title: Scaffold degradation elevates the collagen content and dynamic compressive modulus in engineered articular cartilage.
abstract: OBJECTIVE
  It was hypothesized that controlled, scaffold removal in engineered cartilage constructs would improve their collagen content and mechanical properties over time in culture.
  
  
  METHODS
  Preliminary experiments characterized the effects of agarase on cell-free agarose disks and cartilage explants. Immature bovine chondrocytes were encapsulated in agarose, cultured to day 42, and incubated with 100 units/mL agarase for 48 h. After treatment, constructs were cultured to day 91. The compressive Young's modulus and dynamic modulus of the constructs were determined every 2 weeks and immediately after agarase treatment. Post-mechanical testing, constructs were processed for biochemistry and histology.
  
  
  RESULTS
  Agarase treatment on explants had no detrimental effect on the cartilage matrix. Treatment applied to engineered constructs on day 42 did not affect DNA or collagen content. Agarase treatment decreased tissue GAG content (via GAG loss to the media) and Young's modulus, both of which recovered to control values over time in culture. By day 91 agarase-treated constructs possessed approximately 25% more DNA, approximately 60% more collagen, and approximately 40% higher dynamic modulus compared to untreated controls.
  
  
  CONCLUSIONS
  Scaffold degradation increased construct collagen content and dynamic mechanical properties, affirming the experimental hypothesis. The mechanism may lie in increased nutrient transport, increased space for collagen fibril formation, and cellular response to the loss of GAG with agarase treatment. The results highlight the role of the scaffold in retaining synthesized matrix during early and late tissue formation. This work also shows promise in developing an engineered tissue that may be completely free of scaffold material for clinical implantation.
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA. cth6@columbia.edu
authors.forename: K W
authors.initials: KW
authors.lastname: Ng
authors.forename: L E
authors.initials: LE
authors.lastname: Kugler
authors.forename: S B
authors.initials: SB
authors.lastname: Doty
authors.forename: G A
authors.initials: GA
authors.lastname: Ateshian
authors.forename: C T
authors.initials: CT
authors.lastname: Hung
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000378:metabolism; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D002417:Cattle; D019902:Chondrocytes / Q000166:cytology; D003094:Collagen / Q000378:metabolism*; D019245:Compressive Strength / Q000502:physiology; D006026:Glycoside Hydrolases / Q000494:pharmacology; D008422:Materials Testing / Q000379:methods; D008855:Microscopy, Electron, Scanning; D011509:Proteoglycans / Q000378:metabolism; D012685:Sepharose / Q000378:metabolism; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D011509:Proteoglycans; D003094:Collagen; D012685:Sepharose; D006026:Glycoside Hydrolases; C019624:agarase
references.citation: Ann Biomed Eng. 2000 Feb;28(2):150-9
references.pmid: 10710186
references.citation: Arthritis Rheum. 2007 Jan;56(1):188-98
references.pmid: 17195221
references.citation: J Biomech Eng. 2000 Jun;122(3):252-60
references.pmid: 10923293
references.citation: Osteoarthritis Cartilage. 1994 Sep;2(3):175-85
references.pmid: 11550677
references.citation: J Orthop Res. 2001 Nov;19(6):1089-97
references.pmid: 11781010
references.citation: Osteoarthritis Cartilage. 2002 Feb;10(2):83-99
references.pmid: 11869068
references.citation: Ann Biomed Eng. 2002 Jun;30(6):792-800
references.pmid: 12220079
references.citation: J Biomech. 2003 Apr;36(4):593-8
