title: Regional assessment of energy-producing metabolic activity in the endothelium of donor corneas.
abstract: OBJECTIVE
  We characterized mitochondrial respiration and glycolysis activity of human corneal endothelium, and compared metabolic activity between central and peripheral regions.
  
  
  METHODS
  Endothelial keratoplasty-suitable corneas were obtained from donors aged 50 to 75 years. The endothelium-Descemet membrane complex (EDM) was isolated, and 3-mm punches were obtained from central and peripheral regions. Endothelium-Descemet membrane punches were assayed for mitochondrial respiration (oxygen consumption) and glycolysis (extracellular acidification) using an extracellular flux analyzer. Enzymatic (citrate synthase, glucose hexokinase) and mitochondrial density (MitoTracker) assays also were performed.
  
  
  RESULTS
  Ten corneas were analyzed per assay. Metabolic activity for mitochondrial respiration and glycolysis showed expected changes to assay compounds (P < 0.01, all pairwise comparisons). Basal mitochondrial respiration and glycolysis activity did not differ between regions (P > 0.99). Similarly, central versus peripheral activity after assay compound treatment showed no significant differences (P > 0.99, all time points). The intracorneal coefficient of variation for basal readings between two and four peripheral punches was 18.5% of the mean. Although peripheral samples displayed greater enzymatic activity than central samples (P < 0.05), similar to extracellular flux results, mitochondrial density did not differ between regions (P = 0.78).
  
  
  CONCLUSIONS
  Extracellular flux analysis of oxygen and pH is a valid technique for characterizing metabolic activity of human corneal endothelium. This technique demonstrates high reproducibility, allows quantification of metabolic parameters using small quantities of live cells, and permits estimation of overall metabolic output. Neither oxygen consumption nor extracellular acidification differed between central and peripheral regions of transplant suitable corneas in this series. Our results show that endothelial cell health can be quantified biochemically in transplant suitable corneas.
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States 2Iowa Lions Eye Bank, Coralville, Iowa, United States.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Greiner
authors.affiliation: Iowa Lions Eye Bank, Coralville, Iowa, United States.
authors.forename: Kimberlee A
authors.initials: KA
authors.lastname: Burckart
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Wagoner
authors.affiliation: Iowa Lions Eye Bank, Coralville, Iowa, United States.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Schmidt
authors.affiliation: Iowa Lions Eye Bank, Coralville, Iowa, United States.
authors.forename: Cynthia R
authors.initials: CR
authors.lastname: Reed
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States.
authors.forename: Chase A
authors.initials: CA
authors.lastname: Liaboe
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States.
authors.forename: Miles J
authors.initials: MJ
authors.lastname: Flamme-Wiese
authors.affiliation: University of Iowa College of Public Health, Department of Biostatistics, Iowa City, Iowa, United States.
authors.forename: M Bridget
authors.initials: MB
authors.lastname: Zimmerman
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Mullins
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States 4Iowa City Veterans Affairs Medical Center and Center of Excellence for the Prevention and Treatment of Visual Loss, Iowa City.
authors.forename: Randy H
authors.initials: RH
authors.lastname: Kardon
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States 2Iowa Lions Eye Bank, Coralville, Iowa, United States.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Goins
authors.affiliation: University of Iowa Carver College of Medicine, Department of Ophthalmology and Visual Sciences, Iowa City, Iowa, United States 2Iowa Lions Eye Bank, Coralville, Iowa, United States.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Aldrich
mesh_terms: D000368:Aged; D019069:Cell Respiration; D016039:Corneal Transplantation; D004728:Endothelium, Corneal / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D005125:Eye Banks; D006019:Glycolysis / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D046509:Tissue Culture Techniques; D014019:Tissue Donors