title: Characterization of human primary chondrocytes of osteoarthritic cartilage at varying severity.
abstract: BACKGROUND
  There is a difficulty in evaluating the in vivo functionality of individual chondrocytes, and there is much heterogeneity among cartilage affected by osteoarthritis (OA). In this study, in vitro cultured chondrocytes harvested from varying stages of degeneration were studied as a projective model to further understand the pathogenesis of osteoarthritis.
  
  
  METHODS
  Cartilage of varying degeneration of end-stage OA was harvested, while cell yield and matrix glycosaminoglycan (GAG) content were measured. Cell morphology, proliferation, and gene expression of collagen type I, II, and X, aggrecan, matrix metalloproteinase 13 (MMP-13), and ADAMTS5 of the acquired chondrocytes were measured during subsequent in vitro culture.
  
  
  RESULTS
  Both the number of cells and the GAG content increased with increasing severity of OA. Cell spreading area increased and gradually showed spindle-like morphology during in vitro culture. Gene expression of collagen type II, collagen type X as well as GAG decreased with severity of cartilage degeneration, while expression of collagen type I increased. Expression of MMP-13 increased with severity of cartilage degeneration, while expression of ADAMTS-5 remained stable. Expression of collagen type II, X, GAG, and MMP-13 substantially decreased with in vitro culture. Expression of collagen type I increased with in vitro cultures, while expression of ADAMTS 5 remained stable.
  
  
  CONCLUSIONS
  Expression of functional genes such as collagen type II and GAG decreased during severe degeneration of OA cartilage and in vitro dedifferentiation. Gene expression of collagen I and MMP-13 increased with severity of cartilage degeneration.
authors.affiliation: Department of Biomedical Engineering, College of Engineering, Peking University, Beijing 100871, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yin
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yang
authors.forename: Yong-Ping
authors.initials: YP
authors.lastname: Cao
authors.forename: Zi-Gang
authors.initials: ZG
authors.lastname: Ge
mesh_terms: D051722:ADAM Proteins; D000071116:ADAMTS5 Protein; D002356:Cartilage / Q000473:pathology*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics; D024121:Collagen Type X / Q000235:genetics; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D053509:Matrix Metalloproteinase 13 / Q000235:genetics; D010003:Osteoarthritis / Q000235:genetics* / Q000473:pathology*
chemical_list: D024043:Collagen Type II; D024121:Collagen Type X; D006025:Glycosaminoglycans; D051722:ADAM Proteins; D000071116:ADAMTS5 Protein; C121532:ADAMTS5 protein, human; D053509:Matrix Metalloproteinase 13