This research was supported by the Deutsche Krebshilfe (Max Eder Group to AN: 110972), a DGVS doctoral thesis scholarship (to SMB), and an Else-Kr&#246;ner-Fresenius-Foundation scholarship (to RGG) at the University Medical Center Goettingen. We thank Jutta Blumberg and Ulrike Wegner for expert technical assistance. We also thank all animal technicians at the animal facility of the University Medical Center Goettingen for mouse keeping. All experiments were performed according to German animal welfare regulations.

This protocol is in accordance with the animal care guidelines at the University Medical Centre Goettingen, Germany (33.9-42502-04-15/2056). Depending on specific requirements of individual animal review boards, some of the protocol steps could be modified accordingly.
1. Abdominal Palpation of KPC Mice
<ol>
	<li>To avoid unnecessary ultrasound scans, palpate the mouse abdomen to identify mice which might possibly bear an intraabdominal lesion and should subsequently undergo abdominal ultrasound.
	<ol>
		<li>Perform abdominal palpation weekly starting from 8 weeks of age in the KPC mouse model. High resolution ultrasound can also be applied in transplanted tumor models (e.g., orthotopics) or other genetically engineered mouse models. 
		NOTE: Depending on tumor kinetics and study goal (prevention study, therapeutic intervention study), detection of very small tumors (1-2 mm) is feasible to monitor tumor onset before tumors can be palpated.</li>
	</ol>
	</li>
	<li>Place the mouse on the cage grid and gently lift the mouse by the tail and palpate the abdomen by gently going up and down with index and thumb of the non-fixing hand (Figure 1).</li>
	<li>If the mouse tolerates soft palpation, proceed by slowly increasing the pressure. A larger resistance can easily be detected in the upper and lower abdomen. Sometimes, hard feces can be mistakenly interpreted as a tumor mass.</li>
</ol>
2. Preparation of Work Space
<ol>
	<li>Provide space for at least three different work units: pre-scan area, scanning stage and recovery cage. Required material are depicted in Figure 2.</li>
	<li>Clean the main working plate (for example with 70% Ethanol) and switch on the heating platform prior to scanning (Figure 3). Make sure that the target temperature of 38-40 &#176;C is reached before the first mouse is transferred.</li>
	<li>Switch on the ultrasound machine and create a new folder for the acquired data (Figure 4). The B-mode setting is applied for abdominal imaging. Further, ensure the abdominal transducer is plugged in the active port of the machine. Fix the transducer head at the top of the working stage by using the transducer mounting system.</li>
	<li>Prepare a recovery cage on a heating plate or thermal mat (or use heating lamp) to ensure post-procedural thermoregulation and speedy recovery of scanned mice. Put a thin layer of tissue as cushion at the bottom of this cage to avoid aspiration of bedding with the risk of suffocation (Figure 5).</li>
</ol>
3. Inhalation Anesthesia
<ol>
	<li>Proceed by putting a mouse into the induction chamber. Open the valve for gas carrier flow (1 L/min oxygen or air) and set the isoflurane concentration to 4% allowing a slowly increasing saturation of the induction chamber. Make sure that proper isoflurane scavenging (passive or active filtering) is in place. After about 2-4 min the mouse will usually be under deep sedation.
	<ol>
		<li>Maintain sedation by administering 2% isoflurane through the nose cone on the working stage.</li>
	</ol>
	</li>
	<li>Carefully transfer the animal from the induction chamber to the working stage. Check the nose cone for a constant gas flow. Put the mouse snout in the nose cone of the anesthesia line outlet. The regular position for the initial scanning is supine position. The mouse can also be placed on its right or left side to improve visibility of pancreatic head or tail tumors (Figure 6).</li>
	<li>Although abdominal ultrasound is not painful per se, perform the foot pinch test as an indicator for a pain free condition and deep anesthetic state. If the mouse is still active or actively moving around, retransfer the animal back in the induction chamber for repeated and prolonged induction.</li>
	<li>Use eye protection ointment to prevent corneal injuries due to fluid loss.</li>
	<li>During anesthesia, use a monitoring system. However, ECG and rectal temperature is not regularly used for abdominal ultrasound scanning. Importantly, mice lose the ability to thermoregulate under anesthesia. Therefore, closely observe clinical signs for hypothermia or respiratory distress such as gasping or apnea. If any symptom is obvious stop isoflurane and place the mouse in the recovery cage immediately.</li>
</ol>
4. Ultrasound&#160;Settings
<ol>
	<li>Switch on the ultrasound system as described by manufacturer`s instructions. Make sure the primary setting is put on general imaging with the abdominal package activated. Usually B-Mode-imaging is used for data acquisition as a standard.</li>
