title: Quantification of cells expressing mesenchymal stem cell markers in healthy and osteoarthritic synovial membranes.
abstract: OBJECTIVE
  To quantify cells expressing mesenchymal stem cell (MSC) markers in synovial membranes from human osteoarthritic (OA) and healthy joints.
  
  
  METHODS
  Synovial membranes from OA and healthy joints were digested with collagenase and the isolated cells were cultured. Synovial membrane-derived cells were phenotypically characterized for differentiation experiments using flow cytometry to detect the expression of mesenchymal markers (CD29, CD44, CD73, CD90, CD105, CD117, CD166, and STRO-1) and hematopoietic markers (CD34 and CD45). Chondrogenesis was assessed by staining for proteoglycans and collagen type II, adipogenesis by using a stain for lipids, and osteogenesis by detecting calcium deposits. Coexpression of CD44, CD73, CD90, and CD105 was determined using immunofluorescence.
  
  
  RESULTS
  Cells expressing MSC markers were diffusely distributed in OA synovial membranes; in healthy synovial membrane these cells were localized in the subintimal zone. More numerous MSC markers in OA synovial membranes were observed in cells also expressing the CD90 antigen. FACS analysis showed that more than 90% of OA synovial membrane-derived cells were positive for CD44, CD73, and CD90, and negative for CD34 and CD45. OA synovial membrane-derived cells were also positive for CD29 (85.23%), CD117 (72.35%), CD105 (45.5%), and STRO-1 (49.46%). Micropellet analyses showed that the culture of cells with transforming growth factor-ß3 stimulated proteoglycan and collagen type II synthesis.
  
  
  CONCLUSIONS
  Synovial membranes from patients with OA contain more cells positive for CD44, CD90, and CD105 antigens than those from joints with undamaged cartilage.
authors.affiliation: Laboratorio de Investigación Osteoarticular y del Envejecimiento, CH Universitario A Coruña, C/Xubias 84, 15006 A Coruña, Spain.
authors.forename: Tamara
authors.initials: T
authors.lastname: Hermida-Gómez
authors.forename: Isaac
authors.initials: I
authors.lastname: Fuentes-Boquete
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Gimeno-Longas
authors.forename: Emma
authors.initials: E
authors.lastname: Muiños-López
authors.forename: Silvia
authors.initials: S
authors.lastname: Díaz-Prado
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: de Toro
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Blanco
mesh_terms: D000368:Aged; D015703:Antigens, CD / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002356:Cartilage / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D020219:Chondrogenesis / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007596:Joints / Q000378:metabolism* / Q000473:pathology; D008297:Male; D059630:Mesenchymal Stem Cells / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism* / Q000473:pathology; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology
chemical_list: D015703:Antigens, CD; D015415:Biomarkers