To investigate the biologic effect of mitomycin C, dexamethasone and cyclosporine A 0.05% on cultured human keratocytes in vitro.

Human corneal keratocytes were exposed to a concentration of mitomycin C (0.05%), dexamethasone (0.05%) and cyclosporine A (0.05%) for a period of 3, 5, and 10 minutes. MTT-based colorimetric assay was performed to assess the metabolic activity of cellular proliferation and the concentration of type I procollagen COOH-terminal peptide (PIP) and laminin were measured. Cell damage was determined by using the lactate dehydrogenase (LDH) assay. Apoptotic response was evaluated utilizing flow cytometric analysis with Annexin V and propiodium iodide.

The inhibitory effect of cellular proliferation and cytotoxicity in cultured human keratocytes showed a time-dependent response in all drugs. The production of PIP and laminin showed a time-dependent response in cultured cells. Apoptosis was observed in flow cytometry after being treated with mitomycin C, dexamethasone and cyclosporine A. Cyclosporin A resulted in less apoptosis of keratocytes than mitomycin C and dexamethasone.

The apoptotic response of mitomycin C, dexamethasone and cyclosporine A is associated with the inhibitory effect of human corneal keratocyte proliferation. To decrease corneal opacity, mitomycin C and dexamethasone were more effective than cyclosporine A in the present study. Additionally, a high concentration of cyclosporine A greater than 0.05% is necessary to lower corneal opacity.