	<li>Achieve optimized image quality with following parameters: frequency 40 MHz, 2D-gain 25-30 dB, image depth 10 mm, image width 10 mm, 3 focal zones with center between 3-6 mm.</li>
</ol>
5. Mouse Preparation
<ol>
	<li>Fix the upper and lower extremity using adhesive tape. Be as careful as possible to avoid any injury to the animal due to fixation (Figure 7).</li>
	<li>Remove all abdominal fur using electronic pet clippers. Due to the fur texture, start from the lower abdomen up to the ribcage. Take care at the processus xiphoideus to avoid skin injuries in this area. 
	NOTE: Mouse fur reflects ultrasound waves and decreases visibility.</li>
	<li>Use depilatory cream to perform an optimized skin preparation and complete removal of fur. Administer a thin layer of cream onto the shaved abdomen using cotton tips (Figure 8). Remove the cream (after 30 s or later depending on the cream used) with dry tissues followed by plenty of water to completely remove all remnants (Figure 9, Figure 10, Figure 11). Cream remnants could cause skin and mucosa irritations after the ultrasound and may thus affect the health.</li>
	<li>To ensure adequate scanning conditions apply plenty of ultrasound gel onto the abdomen (Figure 12). Usually, warm ultrasound gel is used in order to minimize hypothermia for the mouse.</li>
	<li>Manually apply a thin layer of ultrasound gel on the transducer head. Perform a test by touching on the transducer end with the notch. At the screen a signal at the left upper side can be seen if the transducer is correctly positioned.</li>
</ol>
6. Abdominal Ultrasound
<ol>
	<li>Adjust the transducer onto the abdomen using firm pressure. Heavy compression of the mouse abdomen may lead to respiratory or circulatory impairment and should be avoided.</li>
	<li>Scan up and down. Adjust the frame of the working platform and the wheels for x-axis and y-axis.</li>
	<li>As the first step identify both kidneys. Usually they appear as hyperechogenic homogenous structures in the lower abdomen. The connected vena renalis can be easily found which further leads to the vena cava inferior (Figure 13).</li>
	<li>Use the vena lienalis serves as landmark vessel for the pancreas. Attempt to distinguish between vena renalis and vena lienalis. Upon detection of the vena lienalis the pancreas can be exactly localized. The normal pancreas is rather a membrane spread through the abdominal cavity than a solid structure (Figure 14 and Figure 15).</li>
</ol>
7. Pancreatic Tumor Detection and Volume Evaluation
<ol>
	<li>Identify pancreatic lesions from all surrounding structures. They generally appear as hypoechoic inhomogeneous round or elongated tissue masses (Figure 16). The tumor is usually firm and can hardly be compressed by the scan head. Note, from time to time it might be tricky to clearly distinguish between a tumor and a small bowel loop. Pay attention to the bowel peristalsis that should not be observed in pancreatic tumors.</li>
	<li>Upon tumor detection screen up and down to get an impression of the total size and measure the largest diameter by using the ultrasound caliper. Once a suitable image is found, freeze the screen and use the measure tool to precisely determine the tumor size. Note, for later use it will be important to differentiate whether a tumor is localized in the tail, body or head of the pancreas.</li>
	<li>Before changing back to live mode, make sure to save pictures to record the work. Note, while freezing the image it might happen that the adjustment wheel is released, and the ultrasound probe is even more pressed to the mouse abdomen. Therefore, fix the adjustment of the compression before changing the mode to freeze.</li>
	<li>After finishing the measurement of the first plane either rotate the scan head by 90&#176; in longitudinal position (Figure 17), or turn the mouse to its side, to detect the tumors&#39; longitudinal expansion. Some tumors may require changing the position of the mouse for adequate visibility. For pancreatic tail tumors, the mouse can be placed on its right side (Figure 10 and Figure 19), for pancreatic head tumors on its left side (Figure 11 and Figure 20).</li>
</ol>
8. Quantification of Tumor Volume
Note: One major aim of all efforts is the correct determination of tumor volume. Although there are several techniques available a calculation method including the formula of an ellipsoid is preferred at the University Medical Center Goettingen.
<ol>
	<li>Equipped with all three previously obtained diameters, calculate the approximate volume of the corresponding tumor (Figure 21).</li>
	<li>Alternatively, use a motor system of the scan head to perform an automated scan of the tumor region with subsequent volume calculation and 3-D-reconstruction.</li>
</ol>
9. Recovery
<ol>
	<li>After the scanning, carefully remove all adhesive tape and carefully remove all ultrasound gel with dry tissue.</li>
	<li>Carefully transfer the mouse into the recovery cage ( Figure 21). Avoid any covering tissue at the mouse&#180;s face that might cause respiratory impairment. A side position for recovery should be preferred.</li>
</ol>

