title: Cell senescence reduced the mechanotransduction sensitivity of porcine angular aqueous plexus cells to elevation of pressure.
abstract: OBJECTIVE
  To investigate the effect of pressure/flow on the barrier function and protein expression of normal and senescent porcine aqueous humor plexus (AAP) cells, which are the porcine equivalent of human Schlemm's canal endothelial cells.
  
  
  METHODS
  AAP cells were grown for 2 weeks in physiological (5% O2) or hyperoxic conditions (40% O2) to model cell senescence. Control and senescent AAP cells were subjected to control and elevated hydrostatic pressure gradient of 10 mm Hg for 72 hours. Hydraulic conductivity (HC) and transendothelial electric resistance (TEER) were measured. The expressions of senescence-associated β-galactosidase and DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) were monitored, and the protein expression profile was analyzed by Western blot.
  
  
  RESULTS
  After 14 days of hyperoxia, AAP cells stained positive for 8-OHdG and β-galactosidase. Pressure elevation/flow resulted in significant increase of HC in control cells (from 1.37 ± 0.12 to 1.64 ± 0.18 μL/mm Hg/min/cm(2), P < 0.05), but not in senescent cells (1.15 ± 0.17 and 1.08 ± 0.10 μL μL/mm Hg/min/cm(2)). TEER changes were consistent with the HC results. Western blot analysis showed that the expression level of myosin light chain, claudin-5, and VE-cadherin significantly reduced under pressure elevation in control cells but not in senescent cells.
  
  
  CONCLUSIONS
  AAP cells are mechano-sensitive; however, cell senescence rendered the cells less responsive to mechanical stimulus, which may have pathological consequences.
authors.affiliation: Research Centre, Eye and ENT Hospital of Fudan University, Shanghai, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lei
authors.forename: William D
authors.initials: WD
authors.lastname: Stamer
authors.forename: Jihong
authors.initials: J
authors.lastname: Wu
authors.forename: Xinghuai
authors.initials: X
authors.lastname: Sun
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000166:cytology*; D015153:Blotting, Western; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology*; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D005901:Glaucoma / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D007429:Intraocular Pressure; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D018384:Oxidative Stress; D013552:Swine; D014129:Trabecular Meshwork / Q000378:metabolism / Q000473:pathology*
keywords: Schlemm's canal; aging; glaucoma