We acknowledge the Cellex Foundation, CIBERONC network, and Instituto de Salud Carlos III for their support. Moreover, we also thank the preclinical imaging platform at the Vall d&#39;Hebron Research Institute (VHIR), where the experiments were performed.

Written informed consent was obtained from all patients. The project was approved by the Research Ethics Committee of the Vall d&#39;Hebron University Hospital, Barcelona, Spain (approval ID: PR(IR)79/2009 PR(AG)114/2014, PR(AG)18/2018). Human colon tissue samples consisted of biopsies from non-necrotic areas of primary adenocarcinomas or liver metastases, corresponding to patients with colon and rectal cancer who underwent tumor resection. Experiments were conducted following the European Union&#39;s animal care directive (86/609/EEC) and were approved by the Ethical Committee of Animal Experimentation of the VHIR-the Vall d&#39;Hebron Research Institute (ID: 40/08 CEEA, 47/08/10 CEEA and 12/18 CEEA).
NOTE: Female NOD-SCID (NOD. CB17-Prkdcscid/NcrCrl) mice from 8 weeks-of-age were purchased from Charles River Laboratories.
1. Derivation of patient cells
<ol>
	<li>Tumor extraction 
	NOTE: The following procedure is performed in a biological cabinet at room temperature (RT) in the animal facility.
	<ol>
		<li>Obtain tumor samples from the patients&#39; surgeries or biopsies and from PDXs growing subcutaneously in mice.</li>
		<li>For the orthotopic injection, prepare the tumor cells from established subcutaneous PDX tumor models instead of tissue obtained directly from patients9.</li>
		<li>Generate PDX tumors by inoculating a suspension of 1 x 105 tumor cells in phosphate buffered saline (PBS) (50 &#181;L) mixed with Matrigel matrix (50 &#181;L) subcutaneously in the flank of NOD-SCID mice2.
		<ol>
			<li>Measure tumor growth using a caliper every other day. 
			NOTE: Importantly, our laboratory has generated a biobank of more than 350 PDX models. The CRC-PDX tumor models used in the protocol are established PDX models in the lab that have been amplified more than three passages in mice, and passed the inclusion/exclusion criteria with a positive result (Table 1).</li>
		</ol>
		</li>
		<li>Euthanize the mice by cervical dislocation when subcutaneous tumors reach the maximum size established by the CEEA (1 cm of diameter), or when the animals reach endpoint criteria.</li>
		<li>Extract the tumor and carefully remove it from the skin and surrounding non-tumor tissue using scissors and forceps.</li>
		<li>Store the harvested tumors in PBS at 4 &#176;C until the next step. 
		NOTE: Dissociate the tumors in cell suspension as soon as possible after removal from their original location in the patients&#39; lesions or subcutaneous xenografts in mice. Cell viability is significantly reduced 24 h after tissue removal, resulting in an inefficient implantation in recipient mice.</li>
	</ol>
	</li>
	<li>Cell preparation 
	NOTE: The following procedure is performed in a biological cabinet at room temperature (RT) in the tissue culture room.
	<ol>
		<li>Dissociate the tumors using a blade in a 10 cm culture plate with 1 mL of complete CoCSCM 6Ab medium (Table 2) (to make mincing easier). Place the homogeneous dissociated sample into a 15 mL conical tube.</li>
		<li>Add complete CoCSCM 6Ab medium to a final volume of 5 mL (use no more than 3 mL of dissociated sample in the same tube). 
		NOTE: Primary CRC resected from patients are naturally contaminated with bacteria and fungus. It is essential to remove pathogens present in the original patient sample using a cocktail of six antibiotics (penicillin, streptomycin, fungizone, kanamycin, gentamycin, and nystatin). Injection of tumor cells contaminated with bacteria in immunodeficient mice may result in animal death.</li>
		<li>Incubate with 50 &#181;L of DNase I (0.08 kU/mL) and 50 &#181;L of collagenase (1.5 mg/mL) (digestion medium; Table 2) for 1 h at 37 &#176;C in a cell culture incubator, at a 45&#176; position. Mix the solution well every 15 min with a 5 mL pipette before the incubation. 
		NOTE: Dissociate the tumor tissue and digest it by pipetting several times to obtain a single cell solution. This is essential for counting the cells before injecting in recipient mice and therefore achieving a homogeneous implantation of tumor cells.</li>
		<li>Add 5 mL of complete CoCSCM 6Ab medium and mix well with a 5 mL pipette.</li>
		<li>Sort the solution with a 100 &#181;m cell strainer using a new sterile 50 mL tube.</li>
		<li>Spin the sorted cells at 500 x g for 8 min at RT.</li>
		<li>Aspirate the supernatant.</li>
		<li>Resuspend the pellet in 3 mL of 1x RBC lysis buffer solution.</li>
		<li>Incubate for 10 min at RT.</li>
		<li>Add 3 mL of complete CoCSCM 6Ab medium, pipette the sample, and spin at 500 x g for 10 min at RT. Aspirate the supernatant.</li>
		<li>Resuspend the pellet with 5-10 mL of complete CoCSCM 6Ab medium, and use a cell counter to calculate the total number of cells.</li>
		<li>Spin the cells at 500 x g for 10 min at RT, and resuspend in 10 mL of PBS.</li>
		<li>Resuspend the pellet to obtain a concentration of 20 x 106 cells/mL, and mix well to obtain a homogeneous cell suspension.</li>
		<li>Prepare 29 G syringes (0.5 mL U 100 needle, 0.33 mm [29 G] x 12.7 mm) for cecum injection in the tissue culture (one syringe/mouse). Load 50 &#181;L of the tumor cell suspension (1 x 106 cells/injection) into the syringe and keep it on ice. Ensure that air bubbles are removed from the cell suspension. 
		NOTE: Eliminating air bubbles when the tumor cells are loaded in the syringe is essential to avoid injection of an excessive volume in the cecum wall, which could result in tissue rupture and sample loss. It is imperative to mix the cell suspension well when loading the syringe to avoid uneven tumor size among mice in the same experiment.</li>
	</ol>
	</li>
</ol>
2. Orthotopic injection in cecum
NOTE: The following procedure is performed on a bench in a specific pathogen free (SPF) room at the animal facility. The equipment used is previously cleaned and sterilized. In addition, it is sterilized again in a portable sterilizer between individuals or zones in the animal facility.
<ol>
	<li>Clean the surgical site by spraying with disinfecting detergent and wiping.</li>
	<li>Depilate the mice abdomen using a mouse hair removal machine.</li>
	<li>Place the mouse in a supine position. Use 2% isoflurane to anesthetize the animal. Confirm the effect of anesthesia by gently pinching the extremity and observing the absence of stimulation.</li>
	<li>Place a 50-100 &#181;L drop of veterinary ointment (3 mg/g Lacryvisc) in the eyes to prevent dryness during anesthesia.</li>
	<li>Disinfect the mouse abdomen by scrubbing with chlorhexidine or povidone-iodine several times in a circular motion.</li>
	<li>Make a 1 cm longitudinal incision over the lower abdomen using surgery scissors. Carefully separate the skin to each site to present the peritoneum that is under the skin.</li>
	<li>Make a 0.5-1 cm incision in the peritoneum membrane, big enough to exteriorize the cecum. 
	NOTE: Exteriorize the cecum without excessively manipulating the internal organs, which could dramatically increase the lethality of the procedure.</li>
