Vascular Network Formation in Expanding versus Static Tissues: Embryos and Tumors.

In this perspectives article, we review scientific literature regarding de novo formation of vascular networks within tissues undergoing a significant degree of motion. Next, we contrast dynamic pattern formation in embryos to the vascularization of relatively static tissues, such as the retina. We argue that formation of primary polygonal vascular networks is an emergent process, which is regulated by biophysical mechanisms. Dynamic empirical data, derived from quail embryos, show that vascular beds readily form within a moving extracellular matrix (ECM) microenvironment-which we analogize to the de novo vascularization of small rapidly growing tumors. Our perspective is that the biophysical rules, which govern cell motion during vasculogenesis, may hold important clues to understanding how the first vessels form in certain malignancies.