Stimulation of endothelial cell growth by sera from diabetic patients with retinopathy

An in-vitro proliferation assay has shown that sera from patients with diabetic retinopathy, particularly those with the proliferative form, are two to four times more effective than sera from non-diabetics at stimulating 3H-thymidine incorporation into both human umbilical vein and human omental microvascular endothelial cells, but not at stimulating incorporation into human dermal fibroblasts or 3T3 cells. The factor(s) is heat stable and of molecular weight greater than 15,000, and its presence is unrelated to metabolic control. It is not present in patients with other forms of diabetic vascular disease, which suggests that it is not related to carbohydrate or lipid metabolism. These results provide evidence against the hypothesis that metabolic disturbances are central to the development of diabetic microvascular disease, and raise possibilities of novel forms of therapeutic intervention.