Variant endothelial cells. Fibronectin as a transducer of signals for migration and neovascularisation.

A morphologic and growth control variant of bovine aortal endothelial cells has been isolated and shown to synthesise factor VIII antigen (McAuslan and Reilly '79). The variant also possesses the endothelial surface markers angiotensin converting enzyme and alpha 2-microglobulin. The normal cell synthesises fibronectin and deposits it underneath the cells; the variant also synthesises fibronectin. At least three times more fibronectin is distributed over the upper cell surface of variants. This correlates with the three-fold increased binding of the replication inhibitor Con A and suggests a role of fibronectin in endothelial cell growth control. When stimulated to migrate by CuII ions, the variant leaves deposits of fibronectin in its trail; in contrast, migrating normal cells do not, but they do redistribute their surface fibronectin. As revealed by scanning electron microscopy, variant cells are unusual in that they grow over or under cultured normal endothelial cells. It is proposed that during the process of neovascularisation, variant cells have a special function as lead cells that lay down fibronectin on which an endothelium can become established.