	<li>Carefully isolate the cecum from the mouse using a pre-cut, sterile gauze.</li>
	<li>Moisten the cecum with saline solution throughout the whole procedure.</li>
	<li>Immobilize the cecum by carefully taking hold of it with forceps, and introduce the needle superficially into the cecum wall. Avoid capillaries and vessels in the injection site. Remove bubbles from the cell suspension.</li>
	<li>Inject the whole 50&#181;L of tumor cell suspension slowly. It usually takes around 10 s to administer. Avoid perforating the cecum lumen with the needle, as this results in the elimination of the tumor cell suspension from the body through intestinal peristalsis. 
	NOTE: Injecting the tumor cell suspension in the cecum of the mice is the most challenging step of the entire procedure. A bright light focused on the injection site and a magnifying loupe should be used in this part of the protocol. Introduce the needle parallel to the cecum surface. The cecum is a very fragile tissue; therefore, immobilization of the cecum should be performed using surgical forceps and by applying gentle pressure to avoid tissue rupture resulting in hemorrhage. Successful implantation results in a white bubble (pellet of cells) in the cecum wall. If the bubble cannot be visualized, it may indicate that the cecum has been perforated and the cells have ended in the cecum lumen, resulting in their clearance by the intestinal tract.</li>
	<li>After injection, slowly remove the needle from the cecum and apply gentle pressure on the injection site with a cotton-tipped applicator, to avoid tumor cells escaping and reduce slight bleeding.</li>
	<li>Clean the cecum with saline solution to remove any debris.</li>
	<li>Return the cecum back into the abdomen of the animal.</li>
	<li>Close the peritoneum using 5/0 sutures.</li>
	<li>Close the skin of the abdomen using 5/0 sutures.</li>
	<li>Administer post-operative antibiotics (100 mg/kg amoxicillin or 20 mg/kg enrofloxacin) and analgesics (5 mg/mL metacam/meloxicam) by subcutaneous injection. Place the mice on a heating pad and keep them there until they have fully recovered. Then, return them to the cage with other animals.</li>
</ol>
3. Evaluation of orthotopic tumor growth using &#181;CT scanning
NOTE: The following procedure is performed in the preclinical imaging platform (PIP) from the animal facility.
<ol>
	<li>Perform all animal procedures following institutional ethical committee regulations.</li>
	<li>Start monitoring the tumor volume by &#181;CT 2 weeks after cell injection, and every week thereafter.</li>
	<li>Freshly dilute the contrast agent iopamiro (300 mg/mL) in saline solution, in a ratio of 3:1 for both doses. Administer 300 mL of iopamiro by oral gavage. 
	NOTE: Due to the poor soft tissue contrast of the &#181;CT, a contrast agent is recommended to improve the sensitivity of the technique. The protocol includes an oral administration of an iodine-based agent (iopamiro) to delimitate the intraluminal tumor burden, and a secondary intraperitoneal administration of the same agent to define the tumor burden in the visceral face of the intestine. Pilot experiments have been previously performed to determine the exact time that the contrast agent needs to arrive to the cecum of mice before its elimination. In the case of iopamiro, it is around 2 h.</li>
	<li>After 2 h, administer an intraperitoneal injection of 300 mL of previously diluted iopamiro. The administration helps to define the tumor limits in the parietal face.</li>
	<li>Anesthetize the animals using 2% isoflurane.</li>
	<li>After confirming that the animal is correctly anesthetized by pinching the foot of the mouse, place the animal in the scanning bed of the &#181;CT. The best position is supine (face up).</li>
	<li>In the control software, start the live mode (fluoroscopy mode) to place the abdominal area into the field of view (FOV) of the scanner. To do that, move the bed forward and backward and laterally until the desired position is achieved. Rotate the X-ray tube and the detector 90&#176;, and move the scanning bed in the y-axis to center the animal completely.</li>
	<li>Use the following parameters for the &#181;CT scan images: 30 mm FOV, 26 s of acquisition time, 90 kV of current voltage, and 200 &#181;A of current amperage, using an FX &#181;CT imaging system.</li>
	<li>Return the animals to their cages for recovery when the scan is finished. Provide thermal support and monitor the animals until they recover from anesthesia before returning to housing.</li>
	<li>The &#181;CT acquisition yields a file 250 Mb in size for each scan. The created data files have a VOX format. In order to make them accessible for any imaging analysis software, convert the files to DICOM format using the database managing software of the &#181;CT. Store the batch of created files in a portable hard disk in order to analyze them using any computer with available imaging software. 
	NOTE: During image analysis, the cecum is localized as a dilated bowel with a radiodense content (iopamiro), frequently in the left side of the caudal abdomen. In the visceral flexure of the cecum, a wall thickening is observed, compared to the adjacent intestinal regions. The thickening corresponds to tumor growth.</li>
	<li>Once the tumor is localized, find the highest diameter in the different views (axial, coronal, and sagittal). Measure these three axes and calculate the tumor volume following the ellipsoid formula: volume = 4/3&#960; x (x-semiaxis x y-semiaxis x z-semiaxis)10.</li>
</ol>
4. Therapeutic intervention in mice bearing orthotopic tumors
<ol>
	<li>Monitor the mice bearing orthotopic tumors weekly.</li>
	<li>When a tumor &#181;CT scan signal is detected in most of the mice, perform another &#181;CT scan the following week to confirm the presence of the tumor. 
	NOTE: The time to start the treatment depends on the PDX model used, and varies from 3-12 weeks after tumor cell inoculation in the cecum.</li>
	<li>Randomize the mice in four groups: a vehicle group (n = 10-15 mice), a testing drug group (n = 10-15 mice), a standard of care chemotherapy group (n = 10-15 mice), and a combination treatment group (n = 10-15 mice).</li>
	<li>Treat the mice intraperitoneally with saline (vehicle group), the testing drug (20 mg/kg) (testing drug group), irinotecan (50 mg/kg) (standard of care group), or the testing drug (20 mg/kg) with irinotecan (50 mg/kg) (combination treatment group). Perform the administration once a week until the end of the experiment.</li>
	<li>Monitor the tumor growth weekly by &#181;CT scanning throughout the course of the experiment.</li>
	<li>At the end of the experiment, euthanize the mice by cervical dislocation and collect livers, lungs, and any other possible lesions in other organs.</li>
	<li>Include the tissue samples in cassettes and incubate them in 4% formalin overnight. Use intestine tissue from a mouse without a tumor in the cecum as a control.</li>
	<li>Remove the cassettes from formalin and incubate with 70% ethanol for at least 3 h.</li>
	<li>Embed the cassettes with paraffin, using histopathology facility standard protocols.</li>
	<li>Perform hematoxylin and eosin (H&#38;E) staining from the cecum, liver, and lung, using histopathology facility standard protocols.</li>
</ol>

