Cas9 technology allows for precise genome editing of cells for organoid generation, this strategy requires extensive selection and screening by sequence analysis, which is both time-consuming and costly. Here, we provide a detailed protocol for efficient viral transduction of intestinal organoids. This approach is rapid and highly efficient, thus decreasing the time and expense inherent in CRISPR/Cas9 technology. We also present a protocol to generate frozen sections from intact organoid cultures for further analysis with immunohistochemical or immunofluorescent staining, which can be used to confirm gene expression or silencing. After successful transduction of viral vectors for gene expression or silencing is achieved, intestinal stem cell and crypt function can be rapidly assessed. Although most organoid studies employ in vitro assays, organoids can also be delivered to mice for in vivo functional analyses. Moreover, our approaches are advantageous for predicting therapeutic responses to drugs because currently available therapies generally function by modulating gene expression or protein function rather than altering the genome.

Here, we describe a rapid and highly efficient transduction technique which harnesses magnetic nanoparticles exposed to a magnetic field to deliver lentivirus to cells of interest. With readily available tools, we have applied this approach not only to transduce freshly isolated crypt cells (Figure 1A), but also for organoids (Figure 2) and other cells that are refractory to more routine transduction approaches. Lentiviral partic...

Watch this Scientific Journal Video about Genetic Engineering of Primary Mouse Intestinal Organoids Using Magnetic Nanoparticle Transduction Viral Vectors for Frozen Sectioning at JoVE.com

Genetic Engineering of Primary Mouse Intestinal Organoids Using Magnetic Nanoparticle Transduction Viral Vectors for Frozen Sectioning

We describe step-by-step instructions to: 1) efficiently engineer intestinal organoids using magnetic nanoparticles for lenti- or retroviral transduction, and, 2) generate frozen sections from engineered organoids. This approach provides a powerful tool to efficiently alter gene expression in organoids for investigation of downstream effects.

Intestinal organoid cultures provide a unique opportunity to investigate intestinal stem cell and crypt biology in vitro, although efficient approaches to ...

Because organoids recapitulate the native structural organization, as well as many molecular features of intestinal epithelium in vivo, this technique allows us to study normal biology and disease states in the laboratory. The main advantage of this technique is the ability to genetically engineer organoids using a very highly efficient transduction approach with low cytotoxicity, thus allowing for functional studies of these genetically manipulated organoids. The implications of this technique extend toward therapy for intestinal disease because we can expose intestinal organoids to drugs and other agents or interventions.This method can be applied to study developmental and pathologic processes in other systems amenable to organoid cultures, such as breast tissues or for cells growing under standard 2D conditions. Generally, individuals new to this method will succeed with transduction in difficult-to-engineer organoids or other cells. We first had the idea for this method when we encountered difficulties transducing our organoids and stem cells.Visual demonstration of this method is critical as structural loss of the organoids can occur if samples are not properly treated during the embedding process into the basement matrix for cryosectioning. To grow organoids for viral transduction, seed organoid cell cultures with 200 microliters of transduction medium per well in a 48-well plate, and incubate in a standard tissue culture incubator. Thaw vials of virus for transduction, allowing for about 50 microliters of concentrated virus for the transduction of each well in 48-well plates.In a 1.5-milliliter tube, mix the virus with 12 microliters of a magnetic nanoparticle solution, and incubate at room temperature for 15 minutes. After 15 minutes, add the magnetic nanoparticle solution and virus mixture to the cells to be transduced. Place the 48-well plate on a magnetic plate, and incubate in a standard tissue culture incubator for at least two hours.When the viral transfection is complete, transfer the infected organoid cell clusters and transduction medium from each well into a 1.5-milliliter tube. Centrifuge at 500 times g for five minutes. Discard the supernatant with gentle suction, and cool the tubes containing the pellet on ice for five minutes.Add 120 microliters of basement membrane matrix to each tube, and resuspend the pellet by slowly pipetting up and down. Seed 30-microliter drops of the matrix-cell mixture into a new 48-well plate. Incubate the plate at 37 degrees Celsius for five to 15 minutes until the matrix solidifies.Add transduction medium to each well, and incubate in a standard tissue culture incubator for three to four days. After three to four days, inspect the cultures under a light microscope at 10x magnification to ensure organization of cell clusters into organoid structures. Gently replace the transduction medium in each well with 250 microliters of organoid culture ENR medium.Return the plate to the incubator. Begin this procedure by removing the ENR medium by gentle suction, being careful not to perturb the basement membrane matrix. Gently wash with 500 microliters of PBS.Fix the organoids by adding one microliter of 4%paraformaldehyde solution per well, and incubate at room temperature for 30 minutes. After 30 minutes, remove the paraformaldehyde solution by suction. Gently add one microliter of PBS per well, and then remove the PBS by gentle suction.In this manner, wash twice with PBS. Remove the PBS from the second wash, and add one microliter of 30%sucrose buffer to each sample. Incubate the fixed organoids in sucrose for one hour at four degrees Celsius to dehydrate the samples.Remove the sucrose buffer by suction, and add just enough embedding compound to cover the matrix layer in each well. Incubate at room temperature for five minutes. Next, place the samples in a minus 80-degree Celsius freezer for 10 minutes or until the embedding compound turns solid and white.Place the plate with frozen embedding compound at room temperature to allow for minimal melting of the compound along the edges. Use a scalpel or spatula to separate the block from the walls of the well. Work quickly to prevent melting, using forceps to remove the matrix embedding compound block, and place it in a specimen block.Fill the mold completely with embedding compound. Freeze at minus 80 degrees Celsius for 30 minutes before using the block for sectioning. This protocol was optimized by first transducing intestinal organoids with lentiviral vectors linked to GFP.The GFP was visualized at each stage in organoid development, including early on when crypt cells organize into cyst-like structures or at later time points when organoids form buds. Successfully transduced intestinal organoids were then formalin-fixed, cryosectioned, and analyzed by immunofluorescence imaging. In this image, nuclei are stained in blue, and the green indicates epithelial cell adhesion molecules, which demarcates cell borders.The red indicates lysosome staining to identify Paneth cells. Once mastered, transducing organoids can be performed in about three hours, and organoids crysection embedding can be done in about 2 1/2 hours. When attempting this procedure, it is important to remember to work on ice when handling basement matrix reagents.After completing this procedure, immunofluorescent analysis and other methods to detect proteins or organelles can be performed to assess localization or relative abundance. This technique paves the ways for researchers to explore normal biology and disease states in vitro and also for in vivo studies if the transduced organoids or cells can be implanted into mice. After watching this video, you should have a good understanding of how to use magnetically labeled viruses to genetically engineer organoids for cryosectioning.Please don't forget that working with viruses can be extremely hazardous, and precautions such as wearing appropriate protective gear should always be undertaken when performing this procedure.

