Fluorescent LYVE-1 antibody to image dynamically lymphatic trafficking of cancer cells in vivo.

BACKGROUND: The lymphatic system is a major route for cancer cell dissemination, and a potential target for antitumor therapy. Despite ongoing interest in this area of research, the real-time behavior of cancer cells trafficking in the lymphatic system is poorly understood due to lack of appropriate tools to image this process. MATERIALS AND METHODS: We have used monoclonal-antibody and fluorescence technology to color-code lymphatic vessels and the cancer cells inside them in a living animal. Monoclonal anti-mouse LYVE-1 antibody was conjugated to a green fluorophore and delivered to the lymphatic system of a nude mouse, allowing imaging of mouse lymphatics. Tumor cells engineered to express red fluorescent protein were then imaged traveling within the labeled lymphatics in real time. RESULTS: AlexaFluor-labeled monoclonal anti-mouse LYVE-1 created a durable signal with clear delineation of lymphatic architecture. The duration of fluorescent signal after conjugated LYVE-1 delivery was far superior to that of fluorescein isothiocyanate-dextran or control fluorophore-conjugated IgG. Tumor cells engineered to express red fluorescent protein delivered to the inguinal lymph node enabled real-time tracking of tumor cell movement within the green fluorescent-labeled lymphatic vessels. CONCLUSIONS: This technology offers a powerful tool for the in vivo study of real-time trafficking of tumor cells within lymphatic vessels, for the deposition of the tumor cells in lymph nodes, as well as for screening of potential antitumor lymphatic therapies.