Reduced levels of prostaglandin I2 (PGI2) may contribute to the platelet hyper-reactivity and vascular complications found in diabetes mellitus. This study compared PGI2 production (PGI2-like activity and 6-keto-PGF1α levels) by vascular endothelial cells cultured in the presence of serum from 15 diabetics with proliferative retinopathy (5 treated by surgical hypophysectomy) and 15 sex-matched nondiabetic controls. Endothelial cells from human umbilical veins were cultured in M199 with either 20 % diabetic or control serum. At confluence, cultures were washed and stimulated with 0.1 NIH u/ml bovine thrombin. After 2 min incubation, the supernatant was tested for i)PGI2-like activity on ADP- induced platelet aggregation, results expressed as % inhibition and ii) 6-keto-PGF1α by radioimmunoassay, results expressed as nmol/ml. There was a significant correlation between PGI2-like activity and 6-keto-PGF-1α levels (r 0.78, p<0.001). The liberation of PGI2 from endothelial cells from different umbilical cords varied, but both PGI2-like activity (mean± SEM 21.9± 4.8 vs 28.3± 5.1 p<0.05) and 6-keto-PGF-1α (3.15± 0.68 vs 3.95 ±0.91 nmol/ml, p <0.05)were significantly lower in superantant from cells cultured in the presence of diabetic compared to control serum. PGI2 production was not significantly different in cells cultured with serum from hypophysectomised and nonhypophysectomised diabetics.These results suggest that serum from diabetics with proliferative retinopathy contains factors which impair the release or production of PGI2 by endothelial cells and that this effect is not mediated by the pituitary.
DC-Based Immunotherapy Using Vascular Endothelial Cells Cultured in Conditioned Medium as a Vaccine Antigen Exerts an Anti-Tumor Effect by Inhibiting Angiogenesis