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Primary cells are derived directly from tissue and are thought to be more representative of the physiological state of cells in vivo than established cell lines. However, primary cell cultures usually have a finite life span and need to be frequently re-established. Fibroblasts are an easily accessible source of primary cells. Here, we discuss a simple and quick experimental procedure to establish primary fibroblast cultures from ears and tails of mice. The protocol can be used to establish primary fibroblast cultures from ears stored at RT for up to 10 days. When the protocol is carefully followed, contaminations are unlikely to occur despite the use of non-sterile tissue stored for extended time in some cases. Fibroblasts proliferate rapidly in culture and can be expanded to substantial numbers before undergoing replicative senescence.

We describe a simple and quick experimental procedure for generating primary fibroblasts from the ears and tails of mice. The procedure does not require special animal training and can be used for the generation of fibroblast cultures from ears stored at RT for up to 10 days.

Primary cells are derived directly from tissue and are thought to be more representative of the physiological state of cells in vivo than established cell ...

Simultaneous Assessment of Cardiomyocyte DNA Synthesis and Ploidy: A Method to Assist Quantification of Cardiomyocyte Regeneration and Turnover

Although it is accepted that the heart has a limited potential to regenerate cardiomyocytes following injury and that low levels of cardiomyocyte turnover occur during normal ageing, quantification of these events remains challenging. This is in part due to the rarity of the process and the fact that multiple cellular sources contribute to myocardial maintenance. Furthermore, DNA duplication within cardiomyocytes often leads to a polyploid cardiomyocyte and only rarely leads to new cardiomyocytes by cellular division. In order to accurately quantify cardiomyocyte turnover discrimination between these processes is essential. The protocol described here employs long term nucleoside labeling in order to label all nuclei which have arisen as a result of DNA replication and cardiomyocyte nuclei identified by utilizing nuclei isolation and subsequent PCM1 immunolabeling. Together this allows the accurate and sensitive identification of the nucleoside labeling of the cardiomyocyte nuclei population. Furthermore, 4&#8242;,6-diamidino-2-phenylindole labeling and analysis of nuclei ploidy, enables the discrimination of neo-cardiomyocyte nuclei from nuclei which have incorporated nucleoside during polyploidization. Although this method cannot control for cardiomyocyte binucleation, it allows a rapid and robust quantification of neo-cardiomyocyte nuclei while accounting for polyploidization. This method has a number of downstream applications including assessing the potential therapeutics to enhance cardiomyocyte regeneration or investigating the effects of cardiac disease on cardiomyocyte turnover and ploidy. This technique is also compatible with additional downstream immunohistological techniques, allowing quantification of nucleoside incorporation in all cardiac cell types.

