[In vitro formation of endothelial cells into capillary-like cords is promoted by keratocytes]

When isolated bovine capillary endothelial cells were co-cultivated with rabbit corneal keratocytes, capillary-like cords extended actively from the capillary endothelial cells in multilayers of keratocytes. The developing cords continued to elongate, branch out and anastomose with each other, forming a capillary-like network by the 12th day of co-culturing. Electron microscopic observation revealed that the cords had tubular structures, which were composed of 3-8 endothelial cells in the multilayers of keratocytes, and that a basal-like matrix was situated on the outer surface of the endothelial cells. The roles of keratocytes in the cord formation by capillary endothelial cells were discussed. This simple in vitro experimental system is proposed as a useful tool in the study of corneal neovascularization.