This research work was supported in part by NIH Grants, K08CA252161(Q.L.), R01CA234162, and R01 CA207757 (D.W.G.), P30CA016056 (NCI Cancer Center Core Support Grant), the Roswell Park Alliance Foundation, and the Friends of Urology Foundation. We thank Marisa Blask and Mila Pakhomova for proofreading the manuscript.

All animal procedures were approved by the Institutional Animal Care and Use Committee (IACUC) at Roswell Park Comprehensive Cancer Center, Buffalo, NY (1395M, Biosafety 180501 and 180502). 
NOTE: Perform Steps 1-3 on the same day.
1. Dissection of mouse bladder
<ol>
	<li>Preparation for dissection
	<ol>
		<li>Prepare all the sterile instruments including scissors, forceps, sterile DPBS in 35 mm culture dishes, 70% ethanol, sterile gauze, and clean paper towels. Clean a...

<ol>
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Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rb1+and+Trp53+cooperate+to+suppress+prostate+cancer+lineage+plasticity,+metastasis,+and+antiandrogen+resistance.">Rb1 and Trp53 cooperate to suppress prostate cancer lineage plasticity, metastasis, and antiandrogen resistance.</a> Science. 355 (6320), 78-83 (2017).</li><li>Lee, S. 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=Tumor+evolution+and+drug+response+in+patient-derived+organoid+models+of+bladder+cancer.">Tumor evolution and drug response in patient-derived organoid models of bladder cancer.</a> Cell. 173 (2), 515-528 (2018).</li><li>Fujii, E., 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+simple+method+for+histopathological+evaluation+of+organoids.">A simple method for histopathological evaluation of organoids.</a> Journal of Toxicologic Pathology. 31 (1), 81-85 (2018).</li><li>Georgas, K. 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=An+illustrated+anatomical+ontology+of+the+developing+mouse+lower+urogenital+tract.">An illustrated anatomical ontology of the developing mouse lower urogenital tract.</a> Development. 142 (10), 1893-1908 (2015).</li><li>Santos, C. P., 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=Urothelial+organoids+originating+from+Cd49f(high)+mouse+stem+cells+display+Notch-dependent+differentiation+capacity.">Urothelial organoids originating from Cd49f(high) mouse stem cells display Notch-dependent differentiation capacity.</a> Nature Communication. 10 (1), 4407 (2019).</li><li>Wang, 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=A+genetically+defined+disease+model+reveals+that+urothelial+cells+can+initiate+divergent+bladder+cancer+phenotypes.">A genetically defined disease model reveals that urothelial cells can initiate divergent bladder cancer phenotypes.</a> Proceedings of the National Academy of Sciences of the United States of America. 117 (1), 563-572 (2020).</li><li>Yang, D., 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=Intertumoral+heterogeneity+in+SCLC+is+influenced+by+the+cell+type+of+origin.">Intertumoral heterogeneity in SCLC is influenced by the cell type of origin.</a> Cancer Discovery. 8 (10), 1316-1331 (2018).</li><li>Sutherland, K. D., 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=Cell+of+origin+of+small+cell+lung+cancer:+inactivation+of+Trp53+and+Rb1+in+distinct+cell+types+of+adult+mouse+lung.">Cell of origin of small cell lung cancer: inactivation of Trp53 and Rb1 in distinct cell types of adult mouse lung.</a> Cancer Cell. 19 (6), 754-764 (2011).</li><li>Bottger, 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=Tumor+heterogeneity+underlies+differential+cisplatin+sensitivity+in+mouse+models+of+small-cell+lung+cancer.">Tumor heterogeneity underlies differential cisplatin sensitivity in mouse models of small-cell lung cancer.</a> Cell Reports. 27 (11), 3345-3358 (2019).</li><li>Puzio-Kuter, A. 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=Inactivation+of+p53+and+Pten+promotes+invasive+bladder+cancer.">Inactivation of p53 and Pten promotes invasive bladder cancer.</a> Genes &amp; Development. 23 (6), 675-680 (2009).</li><li>Park, 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=Novel+mouse+models+of+bladder+cancer+identify+a+prognostic+signature+associated+with+risk+of+disease+progression.">Novel mouse models of bladder cancer identify a prognostic signature associated with risk of disease progression.</a> Cancer Research. 81 (20), 5161-5175 (2021).</li><li>Hawley, S. P., Wills, M. K., Jones, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adenovirus-mediated+genetic+removal+of+signaling+molecules+in+cultured+primary+mouse+embryonic+fibroblasts.">Adenovirus-mediated genetic removal of signaling molecules in cultured primary mouse embryonic fibroblasts.</a> Journal of Visualized Experiments: JoVE. (43), e2160 (2010).</li><li>Feng, W., 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=Rapid+interrogation+of+cancer+cell+of+origin+through+CRISPR+editing.">Rapid interrogation of cancer cell of origin through CRISPR editing.</a> Proceedings of the National Academy of Sciences of the United States of America. 118 (32), 2110344118 (2021).</li></ol>

