Graph analysis of cell clusters forming vascular networks

This manuscript describes the experimental observation of vasculogenesis in chick embryos by means of network analysis. The formation of the vascular network was observed in the area opaca of embryos from 40 to 55 hours of development. On area opaca endothelial cell clusters self-organize as a primitive and approximately regular network of capillaries. The process was observed by bright-field microscopy in control embryos and in embryos treated with Bevacizumab (Avastin), an antibody that inhibits the signalization of the vascular endothelial growth factor VEGF. The sequence of images of the vascular growth were thresholded, and used to quantify the forming network on control and Avastin-treated embryos. This characterization is made by measuring vessels density, number of cell clusters, and the largest cluster density. From the original images the topology of the vascular network was extracted and characterized by means of the usual network metrics such as: the degree distribution, ave...