title: Collagen type XII and versican are present in the early stages of cartilage tissue formation by both redifferentating passaged and primary chondrocytes.
abstract: Current approaches to cartilage tissue engineering require a large number of chondrocytes. Although chondrocyte numbers can be expanded in monolayer culture, the cells dedifferentiate and unless they can be redifferentiated are not optimal to use for cartilage repair. We took advantage of the differential effect of culture conditions on the ability of passaged and primary chondrocytes to form cartilage tissue to dissect out the extracellular matrix (ECM) molecules produced and accumulated in the early stages of passaged cell cartilage tissue formation as we hypothesized that passaged bovine cells that form cartilage accumulate a pericellular matrix that differs from cells that do not form cartilage. Twice passaged bovine chondrocytes (P2) (cartilage forming), or as a control primary chondrocytes (P0) (which do not generate cartilage), were cultured on three-dimensional membrane inserts in serum-free media. P2 redifferentiation was occurring during the first 8 days as indicated by increased expression of the chondrogenic genes Sox9, collagen type II, aggrecan, and COMP, suggesting that this is an appropriate time period to examine the ECM. Mass spectrometry showed that the P2 secretome (molecules released into the media) at 1 week had higher levels of collagen types I, III, and XII, and versican while type II collagen and COMP were found at higher levels in the P0 secretome. There was increased collagen synthesis and retention by P2 cells compared to P0 cells as early as 3 days of culture. Confocal microscopy showed that types XII, III, and II collagen, aggrecan, versican, and decorin were present in the ECM of P2 cells. In contrast, collagen types I, II, and III, aggrecan, and decorin were present in the ECM of P0 cells. As primary chondrocytes grown in serum-containing media, a condition that allows for the generation of cartilage tissue in vitro, also accumulate versican and collagen XII, this study suggests that these molecules may be necessary to provide a microenvironment that supports hyaline cartilage formation. Further study is required to determine if these molecules are also accumulated by passaged human chondrocytes and their role in promoting hyaline cartilage formation.
authors.affiliation: 1 BioEngineering of Skeletal Tissues Team, CIHR , Ottawa, Ontario, Canada .
authors.forename: Drew W
authors.initials: DW
authors.lastname: Taylor
authors.forename: Nazish
authors.initials: N
authors.lastname: Ahmed
authors.forename: Justin
authors.initials: J
authors.lastname: Parreno
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Lunstrum
authors.forename: Allan E
authors.initials: AE
authors.lastname: Gross
authors.forename: Eleftherios P
authors.initials: EP
authors.lastname: Diamandis
authors.forename: Rita A
authors.initials: RA
authors.lastname: Kandel
mesh_terms: D000818:Animals; D061249:Batch Cell Culture Techniques / Q000379:methods; D002356:Cartilage / Q000166:cytology* / Q000254:growth & development*; D002417:Cattle; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000502:physiology*; D020219:Chondrogenesis / Q000502:physiology; D024082:Collagen Type XII / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D023822:Tissue Engineering / Q000379:methods; D053675:Versicans / Q000502:physiology*
chemical_list: D024082:Collagen Type XII; D016326:Extracellular Matrix Proteins; D053675:Versicans