Implantation and Monitoring by PET/CT of an Orthotopic Model of Human Pleural Mesothelioma in Athymic Mice

Summary

This article describes the generation of an orthotopic mouse model of human pleural mesothelioma by implantation of H2052/484 mesothelioma cells into the pleural cavity of immunocompromised athymic mice. The longitudinal monitoring of the development of intrapleural tumors was assessed by non-invasive multimodal [¹⁸F]-2-fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography imaging.

Abstract

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor arising in the mesothelium that covers the lungs, the heart, and the thoracic cavity. MPM development is mainly associated with asbestos. Treatments provide only modest survival since the median survival average is 9–18 months from the time of diagnosis. Therefore, more effective treatments must be identified. Most data describing new therapeutic targets were obtained from in vitro experiments and need to be validated in reliable in vivo preclinical models. This article describes one such reliable MPM orthotopic model obtained after injection of a human MPM cell line H2052/484 into the pleural cavity of immunodeficient athymic mice. Transplantation in the orthotopic site allows studying the progression of tumor in the natural in vivo environment. Positron emission tomography/computed tomography (PET/CT) molecular imaging using the clinical [¹⁸F]-2-fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) radiotracer is the diagnosis method of choice for examining patients with MPM. Accordingly, [¹⁸F]FDG-PET/CT was used to longitudinally monitor the disease progression of the H2052/484 orthotopic model. This technique has a high 3R potential (Reduce the number of animals, Refine to lessen pain and discomfort, and Replace animal experimentation with alternatives) since the tumor development can be monitored non-invasively and the number of animals required could be significantly reduced.

This model displays a high development rate, a rapid tumor growth, is cost-efficient and allows for rapid clinical translation. By using this orthotopic xenograft MPM model, researchers can assess biological responses of a reliable MPM model following therapeutic interventions.

Introduction

Malignant pleural mesothelioma (MPM) is a cancer most often associated with the exposure to asbestos fibers^1,2,3. Although asbestos has been banned in most Western countries^4,5,6, the incidence of MPM is still increasing^7,8. Recently, exposure of mice to carbon nanotubes suggests that they may result in significant health risk in humans^9,10. The data suggest that expo....

Protocol

All the procedures described below were approved by the institutional animal care and use committee and by the veterinarian state office of Geneva, Switzerland (Authorization GE/106/16). The MPM cell line H2052/484 was established and characterized in our laboratory as detailed in the article of Colin DJ and et al.²³. Briefly, H2052/484 cell line was established from a thoracic tumor obtained after an intrapleural injection of NCI-H2052 (ATCC) cells into immunodeficient Nude mice.

1. Experimental Design

1. Determine how many mice are needed according to the experiment using statistical power calculation (e.g....

Results

The H2052/484 orthotopic model
Orthotopic MPM models by intra-thoracic injection of cultured cancer cells, especially H2052/484 cells are relatively easy to setup. The different steps described above only require modest cell culture knowledge and the surgery steps are accessible to moderately trained animal experimenters. Nude mice and cells should be manipulated under sterile conditions to maximize the outcome of the implantations. By carefully following this protocol, which involves short anesthe.......

Discussion

This paper describes an original orthotopic model of MPM H2052/484 cells injected in the pleural cavity of athymic mice and a method of monitoring by small animal PET/CT imaging. This model can be implemented with moderate animal handling and surgery skills and displays a very good development rate. It allows a large experimental window of about 10 weeks in untreated mice and non-invasive longitudinal detection of tumors as early as 2 weeks after injection.

Orthotopic models rely on the implan.......

Materials

Name	Company	Catalog Number	Comments
3-mice bed	Minerve		bed for mice imaging
Athymic Nude-Foxn1n nu/nu	Envigo, Huntingdon, UK	6907F	immunodeficient mouse
Betadine	Mundipharma Medical Company, CH	111131	polyvidone iodine solution
Dulbecco's Phosphate-Buffered Saline (DPBS)	ThermoFisher Scientific, Waltham, MA, USA	14190094	Buffer for cell culture
Fetal bovine serum (FBS)	PAA Laboratories, Pasching, Austria	A15-101	cell culture medium supplement
Insulin syringes	BD Biosciences, San Jose, CA, USA	324826	syringe for cell injection
Penicillin/Streptomycin	ThermoFisher Scientific, Waltham, MA, USA	15140122	antibiotics for cell culture medium
RPMI 1640	ThermoFisher Scientific, Waltham, MA, USA	61870010	basal cell culture medium
Temgesic (Buprenorphin 0.3 mg/mL)	Alloga SA, CH	700320	opioid analgesic product
Triumph PET/SPECT/CT	Trifoil, Chatsworth, CA, USA		imaging equipment
Trypsin	ThermoFisher Scientific, Waltham, MA, USA	25050014	enzymatic cell dissociation buffer
Virkon S 2%	Milian, Vernier, CH	972472	disinfectant
Vivoquant	Invicro, Boston, MA, USA