Cancer cell vascular invasion and extravasation at metastatic sites are hallmarks of malignant progression of cancer and associated with poor disease outcome. Here we describe an in vivo approach to study the invasive ability of cancer cells into the vasculature and their hematogenous metastatic seeding in zebrafish (Danio rerio). In one approach, extravasation of fluorescently labeled cancer cells is monitored in zebrafish embryos whose vasculature is marked by a contrasting fluorescent reporter. After injection into the precardiac sinus of 2-day-old embryos, cancer cells can extravasate from the vasculature into tissues over the next few days. Extravasated cancer cells are identified and counted in live embryos via fluorescence microscopy. In a second approach, intravasation of cancer cells can be evaluated by changing their injection site to the yolk sac of zebrafish embryos. In addition to monitoring the impact of drivers of malignant progression, candidate inhibitors can be studied in this in vivo model system for their efficacy as well as their toxicity for the host.
Keywords: Cancer; Embryo; Extravasation; Fluorescence; Metastasis; Vascular Invasion; Zebrafish.