Multicellular sprouting during vasculogenesis

Abstract

Vasculogenesis, the de novo assembly of vessels from endothelial precursors, is a fundamental process common to both embryonic development and certain pathophysiologies. We studied vasculogenic sprouting, the multicellular patterning mechanisms of vasculogenesis, with time‐lapse microscopy in avian embryos, and in cultures of endothelial cells invading 3D collagen I gels. In quail embryos cell‐autonomous endothelial cell motility and tissue movements were distinguished based on a new method utilizing digitally filtered displacements of immuno‐labeled extracellular matrix components fibrillin and fibronectin. Recently developed TIE1‐GFP transgenic quail lines enabled us to investigate the motility of endothelial cells inside the forming vessels. We correlate the degree of in situ cell‐autonomous motility with the level of TAL1 expression, the morphology of the surrounding vessel network and the structure of the extracellular matrix environment.