Dynamic Contrast Enhanced Magnetic Resonance Imaging of an Orthotopic Pancreatic Cancer Mouse Model
April 18th, 2015
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.
The overall goal of this procedure is to apply dynamic contrast enhanced magnetic resonance imaging or D-C-E-M-R-I to ORTHOTOPIC pancreatic tumor xenografts in mice. This is accomplished by first removing the pancreas from the abdomen and then slowly infusing human pancreatic cancer cells into the tail of the pancreas. The pancreas has then returned to the abdomen, and when the tumor is five to seven millimeters in diameter, a plastic board and a surface coil are placed on top of the tissue mass humas.
Ultimately, the microvascular of the tumor xenograft can be visualized by D-C-E-M-R-I. The main advantage of this technique over conventional method like D-C-M-R-I, of subcutaneous tumor xenograft, is that orthotopic pancreatic tumor models allows the assessment of primary tumor microenvironment, including neovascularization blood supply and tumor cell invasion. The procedure will be demonstrated by Sharon Samuel, research associated and Marie Warren, a research technician both from our lab.
Begin by placing an anesthetized eight week old female skid valve sea mouse on a heating pad after confirming the appropriate level of sedation by toe pinch. Next, remove the hair from the left upper quadrant of the animal's abdomen and administer an analgesic drug into the skin using iris straight scissors. Make a one centimeter incision in the skin and peritoneum and gently lift the pancreas through the incision.
Then use a 0.5 milliliter insulin syringe, equipped with a 28 gauge needle to slowly infuse 2.5 million human pancreatic cancer cells in 30 microliters of DMEM into the tail of the pancreas. Confirm that a small bleb is created in the head of the pancreas by the solution. Then gently place the pancreas back into the abdomen and close the peritoneum in the skin in one layer with two interrupted five zero proline sutures.
Check the tumor size daily with two finger palpation of the surgical area. The tumors typically feel denser and bumpier than the surrounding tissues and organs. Monitor the animals daily for signs of illness as well.
When the tumor reaches five to seven millimeters into diameter, insert a sharp 30 gauge needle into one end of a micro polyethylene tube and a blunt 30 gauge needle tip into the other. Connect a one milliliter syringe containing freshly prepared MRI contrast agent to the blunt needle tip, and slowly depress the plunger to fill the entire tube. Then dilate the animal's tail veins under a heat lamp and use Kelly forceps to grab the shaft of the sharp 30 gauge needle.
Carefully insert the needle into one of the dilated tail veins and tape both the tail and the tube onto a piece of 10 by 100 millimeter plastic to keep the tail straight. Next, place the mouse supine in an animal bed equipped with circulating warm water to regulate the animal's body temperature during imaging. Insert a rectal temperature probe at this time as well.
When the animal is in position, apply an orthogonally bent plastic board into the abdominal area, making sure the tumor is located behind the upper end of the board, and then pull the board down about two millimeters to ensure that the tumor is caught firmly Tape the board to the animal bed. Then tape a respiration pad transducer onto the chest area to monitor the animal's respiration during imaging. Now place the surface coil on the top of the tumor region securely taping it to the animal bed.
Then push the animal bed into the MR scanner until the tumor region is at the center of the volume coil. Apply T two weighted MRI to locate the tumor, followed by T one weighted MRI with various flip angles for T one mapping. Then for the D-C-E-M-R-I imaging, apply T one weighted MRI with a fixed flip angle continuously before, during, and after injection of the gadolinium based MRI contrast.
Monitor the animal's breathing and body temperature continuously during the imaging at the end of the imaging, remove the needle and other probes and place the animal under a heat lamp while softly massaging the lower abdominal area. Until the animal wakes quantitative. D-C-E-M-R-I can be successfully applied for orthotopic pancreatic tumor xenografts.
Using the reference region model, for example, these contrast maps demonstrate the tumor region in color scale at one minute before injection of the MR.Contrast agent. And at five and 40 minutes after overlapped with T two weight MR images in gray scale. The mouse in this experiment bore an orthotopic human pancreatic tumor xenograft.
These contrast enhancement curves were averaged from the tumor region and the paravertebral muscle region. These kts and KEP maps for the tumor demonstrate the wash in and washout rate of the Mr.Contrast agent While attempting this TCMI procedure, it is important to make sure the tumor is located behind the of the upper end of the board.
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Overview
This protocol demonstrates the application of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for orthotopic pancreatic tumor xenografts in mice. DCE-MRI is a non-invasive imaging technique that allows for the analysis of microvasculature in tumors, providing insights into vascular responses following novel therapies.
Key Study Components
Area of Science
- Neuroscience
- Oncology
- Imaging Techniques
Background
- Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is used to visualize tumor microvasculature.
