title: The effects of oxygen level and glucose concentration on the metabolism of porcine TMJ disc cells.
abstract: OBJECTIVE
  To determine the combined effect of oxygen level and glucose concentration on cell viability, ATP production, and matrix synthesis of temporomandibular joint (TMJ) disc cells.
  
  
  METHODS
  TMJ disc cells were isolated from pigs aged 6-8 months and cultured in a monolayer. Cell cultures were preconditioned for 48 h with 0, 1.5, 5, or 25 mM glucose DMEM under 1%, 5%, 10%, or 21% O2 level, respectively. The cell viability was measured using the WST-1 assay. ATP production was determined using the Luciferin-Luciferase assay. Collagen and proteoglycan synthesis were determined by measuring the incorporation of [2, 3-(3)H] proline and [(35)S] sulfate into the cells, respectively.
  
  
  RESULTS
  TMJ disc cell viability significantly decreased (P < 0.0001) without glucose. With glucose present, decreased oxygen levels significantly increased viability (P < 0.0001), while a decrease in glucose concentration significantly decreased viability (P < 0.0001). With glucose present, decreasing oxygen levels significantly reduced ATP production (P < 0.0001) and matrix synthesis (P < 0.0001). A decreased glucose concentration significantly decreased collagen synthesis (P < 0.0001). The interaction between glucose and oxygen was significant in regards to cell viability (P < 0.0001), ATP production (P = 0.00015), and collagen (P = 0.0002) and proteoglycan synthesis (P < 0.0001).
  
  
  CONCLUSIONS
  Although both glucose and oxygen are important, glucose is the limiting nutrient for TMJ disc cell survival. At low oxygen levels, the production of ATP, collagen, and proteoglycan are severely inhibited. These results suggest that steeper nutrient gradients may exist in the TMJ disc and it may be vulnerable to pathological events that impede nutrient supply.
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC, United States.
authors.forename: S E
authors.initials: SE
authors.lastname: Cisewski
authors.affiliation: Department of Oral Health Sciences, Medical University of South Carolina (MUSC), Charleston, SC, United States.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC, United States.
authors.forename: J
authors.initials: J
authors.lastname: Kuo
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC, United States.
authors.forename: G J
authors.initials: GJ
authors.lastname: Wright
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC, United States.
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Oral Health Sciences, Medical University of South Carolina (MUSC), Charleston, SC, United States.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kern
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC, United States; Department of Oral Health Sciences, Medical University of South Carolina (MUSC), Charleston, SC, United States. Electronic address: haiyao@clemson.edu.
authors.forename: H
authors.initials: H
authors.lastname: Yao
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D003094:Collagen / Q000096:biosynthesis*; D005947:Glucose / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011509:Proteoglycans / Q000096:biosynthesis*; D013552:Swine; D019224:Temporomandibular Joint Disc / Q000166:cytology*
chemical_list: D011509:Proteoglycans; D000255:Adenosine Triphosphate; D003094:Collagen; D005947:Glucose; D010100:Oxygen
keywords: Cell metabolism; Glucose concentration; Oxygen level; Temporomandibular joint (TMJ) disc; Tissue nutrition