<ol>
	<li>Kersten, K., de Visser, K. E., van Miltenburg, M. H., Jonkers, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+engineered+mouse+models+in+oncology+research+and+cancer+medicine.">Genetically engineered mouse models in oncology research and cancer medicine.</a> EMBO Molecular Medicine. 9 (2), 137-153 (2017).</li><li>Olive, K. P., Politi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Translational therapeutics in genetically engineered mouse models of cancer. (2), 131-143 (2014).</li><li>Westphalen, C. B., Olive, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+engineered+mouse+models+of+pancreatic+cancer.">Genetically engineered mouse models of pancreatic cancer.</a> The Cancer Journal. 18 (6), 502-510 (2012).</li><li>Hingorani, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trp53R172H+and+KrasG12D+cooperate+to+promote+chromosomal+instability+and+widely+metastatic+pancreatic+ductal+adenocarcinoma+in+mice.">Trp53R172H and KrasG12D cooperate to promote chromosomal instability and widely metastatic pancreatic ductal adenocarcinoma in mice.</a> Cancer Cell. 7 (5), 469-483 (2005).</li><li>Frese, K. 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=nab-Paclitaxel+potentiates+gemcitabine+activity+by+reducing+cytidine+deaminase+levels+in+a+mouse+model+of+pancreatic+cancer.">nab-Paclitaxel potentiates gemcitabine activity by reducing cytidine deaminase levels in a mouse model of pancreatic cancer.</a> Cancer Discovery. 2 (3), 260-269 (2012).</li><li>Paredes, J. 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+non-invasive+method+of+quantifying+pancreatic+volume+in+mice+using+micro-MRI.">A non-invasive method of quantifying pancreatic volume in mice using micro-MRI.</a> PLoS One. 9 (3), e92263 (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>Aung, 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=Immunotargeting+of+Integrin+alpha6beta4+for+Single-Photon+Emission+Computed+Tomography+and+Near-Infrared+Fluorescence+Imaging+in+a+Pancreatic+Cancer+Model.">Immunotargeting of Integrin alpha6beta4 for Single-Photon Emission Computed Tomography and Near-Infrared Fluorescence Imaging in a Pancreatic Cancer Model.</a> Molecular Imaging. 15, (2016).</li><li>Akladios, C. 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=Contribution+of+microCT+structural+imaging+to+preclinical+evaluation+of+hepatocellular+carcinoma+chemotherapeutics+on+orthotopic+graft+in+ACI+rats.">Contribution of microCT structural imaging to preclinical evaluation of hepatocellular carcinoma chemotherapeutics on orthotopic graft in ACI rats.</a> Bulletin du Cancer. 98 (2), 120-132 (2011).</li><li>Neesse, 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=CTGF+antagonism+with+mAb+FG-3019+enhances+chemotherapy+response+without+increasing+drug+delivery+in+murine+ductal+pancreas+cancer.">CTGF antagonism with mAb FG-3019 enhances chemotherapy response without increasing drug delivery in murine ductal pancreas cancer.</a> Proceedings of the National Academy of Science USA. 110 (30), 12325-12330 (2013).</li><li>Sastra, S. A., Olive, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+murine+pancreatic+tumors+by+high-resolution+ultrasound.">Quantification of murine pancreatic tumors by high-resolution ultrasound.</a> Methods in Molecular Biology. 980, 249-266 (2013).</li></ol>

The authors have nothing to disclose.

With this protocol, a detailed description for quantifying pancreatic tumors using high-resolution abdominal ultrasound imaging in genetically engineered mouse models is provided. Recently, Sastra et al. published a detailed description how to quantify pancreatic tumors in mouse models, but no visualized instructions about the preparation and handling as prerequisite for all further steps were shown11. The overall goal of this manuscript is to provide a comprehensive visual guide for high...

