title: Evaluating Osteoarthritic Chondrocytes through a Novel 3-Dimensional In Vitro System for Cartilage Tissue Engineering and Regeneration.
abstract: OBJECTIVE
  To characterize and evaluate osteoarthritic (OA) chondrocytes, in comparison to normal chondrocytes, through a novel 3-dimensional (3-D) culture system, poly(ethylene-glycol) diacrylate (PEGDA). The cytokine interleukin 1β (IL-1β) was also used to simulate an in vitro OA model.
  
  
  METHODS
  Normal and OA chondrocytes were cultured in monolayer and analyzed for changes in cartilage-specific gene expressions due to passage number. Then, cells were encapsulated in PEGDA to evaluate phenotype and matrix production capabilities through the in vitro culture system. Characterization was conducted with polymerase chain reaction (PCR), biochemical analyses, and histological staining. 3-D encapsulated chondrocytes (human and bovine) were also treated with IL-1β to characterize how the cytokine affects gene transcription and extracellular matrix (ECM) content.
  
  
  RESULTS
  In 2-dimensional monolayer, anabolic genes were down-regulated significantly in both normal and OA chondrocytes. In 3-D culture, OA chondrocytes demonstrated significantly higher expressions of catabolic genes when compared to normal cells. Differentiation medium resulted in significantly more matrix production than growth medium from OA chondrocytes, indicated through histological staining. In addition, normal chondrocytes responded more significantly to exogenous administration of IL-1β than OA chondrocytes. Temporary initial stimulation of IL-1β to OA chondrocytes resulted in comparable gene expressions to untreated cells after 3 weeks of in vitro culture.
  
  
  CONCLUSIONS
  Our findings demonstrate the use of OA chondrocytes in tissue engineering and their significance for potential future cartilage regeneration research through their matrix production capabilities and the use of a hydrogel culture system.
authors.affiliation: Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Hanwei
authors.initials: H
authors.lastname: Li
authors.affiliation: Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Noel
authors.initials: N
authors.lastname: Davison
authors.affiliation: Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Moroni
authors.affiliation: Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Felicia
authors.initials: F
authors.lastname: Feng
authors.affiliation: Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Crist
authors.affiliation: Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: Salter
authors.affiliation: Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Clifton O
authors.initials: CO
authors.lastname: Bingham
authors.affiliation: Johns Hopkins School of Medicine, Baltimore, MD, USA ; Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Elisseeff
keywords: extracellular matrix; interleukins; matrix metalloproteinases; osteoarthritis; tissue engineering