Abstract
Purpose: :
Vascular BM thickening, pericyte loss and acellular capillaries are prominent histological lesions of diabetic retinopathy (DR). In this study, we determined the effects of combined antisense oligonucleotides (AS–oligos) against overexpression of extracellular matrix components (fibronectin, laminin, and collagen IV) associated with basement membrane (BM) thickening and vascular lesions in the retinal capillaries of diabetic rats.
Methods: :
Male Sprague–Dawley rats were tail–vein injected with streptozotocin to induce diabetes. The diabetic rats were randomly assigned to receive either combined AS–oligos (fibronectin–AS, laminin–AS, and collagen IV–AS oligos) or random (Ran) oligos. AS oligos or Ran oligos were administered by intravitreal injection together with a block copolymer to facilitate transfection. After 6 months of diabetes, the rats were sacrificed, retinas isolated from each animal and retinal vascular BM thickening determined by electron microscopy. The retinal vasculature was isolated by the retinal trypsin digestion technique and stained with hematoxylin and PAS for analyzing pericyte loss and acellular capillaries.
Results: :
The retinal vascular BM of diabetic rats was significantly thickened compared to those of control non–diabetic rats (115.9±15.6 nm vs 73.3±19.7 nm, p < 0.01). When diabetic rats were treated with combined AS–oligos, BM thickening was significantly reduced compared to those of diabetic rats (62.7±7.5 nm vs. 115.9±15.6 nm, p < 0.001). A significant increase was observed in pericyte loss and number of acellular capillaries in the retinas of diabetic rats compared to those of normal rats (1.9±0.73 vs 3.9±1.7 per mm2, p=0.0001; 0.31±0.59 vs 3.2±1.7 per mm2, p=0.0002, respectively). When rats were treated with combined AS–oligos, the number of pericyte ghosts and acellular capillaries was significantly reduced (3.9±1.7 vs 2.0±1.5 per mm2, p=0.0001; 0.31±0.59 vs 1.1±0.87 per mm2, p=0.0007, respectively). Diabetic rats treated with random oligos, used as control for antisense specificity, exhibited no effect on BM thickening, pericyte loss, or acellular capillaries compared to diabetic rats.
Conclusions: :
Combined antisense oligonucleotide strategy against increased synthesis of extracellular matrix components may be useful in preventing increased vascular BM thickening, pericyte loss and acellular capillaries associated with DR. The finding may have potential for developing a therapeutic strategy against vascular lesions of DR.
Keywords: diabetic retinopathy • extracellular matrix • pathology: experimental