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

Summary

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.

Abstract

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.

Introduction

The overall goal of this method 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 assess microvasculature in a target tissue by monitoring the change of MR contrast over a certain period of time after injection. DCE-MRI has been utilized to diagnose malignant tumors and to assess tumor response to various therapies^1-4. Quantitative DCE-MRI has presented high reproducibility⁵. To quantitate pharmacokinetic parameters of an MR contrast agent in a target tissue, all DCE-MR images acquired at different time points and T1 map obtained befor....

Protocol

All procedures were approved by the Institutional Animal Care and Use Committee at the University of Alabama at Birmingham.

1. Orthotopic Pancreatic Tumor Mouse Modeling

1. Culture standard human pancreatic-cancer cell lines in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum. Maintain all cultures at 37 °C in humidified atmosphere with 5% CO₂.
2. Use 8-10 week-old female severe combined immunodeficient mice. Place animal cages at 12 hr light and 12 hr darkness cycle at RT (21 ± 2 °C) and 60% humidity.
3. Anesthetize all animals using ventilation with 2% of isoflurane mixed....

Results

Human pancreatic tumor cells grow successfully in mouse pancreas creating a solid tumor. Figure 1 shows photographs of (A) a normal pancreas where tumor cell solution is injected, and (B) a representative mouse bearing an orthotopic pancreatic tumor xenograft (MIA PaCa-2). Tumor is located in the left upper quadrant of abdomen, next to the spleen. It usually takes 2 - 4 weeks for the tumors to grow up to 5 - 7 mm in diameter after cell implantation.

Motion of orthotopic pancre.......

Discussion

We have introduced the detailed methods of orthotopic pancreatic tumor modeling using immunodeficient mice, DCE-MRI of abdominal tumors in mice, and quantification of its kinetic parameters. In orthotopic pancreatic tumor modeling, care must be taken when inserting a needle into the tail of pancreas. If successful, cells will be transferred to the head of pancreas creating a small bleb. When applying an orthogonally bent plastic board, it is critical to confirm that the tumor is located below the upper end of the board. .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
DMEM	Invitrogen	11965-118
Fetal bovine serum	Harlan Laboratories	BT-9501
Betadine	Purdue products	67618-153-01
5-0 Prolene sutures	Ethicon	8720H
9.4T MR scanner	Bruker Biospin Corporation	BioSpec 94/20 USR
Gadoteridol	Bracco Diagnostics Inc	NDC 0270-1111-03
Micro-polyethelene tube	Strategic Applications, Inc	#PE-10-25
30 G blunt tip needle	Strategic Applications, Inc	89134-194
Monitoring and gating system	SA instruments, Inc	Model 1030	This is an MR compatiable system to measure resiratory rating and body temperature of small animals at the same time.
Syringe pump	New Era Pump Systems, Inc.	NE-1600