Genetically engineered mouse models have gained an increasing importance in cancer research due to their ability to closely recapitulate the complex nature of human carcinogenesis1,2,3. One of the most frequently used models to study pancreatic cancer development, progression and therapeutic response is characterized by an activating mutation in the Kras oncogene combined with an inactivation of the tumor suppressor p534. This LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mouse model mimics the step-wise progression from pre-invasive pancreatic intraepithelial neoplasia (PanIN) lesions to invasive carcinoma. Phenotypically, nearly all mice develop PDAC within the first six months after birth. However, compared to transplanted models, the KPC model reveals a highly variable tumor onset from 8 weeks to several months4. Once pancreatic tumors reach a certain size (5-9 mm in diameter), tumor growth accelerates rapidly and mice will have to be enrolled in preclinical trials5. Therefore, the exact detection of tumor onset and tumor size is an essential prerequisite for preclinical study logistics and therapy monitoring. In general, several approaches like magnetic resonance imaging (MRI)6, computed tomography scanning7,8,9 or high resolution ultrasound can be employed to conduct tumor screening and therapy10. Each technique has its advantages and drawbacks. Although MRI-or computed tomography (CT) -imaging allows high resolution data acquisition as well as accurate volume calculation, prolonged examination time under general sedation, and very expensive equipment is required, and does not permit frequent scanning over a long period of time. In contrast, small animal ultrasonography is an established method that can be employed to screen for abdominal pathologies in mice11. Advantages of this imaging method are short scanning times, high resolution, and the possibility to use doppler ultrasound or contrast enhanced ultrasound (CEUS) to visualize perfusion of organs in parallel. However, anatomical knowledge, 3D imagination and thorough practical training are required for correct image interpretation.
In the following article, a detailed protocol for utilizing high resolution ultrasound in the KPC model is provided. Furthermore, standard ultrasound images are depicted and labelled with organ structures to facilitate orientation for the investigator.

<table><tbody><tr><td>Visual Sonics Vevo2100 High Resolution Ultrasound System, including imaging stage and anesthesia line</td><td>FUJIFILM VisualSonics Inc, Canada</td><td>VS-11945</td><td></td></tr><tr><td>Vevo 2100 MicroScan Transducer MS-550-D (22-55MHz)</td><td>FUJIFILM VisualSonics Inc, Canada</td><td>VS-11874</td><td></td></tr><tr><td>Vevo Anesthesia System (anesthesia induction chamber with fresh and waste gas inlet)</td><td>FUJIFILM VisualSonics Inc, Canada</td><td>SA-12055</td><td></td></tr><tr><td>Vevo Imaging Station (working stage with nose cone for anesthesia supply)</td><td>FUJIFILM VisualSonics Inc, Canada</td><td>SA-11982</td><td></td></tr><tr><td>&amp;nbsp;electronic pet clippers</td><td>Panasonic Marketing Europe, Germany</td><td>5025232484324</td><td>Panasonic ER-PA10-s</td></tr><tr><td>Labotect Hot plate</td><td>Labor tech G&amp;ouml;ttingen, Germany</td><td>13854</td><td></td></tr><tr><td>eye cream (ophthalmic ointment)</td><td>Sch&amp;uuml;lke&amp;amp;Mayr, Germany</td><td>9080249</td><td></td></tr><tr><td>veterinary isoflurane</td><td>Abbvie, Germany</td><td>4831867</td><td></td></tr><tr><td>depilatory cream</td><td>RB healthcare UK, United Kingdom</td><td>8218535</td><td></td></tr><tr><td>70% ethanol (v/v) in distilled water</td><td>TH. Geyer, Germany</td><td>22941000</td><td></td></tr><tr><td>ultrasound gel</td><td>Asmuth, Germany</td><td>13477</td><td></td></tr><tr><td>tissue wipes</td><td>Kimberly-Clark Germany, Germany</td><td>7558</td><td></td></tr><tr><td>cotton tips</td><td>Meditrade, Germany</td><td>75481116</td><td></td></tr><tr><td>glass bowl for ultrasound gel</td><td>ARC France, France</td><td>H1149</td><td></td></tr><tr><td>water bowl</td><td>W &amp;amp; P Trading Co., USA</td><td>B00K2P6PLQ</td><td></td></tr><tr><td>gauze sponges</td><td>Fuhrmann, Germany</td><td>960504</td><td></td></tr></tbody></table>

utilizing high resolution ultrasound to monitor tumor onset and growth in genetically engineered pancreatic cancer models

The LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mouse model represents an established and frequently used transgenic model to evaluate novel therapies in pancreatic cancer. Tumor onset is variable in the KPC model between 8 weeks and several months. Therefore, non-invasive imaging tools are required to screen for tumor onset and monitor for response to treatment. To address this issue, different approaches have emerged over the last years. High resolution ultrasound has major advantages such as non-invasiveness, fast session times and a high image resolution without radiation exposure. However, ultrasound in mice is not trivial and sufficient anatomical knowledge and practical skills are required to successfully perform high resolution ultrasound in preclinical pancreatic cancer models. With the following article, a detailed hands-on guide for abdominal ultrasound in murine models with a particular focus on endogenous pancreatic cancer models is presented. Furthermore, a summary of common mistakes and how to avoid them is provided.

