title: Increased chondrocyte seeding density has no positive effect on cartilage repair in an MPEG-PLGA scaffold.
abstract: OBJECTIVE
  This study investigates the effect of cell seeding density on cartilage repair in matrix-assisted chondrocyte implantation in vitro and in vivo.
  
  
  METHODS
  In vitro: Four different cell seeding densities of human chondrocytes were seeded onto a porous methoxy-polyethylene glycol-polylactic-co-glycolic acid scaffold (MPEG-PLGA) polymer scaffold ASEED™ (1.2 × 10(6), 4.0 × 10(6), 1.2 × 10(7) and 2.0 × 10(7) cells/cm(3)). The cartilage repair response was evaluated by relative gene expression of the chondrogenic markers sox9, collagen types I, II and X, and aggrecan, total DNA content and sulphated glycosaminoglycan synthesis. In vivo: Using a New Zealand white rabbit intercondylar osteochondral defect model, three different cell seeding densities (1.2 × 10(6), 4.0 × 10(6) and 1.2 × 10(7) cells/cm(3)) were tested with an empty scaffold as control. The cartilage repair response was evaluated using O'Driscoll score.
  
  
  RESULTS
  In vitro: A significant difference (p < 0.05) in total DNA content was found at day 2 but not at day 7. The low cell seeding densities yielded the highest GAG content (p < 0.001) at day 7. Collagen type I was highest (p < 0.01) at the lowest density at day 7. In vivo: No significant difference was found between the 4 groups.
  
  
  CONCLUSIONS
  No positive effect on cartilage repair was found using increased cell seeding density.
  
  
  METHODS
  Controlled experimental study, Level II.
authors.affiliation: Orthopaedic Research Laboratory, Aarhus University Hospital, Noerrebrogade 44 building. 1A, 1. floor, 8000, Århus C, Denmark. ole.moller.hansen@studmed.au.dk
authors.forename: Ole Møller
authors.initials: OM
authors.lastname: Hansen
authors.forename: Casper Bindzus
authors.initials: CB
authors.lastname: Foldager
authors.forename: Bjørn Borsøe
authors.initials: BB
authors.lastname: Christensen
authors.forename: Hanne
authors.initials: H
authors.lastname: Everland
authors.forename: Martin
authors.initials: M
authors.lastname: Lind
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002358:Cartilage, Articular / Q000293:injuries / Q000502:physiology*; D002452:Cell Count; D018929:Cell Culture Techniques; D017690:Cell Transplantation; D019902:Chondrocytes / Q000637:transplantation*; D020869:Gene Expression Profiling; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D011091:Polyesters; D011092:Polyethylene Glycols; D011817:Rabbits; D054457:Tissue Scaffolds; D014182:Transplantation, Autologous; D014945:Wound Healing / Q000502:physiology*
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; C558447:methoxypolyethyleneglycol-poly(lactic-co-glycolic acid); D011092:Polyethylene Glycols