AIM: To investigate the effect of heparanase (HPA-1) inhibitor on the proliferation of human retinal pigment epithelial (RPE) cell. METHODS:Hunan RPE cells were primarily cultured and the fifth generation cells were used in the experiment. The phosphomannopentaose sulfate(PI-88) solutions of different concentrations were added into the medium for 48 and 72 hours to co-culture the cells. The proliferation of human RPE cell was estimated using MTT colorimetric assay as the A₅₇₀ value. The expression of keratin and HPA-1 in the cells was detected by immunochemistry.RESULTS: HPA-1 was intently expressed in both the cytoplasm and nucleus of human RPE cells, and weak expression was seen in RPE cells co-cultured with PI-88. Either in 48 hours or 72 hours, the A₅₇₀ values of various concentrations of PI-88 culture group were significantly declined in comparison with without PI-88. When PI-88 was administered for 72 hours, the A570 values showed the tendency of reduction to those of 48 hours in >100mg/L groups.CONCLUSION:HPA-1 inhibitor can suppress the proliferation of human RPE cell at the concentration- and time-dependent manner in vitro.