<ol>
	<li>Sung, 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=Global+Cancer+Statistics+2020:+GLOBOCAN+estimates+of+incidence+and+mortality+worldwide+for+36+cancers+in+185+countries.">Global Cancer Statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries.</a> CA: a Cancer Journal for Clinicians. 71 (3), 209-249 (2021).</li><li>Puig, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+personalized+preclinical+model+to+evaluate+the+metastatic+potential+of+patient-derived+colon+cancer+initiating+cells.">A personalized preclinical model to evaluate the metastatic potential of patient-derived colon cancer initiating cells.</a> Clinical Cancer Research. 19 (24), 6787-6801 (2013).</li><li>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=Modeling+development+and+disease+with+organoids.">Modeling development and disease with organoids.</a> Cell. 165 (7), 1586-1597 (2016).</li><li>Byrne, A. 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=Interrogating+open+issues+in+cancer+precision+medicine+with+patient-derived+xenografts.">Interrogating open issues in cancer precision medicine with patient-derived xenografts.</a> Nature Reviews. Cancer. 17 (4), 254-268 (2017).</li><li>Vatandoust, S., Price, T. J., Karapetis, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colorectal+cancer:+Metastases+to+a+single+organ.">Colorectal cancer: Metastases to a single organ.</a> World Journal of Gastroenterology. 21 (41), 11767-11776 (2015).</li><li>Cespedes, M. 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=Orthotopic+microinjection+of+human+colon+cancer+cells+in+nude+mice+induces+tumor+foci+in+all+clinically+relevant+metastatic+sites.">Orthotopic microinjection of human colon cancer cells in nude mice induces tumor foci in all clinically relevant metastatic sites.</a> The American Journal of Pathology. 170 (3), 1077-1085 (2007).</li><li>Durkee, B. Y., Weichert, J. P., Halberg, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+animal+micro-CT+colonography.">Small animal micro-CT colonography.</a> Methods. 50 (1), 36-41 (2010).</li><li>Boll, 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=Double-contrast+micro-CT+colonoscopy+in+live+mice.">Double-contrast micro-CT colonoscopy in live mice.</a> International Journal of Colorectal Disease. 26 (6), 721-727 (2011).</li><li>O'Brien, C. A., Pollett, A., Gallinger, S., Dick, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+human+colon+cancer+cell+capable+of+initiating+tumour+growth+in+immunodeficient+mice.">A human colon cancer cell capable of initiating tumour growth in immunodeficient mice.</a> Nature. 445 (7123), 106-110 (2007).</li><li>Jensen, M. M., Jorgensen, J. T., Binderup, T., Kjaer, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+volume+in+subcutaneous+mouse+xenografts+measured+by+microCT+is+more+accurate+and+reproducible+than+determined+by+18F-FDG-microPET+or+external+caliper.">Tumor volume in subcutaneous mouse xenografts measured by microCT is more accurate and reproducible than determined by 18F-FDG-microPET or external caliper.</a> BMC Medical Imaging. 8, 16 (2008).</li><li>Herpers, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+patient-derived+organoid+screenings+identify+MCLA-158+as+a+therapeutic+EGFR+x+LGR5+bispecific+antibody+with+efficacy+in+epithelial+tumors.">Functional patient-derived organoid screenings identify MCLA-158 as a therapeutic EGFR x LGR5 bispecific antibody with efficacy in epithelial tumors.</a> Nature Cancer. 3 (4), 418-436 (2022).</li><li>Chicote, I., Camara, J. 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Over the last few decades, many new anti-cancer therapies have been developed and tested in patients with different tumor types, including colorectal cancer (CRC). Although promising results in preclinical models have been observed in many cases, the therapeutic efficacy in patients with advanced metastatic CRC has been frequently limited. Therefore, there is an urgent need for preclinical models that allow for testing the efficacy of new therapeutic drugs in a clinically relevant metastatic scenario.
<p class="jove_...

