[The preliminary study of Phosphomannopentaose sulfate (PI-88) on the experimental choroidal neovascularization]

To probe the intervention and mechanism of the inhibitor of heparanase (PI-88) on the experimental CNV model .

Experimental CNV was induced by laser photocoagulation in 29 mail (Brown Norway) BN rats (647 nm wave length Krypton laser, 360 mW power, 50 microm spot size, 0.05 second duration), and randomly divided into vacant control group, physiologic saline control group, preventive group and treated group, another 3 rats were acted as normal group, 15 days continuous intraperitoneal injection of PI-88 (25 mg kg(-1) d(-1) was administrated in preventive group (PI-88 was administered the same day as photocoagulation) and treated group (PI-88 was administered 1 week after photocoagulation when CNV had been formed), for the physiologic saline control group, PI-88 was replaced by physiologic saline. To comprehensively evaluate the effect of PI-88 on the CNV by the quantitation of CNV area marked by FITC-dextran in choroid-sclera flat mounts, fluorescence fundus angiography and histopathology; the changes of HPA expression were surveyed by western blot and immunohistochemistry.

CNV area of preventive group and treated group decreased 52.1% and 53.8% respectively at the time point of 3 weeks after photocoagulation; the relative thickness of CNV membrane in eyes of treated group had been decreased 46% as that of control group by histopathology; CNV occurrenced 1 week after photocoagulation both in the control group and preventive group, while the fluorescein leakage of the preventive group had been inhibited significantly; 3 weeks after photocoagulation, there had been 7 days discontinuation for the prevent group, the fluorescein leakage did not enhanced, while there had been 15 days continuous administration for the treated group, the fluorescein leakage had been decreased significantly compared to the time point of 2 week; western blot showed that the relative expressed levels of HPA protein in both preventive and treated group decreased; HPA displayed distribution at the leading edge of CNV membrane migrating toward inner retina and the vascular tissue by immunohistochemistry, the expression of HPA was inhibited significantly in treated group.

PI-88 may not only prevent CNV in certain degree, but also make it partially subsidize for the existed CNV, and the effect is associated with the inhibition of HPA production.