Quantification of cardiomyocyte turnover is challenging. The protocol described here makes an important contribution to this challenge by enabling accurate and sensitive quantification of neo-cardiomyocyte nuclei generation and nuclei ploidy.

Although it is accepted that the heart has a limited potential to regenerate cardiomyocytes following injury and that low levels of cardiomyocyte turnover ...

Immuno-fluorescent Labeling of Microtubules and Centrosomal Proteins in Ex Vivo Intestinal Tissue and 3D In Vitro Intestinal Organoids

The advent of 3D in vitro organoids that mimic the in vivo tissue architecture and morphogenesis has greatly advanced the ability to study key biological questions in cell and developmental biology. In addition, organoids together with recent technical advances in gene editing and viral gene delivery promises to advance medical research and development of new drugs for treatment of diseases. Organoids grown in vitro in basement matrix provide powerful model systems for studying the behavior and function of various proteins and are well suited for live-imaging of fluorescent-tagged proteins. However, establishing the expression and localization of the endogenous proteins in ex vivo tissue and in in vitro organoids is important to verify the behavior of the tagged proteins. To this end we have developed and modified tissue isolation, fixation, and immuno-labeling protocols for localization of microtubules, centrosomal, and associated proteins in ex vivo intestinal tissue and in in vitro intestinal organoids. The aim was for the fixative to preserve the 3D architecture of the organoids/tissue while also preserving antibody antigenicity and enabling good penetration and clearance of fixative and antibodies. Exposure to cold depolymerizes all but stable microtubules and this was a key factor when modifying the various protocols. We found that increasing the ethylenediaminetetraacetic acid (EDTA) concentration from 3 mM to 30 mM gave efficient detachment of villi and crypts in the small intestine while 3 mM EDTA was sufficient for colonic crypts. The developed formaldehyde/methanol fixation protocol gave very good structural preservation while also preserving antigenicity for effective labeling of microtubules, actin, and the end-binding (EB) proteins. It also worked for the centrosomal protein ninein although the methanol protocol worked more consistently. We further established that fixation and immuno-labeling of microtubules and associated proteins could be achieved with organoids isolated from or remaining within the basement matrix.

Immuno-fluorescent Labeling of Microtubules and Centrosomal Proteins in Ex Vivo Intestinal Tissue and 3D In Vitro Intestinal Organoids

We present protocols for isolation of intestinal 3D structures from in vivo tissue and in vitro basement matrix embedded organoids, and detail different fixation and staining protocols optimized for immuno-labeling of microtubule, centrosomal, and junctional proteins as well as cell markers including the stem cell protein Lgr5.

The advent of 3D in vitro organoids that mimic the in vivo tissue architecture and morphogenesis has greatly advanced the ability to study key biological ...

Real-time Measurement of Epithelial Barrier Permeability in Human Intestinal Organoids

Advances in 3D culture of intestinal tissues obtained through biopsy or generated from pluripotent stem cells via directed differentiation, have resulted in sophisticated in vitro models of the intestinal mucosa. Leveraging these emerging model systems will require adaptation of tools and techniques developed for 2D culture systems and animals. Here, we describe a technique for measuring epithelial barrier permeability in human intestinal organoids in real-time. This is accomplished by microinjection of fluorescently-labeled dextran and imaging on an inverted microscope fitted with epifluorescent filters. Real-time measurement of the barrier permeability in intestinal organoids facilitates the generation of high-resolution temporal data in human intestinal epithelial tissue, although this technique can also be applied to fixed timepoint imaging approaches. This protocol is readily adaptable for the measurement of epithelial barrier permeability following exposure to pharmacologic agents, bacterial products or toxins, or live microorganisms. With minor modifications, this protocol can also serve as a general primer on microinjection of intestinal organoids and users may choose to supplement this protocol with additional or alternative downstream applications following microinjection.

This protocol describes the measurement of epithelial barrier permeability in real-time following pharmacologic treatment in human intestinal organoids using fluorescent microscopy and live cell microscopy.

Advances in 3D culture of intestinal tissues obtained through biopsy or generated from pluripotent stem cells via directed differentiation, have resulted ...

