title: Induction of superficial zone protein (SZP)/lubricin/PRG 4 in muscle-derived mesenchymal stem/progenitor cells by transforming growth factor-β1 and bone morphogenetic protein-7.
abstract: BACKGROUND
  Articular cartilage (AC) is an avascular tissue with precise polarity and organization. The three distinct zones are: surface, middle and deep. The production and accumulation of the superficial zone protein (SZP), also known as lubricin, by the surface zone is a characteristic feature of AC. To date, there is a wealth of evidence showing differentiation of AC from mesenchymal stem cells. Most studies that described chondrogenic differentiation did not focus on AC with characteristic surface marker SZP/lubricin. The present investigation was initiated to determine the induction of SZP/lubricin in skeletal muscle-derived mesenchymal stem/progenitor cells (MDMSCs) by transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7).
  
  
  METHODS
  MDMSCs were cultured as a monolayer at a density of 1 × 105 cells/well in 12-well tissue culture plates. Cell cultures were treated for 3, 7 and 10 days with TGF-β1 and BMP-7. The medium was analyzed for SZP. The cells were used to isolate RNA for RT-PCR assays for SZP expression.
  
  
  RESULTS
  The SZP/lubricin increased in a time-dependent manner on Days 3, 7 and 10 in the medium. As early as Day 3, there was a three-fold increase in response to 3 ng/ml of TGF-β1 and 300 ng/ml of BMP-7. This was confirmed by immunochemical localization of SZP as early as Day 3 after treatment with TGF-β1. The expression of SZP mRNA was enhanced by TGF-β1.
  
  
  CONCLUSIONS
  The present investigation demonstrated the efficient and reproducible induction of SZP/lubricin accumulation by TGF-β1 and BMP-7 in skeletal MDMSCs. Optimization of the experimental conditions may permit the utility of MDMSCs in generating surface zone-like cells with phenotypic markers of AC and, therefore, constitute a promising cell source for tissue engineering approaches of superficial zone cartilage.
authors.affiliation: Department of Cell Biology, Genetic and Physiology, Faculty of Sciences, Networking Biomedical Research Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), University of Málaga, 29071-Málaga, Spain. andrades@uma.es
authors.forename: José A
authors.initials: JA
authors.lastname: Andrades
authors.forename: Shirley C
authors.initials: SC
authors.lastname: Motaung
authors.forename: Pedro
authors.initials: P
authors.lastname: Jiménez-Palomo
authors.forename: Silvia
authors.initials: S
authors.lastname: Claros
authors.forename: José M
authors.initials: JM
authors.lastname: López-Puerta
authors.forename: José
authors.initials: J
authors.lastname: Becerra
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Schmid
authors.forename: A Hari
authors.initials: AH
authors.lastname: Reddi
mesh_terms: D000818:Animals; D055419:Bone Morphogenetic Protein 7 / Q000494:pharmacology* / Q000502:physiology; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D006023:Glycoproteins / Q000096:biosynthesis*; D059630:Mesenchymal Stem Cells / Q000187:drug effects / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011509:Proteoglycans / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology* / Q000502:physiology; D000099158:Proteoglycan 4
chemical_list: D055419:Bone Morphogenetic Protein 7; D006023:Glycoproteins; D011509:Proteoglycans; D053773:Transforming Growth Factor beta1; D000099158:Proteoglycan 4; C419197:PRG4 protein, human