title: Characterization of human adipose-derived stem cells and expression of chondrogenic genes during induction of cartilage differentiation.
abstract: OBJECTIVE
  Understanding the changes in chondrogenic gene expression that are involved in the differentiation of human adipose-derived stem cells to chondrogenic cells is important prior to using this approach for cartilage repair. The aims of the study were to characterize human adipose-derived stem cells and to examine chondrogenic gene expression after one, two, and three weeks of induction.
  
  
  METHODS
  Human adipose-derived stem cells at passage 4 were evaluated by flow cytometry to examine the expression of surface markers. These adipose-derived stem cells were tested for adipogenic and osteogenic differentiation capacity. Ribonucleic acid was extracted from the cells for quantitative polymerase chain reaction analysis to determine the expression levels of chondrogenic genes after chondrogenic induction.
  
  
  RESULTS
  Human adipose-derived stem cells were strongly positive for the mesenchymal markers CD90, CD73, CD44, CD9, and histocompatibility antigen and successfully differentiated into adipogenic and osteogenic lineages. The human adipose-derived stem cells aggregated and formed a dense matrix after chondrogenic induction. The expression of chondrogenic genes (collagen type II, aggrecan core protein, collagen type XI, COMP, and ELASTIN) was significantly higher after the first week of induction. However, a significantly elevated expression of collagen type X was observed after three weeks of chondrogenic induction.
  
  
  CONCLUSIONS
  Human adipose-derived stem cells retain stem cell characteristics after expansion in culture to passage 4 and serve as a feasible source of cells for cartilage regeneration. Chondrogenesis in human adipose-derived stem cells was most prominent after one week of chondrogenic induction.
authors.affiliation: Universiti Kebangsaan Malaysia, Department of Physiology, Faculty of Medicine, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia.
authors.forename: Adila A
authors.initials: AA
authors.lastname: Hamid
authors.forename: Ruszymah Bt Hj
authors.initials: RB
authors.lastname: Idrus
authors.forename: Aminuddin Bin
authors.initials: AB
authors.lastname: Saim
authors.forename: Somasumdaram
authors.initials: S
authors.lastname: Sathappan
authors.forename: Kien-Hui
authors.initials: KH
authors.lastname: Chua
mesh_terms: D050156:Adipogenesis / Q000235:genetics; D000273:Adipose Tissue / Q000166:cytology*; D015415:Biomarkers / Q000378:metabolism; D002358:Cartilage, Articular / Q000166:cytology*; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D020219:Chondrogenesis / Q000235:genetics*; D003094:Collagen / Q000235:genetics / Q000378:metabolism*; D004549:Elastin / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor; D003094:Collagen; D004549:Elastin