Abstract
Purpose :
Diabetic retinopathy (DR) is characterized by increased numbers of leukocytes attachment (leukostasis) and vascular hyperpermeability (VP) of the retinal vessels. Previous experimental evidence supports that the heparin-binding VEGF165 isoform, but not the VEGF121 isoform that lacks the heparin-binding domain (HBD), is responsible for inducing retinal leukostasis. Preliminary data showed that the recombinant HBD (rHBD), which likely function as a competitive VEGF165-specific inhibitor for heparan sulfate proteoglycans binding, inhibited VEGF165-induced leukostasis and pathological angiogenesis in an oxygen-induced retinopathy model. Thus, we hypothesize that rHBD also has potential therapeutic effects in a mouse model of DR.
Methods :
Streptozotocin (STZ) injection of 6-8 weeks old C57BL/6 male mice were used to induce diabetes (blood sugar levels of at least 250 mg/dL). Retinal VP was measured with the Fluorotron Master Ocular Fluorophotometer (Laboratory Mouse Edition) and retinal leukostasis was quantified by FITC-concanavalin A perfusion assay with retinal flat-mount and fluorescence microscopy. The mice were injected with rHBD (50 pmol) or vehicle control intravitreally 6 months after induction of diabetes. Statistical analysis of data (mean ± SEM) was performed using t-test and one-way ANOVA.
Results :
Retinal VP was significantly increased in diabetic mice compared to non-diabetic mice (29.23±0.90 vs. 17.17±1.06, P<0.0001). A single intravitreal injection of rHBD significantly reduced retinal VP by about 20% in diabetic mice compared to vehicle injected control (23.78±0.96 vs. 29.41±1.13, P<0.001). Diabetic mice received vehicle treatment had increased leukostasis compared to non-diabetic mice (9.85±0.74 vs. 3.50±0.31, P<0.0001), while rHBD injection significantly reduced leukostasis compared to vehicle injected control (3.13±0.38 vs. 9.85±0.74, P<0.0001), and to the levels comparable to that of the non-diabetic mice.
Conclusions :
These data demonstrated that intraocular injection of rHBD significantly suppress retinal vascular hyperpermeability and leukostasis in a mouse model of DR, therefore rHBD could be an efficacious therapeutic for DR.
This is a 2021 ARVO Annual Meeting abstract.