Colorectal cancer (CRC) is the second leading cause of cancer death worldwide1. The ability to generate in vitro or in vivo tumor models derived from individual patient tumor cells has advanced precision medicine in oncology. Over the last decade, patient derived organoids (PDOs) or xenografts (PDXs) have been used by many research groups around the world2. PDOs are multicellular in vitro structures that resemble the features of the original tumor tissue and can self-organize and self-renew3. These promising in vitro models can successfully be used for drug screening and facilitating translational research. On the other side, PDX models faithfully recapitulate the original CRC at all relevant levels, from histology to molecular traits and drug response2,4.
In vivo PDX models are mostly grown as subcutaneous tumors in immunodeficient mice. Using this approach, PDXs have become the gold standard in cancer research, particularly for studying drug sensitivity or resistance. However, CRC related deaths are mostly associated with the presence of metastatic lesions in the liver, the lung, or the peritoneal cavity, and neither of the two approaches (PDO or PDX) can recapitulate the advanced clinical setting. In addition, the specific site of tumor growth has been shown to determine important biological characteristics that have an impact on drug efficacy and disease prognosis2. Therefore, there is an urgent need to establish preclinical models that can be used to assess the efficacy of anticancer drugs in a clinically relevant metastatic setting6.
Microcomputed tomography (&#181;CT) scanners can function as scaled-down clinical CT scanners, providing primary tumor and metastasis imaging in mice at a scaled image resolution proportional to that of CT images of cancer patients7. To counteract the poor soft tissue contrast of the &#181;CT technique, radiological iodinated contrast agents can be used to improve the contrast and evaluate tumor burden. Using a dual contrast approach, oral and intraperitoneal iodine is administrated at different timings. The contrast administrated orally helps to define the limits between tumor tissue and cecum content inside the bowel. &#160;On the other side, the contrast administered intraperitoneally allows for the identification of the external limits of the tumor mass, which frequently grows and invades the peritoneum8.
The manuscript describes a protocol to perform orthotopic implantation of patient-derived cancer cells in the cecum wall of immunodeficient mice, and the methodology to monitor intestinal tumor growth using &#181;CT scanning. The present manuscript shows that the model recapitulates the clinical scenario of advanced intestinal tumors and metastatic disease in CRC patients that cannot be studied using PDO or PDXO models. Since orthotopic PDX models of CRC recapitulate the clinical scenario of CRC patients, we conclude that they are the best to date for testing the efficacy of anti-tumoral drugs in advanced intestinal tumors and metastatic disease.