- Orthotopic models provide a more accurate representation of the tumor microenvironment compared to subcutaneous models.
- This technique allows for the assessment of neovascularization and tumor cell invasion.
- The study is conducted using human pancreatic cancer cells implanted in mice.
Purpose of Study
- To visualize the microvascular structure of pancreatic tumor xenografts.
- To assess the vascular response of tumors to novel therapies.
- To improve understanding of tumor biology in a more physiologically relevant model.
Methods Used
- Removal of the pancreas from the abdomen.
- Infusion of human pancreatic cancer cells into the tail of the pancreas.
- Placement of a plastic board and surface coil for imaging.
- Utilization of DCE-MRI to visualize the tumor microvasculature.
Main Results
- DCE-MRI successfully visualizes the microvascular structure of the tumor.
- Orthotopic models show enhanced neovascularization compared to subcutaneous models.
- The technique provides insights into tumor blood supply and invasion.
- Demonstrates the effectiveness of DCE-MRI in assessing tumor response to therapies.
Conclusions
- DCE-MRI is a valuable tool for studying pancreatic tumors in vivo.
- Orthotopic models are essential for understanding the tumor microenvironment.
- This method can aid in evaluating the efficacy of new cancer therapies.
Frequently Asked Questions
Executive Industry Relevance
This protocol enables non-invasive assessment of tumor microvasculature in orthotopic pancreatic cancer models, supporting target validation and mechanistic de-risking in oncology drug discovery. By quantifying pharmacokinetic parameters such as Ktrans and KEP, DCE-MRI provides predictive confidence in vascular response to therapies, informing go/no-go decisions in preclinical pipelines. The method addresses a key discovery-stage challenge: evaluating tumor microenvironment fidelity in vivo to improve translational continuity from target identification to lead optimization.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Interrogates therapeutic hypotheses by visualizing neovascularization and blood supply in physiologically relevant tumor microenvironment.
- Operational Value: Enables functional target validation through longitudinal monitoring of vascular changes post-treatment.
- Predictive Value: Supports portfolio triage by quantifying vascular normalization or regression as a pharmacodynamic biomarker.
Screening & Assay Development
- Assay Readiness: Prepares validated orthotopic models for downstream compound screening with standardized vascular readouts.
- Quantitative Output: Generates pharmacokinetic maps (Ktrans, KEP, ve) enabling dose-response and time-course analysis.
- Platform Reuse: Establishes a reproducible imaging workflow applicable to other gastrointestinal cancer models.
Translational & Preclinical Research
- Disease Relevance: Models primary tumor microenvironment affecting invasion and metastasis, enhancing translational biomarker alignment.
- Preclinical Continuity: Bridges discovery and preclinical validation by providing longitudinal vascular monitoring.
- Risk-Adjusted Decisions: Informs advancement criteria based on vascular response thresholds and reproducibility across cohorts.
Pipeline & Workflow Integration
DCE-MRI fits within the discovery continuum from target validation through lead identification to preclinical efficacy testing, providing quantitative vascular metrics that support mechanism-of-action confirmation and therapeutic index estimation.
- Discovery Biology: Supports hypothesis testing of angiogenesis-dependent targets and pathway modulation in orthotopic context.
- Screening: Delivers assay-ready models with reproducible, quantitative DCE-MRI outputs for compound evaluation.
- Analytics: Provides pharmacokinetic parameters (Ktrans, KEP, ve) that enable comparison of vascular phenotypes across treatment groups.
- Translational Research: Connects to preclinical validation via longitudinal monitoring of tumor vascular response, supporting biomarker qualification.
- Enterprise Reuse: Establishes a standardized, scalable imaging platform for oncology portfolio applications beyond pancreatic cancer.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in target validation by reducing mechanistic ambiguity in vascular response.
- Operational Value: Standardizes tumor imaging procedures, improving reproducibility and cross-site comparability.
- Strategic Value: Enhances capital efficiency by enabling early vascular response assessment, reducing late-stage failure risk.
- Portfolio Impact: Supports risk-adjusted prioritization through quantitative pharmacodynamic readouts tied to target engagement.
Implementation Considerations
- Requires expertise in small animal surgery, orthotopic implantation, and MRI operation.
- Depends on access to preclinical MRI systems with surface coils and contrast agent delivery infrastructure.
- Necessitates standardization of tumor size thresholds (5–7 mm) and immobilization techniques (orthogonal board) across studies.
- Involves adaptation considerations for other orthotopic gastrointestinal models based on anatomical accessibility.
- Limited by respiratory motion sensitivity, mitigated but not eliminated by external immobilization.
