A new image analysis method based on topological and fractal parameters to evaluate the angiostatic activity of docetaxel by using the Matrigel assay in vitro.

Angiogenesis is regulated both by positive and negative factors that modulate the migration, proliferation, proteolytic activity, and differentiation of endothelial cells. Various in vivo and in vitro models have been developed to test the effect of angiogenic agonists or antagonists. Until very recently, morphometric methods to evaluate the effects of angiogenic inducers and inhibitors were mostly descriptive. Here, we have described a new, automatic, image analysis method to evaluate the angiostatic activity of docetaxel by using the in vitro Matrigel assay. This method allows to establish several parameters, such as dimensional (area % covered by endothelial cells and the total length of the cellular network per field), topological (the number of meshes and the number of branching points per field), and fractal (fractal dimension, lacunarity) of the capillary-like network. Following docetaxel treatment, a reduction of about 25% in the size parameters of cell network, of about 45% in branching points per field, and more 50% in mesh number were observed. The resulting fractal analysis was consistent with these findings and fractal dimension significantly correlated with both the number of branching points and the number of meshes. These results indicate that both topological and fractal parameters allowed a characterization of the spatial texture generated by endothelial cells during in vitro angiogenesis, the former being easier to implement in a computer program and faster to calculate. Finally, topological parameters seem to exhibit a wider dynamic range than the fractal ones.