references.pmid: 12600349
references.citation: Tissue Eng. 2003 Aug;9(4):625-34
references.pmid: 13678441
references.citation: J Biomech Eng. 2003 Oct;125(5):602-14
references.pmid: 14618919
references.citation: Osteoarthritis Cartilage. 2003 Dec;11(12):879-90
references.pmid: 14629964
references.citation: Ann Biomed Eng. 2003 Nov;31(10):1162-70
references.pmid: 14649490
references.citation: Methods Mol Med. 2004;100:307-24
references.pmid: 15280603
references.citation: Biorheology. 2004;41(3-4):445-58
references.pmid: 15299276
references.citation: Biochim Biophys Acta. 1966 Mar 28;117(1):258-61
references.pmid: 5914338
references.citation: Clin Chim Acta. 1967 Nov;18(2):267-73
references.pmid: 4864804
references.citation: J Biol Chem. 1969 Jan 10;244(1):77-87
references.pmid: 4237578
references.citation: J Biol Chem. 1969 May 25;244(10):2790-8
references.pmid: 5770002
references.citation: J Cell Biol. 1971 Jun;49(3):650-63
references.pmid: 4103953
references.citation: J Biol Chem. 1973 May 25;248(10):3681-90
references.pmid: 4267299
references.citation: In Vitro. 1977 Jul;13(7):417-22
references.pmid: 885561
references.citation: Biochim Biophys Acta. 1978 Nov 20;537(1):31-43
references.pmid: 718980
references.citation: Ann Rheum Dis. 1980 Oct;39(5):514-23
references.pmid: 7436585
references.citation: J Biomech Eng. 1981 May;103(2):61-6
references.pmid: 7278183
references.citation: Connect Tissue Res. 1982;9(4):247-8
references.pmid: 6215207
references.citation: Eur J Biochem. 1983 Dec 1;137(1-2):149-54
references.pmid: 6653550
references.citation: Biochem J. 1990 Oct 1;271(1):243-5
references.pmid: 2222415
references.citation: J Biomech Eng. 1991 Aug;113(3):245-58
references.pmid: 1921350
references.citation: Tissue Eng. 2007 Apr;13(4):683-91
references.pmid: 17266401
references.citation: J Biol Chem. 2007 Aug 24;282(34):24591-8
references.pmid: 17588949
references.citation: Osteoarthritis Cartilage. 2007 Sep;15(9):1025-33
references.pmid: 17498976
references.citation: Amino Acids. 2008 Aug;35(2):433-8
references.pmid: 17713744
references.citation: Tissue Eng Part A. 2008 Nov;14(11):1821-34
references.pmid: 18611145
references.citation: Tissue Eng Part A. 2009 Aug;15(8):2065-72
references.pmid: 19196151
references.citation: J Orthop Res. 1992 Nov;10(6):745-58
references.pmid: 1403287
references.citation: Science. 1993 May 14;260(5110):920-6
references.pmid: 8493529
references.citation: J Clin Invest. 1994 Apr;93(4):1722-32
references.pmid: 7512992
references.citation: Biotechnology (N Y). 1994 Jul;12(7):689-93
references.pmid: 7764913
references.citation: Biophys J. 1996 Feb;70(2):1017-23
references.pmid: 8789119
references.citation: Osteoarthritis Cartilage. 1993 Apr;1(2):137-46
references.pmid: 8886090
references.citation: Arch Biochem Biophys. 1998 Mar 15;351(2):207-19
references.pmid: 9515057
references.citation: Electrophoresis. 1998 Jul;19(10):1606-10
references.pmid: 9719534
references.citation: J Cell Biochem. 1998 Dec 1;71(3):313-27
references.pmid: 9831069
references.citation: J Orthop Res. 2005 Jan;23(1):134-41
references.pmid: 15607885
references.citation: Biophys J. 2005 Sep;89(3):1543-50
references.pmid: 15980166
references.citation: Osteoarthritis Cartilage. 2005 Sep;13(9):828-36
references.pmid: 16006153
references.citation: J Biomech. 2006;39(8):1489-97
references.pmid: 15990101
references.citation: Cell. 1982 Aug;30(1):215-24
references.pmid: 7127471
references.citation: Biorheology. 2006;43(3-4):497-507
references.pmid: 16912421
references.citation: Macromol Biosci. 2006 Aug 7;6(8):623-33
references.pmid: 16881042
references.citation: J Biomech. 2000 Sep;33(9):1049-54
references.pmid: 10854876