title: Fibrinogen, riboflavin, and UVA to immobilize a corneal flap--molecular mechanisms.
abstract: OBJECTIVE
  Tissue glue containing fibrinogen (FIB) and riboflavin (RF), upon exposure to long wavelength ultraviolet light (UVA, 365 nM) has been proposed potentially to solve long-standing problems presented by corneal wound and epithelial ingrowth side-effects from laser-assisted in situ keratomileuis (LASIK). Data presented in a previous study demonstrated an ability of FIB + RF + UVA to adhere two stromal surfaces; however, to our knowledge no molecular mechanisms have been proposed to account for interactions occurring between corneal extracellular matrix (ECM) and tissue glue molecules. Here, we document several covalent and noncovalent interactions between these classes of macromolecules.
  
  
  METHODS
  SDS-PAGE and Western blot techniques were used to identify covalent interactions between tissue glue molecules and corneal ECM molecules in either the presence or absence of RF and UVA, in vitro and ex vivo. Surface plasmon resonance (SPR) was used to characterize noncovalent interactions, and obtain k(a), k(d), and K(D) binding affinity values.
  
  
  RESULTS
  SDS-PAGE and Western blot analyses indicated that covalent interactions occurred between neighboring FIB molecules, as well as between FIB and collagen type I (Coll-I) proteins (in vitro and ex vivo). These interactions occurred only in the presence of RF and UVA. SPR data demonstrated the ability of FIB to bind noncovalently to corneal stroma molecules, Coll-I, decorin, dermatan sulfate, and corneal basement membrane molecules, laminin and heparan sulfate--only in the presence of Zn(2+).
  
  
  CONCLUSIONS
  Covalent and (zinc-mediated) noncovalent mechanisms involving FIB and stromal ECM molecules contribute to the adhesion created by FIB + RF + UVA.
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas 66506-4901, USA. stacy.little08@gmail.com
authors.forename: Stacy L
authors.initials: SL
authors.lastname: Littlechild
authors.forename: Yuntao
authors.initials: Y
authors.lastname: Zhang
authors.forename: John M
authors.initials: JM
authors.lastname: Tomich
authors.forename: Gary W
authors.initials: GW
authors.lastname: Conrad
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D015153:Blotting, Western; D024042:Collagen Type I / Q000378:metabolism*; D003319:Corneal Stroma / Q000378:metabolism*; D058575:Decorin / Q000378:metabolism; D003871:Dermatan Sulfate / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D012256:Riboflavin / Q000378:metabolism*; D020349:Surface Plasmon Resonance; D013524:Surgical Flaps; D000267:Tissue Adhesions; D014466:Ultraviolet Rays
chemical_list: D024042:Collagen Type I; D058575:Decorin; D003871:Dermatan Sulfate; D005340:Fibrinogen; D006497:Heparan Sulfate; D007797:Laminin; D012256:Riboflavin