title: Cytotoxicity testing of multipurpose contact lens solutions using monolayer and stratified cultures of human corneal epithelial cells.
abstract: 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.
authors.affiliation: Department of Biology, Calvin College, Grand Rapids, MI 49546, USA.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Lim
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Hurst
authors.forename: B J
authors.initials: BJ
authors.lastname: Konynenbelt
authors.forename: John L
authors.initials: JL
authors.lastname: Ubels
mesh_terms: D018929:Cell Culture Techniques; D002461:Cell Line, Transformed; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D018639:Contact Lens Solutions / Q000633:toxicity*; D017097:Electric Impedance; D019573:Epithelium, Corneal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D005434:Flow Cytometry; D019793:Fluorescein / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D006801:Humans; D007158:Immunologic Techniques; D008856:Microscopy, Fluorescence; D010539:Permeability; D013194:Staining and Labeling; D013997:Time Factors; D018675:Toxicity Tests
chemical_list: D018639:Contact Lens Solutions; D005456:Fluorescent Dyes; D019793:Fluorescein