Purpose:
Uveal melanoma is the most common primary intraocular tumor in adults, which metastasizes predominantly to the liver and usually results in death within a year. Due to the lack of a lymphatic system, uveal melanoma cells can only exit the eye through the bloodstream effectively reducing the number of variables involved in the metastatic cascade. The objective of this study was to establish an animal model for liver metastasis utilizing fluorescent–labeled human uveal melanoma cells injected into the bloodstream of nude mice.
Methods:
The human uveal melanoma cell line 92.1 was transfected with Green Fluorescent Protein (GFP) and infused with a transient fluorescent marker. Three nude mice were sedated and 5 x 105 fluorescently labeled uveal melanoma cells were injected into the tail vein. Following injection, a skin flap was made in the abdomen of the mice to allow for imaging using an inverted epifluorescence microscope. The mice were sacrificed and all organs were harvested for histopathological examination.
Results:
Immediately following injection, fluorescing cells were visible in vivo. The cells were visualized in the liver parenchyma and sinusoids of each mouse. In the first five minutes, small clusters of cells and isolated individual melanoma cells were detected. Between five and ten minutes, increased numbers of melanoma cells were detected in both the liver parenchyma and sinusoids. At 15 minutes, a further increase in the number of melanoma cells were noted in the liver parenchyma. The signal to noise ratio was low, allowing for clear distinction between the human uveal melanoma cells and liver tissue. An example of the fluorescent human uveal melanoma cells detected in the mouse liver can be seen in Fig. 1.
Conclusions:
This study demonstrates the feasibility of visualizing tail–vein injected, fluorescent–labeled human uveal melanoma cells in nude mice. These positive results have initiated the establishment of a haematogenous dissemination model of metastasis in nude mice. This information will allow us to develop a time line of metastatic growth in order to test any future systemic treatments.
Keywords: melanoma • microscopy: light/fluorescence/immunohistochemistry • pathology: experimental