heparitin-sulfate and Corneal-Neovascularization

Heparan sulfate (HS), a ubiquitous and structurally diverse cell surface polysaccharide and extracellular matrix component, is a factor common to several major eye pathologies. Its multitude of functions and variable distribution among the different ocular tissues makes it an important contributor to a variety of disease states. Although HS facilitates the pathogenesis of many disorders, its role in each varies. Unique functions of HS have been particularly noted in viral and bacterial keratitis and age-related macular degeneration. Combined, these pathologies comprise a large portion of conditions leading to visual impairment worldwide. Given this prevalence of diseases facilitated by HS, it is prudent to take an in-depth look at this compound in the context of these pathologic states. While the initial part of the review will discuss the pathogenic aspects of HS, it is also important to consider the wider implications of such roles for HS. The remainder of the article will specifically address one such implication, the possibility for future use of novel HS-based therapeutics to combat these eye pathologies.

Topics: Animals; Corneal Neovascularization; Corneal Ulcer; Eye Diseases; Heparitin Sulfate; Humans; Keratitis, Herpetic; Macular Degeneration

The purpose of this study was to evaluate the inhibitory activity of the heparan sulfate suleparoide on vascular cell growth in vitro and angiogenesis in vivo. Human HUV-EC-C endothelial cell proliferation and microvessel sprouting from cultured rat aortic rings were assayed by the bioreduction of 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide. The inhibition of the neoforming capillary network in the chorioallantoic membrane of chick embryo (CAM) was evaluated by agarose disks containing suleparoide and applied on the CAM surface. AgNO3/KNO3 injury was used to induce corneal neovascularization and to evaluate the therapeutic effect of topical suleparoide, while the involvement of bFGF in angiogenesis was evidenced by immunohistochemistry of corneal tissue. Quantitation of angiogenesis in the CAM and the cornea was accomplished by image analysis. Suleparoide dose-dependently inhibited HUV-EC-C cell proliferation (50% inhibitory concentration [IC50], 197.5+/-15.2 microg ml-1) and reduced microvessel sprouting in vitro (IC50, 351+/-22 microg ml-1). Likewise, suleparoide 150 microg in agarose disks produced an avascular area of 19.7+/-2.7% of the total area of the CAM (P<0.05 as compared to controls). bFGF levels were significantly enhanced in the cornea after AgNO3/KNO3 injury, and the increase appeared to be time-dependent (25.6+/-1.8 and 43.2+/-7.4%, vs. uninjured controls after 24 hr and 48 hr, respectively, P<0.05). Suleparoide 4.8 mg eye-1 day-1 for six days reduced the length of blood vessels and the area of the cornea infiltrated by them (59.6+/-7.4% decrease vs. controls, P<0.05). These results demonstrate that suleparoide is an active agent against angiogenesis and suggest that the therapeutic effect of the drug could be of value to treat corneal neovascularization.

Topics: Allantoin; Animals; Aorta, Thoracic; Cell Division; Chick Embryo; Chorion; Cornea; Corneal Injuries; Corneal Neovascularization; Endothelium, Vascular; Fibroblast Growth Factor 2; Heparitin Sulfate; Humans; Immunoenzyme Techniques; In Vitro Techniques; Neovascularization, Physiologic; Rats

Vascularization of the cornea occurs in many pathological conditions and can result in loss of visual acuity. It is also thought that vascularization predisposes the cornea to reject grafts by facilitating the detection of foreign antigens in donor material. A rat corneal assay for angiogenesis was adopted in the present study to evaluate the possible angiostatic activity of a low molecular weight heparan sulphate (LMW-HS). Corneal lesions were induced by chemical cauterization at 2 mm from the corneoscleral limbus. Rats were randomized to receive two drops/eye four times daily, for 6 days, of a solution of LMW-HS in vehicle (2.5% carboxymethylcellulose), heparin, heparin plus hydrocortisone, or vehicle alone. After a 6 day-treatment period, the eyes were perfused with india ink and the degree of neovascularization was evaluated. In rats treated with vehicle alone a dense vascular network extending from the corneoscleral limbus to the cauterized site was observed; on the contrary, a markedly reduced vascular network was evidenced in animals treated with LMW-HS. The distribution of basic fibroblast growth factor (bFGF) in the cauterized cornea was also evaluated by using an immunohistochemical method. A marked bFGF immunoreactivity was demonstrated in corneal epithelium and stroma of control rats 12-48 hours after the cautery. These results lead to the assumption that LMW-HS could be used in ophthalmology to inhibit corneal neovascularization.

Topics: Animals; Cornea; Corneal Neovascularization; Drug Therapy, Combination; Female; Fibroblast Growth Factor 2; Heparin; Heparitin Sulfate; Hydrocortisone; Immunoenzyme Techniques; Molecular Weight; Nitrates; Ophthalmic Solutions; Potassium Compounds; Random Allocation; Rats; Rats, Wistar; Silver Nitrate