Angiogenic activity of vitreous and retinal extract.

An angiogenic activity was demonstrated in both vitreous and retina by two assay systems using rabbit corneal micropocket technique and aortic endothelial cell culture. With the former technique, the only demonstrable angiogenic activity was found in vitreous of dogs 8 days of age or younger, with or without oxygen treatment. However, with the assay using aortic endothelial cell culture, angiogenic activity was found in both vitreous and retina of all species surveyed, including bovine, dog, pig; lamb, and rabbit. The angiogenic activity varied from species to species. Vitreous, with or without dialysis, had a stimulatory effect on the growth of cultured endothelial cells. Aging, studied with bovines and dogs, caused a significant decrease in angiogenic activity in vitreous and a slight decrease in retina. Effect of hyperoxia on angiogenic activity was studied with dogs. Following oxygen treatment, when retinal neovascularization was at its peak, the angiogenic activity in vitreous decreased dramatically, with no significant change in retinal angiogenic activity. These findings suggest that angiogenic activity may normally be present in vitreous and retina and not, as previously suggested by others, that angiogenic factor is liberated primarily by ischemic retina. The angiogenic activity of normal lens and liver tissue is negligible, and. that of dog brain and fetal calf cornea is 17% and 25% of the activity of the respective retinal tissue. The origin of this angiogenic factor is not known. The possible relation of this factor to normal vasculaiization and abnormal neovascularization is discussed.