title: Cell therapy: a therapeutic alternative to treat focal cartilage lesions.
abstract: BACKGROUND
  Human mesenchymal stem cells (MSCs) are present in most of the tissue matrix, taking part in their regeneration when injury or damage occurs. The aim of this study was to investigate the presence of cells with pluripotential characteristics in synovial membranes from osteoarthritic (OA) patients and the capacity of these cells to differentiate to chondrocytes.
  
  
  METHODS
  Synovial membranes (n = 8) from OA patients were digested with collagenase. Isolated cells were cultured with DMEM, 20% FBS, and FGFb10 ng/mL. Cells from second subculture were used to carry out phenotypic characterization experiments (flow cytometry analysis with 11 monoclonal antibodies) and chondrogenic differentiation experiments(micropellet cultured in chondrogenic medium). Chondrogenic differentiation of cells was assessment by quantification of cartilage extracellular matrix components by following techniques: Safranin O, Toluidine Blue, and Alcian Blue stains to detect proteoglycans and immunohistochemistry to detect type I and II collagen.
  
  
  RESULTS
  Flow cytometry analyses showed that in our population more than 90% of cells were positive for MSC markers: CD29 (95%), CD44 (90%), CD73 (95%), CD90 (98%). Cells were negative for hematopoietic markers (CD11b, CD34, and CD45). Furthermore, cells showed positive stain to multipotent markers such as CD117 (c-kit) (98%), CD166 (74%), and STRO-1 (88%) and to quiescent satellite cells like PAX-7 (35%). The micropellet analyses showed that the culture of these cells with TGFbeta-3 for 2 and 3 weeks stimulates proteoglycan and collagen type II synthesis. Both molecules are characteristic of hyaline articular cartilage.
  
  
  CONCLUSIONS
  In this work, we demonstrate the presence of a cellular population with MSC characteristics in synovial tissue from OA patients. As MSC takes part in reparative processes of adult tissues, these cells could play an important role in OA pathogenesis and treatment.
authors.affiliation: Unidad de Investigación del Envejecimiento Osteoarticular and Cátedra Bioiberica de Terapia Celular, Universidade da Coruña, CH Universitario Juan Canalejo, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Gimeno
authors.forename: E
authors.initials: E
authors.lastname: Maneiro
authors.forename: E
authors.initials: E
authors.lastname: Rendal
authors.forename: M
authors.initials: M
authors.lastname: Ramallal
authors.forename: L
authors.initials: L
authors.lastname: Sanjurjo
authors.forename: F J
authors.initials: FJ
authors.lastname: Blanco
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D002356:Cartilage / Q000293:injuries*; D002454:Cell Differentiation; D019902:Chondrocytes / Q000166:cytology*; D005434:Flow Cytometry; D006801:Humans; D010003:Osteoarthritis / Q000473:pathology* / Q000503:physiopathology*; D033581:Stem Cell Transplantation / Q000379:methods*; D013234:Stem Cells / Q000166:cytology / Q000502:physiology; D013583:Synovial Membrane / Q000473:pathology / Q000503:physiopathology
chemical_list: D015703:Antigens, CD