<table><tbody><tr><td>&lt;strong&gt;REAGENT&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Apo-Transferrin</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>T1147-500MG</td><td></td></tr><tr><td>B27 Supplement</td><td>Life Technologies S.A (Spain)</td><td>17504044</td><td></td></tr><tr><td>Chlorhexidine Aqueous Solution 2%</td><td>DH MATERIAL M&amp;Eacute;DICO, S.L.</td><td>1111696250</td><td></td></tr><tr><td>Collagenase</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>C0130-500MG</td><td></td></tr><tr><td>D-(+)-Glucose</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>G6152</td><td></td></tr><tr><td>DMEM /F12&amp;nbsp;</td><td>LIFE TECHNOLOGIES S.A.</td><td>21331-020</td><td></td></tr><tr><td>DNase I&amp;nbsp;&amp;nbsp;</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>D4263-5VL</td><td></td></tr><tr><td>EGF</td><td>PEPRO TECH EC LTD.</td><td>AF-100-15-500 &amp;micro;g</td><td></td></tr><tr><td>FGF basic</td><td>PEPRO TECH EC LTD.</td><td>100-18B</td><td></td></tr><tr><td>Fungizone</td><td>Life Technologies S.A (Spain)</td><td>15290026</td><td></td></tr><tr><td>Gentamycin</td><td>LIFE TECHNOLOGIES S.A.</td><td>15750037</td><td></td></tr><tr><td>Heparin Sodium Salt</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>H4784-250MG</td><td></td></tr><tr><td>Insulin</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>I9278-5ML</td><td></td></tr><tr><td>Iopamiro</td><td></td><td></td><td></td></tr><tr><td>Isoflurane&amp;nbsp;</td><td>-</td><td>-</td><td></td></tr><tr><td>Kanamycin</td><td>LIFE TECHNOLOGIES S.A.</td><td>15160047</td><td></td></tr><tr><td>L-Glutamine</td><td>LIFE TECHNOLOGIES S.A.</td><td>25030032</td><td></td></tr><tr><td>Matrigel Matrix</td><td>CULTEK, S.L.U.</td><td>356235/356234/354234</td><td></td></tr><tr><td>Metacam, 5 mg/mL</td><td>-</td><td>-</td><td></td></tr><tr><td>Non-essential amino acids</td><td>LIFE TECHNOLOGIES S.A.</td><td>11140035</td><td></td></tr><tr><td>Nystatin</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>N4014-50MG</td><td></td></tr><tr><td>Pen/Strep</td><td>Life Technologies S.A (Spain)</td><td>15140122</td><td></td></tr><tr><td>Phosphate-buffered saline (PBS), sterile</td><td>Labclinics S.A</td><td>L0615-500</td><td></td></tr><tr><td>Progesterone</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>P0130-25G</td><td></td></tr><tr><td>Putrescine</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>P5780-5G</td><td></td></tr><tr><td>RBC Lysis Buffer&amp;nbsp;</td><td>Labclinics S.A</td><td>00-4333-57</td><td></td></tr><tr><td>Sodium Pyruvate</td><td>LIFE TECHNOLOGIES S.A.</td><td>11360039</td><td></td></tr><tr><td>Sodium Selenite</td><td>MERCK LIFE SCIENCE S.L.U.</td><td>S5261-25G</td><td></td></tr><tr><td>&lt;strong&gt;ESSENTIAL SUPPLIES&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>8 weeks-old NOD.CB17-Prkdcscid/NcrCrl mice</td><td>-</td><td>-</td><td></td></tr><tr><td>BD Micro-Fine 0.5 ml U 100 needle 0.33 mm (29G) x 12.7 mm&amp;nbsp;</td><td>BECTON DICKINSON, S.A.U.</td><td>320926</td><td></td></tr><tr><td>Blade #24</td><td>-</td><td>-</td><td></td></tr><tr><td>Cell Strainer 100 &amp;micro;m</td><td>Cultek, SLU</td><td>45352360</td><td></td></tr><tr><td>Forceps and Surgical scissors</td><td>-</td><td>-</td><td></td></tr><tr><td>Heating pad</td><td>-</td><td>-</td><td></td></tr><tr><td>Lacryvisc, 3 mg/g, ophthalmic gel</td><td>-</td><td>-</td><td></td></tr><tr><td>Surfasafe</td><td>-</td><td>-</td><td></td></tr><tr><td>Suture PROLENE 5-0&amp;nbsp;</td><td>JOHNSON&amp;amp;JOHNSON S, A.</td><td>8720H</td><td></td></tr><tr><td>&lt;strong&gt;EQUIPMENT/SOFTWARE&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Quantum FX &amp;micro;CT Imaging system</td><td>Perkin Elmer</td><td>Perkin Elmer</td><td>http://www.perkinelmer.com/es/product/quantum-gx-instrument-120-240-cls140083</td></tr></tbody></table>

orthotopic implantation of patient-derived cancer cells in mice recapitulates advanced colorectal cancer

Over the last decade, more sophisticated preclinical colorectal cancer (CRC) models have been established using patient-derived cancer cells and 3D tumoroids. Since patient derived tumor organoids can retain the characteristics of the original tumor, these reliable preclinical models enable cancer drug screening and the study of drug resistance mechanisms. However, CRC related death in patients is mostly associated with the presence of metastatic disease. It is therefore essential to evaluate the efficacy of anti-cancer therapies in relevant in vivo models that truly recapitulate the key molecular features of human cancer metastasis. We have established an orthotopic model based on the injection of CRC patient-derived cancer cells directly into the cecum wall of mice. These tumor cells develop primary tumors in the cecum that metastasize to the liver and lungs, which is frequently observed in patients with advanced CRC. This CRC mouse model can be used to evaluate drug responses monitored by microcomputed tomography (&#181;CT), a clinically relevant small-scale imaging method that can easily identify primary tumors or metastases in patients. Here, we describe the surgical procedure and the required methodology to implant patient-derived cancer cells in the cecum wall of immunodeficient mice.

Mice orthotopically implanted with patient-derived cancer cells were monitored weekly by &#181;CT scanning. At the end of the experiment, the animals were euthanized. Intestines, ceca (Figure 1A,B), livers, lungs,&#160;and any other possible lesion were collected, included in a cassette, and fixed with 4% formalin overnight. Intestine tissue from a mouse without a tumor in the cecum was used as a control (Figure 1C). Finally, cassettes were chan...

