Taxol inhibits proliferation of primarily cultured human retinal pigment epithelial cells

Objective To study the inhibitory effect of Taxol on proliferation of primarily cultured in vitro human retinal pigment epithelial（hRPE） cells and its mechanism. Methods After in vitro isolation and primary culture, hRPE cells were identified with immunocytochemistry method. Inhibitory effects of Taxol at different concentrations（0, 0.005, 0.05, 0.5, and 5mg/L） on growth of hRPE cells were observed by morphology, growth curve and MTT assay, respectively, while its cell cyclearresting and apoptosis-inducing effects were detected by flow cytometry. Results Rich pigment was found in the hRPE cells after primary culture, which increased with the number of passages. However, black pigment granules decreased gradually and even completely disappeared. Specific positive reactions were observed in hRPE cells by immunocytochemistry using anti-human keratin. Cell growth curve and MTT assay demonstrated that the IC₅₀ value of Taxol for the growth inhibition of hRPE cells was 5.24mg/L and 3.24mg/L, after 24h and 72h, respectively. Flow cytometric analysis displayed that 0.5mg/L Taxol could significantly delay the G₂/M arrest and induce apoptosis of hRPE cells 48h after it was used（P＜0.05）. Transmission electron microscopy revealed that 0.5mg/L Taxol decreased the microvilli on cell surface and cell organs, and increased the electron density in hRPE cells with marginal accumulation of heterochromatin masses. Conclusion Taxol can exert its direct effects on the proliferation of hRPE cells in vitro by inducing G₂/M arrest and apoptosis.