title: Dynamic compression of chondrocyte-seeded fibrin gels: effects on matrix accumulation and mechanical stiffness.
abstract: OBJECTIVE
  Various strategies have been tested to direct and control matrix synthesis in tissue engineered cartilage, including mechanical stimulation of the construct both before and after implantation. This study examined the effects of oscillatory compression on chondrocytes in a fibrin-based tissue engineered cartilage.
  
  
  METHODS
  Chondrocyte-seeded fibrin gels were cultured under unconfined mechanical compression for 10 or 20 days (free-swelling, 10% static, or 10+/-4% at 0.1 or 1Hz). During the culture period, accumulation of nitrite, sGAG, and proteolytic enzymes in the culture media were monitored. Following culture, the mechanical stiffness and biochemical content of the gels (DNA, sGAG, and hydroxyproline content and GAG Delta-disaccharide composition) were assessed.
  
  
  RESULTS
  Compared to free-swelling conditions, static compression had little effect on the mechanical stiffness or biochemical content of the gels. Compared to static compression, oscillatory compression produced softer gels, inhibited sGAG and hydroxyproline accumulation in the gels, and stimulated accumulation of nitrite and sGAG in the culture media. Minimal differences were observed in DNA content and Delta-disaccharide composition across treatment conditions.
  
  
  CONCLUSIONS
  In this study, oscillatory compression inhibited formation of cartilage-like tissues by chondrocytes in fibrin gels. These results suggest that the effects of mechanical stimuli on tissue engineered cartilage may vary substantially between different scaffold systems.
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hunter
authors.forename: Janna K
authors.initials: JK
authors.lastname: Mouw
authors.forename: Marc E
authors.initials: ME
authors.lastname: Levenston
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D003470:Culture Media; D004247:DNA / Q000032:analysis; D004586:Electrophoresis / Q000379:methods; D005109:Extracellular Matrix; D005337:Fibrin / Q000378:metabolism*; D005782:Gels; D006025:Glycosaminoglycans / Q000032:analysis; D006909:Hydroxyproline / Q000032:analysis; D009573:Nitrites / Q000032:analysis; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods
chemical_list: D003470:Culture Media; D005782:Gels; D006025:Glycosaminoglycans; D009573:Nitrites; D005337:Fibrin; D004247:DNA; D006909:Hydroxyproline