The authors have nothing to disclose.

GEMMs have been the gold standards for cancer modeling initiated from normal cells, allowing the consequences of potential oncogenic perturbations (oncogene activation and/or loss of tumor suppressors) to be tested rigorously. Here, a rapid and efficient protocol is provided to generate bladder cancer organoids via ex vivo gene editing of normal mouse urothelial cells carrying floxed alleles in genes of interest. H&#38;E and IHC staining demonstrate that TKO organoids exhibit histology consistent with high-grade...

Bladder cancer is the fourth most common cancer in men and affects more than 80,000 people annually in the United States1. Platinum-based chemotherapy has been the standard of care for patients with advanced bladder cancer for more than three decades. The landscape of bladder cancer treatment has been revolutionized by the recent Food and Drug Administration (FDA) approval of immunotherapy (anti-PD-1 and anti-PD-L1 immune checkpoint inhibitors), erdafitinib (a fibroblast growth factor receptor inhibitor) and enfortumab vedotin (an antibody-drug conjugate)2,3,4. However, no clinically approved biomarkers are available for predicting the responses to chemotherapy or immunotherapy. There is a critical need to generate informative preclinical models that can improve the understanding of the mechanisms driving bladder cancer progression and develop predictive biomarkers for different treatment modalities.
A major obstacle in bladder translational research is the lack of preclinical models that recapitulate human bladder cancer pathogenesis and treatment responses5,6. Multiple preclinical models have been developed, including in vitro 2D models (cell lines or conditionally reprogrammed cells), in vitro 3D models (organoids, 3D printing), and in vivo models (xenograft, carcinogen-induced, genetically engineered models, and patient-derived xenograft)2,6. Genetically engineered mouse models (GEMMs) are useful for many applications in bladder cancer biology, including analyses of tumor phenotypes, mechanistic investigations of candidate genes and/or signaling pathways, and the preclinical evaluation of therapeutic responses6,7. GEMMs can utilize site-specific recombinases (Cre-loxP) to control genetic deletions in one or more tumor suppressor genes. The process of generating desired GEMMs with multiple gene deletions is time-consuming, laborious, and expensive5. The overall goal of this method is to develop a rapid and efficient method of ex vivo Cre delivery for establishing bladder triple knockout (TKO) models from normal mouse urothelial cells carrying triple floxed alleles (Trp53, Pten, and Rb1)8. The major advantage of the ex vivo method is the fast workflow (1-2 weeks instead of years of mouse breeding). This article describes the protocol for harvesting normal urothelial cells with floxed alleles, ex vivo adenovirus transduction, organoid cultures, and in vitro and in vivo characterization in immunocompetent C57 BL/6J mice. This method can be further used to generate clinically relevant bladder cancer organoids in immunocompetent mice harboring any combination of floxed alleles.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>100 &#956;m sterile cell strainer</td>
