Synthesis of factor VIII antigen by cultured human endothelial cells.

Endothelial cells have been isolated from freshly obtained human umbilical cords by collagenase digestion of the interior of the umbilical vein and grown in tissue culture. These cells have been identified by morphologic and immunologic criteria. It has been demonstrated that these cultured human endothelial cells synthesize and release factor VIII antigen but not factor VIII clot-promoting activity.