title: The beneficial effect of delayed compressive loading on tissue-engineered cartilage constructs cultured with TGF-beta3.
abstract: OBJECTIVE
  To determine whether the functional properties of tissue-engineered constructs cultured in a chemically-defined medium supplemented briefly with TGF-beta3 can be enhanced with the application of dynamic deformational loading.
  
  
  METHODS
  Primary immature bovine cells (2-3 months old) were encapsulated in agarose hydrogel (2%, 30 x 10(6)cells/ml) and cultured in chemically-defined medium supplemented for the first 2 weeks with transforming growth factor beta 3 (TGF-beta3) (10 microg/ml). Physiologic deformational loading (1 Hz, 3 h/day, 10% unconfined deformation initially and tapering to 2% peak-to-peak deformation by day 42) was applied either concurrent with or after the period of TGF-beta3 supplementation. Mechanical and biochemical properties were evaluated up to day 56.
  
  
  RESULTS
  Dynamic deformational loading applied concurrently with TGF-beta3 supplementation yielded significantly lower (-90%) overall mechanical properties when compared to free-swelling controls. In contrast, the same loading protocol applied after the discontinuation of the growth factor resulted in significantly increased (+10%) overall mechanical properties relative to free-swelling controls. Equilibrium modulus values reach 1306+/-79 kPa and glycosaminoglycan levels reach 8.7+/-1.6% w.w. during this 8-week period and are similar to host cartilage properties (994+/-280 kPa, 6.3+/-0.9% w.w.).
  
  
  CONCLUSIONS
  An optimal strategy for the functional tissue engineering of articular cartilage, particularly to accelerate construct development, may incorporate sequential application of different growth factors and applied deformational loading.
authors.affiliation: Department of Biomedical Engineering, Columbia University, 1210 Amsterdam Avenue, New York, NY 10027, USA.
authors.forename: E G
authors.initials: EG
authors.lastname: Lima
authors.forename: L
authors.initials: L
authors.lastname: Bian
authors.forename: K W
authors.initials: KW
authors.lastname: Ng
authors.forename: R L
authors.initials: RL
authors.lastname: Mauck
authors.forename: B A
authors.initials: BA
authors.lastname: Byers
authors.forename: R S
authors.initials: RS
authors.lastname: Tuan
authors.forename: G A
authors.initials: GA
authors.lastname: Ateshian
authors.forename: C T
authors.initials: CT
authors.lastname: Hung
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D002417:Cattle; D018929:Cell Culture Techniques; D019902:Chondrocytes / Q000166:cytology* / Q000502:physiology; D003094:Collagen / Q000032:analysis; D006025:Glycosaminoglycans / Q000032:analysis; D008954:Models, Biological; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods*; D053782:Transforming Growth Factor beta3
chemical_list: D006025:Glycosaminoglycans; D053782:Transforming Growth Factor beta3; D003094:Collagen