Mesh-loosening quantification of inhibition of angiogenic tube formation through image analysis

Angiogenesis is a key step in tumor development, and anti-angiogenesis processes are important for drug discovery and development. The dose-response relationship for an inhibitor is studied using images of endothelial cells captured in vitro by Matrigel assay. In order to improve the quantification of anti-angiogenic processes for faithful synchronization with continuous variation of an inhibitor dose, we have developed an automated image analysis method-mesh-loosening analysis-to evaluate the disruption of tube formation from endothelial cells. The method is based on numerical and morphological changes of mesh regions surrounded by tubes and perceived by considering the spaces between the tubes rather than the tubes themselves. The anti-angiogenic effect of suramin is analyzed comprehensively using four attributes obtained from the mesh regions. The relation between the dose of suramin and response shows an exponential curve that can be approximated as a sigmoid function, even though human assessments yield strong inhibition at moderate doses. The calculated half-minimal inhibitory concentration was in agreement with prior published reports. The results show that mesh-loosening analysis is useful and appropriate for screening applications that need precise and comprehensive quantification of the anti-angiogenic process to compensate for the inadequacy of human assessment. Feasibility study with shikonin shows the robustness of the mesh-loosening analysis.