title: Advanced glycation end-product accumulation reduces vitreous permeability.
abstract: OBJECTIVE
  To evaluate the effect of nonenzymatic cross-linking (glycation) upon the permeability of the vitreous to small- and large-solute diffusion.
  
  
  METHODS
  Vitreous from freshly excised porcine eyes was treated for 30 minutes with control or 0.01%, 0.1%, or 1% methylglyoxal (MG) solution. The efficacy of the glycation regimen was verified by measuring nonenzymatic cross-link density by fluorescence in the vitreous samples. Resistance to collagenase digestion as well as N(ε)-(carboxyethyl) lysine (CEL) content were also measured. The permeability coefficient for fluorescein and fluorescein isothiocyanate (FITC)-IgG diffusion through 3 mL of the vitreous samples was determined by using a custom permeability tester.
  
  
  RESULTS
  Vitreous cross-linking with MG treatment was confirmed by increased fluorescence, increased CEL concentration, and increased resistance to collagenase digestion. Vitreous glycation resulted in a statistically significant decrease in the permeability coefficient for fluorescein diffusion when either 0.1% or 1% MG solution was used (5.36 ± 5.24 × 10(-5) cm s(-1), P = 0.04; and 4.03 ± 2.1 × 10(-5) cm s(-1), P = 0.001; respectively, compared with control, 9.77 ± 5.45 × 10(-5) cm s(-1)). The permeability coefficient for diffusion of FITC-IgG between control (9.9 ± 6.37 × 10(-5) cm s(-1)) and treatment groups was statistically significant at all MG concentrations (0.01% MG: 3.95 ± 3.44 × 10(-5) cm s(-1), P = 0.003; 0.1% MG: 4.27 ± 1.32 × 10(-5) cm s(-1), P = 0.004; and 0.1% MG: 3.72 ± 2.49 × 10(-5) cm s(-1), P = 0.001).
  
  
  CONCLUSIONS
  Advanced glycation end-product (AGE) accumulation reduces vitreous permeability when glycation is performed in ex vivo porcine vitreous. The permeability change was more pronounced for the larger solute, suggesting a lower threshold for AGE-induced permeability changes to impact the movement of proteins through the vitreous when compared with smaller molecules.
authors.forename: On-Tat
authors.initials: OT
authors.lastname: Lee
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Good
authors.forename: Ricardo
authors.initials: R
authors.lastname: Lamy
authors.forename: Max
authors.initials: M
authors.lastname: Kudisch
authors.forename: Jay M
authors.initials: JM
authors.lastname: Stewart
mesh_terms: D000818:Animals; D003432:Cross-Linking Reagents / Q000008:administration & dosage / Q000494:pharmacology; D004058:Diffusion; D004305:Dose-Response Relationship, Drug; D019793:Fluorescein / Q000493:pharmacokinetics; D016650:Fluorescein-5-isothiocyanate / Q000493:pharmacokinetics; D017127:Glycation End Products, Advanced / Q000378:metabolism / Q000502:physiology*; D010539:Permeability / Q000187:drug effects; D011765:Pyruvaldehyde / Q000008:administration & dosage / Q000494:pharmacology; D034421:Sus scrofa; D046509:Tissue Culture Techniques; D014822:Vitreous Body / Q000187:drug effects / Q000378:metabolism*
chemical_list: D003432:Cross-Linking Reagents; D017127:Glycation End Products, Advanced; D011765:Pyruvaldehyde; D016650:Fluorescein-5-isothiocyanate; D019793:Fluorescein