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Updated: Feb 22, 2026
Ortho- and Ectopic Zebrafish Xeno-Engraftment of Ocular Melanoma to Recapitulate Primary Tumor and Experimental Metastasis Development
Published on: September 4, 2021
Intravital imaging of metastasis in adult Zebrafish
David C Benjamin1,2,3, Richard O Hynes4,5,6
1Department of Biology, Massachusetts Institute of Technology, 31 Ames Street, Cambridge, MA, 02139, USA.
Background:
Metastasis is a major clinical problem whose biology is not yet fully understood. This lack of understanding is especially true for the events at the metastatic site, which include arrest, extravasation, and growth into macrometastases. Intravital imaging is a powerful technique that has shown great promise in increasing our understanding of these events. To date, most intravital imaging studies have been performed in mice, which has limited its adoption. Zebrafish are also a common system for the intravital imaging of metastasis. However, as imaging in embryos is technically simpler, relatively few studies have used adult zebrafish to study metastasis and none have followed individual cells at the metastatic site over time. The aim of this study was to demonstrate that adult casper zebrafish offer a convenient model system for performing intravital imaging of the metastatic site over time with single-cell resolution.
Methods:
ZMEL1 zebrafish melanoma cells were injected into 6 to 10-week-old casper fish using an intravenous injection protocol. Because casper fish are transparent even as adults, they could be imaged without surgical intervention. Individual cells were followed over the course of 2 weeks as they arrested, extravasated, and formed macroscopic metastases.
Results:
Our injection method reliably delivered cells into circulation and led to the formation of tumors in multiple organs. Cells in the skin and sub-dermal muscle could be imaged at high resolution over 2 weeks using confocal microscopy. Arrest was visualized and determined to be primarily due to size restriction. Following arrest, extravasation was seen to occur between 1 and 6 days post-injection. Once outside of the vasculature, cells were observed migrating as well as forming protrusions.
Conclusions:
Casper fish are a useful model for studying the events at the metastatic site using intravital imaging. The protocols described in this study are relatively simple. Combined with the reasonably low cost of zebrafish, they offer to increase access to intravital imaging.
Insights
Adult casper zebrafish provide a novel model for intravital imaging of metastasis. This study demonstrates their utility for observing single cancer cells at metastatic sites over time.
Area of Science:
- Oncology
- Cell Biology
- Zebrafish Models
Background:
- Metastasis remains a significant clinical challenge due to incomplete biological understanding.
- Intravital imaging offers insights into metastatic processes like arrest, extravasation, and growth.
- Current intravital imaging predominantly uses mice, limiting broader application.
Purpose of the Study:
- To establish adult casper zebrafish as a model for intravital imaging of metastasis.
- To enable long-term, single-cell resolution tracking of metastatic events in vivo.
- To overcome limitations of existing models and enhance accessibility of intravital imaging.
Main Methods:
- Intravenous injection of ZMEL1 zebrafish melanoma cells into adult casper fish.
- Utilizing the natural transparency of adult casper fish for non-invasive imaging.
- Confocal microscopy to track individual cells over two weeks post-injection.
Main Results:
- Successful tumor formation in multiple organs following cell injection.
- High-resolution imaging of cells in skin and muscle over 14 days.
- Observed arrest primarily due to size, followed by extravasation within 1-6 days.
- Documented cell migration and protrusion formation post-extravasation.
Conclusions:
- Adult casper zebrafish are a viable model for intravital imaging of metastatic processes.
- The established protocols are straightforward and cost-effective.
- This model system has the potential to increase access to intravital imaging research.
