An Intravital Multiphoton Microscopy Model for visualization of tumor cell dissemination and lymphatic vasculature

Tumor metastasis and its impact on the organism are the main causes of death in patients with squamous cell carcinoma of the head and neck region. The presence of metastasis at the time of diagnosis represents a negative prognostic parameter of overall survival and correlates with a 50 % mean reduction of life expectancy, independent of tumor size. The potential for metastasis depends on factors such as the proliferation rate, neoangiogenesis and invasive capacity in intact tissue structures. Many aspects of the molecular mechanisms and supportive factors are not understood. To allow the investigation of such factors, we developed an intravital mouse model for the visualization of tumor cell proliferation, dissemination and lymphatic vasculature by multiphoton microscopy. This technology offers deep tissue penetration, low phototoxicity, superior image contrast, and four-dimensional resolution for investigations at the single cell level in a physiological setting. The human oral cancer cell line OSC-19 was transfected with turbo-red fluorescent protein and implanted in murine pinna. Lymphatic structures were labeled with a deep red-labeled antibody specific for lymphatic vessel endothelial receptor-1. In future research, this model might serve as a tool to gain deeper insights in surface molecules involved in lymphatic metastasis as well as other molecular mechanisms of metastasis and tumor cell