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Orthotopic Implantation of Patient-Derived Cancer Cells in Mice Recapitulates Advanced Colorectal Cancer

This protocol describes the orthotopic implantation of patient-derived cancer cells in the cecum wall of immunodeficient mice. The model recapitulates advanced colorectal cancer metastatic disease and allows for the evaluation of new therapeutic drugs in a clinically relevant scenario of lung and liver metastases.

Over the last decade, more sophisticated preclinical colorectal cancer (CRC) models have been established using patient-derived cancer cells and 3D ...

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Research

JoVE Journal

Cancer Research

1.7K Views.  Vall d’Hebron Institute of Oncology (VHIO). Dit protocol beschrijft de orthotope implantatie van kankercellen van patiënten in de blindedarmwand van immunodeficiënte muizen. Dit model recapituleert gevorderde colorectale kanker gemetastaseerde ziekte. Het orthotope colorectale kankermodel dat hier wordt gepresenteerd, recapituleert het klinische scenario van gevorderde darmtumoren en gemetastaseerde ziekte bij patiënten met colorectale kanker die niet kunnen worden bestudeerd met behulp van van patiënten afgeleide organoïden of va...

Video: Orthotopic Implantation of Patient-Derived Cancer Cells in Mice Recapitulates Advanced Colorectal Cancer

Advanced Animal Model of Colorectal Metastasis in Liver: Imaging Techniques and Properties of Metastatic Clones

Patients with a limited number of hepatic metastases and slow rates of progression can be successfully treated with local treatment approaches1,2. However, little is known about the heterogeneity of liver metastases, and animal models capable of evaluating the development of individual metastatic colonies are needed. Here, we present an advanced model of hepatic metastases that provides the ability to quantitatively visualize the development of individual tumor clones in the liver and estimate their growth kinetics and colonization efficiency. We generated a panel of monoclonal derivatives of HCT116 human colorectal cancer cells stably labeled with luciferase and tdTomato and possessing different growth properties. With a splenic injection followed by a splenectomy, the majority of these clones are able to generate hepatic metastases, but with different frequencies of colonization and varying growth rates. Using the In Vivo&#160;Imaging System (IVIS), it is possible to visualize and quantify metastasis development with in vivo luminescent and ex vivo fluorescent imaging. In addition, Diffuse Luminescent Imaging Tomography (DLIT) provides a 3D distribution of liver metastases in vivo. Ex vivo fluorescent imaging of harvested livers provides quantitative measurements of individual hepatic metastatic colonies, allowing for the evaluation of the frequency of liver colonization and the growth kinetics of metastases. Since the model is similar to clinically observed liver metastases, it can serve as a modality for detecting genes associated with liver metastasis and for testing potential ablative or adjuvant treatments for liver metastatic disease.

The ability of metastatic clones to colonize distant sites depends on their proliferation capacity and/or their ability to survive in the host microenvironment without significant proliferation. Here, we present an animal model that allows quantitative visualization of both types of liver colonization by metastatic clones.

Patients with a limited number of hepatic metastases and slow rates of progression can be successfully treated with local treatment approaches1,2. ...

Isolation of Circulating Tumor Cells in an Orthotopic Mouse Model of Colorectal Cancer

Despite the advantages of easy applicability and cost-effectiveness, subcutaneous mouse models have severe limitations and do not accurately simulate tumor biology and tumor cell dissemination. Orthotopic mouse models have been introduced to overcome these limitations; however, such models are technically demanding, especially in hollow organs such as the large bowel. In order to produce uniform tumors which reliably grow and metastasize, standardized techniques of tumor cell preparation and injection are critical. 
We have developed an orthotopic mouse model of colorectal cancer (CRC) which develops highly uniform tumors and can be used for tumor biology studies as well as therapeutic trials. Tumor cells from either primary tumors, 2-dimensional (2D) cell lines or 3-dimensional (3D) organoids are injected into the cecum and, depending on the metastatic potential of the injected tumor cells, form highly metastatic tumors. In addition, CTCs can be found regularly. We here describe the technique of tumor cell preparation from both 2D cell lines and 3D organoids as well as primary tumor tissue, the surgical and injection techniques as well as the isolation of CTCs from the tumor-bearing mice, and present tips for troubleshooting.

We describe the establishment of orthotopic colorectal tumors via injection of tumor cells or organoids into the cecum of mice and the subsequent isolation of circulating tumor cells (CTCs) from this model.

Despite the advantages of easy applicability and cost-effectiveness, subcutaneous mouse models have severe limitations and do not accurately simulate ...

A Genetically Engineered Mouse Model of Sporadic Colorectal Cancer

Despite the advantages of easy applicability and cost-effectiveness, colorectal cancer mouse models based on tumor cell injection have severe limitations and do not accurately simulate tumor biology and tumor cell dissemination. Genetically engineered mouse models have been introduced to overcome these limitations; however, such models are technically demanding, especially in large organs such as the colon in which only a single tumor is desired.
As a result, an immunocompetent, genetically engineered mouse model of colorectal cancer was developed which develops highly uniform tumors and can be used for tumor biology studies as well as therapeutic trials. Tumor development is initiated by surgical, segmental infection of the distal colon with adeno-cre virus in compound conditionally mutant mice. The tumors can be easily detected and monitored via colonoscopy. We here describe the surgical technique of segmental adeno-cre infection of the colon, the surveillance of the tumor via high-resolution colonoscopy and present the resulting colorectal tumors.

