title: Collagen fibrillogenesis by chondrocytes in alginate.
abstract: Collagen is the primary structural component in connective tissue. The poor mechanical properties of most cell-seeded cartilage grafts used for cartilage repair can be attributed to the low level of collagen synthesized compared with native cartilage. In this study, the synthesis and assembly of collagen by chondrocytes in hydrogels were investigated, with particular attention paid to the role of cross-link formation in this process. Primary bovine chondrocytes were seeded in alginate and collagen synthesis was assessed in the presence and absence of beta-aminopropronitrile (BAPN), a potent inhibitor of the enzyme lysyl oxidase and collagen cross-link formation. Cultures on days 21, 35, and 49 were evaluated by stereology, biochemistry, and real-time reverse transcriptase-polymerase chain reaction. All measures of collagen synthesis (except hydroxyproline) significantly increased in the presence of 0.25 mM BAPN. By 35 days of culture, the average collagen fibril diameter was 62 +/- 10 nm in control cultures and 109 +/- 20 nm with BAPN supplementation. The collagen volume density increased from 5 +/- 3% in control cultures to 17 +/- 1% in the presence of BAPN. Likewise, the expression of cartilage-specific collagens (type II and XI) and aggrecan increased significantly as a result of BAPN culture. These findings demonstrate the prominent role of collagen cross-linking in collagen fibrillogenesis and suggest approaches by which collagen synthesis and assembly could be controlled in tissue-engineered constructs.
authors.affiliation: M.E. Müller Institute for Biomechanics, University of Bern, Bern, Switzerland. wong@mem.unibe.ch
authors.forename: Marcy
authors.initials: M
authors.lastname: Wong
authors.forename: Mark
authors.initials: M
authors.lastname: Siegrist
authors.forename: Veronique
authors.initials: V
authors.lastname: Gaschen
authors.forename: Yongdoo
authors.initials: Y
authors.lastname: Park
authors.forename: Werner
authors.initials: W
authors.lastname: Graber
authors.forename: Daniel
authors.initials: D
authors.lastname: Studer
mesh_terms: D000464:Alginates; D000629:Aminopropionitrile / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D003094:Collagen / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D020723:Glucuronic Acid; D006025:Glycosaminoglycans / Q000378:metabolism; D006603:Hexuronic Acids; D006909:Hydroxyproline / Q000378:metabolism
chemical_list: D000464:Alginates; D006025:Glycosaminoglycans; D006603:Hexuronic Acids; D000629:Aminopropionitrile; D020723:Glucuronic Acid; D003094:Collagen; D006909:Hydroxyproline