Ultrasound imaging is a versatile and non-invasive technique that is used to address several issues in murine models of human diseases. Compared to all other imaging approaches major advantages are high-throughput, cost efficiency, short acquisition time and real-time imaging. However, this tool needs expertise to generate accurate, high quality images. Particularly in the case of unwanted artefacts at least some experience with ultrasound imaging in general is very helpful. In relation t...

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Utilizing High Resolution Ultrasound to Monitor Tumor Onset and Growth in Genetically Engineered Pancreatic Cancer Models

This article describes the utilization of high-resolution ultrasound in genetically engineered pancreatic cancer mice. The primary aim is to provide a detailed instruction for detection and evaluation of endogenous pancreatic tumors.

The LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mouse model represents an established and frequently used transgenic model to evaluate novel ...

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10.7K Views.  University Medical Center Goettingen. This article describes the utilization of high-resolution ultrasound in genetically engineered pancreatic cancer mice. The primary aim is to provide a detailed instruction for detection and evaluation of endogenous pancreatic tumors.

Video: Utilizing High Resolution Ultrasound to Monitor Tumor Onset and Growth in Genetically Engineered Pancreatic Cancer Models

Fluorescent Orthotopic Mouse Model of Pancreatic Cancer

Pancreatic cancer remains one of the cancers for which survival has not improved substantially in the last few decades. Only 7% of diagnosed patients will survive longer than five years. In order to understand and mimic the microenvironment of pancreatic tumors, we utilized a murine orthotopic model of pancreatic cancer that allows non-invasive imaging of tumor progression in real time. Pancreatic cancer cells expressing green fluorescent protein (PANC-1 GFP) were suspended in basement membrane matrix, high concentration, (e.g., Matrigel HC) with serum-free media and then injected into the tail of the pancreas via laparotomy. The cell suspension in the high concentration basement membrane matrix becomes a gel-like substance once it reaches room temperature; therefore, it gels when it comes in contact with the pancreas, creating a seal at the injection site and preventing any cell leakage. Tumor growth and metastasis to other organs are monitored in live animals by using fluorescence. It is critical to use the appropriate filters for excitation and emission of GFP. The steps for the orthotopic implantation are detailed in this article so researchers can easily replicate the procedure in nude mice. The main steps of this protocol are preparation of the cell suspension, surgical implantation, and whole body fluorescent in vivo imaging. This orthotopic model is designed to investigate the efficacy of novel therapeutics on primary and metastatic tumors.

A procedure to implant green fluorescent protein-expressing pancreatic cancer cells (PANC-1 GFP) orthotopically into the pancreas of Balb-c Ola Hsd-Fox1nu mice to assess tumor progression and metastasis is presented here.

Pancreatic cancer remains one of the cancers for which survival has not improved substantially in the last few decades. Only 7% of diagnosed patients will ...

Ultrasound-Guided Orthotopic Implantation of Murine Pancreatic Ductal Adenocarcinoma

The recent success of immune checkpoint blockade in melanoma and lung adenocarcinoma has galvanized the field of immuno-oncology as well as revealed the limitations of current treatments, as the majority of patients do not respond to immunotherapy. Development of accurate preclinical models to quickly identify novel and effective therapeutic combinations are critical to address this unmet clinical need. Pancreatic ductal adenocarcinoma (PDA) is a canonical example of an immune checkpoint blockade resistant tumor with only 2% of patients responding to immunotherapy. The genetically engineered KrasG12D+/-;Trp53R172H+/-;Pdx-1 Cre (KPC) mouse model of PDA recapitulates human disease and is a valuable tool for assessing therapies for immunotherapy resistant in the preclinical setting, but time to tumor onset is highly variable. Surgical orthotopic tumor implantation models of PDA maintain the immunobiological hallmarks of the KPC tissue-specific tumor microenvironment (TME) but require a time-intensive procedure and introduce aberrant inflammation. Here, we use an ultrasound-guided orthotopic tumor implantation model (UG-OTIM) to non-invasively inject KPC-derived PDA cell lines directly into the mouse pancreas. UG-OTIM tumors grow in the endogenous tissue site, faithfully recapitulate histological features of the PDA TME, and reach enrollment-sized tumors for preclinical studies by four weeks after injection with minimal seeding on the peritoneal wall. The UG-OTIM system described here is a rapid and reproducible tumor model that may allow for high throughput analysis of novel therapeutic combinations in the murine PDA TME.