A protocol for the establishment of a genetically engineered mouse model of colorectal cancer by segmental adeno-cre infection and its surveillance via high-resolution colonoscopy is presented.

Despite the advantages of easy applicability and cost-effectiveness, colorectal cancer mouse models based on tumor cell injection have severe limitations ...

High-sensitivity Detection of Micrometastases Generated by GFP Lentivirus-transduced Organoids Cultured from a Patient-derived Colon Tumor

Despite current advances in human colorectal cancer (CRC) treatment, few radical therapies are effective for the late stages of CRC. To overcome this clinical challenge, tumor xenograft mouse models using long-established human carcinoma cell lines and many transgenic mouse models with tumors have been developed as preclinical models. They partially mimic the features of human carcinomas, but often fail to recapitulate the key aspects of human malignancies including invasion and metastasis. Thus, alternative models that better represent the malignant progression in human CRC have long been awaited.
We herein show generation of patient-derived tumor xenografts (PDXs) by subcutaneous implantation of small CRC fragments surgically dissected from a patient. The colon PDXs develop and histopathologically resemble the CRC in the patient. However, few spontaneous micrometastases are detectable in conventional cross-sections of affected distant organs in the PDX model. To facilitate the detection of metastatic dissemination into distant organs, we extracted the tumor organoid cells from the colon PDXs in culture and infected them with GFP lentivirus prior to injection into highly immunodeficient NOD/Shi-scid IL2R&#947;null (NOG) mice. Orthotopically injected PDX-derived CRC organoid cells consistently form primary tumors positive for GFP in recipient mice. Moreover, spontaneously developing micrometastatic colonies expressing GFP are notably detected in the lungs of these mice by fluorescence microscopy. Moreover, intrasplenic injection of CRC organoids frequently produces hepatic colonization. Taken together, these findings indicate GFP-labelled PDX-derived CRC organoid cells to be visually detectable during a multistep process termed the invasion-metastasis cascade. The described protocols include the establishment of PDXs of human CRC and 3D culture of the corresponding CRC organoid cells transduced by GFP lentiviral particles.

To allow highly sensitive detection of the disseminating human colorectal cancer (CRC) cells colonizing tissues, we herein show a protocol for efficient transduction of green fluorescent protein (GFP) lentiviral particles into PDX-derived CRC organoid cells prior to their injection into recipient mice, with stereo-fluorescence microscopic observation.

Despite current advances in human colorectal cancer (CRC) treatment, few radical therapies are effective for the late stages of CRC. To overcome this ...

Orthotopic Mouse Model of Colorectal Cancer

The traditional subcutaneous tumor model is less than ideal for studying colorectal cancer. Orthotopic mouse models of colorectal cancer, which feature cancer cells growing in their natural location, replicate human disease with high fidelity. Two techniques can be used to establish this model. Both techniques are similar and require mouse anesthesia and laparotomy for exposure of the cecum. One technique involves injection of a colorectal cancer cell suspension into the cecal wall. Cancer cells are first grown in culture, harvested when subconfluent and prepared as a single cell suspension. A small volume of cells is injected slowly to avoid leakage. The other technique involves transplantation of a piece of subcutaneous tumor onto the cecum. A mouse with a previously established subcutaneous colorectal tumor is euthanized and the tumor is removed using sterile technique. The tumor piece is divided into small pieces for transplantation to another mouse. Prior to transplantation, the cecal wall is lightly damaged to facilitate tumor cell infiltration. The time to developing primary tumors and liver metastases will vary depending on the technique, cell line, and mouse species used. This orthotopic mouse model is useful for studying the natural progression of colorectal cancer and testing new therapeutic agents against colorectal cancer.

Two techniques can be used to establish this model: injection of a cancer cell suspension into the cecal wall or transplantation of a piece of subcutaneous tumor onto the cecum. This model is useful for studying the natural progression of colorectal cancer and testing new therapeutic agents against colorectal cancer.

The traditional subcutaneous tumor model is less than ideal for studying colorectal cancer. Orthotopic mouse models of colorectal cancer, which feature ...

Biology

Patient-derived Orthotopic Xenograft Models for Human Urothelial Cell Carcinoma and Colorectal Cancer Tumor Growth and Spontaneous Metastasis

Cancer patients have poor prognoses when lymph node (LN) involvement is present in both high-grade urothelial cell carcinoma (HG-UCC) of the bladder and colorectal cancer (CRC). More than 50% of patients with muscle-invasive UCC, despite curative therapy for clinically-localized disease, will develop metastases and die within 5 years, and metastatic CRC is a leading cause of cancer-related deaths in the US. Xenograft models that consistently mimic UCC and CRC metastasis seen in patients are needed. This study aims to generate patient-derived orthotopic xenograft (PDOX) models of UCC and CRC for primary tumor growth and spontaneous metastases under the influence of LN stromal cells mimicking the progression of human metastatic diseases for drug screening. Fresh UCC and CRC tumors were obtained from consented patients undergoing resection for HG-UCC and colorectal adenocarcinoma, respectively. Co-inoculated with LN stromal cell (LNSC) analog HK cells, luciferase-tagged UCC cells were intra-vesically (IB) instilled into female non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice, and CRC cells were intra-rectally (IR) injected into male NOD/SCID mice. Tumor growth and metastasis were monitored weekly using bioluminescence imaging (BLI). Upon sacrifice, primary tumors and mouse organs were harvested, weighed, and formalin-fixed for Hematoxylin and Eosin and immunohistochemistry staining. In our unique PDOX models, xenograft tumors resemble patient pre-implantation tumors. In the presence of HK cells, both models have high tumor implantation rates measured by BLI and tumor weights, 83.3% for UCC and 96.9% for CRC, and high distant organ metastasis rates (33.3% detected liver or lung metastasis for UCC and 53.1% for CRC). In addition, both models have zero mortality from the procedure. We have established unique, reproducible PDOX models for human HG-UCC and CRC, which allow for tumor formation, growth, and metastasis studies. With these models, testing of novel therapeutic drugs can be performed efficiently and in a clinically-mimetic manner.

