In Vivo Imaging and Quantitation of the Host Angiogenic Response in Zebrafish Tumor Xenografts

Summary

The aim of this method is to generate an in vivo model of tumor angiogenesis by xenografting mammalian tumor cells into a zebrafish embryo that has fluorescently-labelled blood vessels. By imaging the xenograft and associated vessels, a quantitative measurement of the angiogenic response can be obtained.

Abstract

Tumor angiogenesis is a key target of anti-cancer therapy and this method has been developed to provide a new model to study this process in vivo. A zebrafish xenograft is created by implanting mammalian tumor cells into the perivitelline space of two days-post-fertilization zebrafish embryos, followed by measuring the extent of the angiogenic response observed at an experimental endpoint up to two days post-implantation. The key advantage to this method is the ability to accurately quantitate the zebrafish host angiogenic response to the graft. This enables detailed examination of the molecular mechanisms as well as the host vs tumor contribution to the angiogenic response. The xenografted embryos can be subjected to a variety of treatments, such as incubation with potential anti-angiogenesis drugs, in order to investigate strategies to inhibit tumor angiogenesis. The angiogenic response can also be live-imaged in order to examine more dynamic cellular processes. The relatively undemanding experimental technique, cheap maintenance costs of zebrafish and short experimental timeline make this model especially useful for the development of strategies to manipulate tumor angiogenesis.

Introduction

Angiogenesis is one of the classic hallmarks of cancer and represents a target of anti-cancer therapy^1,2. To study this process, xenograft models of cancer have been created by implanting mammalian tumor cells into animals such as mice³. A zebrafish xenograft model has also been developed, which involves the implantation of tumor cells into 2 days post fertilization (dpi) zebrafish which results in rapid growth of zebrafish blood vessels into the xenograft⁴.

This protocol describes an in vivo zebrafish embryo tumor xenograft model in w....

Protocol

1. Preparation of Microinjection Needles

1. Turn on a micropipette puller and set the following parameters (calibrated for the micropipette puller model listed in Table of Materials): Heat, 680; Pull, 75; Velocity, 40; Time, 55; Pressure: 530.
2. Secure a borosilicate glass capillary into the micropipette puller and pull the capillary to make two needles. Repeat for as many needles as desired.

2. Cell Culture for Implantation

Discussion

The first critical step in the protocol is the implantation of tumor cells. It is essential that cells are injected into a location that will allow the xenograft to implant successfully in the embryo without making the embryo edematous. An injection that is too anterior can allow the cells to move towards the heart, blocking the bloodstream and leading to edema, while an injection that is too posterior will result in a poorly implanted xenograft. An anterior injection is best avoided by inserting the needle through the y.......

Materials

Name	Company	Catalog Number	Comments
Air cylinder	BOC	011G	Xenotransplantation
B16-F1 cells	ATCC		Cell culture
BD Matrigel LDEV-free (extracellular matrix mixture)	Corning	356235	Xenotransplantation
Borosillicate glass capillaries	Warner Instruments	G100T-4	OD=1.00 mm, ID=0.78 mm, Length =10 cm Cell injection
Cell culture dish -35 mm diameter	Thermofisher NZ	NUN153066	Fish husbandry
Cell culture dish -100 mm diameter	Sigma-Aldrich	CLS430167-500EA	Fish husbandry
Cell culture flask 75 cm2	In Vitro Technologies	COR430641	Cell culture
CellTracker Green	Invitrogen	C2925	Cell labelling, Stock concentration (10 mM in DMSO), working concentration (0.2 μM in serum-free media)
Dimethyl sulfoxide	Sigma-Aldrich	D8418	Drug treatment, Cell labelling
E3 Media (60x in 2 L of water) 34.8 g NaCl 1.6 g KCl 5.8 g CaCl2·2H2O 9.78 g MgCl2·6H2O adjust to pH 7.2 with NaOH	In house [1]		Fish husbandry
Ethyl-3-aminobenzoate methanesulfonate (Tricaine)	Sigma-Aldrich	E10521	Xenotransplantation, Imaging
Filter tip 1000 μL	VWR	732-1491	Used during multiple steps
Filter tip 200 μL	VWR	732-1489	Used during multiple steps
Filter tip 10 μL	VWR	732-1487	Used during multiple steps
Fluorescence microscope	Leica	MZ16FA	Preparation of embryos
FBS (NZ origin)	Thermofisher Scientific	10091148	Cell culture
Gloves	Any commercial brand		Used during multiple steps
Haemocytometer cell counting chamber Improved Neubauer	HawksleyVet	AC1000	Xenotransplantation
Heraeus Multifuge X3R Centrifuge	Thermofisher Scientific	75004500	Cell culture, Cell labelling
Hoechst 33342	Thermofisher Scientific	62249	Cell labelling, Stock concentration (1 mg/ml in DMSO), working concentration (6 μg/ml in serum-free media)
Low Melting Point, UltraPure Agarose	Thermofisher Scientific	16520050	Imaging
Methycellulose	Sigma-Aldrich	9004 67 5	Xenotransplantation
Methylene blue	sigma-Aldrich	M9140	Fish husbandry
Microloader 0.5-20 μL pipette tip for loading microcapillaries	Eppendorf	5242956003	Xenotransplantation
Micropipettes	Any commercial brand		Used during multiple steps
Micropipette puller P 87	Sutter Instruments		Xenotransplantation
Microscope cage incubator	Okolab		Time-lapse imaging
Microwave	Any commercial brand		Imaging
Mineral oil	Sigma-Aldrich	M3516	Xenotransplantation
Minimal Essential Media (MEM) - alpha	Thermofisher Scientfic	12561056	Cell Culture
MPPI-2 Pressure Injector	Applied Scientific Instrumentation		Xenotransplantation
Narishige micromanipulator	Narishige Group		Xenotransplantation
Nikon D Eclipse C1 Confocal Microscope	Nikon		Imaging
N-Phenylthiourea (PTU)	Sigma-Aldrich	P7629	Fish husbandry
PBS	Gibco	10010023	Cell culture
Penicillin Streptomycin	Life Technologies	15140122	Cell culture
S1 pipet filler	Thermoscientific	9501	Cell culture
Serological stripette 10 mL	Corning	4488	Cell culture
Serological stripette 25 mL	Corning	4489	Cell culture
Serological stripette 5 mL	Corning	4485	Cell culture
Serological stripette 2 mL	Corning	4486	Cell culture
Terumo Needle 22 gauge	Amtech	SH 182	Fish husbandry
Tissue culture incubator	Thermofisher Scientfic	HeraCell 150i	Cell culture
Tivozanib (AV951)	AVEO Pharmaceuticals		Drug treatment
Transfer pipette 3 mL	Mediray	RL200C	Fish husbandry
Trypsin/EDTA (0.25% )	Life Technologies	T4049	Cell culture
Tweezers	Fine Science Tools	11295-10	Fish husbandry
Volocity Software (v6.3)	Improvision/Perkin Elmer		Image analysis