We describe a protocol for the ultrasound guided implantation of murine-derived pancreatic ductal adenocarcinoma cell lines directly into the native tumor site. This approach resulted in pancreatic tumors detectable by ultrasound scanning within 2-4 weeks of injection, and significantly reduced the proportion tumor cell seeding on the peritoneal wall as compared to surgical orthotopic implantation.

The recent success of immune checkpoint blockade in melanoma and lung adenocarcinoma has galvanized the field of immuno-oncology as well as revealed the ...

Detection of Lung Tumor Progression in Mice by Ultrasound Imaging

With ~1.6 million victims per year, lung cancer contributes tremendously to the worldwide burden of cancer. Lung cancer is partly driven by genetic alterations in oncogenes such as the KRAS oncogene, which constitutes ~25% of lung cancer cases. The difficulty in therapeutically targeting KRAS-driven lung cancer partly stems from having poor models that can mimic the progression of the disease in the lab. We describe a method that permits the relative quantification of primary KRAS lung tumors in a Cre-inducible LSL-KRAS G12D mouse model via ultrasound imaging. This method relies on brightness (B)-mode acquisition of the lung parenchyma. Tumors that are initially formed in this model are visualized as B-lines and can be quantified by counting the number of B-lines present in the acquired images. These would represent the relative tumor number formed on the surface of the mouse lung. As the formed tumors develop with time, they are perceived as deep clefts within the lung parenchyma. Since the circumference of the formed tumor is well-defined, calculating the relative tumor volume is achieved by measuring the length and width of the tumor and applying them in the formula used for tumor caliper measurements. Ultrasound imaging is a non-invasive, fast and user-friendly technique that is often used for tumor quantifications in mice. Although artifacts may appear when obtaining ultrasound images, it has been shown that this imaging technique is more advantageous for tumor quantifications in mice compared to other imaging techniques such as computed tomography (CT) imaging and bioluminescence imaging (BLI). Researchers can investigate novel therapeutic targets using this technique by comparing lung tumor initiation and progression between different groups of mice.

This protocol describes the steps taken to induce KRAS lung tumors in mice as well as the quantification of formed tumors by ultrasound imaging. Small tumors are visualized in early timepoints as B-lines. At later timepoints, relative tumor volume measurements are achieved by the measurement tool in the ultrasound software.

With ~1.6 million victims per year, lung cancer contributes tremendously to the worldwide burden of cancer. Lung cancer is partly driven by genetic ...

Bioluminescent Orthotopic Model of Pancreatic Cancer Progression

Pancreatic cancer has an extremely poor five-year survival rate of 4-6%. New therapeutic options are critically needed and depend on improved understanding of pancreatic cancer biology. To better understand the interaction of cancer cells with the pancreatic microenvironment, we demonstrate an orthotopic model of pancreatic cancer that permits non-invasive monitoring of cancer progression. Luciferase-tagged pancreatic cancer cells are resuspended in Matrigel and delivered into the pancreatic tail during laparotomy. Matrigel solidifies at body temperature to prevent leakage of cancer cells during injection. Primary tumor growth and metastasis to distant organs are monitored following injection of the luciferase substrate luciferin, using in vivo imaging of bioluminescence emission from the cancer cells. In vivo imaging also may be used to track primary tumor recurrence after resection. This orthotopic model is suited to both syngeneic and xenograft models and may be used in pre-clinical trials to investigate the impact of novel anti-cancer therapeutics on the growth of the primary pancreatic tumor and metastasis.

Improved understanding of pancreatic cancer biology is critically needed to enable the development of better therapeutic options to treat pancreatic cancer. To address this need, we demonstrate an orthotopic model of pancreatic cancer that permits non-invasive monitoring of cancer progression using in vivo bioluminescence imaging.

Pancreatic cancer has an extremely poor five-year survival rate of 4-6%.  New therapeutic options are critically needed and depend on improved ...