This protocol describes the generation of patient-derived orthotopic xenograft models by intra-vesically instilling high-grade urothelial cell carcinoma cells or intra-rectally injecting colorectal cancer cells into non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice for primary tumor growth and spontaneous metastases under the influence of lymph node stromal cells, which mimics the progression of human metastatic diseases.

Cancer patients have poor prognoses when lymph node (LN) involvement is present in both high-grade urothelial cell carcinoma (HG-UCC) of the bladder and ...

Portal Vein Injection of Colorectal Cancer Organoids to Study the Liver Metastasis Stroma

Hepatic metastasis of colorectal cancer (CRC) is a leading cause of cancer-related death. Cancer-associated fibroblasts (CAFs), a major component of the tumor microenvironment, play a crucial role in metastatic CRC progression and predict poor patient prognosis. However, there is a lack of satisfactory mouse models to study the crosstalk between metastatic cancer cells and CAFs. Here, we present a method to investigate how liver metastasis progression is regulated by the metastatic niche and possibly could be restrained by stroma-directed therapy. Portal vein injection of CRC organoids generated a desmoplastic reaction, which faithfully recapitulated the fibroblast-rich histology of human CRC liver metastases. This model was tissue-specific with a higher tumor burden in the liver when compared to an intra-splenic injection model, simplifying mouse survival analyses. By injecting luciferase-expressing tumor organoids, tumor growth kinetics could be monitored by in vivo imaging. Moreover, this preclinical model provides a useful platform to assess the efficacy of therapeutics targeting the tumor mesenchyme. We describe methods to examine whether adeno-associated virus-mediated delivery of a tumor-inhibiting stromal gene to hepatocytes could remodel the tumor microenvironment and improve mouse survival. This approach enables the development and assessment of novel therapeutic strategies to inhibit hepatic metastasis of CRC.

Portal vein injection of colorectal cancer (CRC) organoids generates stroma-rich liver metastasis. This mouse model of CRC hepatic metastasis represents a useful tool to study tumor-stroma interactions and develop novel stroma-directed therapeutics such as adeno-associated virus-mediated gene therapies.

Hepatic metastasis of colorectal cancer (CRC) is a leading cause of cancer-related death. Cancer-associated fibroblasts (CAFs), a major component of the ...

Intracecal Tumor Cell Injection: A Technique to Deliver Cancer Cells for Establishing Orthotopic Colorectal Cancer Mouse Model

Source: Kochall, S., et al. <a href="https://www.jove.com/v/55357"> Isolation of Circulating Tumor Cells in an Orthotopic Mouse Model of Colorectal Cancer </a> J. Vis. Exp. (2017)
The video describes the technique for intracecal injection of cancerous cells to develop an orthotopic mouse model with highly uniform tumors. Therefore, the orthotopic mouse model allows realistic simulation of metastasis, providing a valuable tool to study the phenotype changes during tumor growth and dissemination.

Source: Kochall, S., et al.  Isolation of Circulating Tumor Cells in an Orthotopic Mouse Model of Colorectal Cancer  J. Vis. Exp. (2017)
The video ...

JoVE Encyclopedia of Experiments

Colorectal Cancer

Animal model studies

Orthotopic Injection: Implanting Tissue Specific Cancer Cells into an Adult Mouse

Source: Katsuta, E., et al. <a href="https://www.jove.com/v/57849/generating-murine-orthotopic-metastatic-breast-cancer-model">Generating a Murine Orthotopic Metastatic Breast Cancer Model and Performing Murine Radical Mastectomy.</a>&#160;J. Vis. Exp.&#160;(2018).
The video demonstrates the breast cancer orthotopic inoculation technique in a mouse model. This technique produces a high tumorigenesis rate with less variability in tumor size and shape compared to subcutaneous or non-surgical injection.

Source: Katsuta, E., et al. Generating a Murine Orthotopic Metastatic Breast Cancer Model and Performing Murine Radical Mastectomy.&#160;J. Vis. ...

Breast Cancer

Procedures and techniques

Establishing Experimental Metastases Mouse Model: Implanting GFP Expressing CRC Organoid Cells in PDX Model to Detect Micrometastases

Source: Okazawa, Y. et al.&#160; <a href="https://www.jove.com/v/57374"> High-sensitivity Detection of Micrometastases Generated by GFP Lentivirus-transduced Organoids Cultured from a Patient-derived Colon Tumor.</a> J. Vis. Exp. (2018).
This video describes the protocol for generating metastases by the PDX derived CRC organoids labeled with GFP lentivirus into the spleen of an immunodeficient mouse. Cancer micrometastases colonizing other organs can be detected using a fluorescence microscope to assess the GFP expression.

Orthotopic Implantation of Patient-Derived Cancer Cells in Mice Recapitulates Advanced Colorectal Cancer

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