title: Influence of temporary chondroitinase ABC-induced glycosaminoglycan suppression on maturation of tissue-engineered cartilage.
abstract: OBJECTIVE
  A fundamental challenge of cartilage tissue engineering has been the inability to promote collagen synthesis up to native levels. In contrast, recent protocols have demonstrated that glycosaminoglycans (GAG) can be synthesized to native levels in 4-6 weeks of in vitro culture. We hypothesize that rapid GAG synthesis may be an impediment to collagen synthesis, possibly by altering transport pathways of nutrients or synthesis products. In this study, this hypothesis is tested by inducing enzymatic GAG loss in the early culture period of cartilage tissue constructs, and monitoring collagen content at various time points after cessation of enzymatic treatment.
  
  
  METHODS
  In Study 1, to induce breakdown of proteoglycans, chondroitinase ABC (CABC, 0.002U/mL) was continuously added into the culture media for the initial 4 weeks of culture or for 2 weeks starting on day 14 of culture. In Study 2, multiple transient CABC treatments (0.15U/mL, for 2 days) were applied to the matured tissue-engineered constructs.
  
  
  RESULTS
  Continuous and transient CABC treatments significantly increased the collagen concentration of the constructs, improving their tensile properties. The GAG content of the treated constructs recovered quickly to the pretreatment level after 2-3 weeks.
  
  
  CONCLUSIONS
  This study demonstrates that tissue-engineered cartilage constructs with improved tensile properties can be achieved by temporarily suppressing the GAG content enzymatically.
authors.affiliation: Cellular Engineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York, USA.
authors.forename: Liming
authors.initials: L
authors.lastname: Bian
authors.forename: Keith M
authors.initials: KM
authors.lastname: Crivello
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Ng
authors.forename: Duo
authors.initials: D
authors.lastname: Xu
authors.forename: David Y
authors.initials: DY
authors.lastname: Williams
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Ateshian
authors.forename: Clark T
authors.initials: CT
authors.lastname: Hung
mesh_terms: D000818:Animals; D002356:Cartilage / Q000166:cytology* / Q000201:enzymology*; D002417:Cattle; D002454:Cell Differentiation; D019765:Chondroitin ABC Lyase / Q000378:metabolism*; D006025:Glycosaminoglycans / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism; D010619:Phenazines / Q000378:metabolism; D013194:Staining and Labeling; D013718:Tensile Strength; D013997:Time Factors; D023822:Tissue Engineering
chemical_list: D006025:Glycosaminoglycans; D010619:Phenazines; D006026:Glycoside Hydrolases; C019624:agarase; D019765:Chondroitin ABC Lyase; C009195:safranine T