Antibodies to beta 1-integrins cause alterations of aortic vasculogenesis, in vivo.

Vasculogenesis is the de novo formation of blood vessels from mesoderm. This process occurs very early in development and provides a convenient system for studying morphogenesis in higher vertebrates. The cell-extracellular matrix (ECM) interactions that occur during dorsal aortic vasculogenesis were examined using the monoclonal antibody, CSAT, a reagent known to neutralize the ligand-binding activity of avian beta 1-integrins. We injected CSAT into quail embryos during a period of active vasculogenesis (4-10 somites). The CSAT antibodies, but not controls, had a marked and reproducible effect on aortic vessel formation. Vasculogenesis appeared to be arrested at the stage when slender cord-like assemblies of angioblasts rearrange to form tubules. Indeed, aortic primordia near the site of CSAT injection did not form patent vessels.