Mobilization of capillary endothelium in vitro induced by effectors of angiogenesis in vivo.

An assay to measure endothelial cell mobilization on a gelatin substratum has been developed. Utilization of the gelatin-agarose and Boyden chamber assays established that: (a) fragments or extracts of corneas treated with several effectors of angiogenesis in vivo acquired the capacity to mobilize the capillary endothelium in vitro; (b) this mobilization was selective for the capillary endothelium; endothelium from aorta and fibroblasts from human skin or rabbit cornea were unresponsive; and (c) among the effectors of angiogenesis utilized alone; i.e., without the intermediary action of the cornea, none were able to mobilize the capillary endothelium in vitro, except for the heparin-copper complex. The data are interpreted to indicate that new formation of capillaries in vivo is the end result of a cascade of events of which heparin and copper are important components.