			<td>Corning</td>
			<td>431752</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL syringe</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr>
			<td>25G 1.5 inches needle</td>
			<td>EXELINT International</td>
			<td>26406</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenovirus (Ad5CMVCre High Titer, 1E11 pfu/ml)</td>
			<td>UI Viral Vector Core</td>
			<td>VVC-U of Iowa-5-HT</td>
			<td></td>
		</tr>
		<tr>
			<td>C57 BL/6J</td>
			<td>Jackson Lab</td>
			<td>000664</td>
			<td></td>
		</tr>
		<tr>
			<td>Charcoal-stripped FBS</td>
			<td>Gibco</td>
			<td>A3382101</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase/hyaluronidase</td>
			<td>Stemcell Technologies</td>
			<td>07912</td>
			<td></td>
		</tr>
		<tr>
			<td>Dispase</td>
			<td>Stemcell Technologies</td>
			<td>07913</td>
			<td></td>
		</tr>
		<tr>
			<td>DPBS, 1x</td>
			<td>Corning</td>
			<td>21-031-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine substitute (GlutaMAX)</td>
			<td>Gibco</td>
			<td>35-050-061</td>
			<td></td>
		</tr>
		<tr>
			<td>Mammary Epithelial Cell Growth medium</td>
			<td>Lonza</td>
			<td>CC-3150</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrix extracts from Engelbreth&#8211;Holm&#8211;Swarm mouse sarcomas (Matrigel)</td>
			<td>Corning</td>
			<td>CB-40234</td>
			<td></td>
		</tr>
		<tr>
			<td>Monoclonal mouse anti-CK20</td>
			<td>DAKO</td>
			<td>M7019</td>
			<td>IF 1:100</td>
		</tr>
		<tr>
			<td>Monoclonal mouse anti-CK7</td>
			<td>Santa Cruz Biotechnology</td>
			<td>SC-23876</td>
			<td>IHC 1:50</td>
		</tr>
		<tr>
			<td>Monoclonal mouse anti-p63</td>
			<td>Abcam</td>
			<td>ab735</td>
			<td>IHC 1:100, IF 1:50</td>
		</tr>
		<tr>
			<td>Monoclonal mouse anti-Upk3</td>
			<td>Fitzgerald</td>
			<td>10R-U103A</td>
			<td>IHC 1:50</td>
		</tr>
		<tr>
			<td>Monoclonal mouse anti-Vimentin</td>
			<td>Santa Cruz Biotechnology</td>
			<td>SC-6260</td>
			<td>IF 1:100</td>
		</tr>
		<tr>
			<td>Monoclonal rat anti-CK8</td>
			<td>Developmental Studies Hybridoma Bank</td>
			<td>TROMA-I-s</td>
			<td>IF 1:100</td>
		</tr>
		<tr>
			<td>HERAcell vios 160i CO2 incubator</td>
			<td>Thermo Fisher</td>
			<td>51033557</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyclonal chicken anti-CK5</td>
			<td>Biolegend</td>
			<td>905901</td>
			<td>IF 1:500</td>
		</tr>
		<tr>
			<td>Primocin</td>
			<td>InvivoGen</td>
			<td>ant-pm-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant enzyme of trypsin substitute (TrypLE Express Enzyme)</td>
			<td>Thermo Fisher</td>
			<td>12605036</td>
			<td></td>
		</tr>
		<tr>
			<td>Signature benchtop shaking incubator Model 1575</td>
			<td>VWR</td>
			<td>35962-091</td>
			<td></td>
		</tr>
		<tr>
			<td>Specimen Processing Gel (HistoGel)</td>
			<td>Thermo Fisher</td>
			<td>HG-4000-012</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical blade size 10</td>
			<td>Integra Miltex</td>
			<td>4-110</td>
			<td></td>
		</tr>
		<tr>
			<td>Sorvall T1 centrifuge</td>
			<td>Thermo Fisher</td>
			<td>75002383</td>
			<td></td>
		</tr>
		<tr>
			<td>Y-27632</td>
			<td>Selleckchem</td>
			<td>S1049</td>
			<td></td>
		</tr>
	</tbody>
</table>

ex vivo organoid model of adenovirus-cre mediated gene deletions in mouse urothelial cells

