RESUMO
OBJECTIVE: To investigate in vitro cytotoxicity of five marketed multipurpose contact lens solutions (MPS) on the morphology, viability, and barrier function of monolayer and stratified human corneal-limbal epithelial cells. METHODS: Cells were exposed to MPS for 10, 20, or 60 minutes. In monolayer cultures, effects of the MPS on cell morphology were observed using Hoffman modulation contrast microscopy. Cell proliferation after exposure to MPS was evaluated and cytotoxicity of the MPS was determined using a live/dead cell assay and flow cytometry. In stratified cultures, multilayer corneal epithelial constructs were established on membrane inserts. Effects of the MPS on the morphology and barrier function of stratified cultures were determined using microscopy, a fluorescein permeability test, and measurement of trans-epithelial resistance. RESULTS: In monolayer cultures, none of the MPS damaged cells during a 10-min exposure. All of the MPS had varying time-dependent adverse effects on cell morphology, viability, and proliferation during 20- and 60-min exposures. In stratified cultures, none of the MPS had an adverse effect on the structure or barrier function of stratified cultures. CONCLUSIONS: Monolayer cultures are highly sensitive to damage by MPS. In contrast, because stratified human corneal-limbal epithelial cultures are resistant to adverse effects of MPS, it is suggested that models that simulate the stratified structure of the corneal epithelium should be used for in vitro toxicologic testing. Caution should be used when interpreting such studies, because in vitro tests may not be predictive of clinical responses to contact lens products that are known to be safe when used as directed.