Medicine

Analysis of Lymph Node Volume by Ultra-High-Frequency Ultrasound Imaging in the Braf/Pten Genetically Engineered Mouse Model of Melanoma

Tyr::CreER+,BrafCA/+,Ptenlox/lox&#160;genetically engineered mice (Braf/Pten mice) are widely used as an in vivo model of metastatic melanoma. Once a primary tumor has been induced by tamoxifen treatment, an increase in metastatic burden is observed within 4-6 weeks after induction. This paper shows how Ultra-High-Frequency UltraSound (UHFUS) imaging can be exploited to monitor the increase in metastatic involvement of the inguinal lymph nodes by measuring the increase in their volume.
The UHFUS system is used to scan anesthetized mice with a UHFUS linear probe (22-55 MHz, axial resolution 40 &#181;m). B-mode images from the inguinal lymph nodes (both left and right sides) are acquired in a short-axis view, positioning the animals in dorsal recumbency. Ultrasound records are acquired using a 44 &#181;m step size on a motorized mechanical arm. Afterward, two-dimensional (2D) B-mode acquisitions are imported into the software platform for ultrasound image post-processing, and inguinal lymph nodes are identified and segmented semi-automatically in the acquired cross-sectional 2D images. Finally, a total reconstruction of the three-dimensional (3D) volume is automatically obtained along with the rendering of the lymph node volume, which is also expressed as an absolute measurement.
This non-invasive in vivo technique is very well tolerated and allows the scheduling of multiple imaging sessions on the same experimental animal over 2 weeks. It is, therefore, ideal to assess the impact of pharmacological treatment on metastatic disease.

Melanoma is a very aggressive disease that quickly spreads to other organs. This protocol describes the application of ultra-high-frequency ultrasound imaging, coupled with 3D rendering, to monitor the volume of the inguinal lymph nodes in the Braf/Pten mouse model of metastatic melanoma.

Tyr::CreER+,BrafCA/+,Ptenlox/lox&#160;genetically engineered mice (Braf/Pten mice) are widely used as an in vivo model of metastatic melanoma. Once a ...

Generation of an Orthotopic Xenograft of Pancreatic Cancer Cells by Ultrasound-Guided Injection

Pancreatic cancer (PCa) represents one of the deadliest cancer types worldwide. The reasons for PCa malignancy mainly rely on its intrinsic malignant behavior and high resistance to therapeutic treatments. Indeed, despite many efforts, both standard chemotherapy and innovative target therapies have substantially failed when moved from preclinical evaluation to the clinical setting. In this scenario, the development of preclinical mouse models better mimicking in vivo characteristics of PCa is urgently needed to test newly developed drugs. The present protocol describes a method to generate a mouse model of PCa, represented by an orthotopic xenograft obtained by ultrasound-guided injection of human pancreatic tumor cells. Using such a reliable and minimally invasive protocol, we also provide evidence of in vivo engraftment and development of tumor masses, which can be monitored by ultrasound (US) imaging. A noteworthy aspect of the PCa model described here is the slow development of the tumor masses over time, which allows precise identification of the starting point for pharmacological treatments and better monitoring of the effects of therapeutic interventions. Moreover, the technique described here is an example of implementation of the 3Rs principles since it minimizes pain and suffering and directly improves the welfare of animals in research.

We present a protocol to generate a minimally invasive orthotopic pancreatic cancer model by ultrasound-guided injection of human pancreatic cancer cells and the subsequent monitoring of tumor growth in vivo by ultrasound imaging.

Pancreatic cancer (PCa) represents one of the deadliest cancer types worldwide. The reasons for PCa malignancy mainly rely on its intrinsic malignant ...

High-Resolution Ultrasonography for the Analysis of Orthotopic ATC Tumors in a Genetically Engineered Mouse Model

Anaplastic thyroid carcinoma (ATC) is associated with a poor prognosis and short median survival time, but no effective treatment improves the outcomes significantly. Genetically engineered murine models that mimic ATC&#39;s progression may help researchers to study treatments for this disease. Crossing three different genotypes of mice, a TPO-cre/ERT2; BrafCA/wt; Trp53&#916;ex2-10/&#916;ex2-10&#160;transgenic ATC model was developed. The ATC murine model was induced by an intraperitoneal injection of tamoxifen with overexpression of BrafV600E and deletion of Trp53, and the tumors were generated within about 1 month. High-resolution ultrasound was applied to investigate the tumor initiation and progression, and the dynamic growth curve was obtained by measuring the tumor sizes. Compared to magnetic resonance imaging (MRI) and computed tomography scanning, ultrasound has advantages in observing the ATC murine model, such as being noninvasive, portable, in real-time, and without radiation exposure. High-resolution ultrasound is suitable for dynamic and multiple measurements. However, ultrasonographic examination of the thyroid in mice requires relevant anatomical knowledge and experience. This article provides a detailed procedure for utilizing high-resolution ultrasound to scan tumors in the transgenic ATC model. Meanwhile, ultrasonic parameter adjustment, ultrasound scanning skills, anesthesia and recovery of the animals, and other elements that need attention during the process are listed.

The present protocol describes high-frequency ultrasonography for visualizing the entire mouse thyroid gland and monitoring the growth of anaplastic thyroid carcinoma.