Bladder cancer is an understudied area, particularly in genetically engineered mouse models (GEMMs). Inbred GEMMs with tissue-specific Cre and loxP sites have been the gold standards for conditional or inducible gene targeting. To provide faster and more efficient experimental models, an ex vivo organoid culture system is developed using adenovirus Cre and normal urothelial cells carrying multiple loxP alleles of the tumor suppressors Trp53, Pten, and Rb1. Normal urothelial cells are enzymatically disassociated from four bladders of triple floxed mice (Trp53f/f: Ptenf/f: Rb1f/f). The urothelial cells are transduced ex vivo with adenovirus-Cre driven by a CMV promoter (Ad5CMVCre). The transduced bladder organoids are cultured, propagated, and characterized in vitro and in vivo. PCR is used to confirm gene deletions in Trp53, Pten, and Rb1. Immunofluorescence (IF) staining of organoids demonstrates positive expression of urothelial lineage markers (CK5 and p63). The organoids are injected subcutaneously into host mice for tumor expansion and serial passages. The immunohistochemistry (IHC) of xenografts exhibits positive expression of CK7, CK5, and p63 and negative expression of CK8 and Uroplakin 3. In summary, adenovirus-mediated gene deletion from mouse urothelial cells engineered with loxP sites is an efficient method to rapidly test the tumorigenic potential of defined genetic alterations.

The workflow of adenovirus-Cre mediated gene deletions in mouse urothelial cells is shown in Figure 1A. The accompanying video demonstrates how the urothelial cells are disassociated from the fundus of the bladder and how the triple floxed cells are transduced ex vivo with Ad5CMVCre. Figure 1A showed that minimal submucosa and muscle cells were disassociated after enzyme digestion. To confirm the efficiency of adenovirus-Cre delivery, disassociated urot...

Watch this Scientific Journal Video about Ex Vivo Organoid Model of Adenovirus-Cre Mediated Gene Deletions in Mouse Urothelial Cells at JoVE.com

Ex Vivo Organoid Model of Adenovirus-Cre Mediated Gene Deletions in Mouse Urothelial Cells

This protocol describes the process of the generation and characterization of mouse urothelial organoids harboring deletions in genes of interest. The methods include harvesting mouse urothelial cells, ex vivo transduction with adenovirus driving Cre expression with a CMV promoter, and in vitro as well as in vivo characterization.

Ex Vivo Organoid Model of Adenovirus-Cre Mediated Gene Deletions in Mouse Urothelial Cells

Bladder cancer is an understudied area, particularly in genetically engineered mouse models (GEMMs). Inbred GEMMs with tissue-specific Cre and loxP sites ...

