The role of growth factors in the pathogenesis of diabetic retinopathy

Abstract
Diabetic retinopathy (DR) is the most severe of several ocular complications of diabetes. The earliest clinical signs of DR are microaneurysms and haemorrhages. Later signs include dilated, tortuous irregular veins and retinal non-profusion, leading to retinal ischaemia that ultimately results in neovascularisation. Diabetic macular oedema, which involves the breakdown of the blood–retinal barrier, also occurs and is responsible for a major part of vision loss, particularly in Type 2 diabetes. The pathogenesis of DR is very complex. Many biochemical mechanisms have been proposed as explanations for the development and progression of DR. Chronic hyperglycaemia leads to oxidative injury, microthrombi formation, cell adhesion molecule activation, leukostasis and cytokine activation. Next, ischaemia-mediated overexpression of growth factors and cytokines occurs. These factors include vascular endothelial growth factor, insulin-like growth factor-1, angiopoetin-1 and -2, stromal-derived factor-1, fibroblast gr...