Anaplastic thyroid carcinoma (ATC) is associated with a poor prognosis and short median survival time, but no effective treatment improves the outcomes ...

Murine Pancreatic Imaging Using Implanted Stabilized Window

Stabilized Window for Intravital Imaging of the Murine Pancreas

The physiology and pathophysiology of the pancreas are complex. Diseases of the pancreas, such as pancreatitis and pancreatic adenocarcinoma (PDAC) have high morbidity and mortality. Intravital imaging (IVI) is a powerful technique enabling the high-resolution imaging of tissues in both healthy and diseased states, allowing for real-time observation of cell dynamics. IVI of the murine pancreas presents significant challenges due to the deep visceral and compliant nature of the organ, which make it highly prone to damage and motion artifacts. 
Described here is the process of implantation of the Stabilized Window for Intravital imaging of the murine Pancreas (SWIP). The SWIP allows IVI of the murine pancreas in normal healthy states, during the transformation from the healthy pancreas to acute pancreatitis induced by cerulein, and in malignant states such as pancreatic tumors. In conjunction with genetically labeled cells or the administration of fluorescent dyes, the SWIP enables the measurement of single-cell and subcellular dynamics (including single-cell and collective migration) as well as serial imaging of the same region of interest over multiple days. 
The ability to capture tumor cell migration is of particular importance as the primary cause of cancer-related mortality in PDAC is the overwhelming metastatic burden. Understanding the physiological dynamics of metastasis in PDAC is a critical unmet need and crucial for improving patient prognosis. Overall, the SWIP provides improved imaging stability and expands the application of IVI in the healthy pancreas and malignant pancreas diseases.

Author Spotlight: Revolutionizing Pancreatic Disease Understanding Through Advanced Intravital Imaging 

We present a protocol for the surgical implantation of a stabilized indwelling optical window for subcellular-resolution imaging of the murine pancreas, allowing serial and longitudinal studies of the healthy and diseased pancreas.

The physiology and pathophysiology of the pancreas are complex. Diseases of the pancreas, such as pancreatitis and pancreatic adenocarcinoma (PDAC) have ...

Dynamic Contrast Enhanced Magnetic Resonance Imaging of an Orthotopic Pancreatic Cancer Mouse Model

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) has been limitedly used for orthotopic pancreatic tumor xenografts due to severe respiratory motion artifact in the abdominal area. Orthotopic tumor models offer advantages over subcutaneous ones, because those can reflect the primary tumor microenvironment affecting blood supply, neovascularization, and tumor cell invasion. We have recently established a protocol of DCE-MRI of orthotopic pancreatic tumor xenografts in mouse models by securing tumors with an orthogonally bent plastic board to prevent motion transfer from the chest region during imaging. The pressure by this board was localized on the abdominal area, and has not resulted in respiratory difficulty of the animals. This article demonstrates the detailed procedure of orthotopic pancreatic tumor modeling using small animals and DCE-MRI of the tumor xenografts. Quantification method of pharmacokinetic parameters in DCE-MRI is also introduced. The procedure described in this article will assist investigators to apply DCE-MRI for orthotopic gastrointestinal cancer mouse models.

The goal of this protocol is to apply dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for orthotopic pancreatic tumor xenografts in mice. DCE-MRI is a non-invasive method to analyze microvasculature in a target tissue, and useful to assess vascular response in a tumor following a novel therapy.

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) has been limitedly used for orthotopic pancreatic tumor xenografts due to severe ...

Bioluminescent Orthotopic Pancreatic Cancer Mouse Model: A Non-invasive Technique to Monitor Cancer Progression in Mice

Source: Chai, M. G., et al. <a href="https://www.jove.com/v/50395/" target="_blank">Bioluminescent Orthotopic Model of Pancreatic Cancer Progression</a>.&#160;J. Vis. Exp.&#160;(2013).
This video demonstrates an orthotopic model of pancreatic cancer that utilizes Matrigel for localized cell delivery and&#160;in vivo&#160;bioluminescence imaging for non-invasive monitoring of tumor progression. The orthotopic model is suited to both syngeneic and xenograft models and could be used in pre-clinical trials to investigate the impact of novel anti-cancer therapeutics on the growth of the primary pancreatic tumor and metastasis.

Bioluminescencyjny ortotopowy model myszy raka trzustki: nieinwazyjna technika monitorowania progresji raka u myszy

Source: Chai, M. G., et al. Bioluminescent Orthotopic Model of Pancreatic Cancer Progression.&#160;J. Vis. Exp.&#160;(2013).
This video demonstrates an ...