We developed a rapid and efficient protocol to generate bladder cancer organoids via ex vivo gene editing of normal mouse urothelial cells carrying floxed alleles in genes of interest. This ex vivo method has a one-to-two-week workflow instead of years of mouse breeding, and it is highly efficient in adenovirus transduction on the Cre-mediated gene deletions. To begin, prepare all sterile instruments and reagents, including scissors, forceps, DPBS in 35-milliliter culture dishes, 70%ethanol, gauze, and clean paper towels.Next, clean all surfaces of the dissection area and cover the dissection area with a clean paper towel. Place the euthanized mouse on the gauze in the dissection area and spray 70%ethanol on the mouse's abdomen, then using sterile dissection scissors, make a lower midline abdominal incision to expose the bladder. Now, use the forceps to grasp and gently pull up the bladder to identify the bilateral ureterovesical junction.Using scissors, remove the bladder fundus, following the boundary line between the two ureter openings and transfer the bladder into a sterile dish containing 2 milliliters of DPBS, then remove the fatty and connective tissue and put the bladder into a new dish containing 2 milliliters of DPBS. Also remove the adenovirus from the minus 80-degree Celsius storage and keep it on ice. For cell dissociation, prepare all sterile instruments and reagents as described in the manuscript, then in a biosafety cabinet, transfer the bladder to a 35-millimeter dish and wash with 2 milliliters of sterile DPBS.Collect bladder tissues from four mice into a dish with one milliliter of complete culture medium without charcoal-stripped FBS. Next, using a surgical blade, mince each bladder into four equal pieces, then using forceps, unfold the bladder to expose the urothelium surface to the medium. Transfer the bladder pieces and medium into a 15-milliliter centrifuge tube.Wash the dish twice with 2 milliliters of complete culture medium without charcoal-stripped FBS and add the wash to the centrifuge tube, bringing the total volume to 5 milliliters. Next, add a collagenase and hyaluronidase mixture and place the tube horizontally in a 37-degree Celsius orbital shaker incubator for 30 minutes at 200 RPM. After tissue digestion, add an equal volume of 10%charcoal-stripped FBS and DPBS into the tube and centrifuge at 200 times g for 5 minutes.After discarding the supernatant, add 2 milliliters of trypsin substitute into the cell pellet and mix well, then incubate the tube at 37 degrees Celsius and 5%carbon dioxide for 4 minutes. After incubation, pipette the cells up and down 10 times with a standard P1000 tip and add 5 milliliters of 10%charcoal-stripped FBS and DPBS. Strain the dissociated cells through a 100-micrometer sterile cell strainer and collect the cell suspension in a 50-milliliter tube.Transfer the cell suspension to a 15-milliliter tube and centrifuge at 200 times g for 5 minutes. After removing the supernatant, resuspend the pellet in 1 milliliter of complete culture medium. Count the number of cells using a hemocytometer and plate 0.5 times 10 to the 6th cells into each well of a 24-well plate with 0.5 milliliters of fresh complete culture medium.Next, take out the matrix extracts of Engelbreth-Holm-Swarm mouse sarcoma cells from minus 20-degree Celsius storage and thaw them on ice. Also, prewarm a 6-well plate in a 37-degree Celsius cell incubator. For adenoviral transduction, add 2 microliters of adenovirus into the 24-well plate and mix well with the dissociated urothelial cells.To enhance transduction efficacy, perform spinoculation by centrifuging the plate at 300 times g for 30 minutes, then incubate the plate at 37 degrees Celsius and 5%carbon dioxide for 1 hour. Transfer cells and medium from the well into a 15-milliliter tube and centrifuge at 200 times g for 5 minutes. After discarding the supernatant, add 50 microliters of complete culture medium and mix well with the cells at the bottom.Next, add 140 microliters of matrix extract and gently mix well to avoid air bubbles, then create domes for organoids by quickly adding 50 microliters of the solution per dome into the prewarmed 6-well plate. Incubate the plate and allow the domes to solidify for 5 minutes. After 5 minutes, flip the 6-well plate upside down and continue solidification for an additional 25 minutes.After incubation, add 2.5 milliliters of complete culture medium to each well and place the plate in an incubator for organoid culture. The green fluorescent protein was detected in nearly 100%of cells, suggesting high efficiency of adenovirus transduction. Hematoxylin and eosin staining and immunohistochemistry of triple knockout organoids tumors showed the morphology of high-grade urothelial carcinoma with positive protein expression of basal subtype markers of CK5 and p63.The un-recombined floxed alleles were detected in urothelial cells, untreated with adenovirus, whereas the recombined alleles were observed in the triple knockout organoids. In general, 2 to 3 weeks were needed to form a 2-centimeter subcutaneous tumor. The immunohistochemistry of triple knockout organoids, in vivo xenografts, displayed positive expression of CK7, CK5, and p63 proteins.Negative expression was detected for CK8 and uroplakin proteins. The mesenchyme marker, vimentin, was detected only in the tumor capsule or stroma. The mouse bladder dissociation must not exceed 30 minutes.A longer dissociation time may increase in the percentage of the stroma cells, such as endothelial cells and the fibroblasts This approach can be combined with cell sorting or cell-type a specific adenovirus to generate the cell type of specific organoids, such as lumen versus basal organoids.

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2.5K Views.  Roswell Park Comprehensive Cancer Center. We developed a rapid and efficient protocol to generate bladder cancer organoids via ex vivo gene editing of normal mouse urothelial cells carrying floxed alleles in genes of interest. This ex vivo method has a one-to-two-week workflow instead of years of mouse breeding, and it is highly efficient in adenovirus transduction on the Cre-mediated gene deletions. To begin, prepare all sterile instruments and reagents, including scissors, forceps, DPBS in 35-milliliter culture dishes, 70%ethanol, ...