ABSTRACT: Heparanase, an endoglycosidase, exhibits strong proangiogenic capacity that can induce vascular endothelial growth factor (VEGF) expression in tumour angiogenesis. The purpose of this study was to evaluate heparanase expression and its relationship with VEGF in streptozotocin (STZ)-induced diabetic rats' retinas.
STZ-induced rats and non-diabetic control rats.
Heparanase expression was initially evaluated in cultured human retinal microvascular endothelial cells (HRECs) under high-glucose conditions by Western blot. Diabetes was induced in Sprague-Dawley rats by STZ intraperitoneal injection. Retinal heparanase expression was assayed in rats by immunohistochemistry. Heparanase inhibitor (phosphomannopentaose sulfate) was administrated to high-glucose-treated HRECs and diabetic rats. VEGF levels were evaluated in HRECs and retinas using enzyme-linked immunosorbent assay.
Heparanase expression was increased in HRECs under high-glucose conditions compared with controls (p < 0.01). Immunohistochemical studies indicated that heparanase signals were intense in the retinal vascular endothelia of diabetic rats, but faint in those of nondiabetic control rats. Quantitative analysis showed that heparanase protein expression was increased by 3.2-fold in diabetic rats' retinas compared with nondiabetic rats' retinas (p < 0.01). VEGF level was increased, as was heparanase expression, in high-glucose-treated HRECs and in the retinas of diabetic rats, and these increases were significantly decreased by phosphomannopentaose sulfate administration (p < 0.01).
Heparanase expression was upregulated and associated with an increase of VEGF expression in STZ-induced diabetic rat retinas. The data suggest that heparanase may be involved in the development of diabetic retinopathy and represents a possible novel target for therapeutic intervention.
Canadian Journal of Ophthalmology 02/2010; 45(1):46-51. · 1.47 Impact Factor
ABSTRACT: Retinal leukostasis, mediated by intracellular adhesion molecule-1 (ICAM-1) and vascular endothelial growth factor (VEGF), has been implicated in the pathogenesis of early diabetic retinopathy. Phosphomannopentaose sulfate (PI-88) is a highly sulfonated oligosaccharide which inhibits heparanase activity and competes with heparan sulfate binding to growth factors. In this study, we evaluated whether PI-88 could inhibit retinal leukostasis in strepotzotocin(STZ)-induced diabetic rat and elucidated the possible mechanisms. Diabetes was induced in Sprague-Dawley rats by intraperitoneal injection (i.p.) of STZ. Three months after induction, diabetic rats were administered PI-88 (25 mg/kg body weight) or vehicle solution daily via i.p. for 14 consecutive days. Leukostasis was analyzed on retinal flatmounts by concanavalin A and CD45 immunofluorescence staining. Retinal function was analyzed by electroretinography (ERG). ICAM-1 and VEGF levels in retinas were studied by Western blot and enzyme-linked immunosorbent assay (ELISA) respectively. The systemic administration of PI-88, but not vehicle, significantly decreased the number of adherent leukocytes in retinas by 52.24% (P<0.001) and led to significant preservation (about 50%, P<0.001) of scotopic ERG a- and b-wave amplitudes in treated diabetic rats as compared to those of diabetic control rats. These changes were associated with downregulation of ICAM-1 (45%, P<0.001) and VEGF (26.83+/-2.01 versus 40.8+/-3.24 pg/mg, P<0.01) in retinas of PI-88 treated diabetic rats as compared to those of diabetic control rats. PI-88 significantly inhibited retinal leukostasis and reversed retinal dysfunction by a mechanism that may include decreased ICAM-1 and VEGF expression in diabetic rats. Our data suggests that PI-88 is a promising agent for the treatment of diabetic retinopathy.
Biochemical and Biophysical Research Communications 01/2009; 380(2):402-6. · 2.48 Impact Factor
ABSTRACT: To observe the role of blood glucose control on morphology changes of retinal vessels and retinal vascular endothelial growth factor (VEGF) expression in early diabetic rats.
Diabetes was induced in 8-week-old male Wistar rats by a single intraperitoneal injection of Streptozotocin (STZ). After 3 weeks, the animals were randomly divided into four groups: (1) normal rats group, (2) diabetic rats group, (3) diabetic rats with glucose controlled group, received intensive insulin therapy for 20 days, and (4) diabetic rats with uncontrolled blood glucose group, received unregular insulin therapy, which caused the abrupt fluctuation of glucose. After the treatment period, the animals were perfused with 30 mg/ml Fluorescein isothiocyanate-dextran (FITC-Dextran). The eyes were enucleated and fixed in 4% paraformaldehyde immediately. Retinal flat mounts and paraffin sections were prepared. Morphology of impaired retinal vessels and retinal VEGF expression were assessed by immunofluorescence stain and image analysis.
The flat-mounted retinas showed more FITC-Dextran aggregated locally at vessels and capillary meandered or dilated in STZ-diabetic rats with uncontrolled blood glucose than in STZ-diabetic rats with controlled blood glucose. Retinal VEGF expression decreased in group 3 compared with group 2 or with group 4. The statistical difference was significant (P < 0.05).
Strict control of blood glucose by insulin could decrease VEGF expression in retina and protect retinal vessels from impairing in early STZ-diabetic rats.
Yan ke xue bao = Eye science / "Yan ke xue bao" bian ji bu 01/2008; 23(4):205-11.
ABSTRACT: To compare the healing condition of sclerotomy sites after 25-gauge transconjunctival sutureless sclerotomy and conventional 20-gauge vitrectomy in minipigs.
Four minipigs qualified for experiment were included in the study. One eye underwent sclerotomy with 25G trocar (25G group) and the other underwent 20G-PPV (20G group). The healing processes of sclerotomy sites were observed grossly and by Hematoxylin-Eosin (HE) staining under light microscopy at 0, 10, 20 and 60 days after operation.
Compared with 20G group, scleral incisions in 25G group were much smaller. One day after operation, conjunctival hyperemia in 20G group was more severe than that in 25G group. Sclerotomy sites in 25G group mostly healed 10 days after operation with a few inflammation cells. Sclerotomy sites in 20G group bad not healed 20 days after operation and were infiltrated by a great number of inflammation cells. One case in 25-gauge group and 2 cases in 20-gauge group had vitreous incarceration. Two cases in 25-gauge group and 4 cases in 20-gauge group had fibrous ingrowth.
Compared with 20-gauge vitrectomy, the smaller sclerotomy sites in 25-gauge transconjunctival sutureless sclerotomy heal faster and have lighter inflammation reaction. Vitreous incarceration and proliferation ingrowth could be found in both surgeries.
Yan ke xue bao = Eye science / "Yan ke xue bao" bian ji bu 04/2007; 23(1):37-42.