Functional lymphatic imaging in tumor-bearing mice

The lymphatic system provides a route for dissemination of metastatic cancer cells. Yet to date transient changes in lymphatic drainage pathways and function as a result of tumor growth and metastasis have not been completely elucidated. Herein, we non-invasively imaged functional and architectural lymphatic changes in mice with regional, palpable lymph node (LN) involvement using dynamic near-infrared (NIR) fluorescence imaging with intradermal injection of indocyanine green (ICG) to both tumor-free mice and mice bearing C6/LacZ rat glioma tumors in the tail or hindlimb. We found that lymphatic drainage pathways were transiently altered and the contractile function of regional conducting lymphatic vessels was reduced or lost with progressive disease. Therefore, transient changes in the regional lymphatic architecture and function that occur with progressive disease, can be imaged using NIR fluorescence, and may provide a new method to stage disease.