title: Phenotypic re-expression of near quiescent chondrocytes: The effects of type II collagen and growth factors.
abstract: After extensively expanding in monolayer culture, the cultured chondrocytes become quiescent. The aim of this study was to establish the hypothesis that the phenotypic function of extensively expanded primary chondrocytes may be restored with extracellular matrix (ECM) compositions with or without growth factors. The restoring effects of these microenvironmental factors on the near quiescent passage 9 (P9) chondrocyte were investigated. The data showed that exogenous type I collagen and type II collagen at 1:1 ratio stimulate cell proliferation greatly while type II collagen alone was enough to revive most of cartilaginous functions of near quiescent P9 chondrocytes. Exogenous type II collagen by itself was more effective in restoring cell proliferation rate, elevating glycosaminoglycan (GAG) accumulation and promoting the re-expression of type II collagen mRNAs in the near quiescent chondrocytes. The supplement of P9 chondrocytes with type II collagen plus TGF-beta1 and IGF-I appeared essential for the re-expression of aggrecan and type II collagen mRNA in monolayer culture. In 3D type II collagen construct, P9 chondrocytes appeared healthy as chondrocytes and showed clear lacuna. However, in 3D type I collagen matrix, only some P9 chondrocytes exhibited lacuna. The cartilaginous microenvironments are crucial to restoring chondrocyte-phenotypic features of the quiescent or 'dedifferentiated' chondrocytes, implicating the potential of expanding a scarcity of healthy chondrocytes for cartilage repair or regeneration.
authors.affiliation: Department of Orthopaedic Surgery, WanFang Hospital, Taipei Medical University, Taiwan.
authors.forename: Chin-Chean
authors.initials: CC
authors.lastname: Wong
authors.forename: Li-Hsuan
authors.initials: LH
authors.lastname: Chiu
authors.forename: Wen-Fu T
authors.initials: WF
authors.lastname: Lai
authors.forename: Tsung-Tan
authors.initials: TT
authors.lastname: Tsai
authors.forename: Chia-Lang
authors.initials: CL
authors.lastname: Fang
authors.forename: Shih-Ching
authors.initials: SC
authors.lastname: Chen
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Tsai
mesh_terms: D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D019902:Chondrocytes / Q000166:cytology*; D024043:Collagen Type II / Q000502:physiology*; D017931:DNA Primers; D006133:Growth Substances / Q000502:physiology*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011817:Rabbits
chemical_list: D024043:Collagen Type II; D017931:DNA Primers; D006133:Growth Substances