RESUMO
OBJECTIVE: Parstatin, the N-terminal 41-amino-acid peptide cleaved by thrombin from protease-activated-receptor 1, was shown to be highly effective in preventing ocular angiogenesis and as such it has potential therapeutic applications in ocular neovascular diseases. In the frame of a safety program in preclinical development, we investigated whether parstatin exerts any cytotoxic effect in critical ocular cell populations. MATERIALS AND METHODS: Human retinal pigment epithelium cell-19 line (ARPE-19) and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay were used to investigate parstatin's effect in cell cultures. Parstatin 24-41 was used as a control peptide which lacks the hydrophobic domain to demonstrate the specificity and the structure-dependent effect of parstatin. Both peptides were used at concentrations ranging from 0.1-30 µM for 24, 48 and 72 hours. RESULTS: In the presence of parstatin the rate of ARPE-19 cell growth and viability were significantly decreased in a concentration-dependent and time-dependent manner, with an IC50 of approximately 10 µM. When ARPE-19 cells were treated with parstatin 24-41 no inhibitory effect was observed at any concentration or exposure time used. CONCLUSIONS: Parstatin has a clear detrimental effect on the viability of ARPE-19 cells and raises concerns about its use in the eye because of its possible toxic effects.