Generation of Organoids from Mouse Extrahepatic Bile Ducts

Cholangiopathies, which affect extrahepatic bile ducts (EHBDs), include biliary atresia, primary sclerosing cholangitis, and cholangiocarcinoma. They have no effective therapeutic options. Tools to study EHBD are very limited. Our purpose was to develop an organ-specific, versatile, adult stem cell-derived, preclinical cholangiocyte model that can be easily generated from wild type and genetically engineered mice. Thus, we report on the novel technique of developing an EHBD organoid (EHBDO) culture system from adult mouse EHBDs. The model is cost-efficient, able to be readily analyzed, and has multiple downstream applications. Specifically, we describe the methodology of mouse EHBD isolation and single cell dissociation, organoid culture initiation, propagation, and long-term maintenance and storage. This manuscript also describes EHBDO processing for immunohistochemistry, fluorescent microscopy, and mRNA abundance quantitation by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). This protocol has significant advantages in addition to producing EHBD-specific organoids. The use of a conditioned medium from L-WRN cells significantly reduces the cost of this model. The use of mouse EHBDs provides almost unlimited tissue for culture generation, unlike human tissue. Generated mouse EHBDOs contain a pure population of epithelial cells with markers of endodermal progenitor and differentiated biliary cells. Cultured organoids maintain homogenous morphology through multiple passages and can be recovered after a long-term storage period in liquid nitrogen. The model allows for the study of biliary progenitor cell proliferation, can be manipulated pharmacologically, and may be generated from genetically engineered mice. Future studies are needed to optimize culture conditions in order to increase plating efficiency, evaluate functional cell maturity, and direct cell differentiation. Development of co-culture models and a more biologically neutral extracellular matrix are also desirable.

This protocol describes the production of a mouse extrahepatic bile duct 3-dimensional organoid system. These biliary organoids can be maintained in culture to study cholangiocyte biology. Biliary organoids express markers of both progenitor and biliary cells and are composed of polarized epithelial cells.

Cholangiopathies, which affect extrahepatic bile ducts (EHBDs), include biliary atresia, primary sclerosing cholangitis, and cholangiocarcinoma. They have ...

Generation of Multicellular Human Primary Endometrial Organoids

The human endometrium is one of the most hormonally responsive tissues in the body and is essential for the establishment of pregnancy. This tissue can also become diseased and cause morbidity and even death. Model systems to study human endometrial biology have been limited to in vitro culture systems of single cell types. In addition, the epithelial cells, one of the major cell types of the endometrium, do not propagate well or retain their physiological traits in culture, and thus our understanding of endometrial biology remains limited. We have generated, for the first time, endometrial organoids that consist of both epithelial and stromal cells of the human endometrium. These organoids do not require any exogenous scaffold materials and specifically organize so that epithelial cells encompass the spheroid-like structure and become polarized with stromal cells in the center that produce and secrete collagen. Estrogen, progesterone and androgen receptors are expressed in the epithelial and stromal cells and treatment with physiological levels of estrogen and testosterone promote the organization of the organoids. This new model system can be used to study normal endometrial biology and disease in ways that were not possible before.

A protocol to generate human primary endometrial organoids that consist of epithelial and stromal cells and retain characteristics of the native endometrial tissue is presented. This protocol describes methods from uterine tissue acquisition to the histologic processing of endometrial organoids.

The human endometrium is one of the most hormonally responsive tissues in the body and is essential for the establishment of pregnancy. This tissue can ...

Clonal Genetic Tracing using the Confetti Mouse to Study Mineralized Tissues

Labeling an individual cell in the body to monitor which cell types it can give rise to and track its migration through the organism or determine its longevity can be a powerful way to reveal mechanisms of tissue development and maintenance. One of the most important tools currently available to monitor cells in vivo is the Confetti mouse model. The Confetti model can be used to genetically label individual cells in living mice with various fluorescent proteins in a cell type-specific manner and monitor their fate, as well as the fate of their progeny over time, in a process called clonal genetic tracing or clonal lineage tracing. This model was generated almost a decade ago and has contributed to an improved understanding of many biological processes, particularly related to stem cell biology, development, and renewal of adult tissues. However, preserving the fluorescent signal until image collection and simultaneous capturing of various fluorescent signals is technically challenging, particularly for mineralized tissue. This publication describes a step-by-step protocol for using the Confetti model to analyze growth plate cartilage that can be applied to any mineralized or nonmineralized tissue.

