Increased levels of platelet-derived microparticles in patients with diabetic retinopathy

Diabetic retinopathy is caused by capillary occlusions. Platelet-derived microparticles (PMPs) stimulate the coagulation cascade and increase leukocyte and endothelial cell adhesions, both of which are key events in the development of diabetic retinopathy. However, the correlation between the levels of PMPs and diabetic retinopathy has not been precisely determined. The PMPs levels and the expression of platelet CD62P and CD63 were measured in 92 diabetic patients. The level of PMPs was significantly correlated with the expression of CD62P (r = 0.76, P < 0.0001) and CD63 (r = 0.71, P < 0.0001). The mean level of PMPs in diabetics (507 ± 15/104 platelets (plt), mean ± S.E.) was significantly higher than that in normal. The PMPs levels increased with the progression of the diabetic retinopathy; 480 ± 28/104 plt in diabetic patients without retinopathy (n = 25), 504 ± 40/104 plt with mild or moderate non-proliferative diabetic retinopathy (n = 13), 512 ± 29/104 plt with severe non-proliferative diabetic retinopathy (n = 25), and 528 ± 25/104 plt with proliferative diabetic retinopathy (n = 29). The PMPs level in patients with non-perfused retinal areas (582 ± 27/104 plt, n = 24) was significantly higher than patients without non-perfused areas (469 ± 23/104 plt, n = 30; P = 0.0096) and without diabetic retinopathy (P = 0.024). These high correlations indicate that increased levels of PMPs may accelerate diabetic retinopathy.