An In Vitro Assay to Assess Uveal Melanoma Invasion across Endothelial and Basement Membrane Barriers

To develop a modified in vitro invasion assay to assess uveal melanoma invasion across endothelial and basement membrane barriers. Using permeable cell culture supports, endothelial cells were grown to confluence on an 8-microM pore polycarbonate membrane precoated with an artificial basement membrane. Primary uveal melanomas were grown as short-term cultures at 37 degrees C and 5% CO2 and invaded through the endothelial cell layer and basement membrane. Invading cells were counted under x400 magnification on the lower surface of the membrane. Levels of invasion were correlated with histopathologic markers of prognosis. The relative invasion of individual tumors was established by comparison of invasion through both endothelial and basement membrane barriers with invasion through basement membrane components alone. A series of 13 primary tumors were studied using the modified invasion assay. Tumors varied in their propensity to permeate both barriers. In all cases the endothelial cell layer reduced invasion, but the effect varied between tumors. Some tumors were more adept at overcoming the additional endothelial cell layer, whereas invasion of others was severely inhibited. Tumor invasion through the transendothelial model was found to correlate more closely with clinical characteristics associated with invasion, than was invasion through basement membrane components alone. The transendothelial model may represent a more realistic model for the in vitro study of invasion of uveal melanoma cells, providing a useful in vitro system for the investigation of cellular interactions during the invasion process.