This method describes the use of the R26R-Confetti (Confetti) mouse model to study mineralized tissues, covering all steps from the breeding strategy to the image acquirements. Included is a general protocol that can be applied to all soft tissues and a modified protocol that can be applied to mineralized tissues.

Labeling an individual cell in the body to monitor which cell types it can give rise to and track its migration through the organism or determine its ...

Recapitulating Suckling-to-Weaning Transition In Vitro using Fetal Intestinal Organoids

At the end of the suckling period, many mammalian species undergo major changes in the intestinal epithelium that are associated with the capability to digest solid food. This process is termed suckling-to-weaning transition and results in the replacement of neonatal epithelium with adult epithelium which goes hand in hand with metabolic and morphological adjustments. These complex developmental changes are the result of a genetic program that is intrinsic to the intestinal epithelial cells but can, to some extent, be modulated by extrinsic factors. Prolonged culture of mouse primary intestinal epithelial cells from late fetal period, recapitulates suckling-to-weaning transition in vitro. Here, we describe a detailed protocol for mouse fetal intestinal organoid culture best suited to model this process in vitro. We describe several useful assays designed to monitor the change of intestinal functions associated with suckling-to-weaning transition over time. Additionally, we include an example of an extrinsic factor that is capable to affect suckling-to-weaning transition in vivo, as a representation of modulating the timing of suckling-to-weaning transition in vitro. This in vitro approach can be used to study molecular mechanisms of the suckling-to-weaning transition as well as modulators of this process. Importantly, with respect to animal ethics in research, replacing in vivo models by this in vitro model contributes to refinement of animal experiments and possibly to a reduction in the use of animals to study gut maturation processes.

This protocol describes how to mimic suckling-to-weaning transition in vitro using mouse late fetal intestinal organoids cultured for 30 days.

At the end of the suckling period, many mammalian species undergo major changes in the intestinal epithelium that are associated with the capability to ...

Monocular Visual Deprivation and Ocular Dominance Plasticity Measurement in the Mouse Primary Visual Cortex

Monocular visual deprivation is an excellent experimental paradigm to induce primary visual cortical response plasticity. In general, the response of the cortex to the contralateral eye to a stimulus is much stronger than the response of the ipsilateral eye in the binocular segment of the mouse primary visual cortex (V1). During the mammalian critical period, suturing the contralateral eye will result in a rapid loss of responsiveness of V1 cells to contralateral eye stimulation. With the continuing development of transgenic technologies, more and more studies are using transgenic mice as experimental models to examine the effects of specific genes on ocular dominance (OD) plasticity. In this study, we introduce detailed protocols for monocular visual deprivation and calculate the change in OD plasticity in mouse V1. After monocular deprivation (MD) for 4 days during the critical period, the orientation tuning curves of each neuron are measured, and the tuning curves of layer four neurons in V1 are compared between stimulation of the ipsilateral and contralateral eyes. The contralateral bias index (CBI) can be calculated using each cell&#39;s ocular OD score to indicate the degree of OD plasticity. This experimental technique is important for studying the neural mechanisms of OD plasticity during the critical period and for surveying the roles of specific genes in neural development. The major limitation is that the acute study cannot investigate the change in neural plasticity of the same mouse at a different time.

Here, we present detailed protocols for monocular visual deprivation and ocular dominance plasticity analysis, which are important methods for studying the neural mechanisms of visual plasticity during the critical period and the effects of specific genes on visual development.

Monocular visual deprivation is an excellent experimental paradigm to induce primary visual cortical response plasticity. In general, the response of the ...

Analysis of Congenital Heart Defects in Mouse Embryos Using Qualitative and Quantitative Histological Methods

Congenital heart defects (CHD) are the most common type of birth defect in humans, affecting up to 1% of all live births. However, the underlying causes for CHD are still poorly understood. The developing mouse constitutes a valuable model for the study of CHD, because cardiac developmental programs between mice and humans are highly conserved. The protocol describes in detail how to produce mouse embryos of the desired gestational stage, methods to isolate and preserve the heart for downstream processing, quantitative methods to identify common types of CHD by histology (e.g., ventricular septal defects, atrial septal defects, patent ductus arteriosus), and quantitative histomorphometry methods to measure common muscular compaction phenotypes. These methods articulate all the steps involved in sample preparation, collection, and analysis, allowing scientists to correctly and reproducibly measure CHD.

In this protocol, we describe procedures to qualitatively and quantitatively analyze developmental phenotypes in mice associated with congenital heart defects.

Congenital heart defects (CHD) are the most common type of birth defect in humans, affecting up to 1% of all live births. However, the underlying causes ...