title: Effect of Stratification on Surface Properties of Corneal Epithelial Cells.
abstract: OBJECTIVE
  The purpose of this study was to determine the influence of mucin expression in an immortalized human corneal epithelial cell line (hTCEpi) on the surface properties of cells, such as wettability, contact angle, and surface heterogeneity.
  
  
  METHODS
  hTCEpi cells were cultured to confluence in serum-free medium. The medium was then replaced by stratification medium to induce mucin biosynthesis. The mucin expression profile was analyzed using quantitative PCR and Western blotting. Contact angles were measured using a two-immiscible liquid method, and contact angle hysteresis was evaluated by tilting the apparatus and recording advancing and receding contact angles. The spatial distribution of mucins was evaluated with fluorescently labeled lectin.
  
  
  RESULTS
  hTCEpi cells expressed the three main ocular mucins (MUC1, MUC4, and MUC16) with a maximum between days 1 and 3 of the stratification process. Upon stratification, cells caused a very significant increase in contact angle hysteresis, suggesting the development of spatially discrete and heterogeneously distributed surface features, defined by topography and/or chemical functionality. Although atomic force microscopy measurements showed no formation of appreciable topographic features on the surface of the cells, we observed a significant increase in surface chemical heterogeneity.
  
  
  CONCLUSIONS
  The surface chemical heterogeneity of the corneal epithelium may influence the dynamic behavior of tear film by "pinning" the contact line between the cellular surface and aqueous tear film. Engineering the surface properties of corneal epithelium could potentially lead to novel treatments in dry eye disease.
authors.affiliation: Instituto de Física Manuel Sandoval Vallarta, Universidad Autónoma de San Luis Potosí, San Luis Potosí, San Luis Potosí, México 2Department of Veterinary Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Da.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Yáñez-Soto
authors.affiliation: William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California Davis, Davis, California, United States.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Leonard
authors.affiliation: Department of Veterinary Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, California, United States.
authors.forename: Vijay Krishna
authors.initials: VK
authors.lastname: Raghunathan
authors.affiliation: Department of Chemical and Biological Engineering, School of Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Abbott
authors.affiliation: Department of Veterinary Surgical and Radiological Sciences, School of Veterinary Medicine, University of California Davis, Davis, California, United States 5Department of Ophthalmology and Vision Science, School of Medicine, University of California Davi.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Murphy
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D015352:Dry Eye Syndromes / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019573:Epithelium, Corneal / Q000166:cytology / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009077:Mucins / Q000235:genetics* / Q000378:metabolism; D012313:RNA / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D013499:Surface Properties; D013666:Tears / Q000378:metabolism*
chemical_list: D009077:Mucins; D012313:RNA