title: Cartilage Derived from Bone Marrow Mesenchymal Stem Cells Expresses Lubricin In Vitro and In Vivo.
abstract: OBJECTIVE
  Lubricin expression in the superficial cartilage will be a crucial factor in the success of cartilage regeneration. Mesenchymal stem cells (MSCs) are an attractive cell source and the use of aggregates of MSCs has some advantages in terms of chondrogenic potential and efficiency of cell adhesion. Lubricin expression in transplanted MSCs has not been fully elucidated so far. Our goals were to determine (1) whether cartilage pellets of human MSCs expressed lubricin in vitro chondrogenesis, (2) whether aggregates of human MSCs promoted lubricin expression, and (3) whether aggregates of MSCs expressed lubricin in the superficial cartilage after transplantation into osteochondral defects in rats.
  
  
  METHODS
  For in vitro analysis, human bone marrow (BM) MSCs were differentiated into cartilage by pellet culture, and also aggregated using the hanging drop technique. For an animal study, aggregates of BM MSCs derived from GFP transgenic rats were transplanted to the osteochondral defect in the trochlear groove of wild type rat knee joints. Lubricin expression was mainly evaluated in differentiated and regenerated cartilages.
  
  
  RESULTS
  In in vitro analysis, lubricin was detected in the superficial zone of the pellets and conditioned medium. mRNA expression of Proteoglycan4 (Prg4), which encodes lubricin, in pellets was significantly higher than that of undifferentiated MSCs. Aggregates showed different morphological features between the superficial and deep zone, and the Prg4 mRNA expression increased after aggregate formation. Lubricin was also found in the aggregate. In a rat study, articular cartilage regeneration was significantly better in the MSC group than in the control group as shown by macroscopical and histological analysis. The transmission electron microscope showed that morphology of the superficial cartilage in the MSC group was closer to that of the intact cartilage than in the control group. GFP positive cells remained in the repaired tissue and expressed lubricin in the superficial cartilage.
  
  
  CONCLUSIONS
  Cartilage derived from MSCs expressed lubricin protein both in vitro and in vivo. Aggregation promoted lubricin expression of MSCs in vitro and transplantation of aggregates of MSCs regenerated cartilage including the superficial zone in a rat osteochondral defect model. Our results indicate that aggregated MSCs could be clinically relevant for therapeutic approaches to articular cartilage regeneration with an appropriate superficial zone in the future.
authors: Department of Joint Surgery and Sports Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.|Center for Stem Cell and Regenerative Medicine, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Yusuke
authors: Y
authors: Nakagawa
authors: Department of Joint Surgery and Sports Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Takeshi
authors: T
authors: Muneta
authors: Center for Stem Cell and Regenerative Medicine, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Koji
authors: K
authors: Otabe
authors: Center for Stem Cell and Regenerative Medicine, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Nobutake
authors: N
authors: Ozeki
authors: Center for Stem Cell and Regenerative Medicine, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Mitsuru
authors: M
authors: Mizuno
authors: Department of Joint Surgery and Sports Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Mio
authors: M
authors: Udo
authors: Department of Joint Surgery and Sports Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Ryusuke
authors: R
authors: Saito
authors: Department of Joint Surgery and Sports Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Katsuaki
authors: K
authors: Yanagisawa
authors: Research Center for Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Shizuko
authors: S
authors: Ichinose
authors: Department of Joint Surgery and Sports Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Hideyuki
authors: H
authors: Koga
authors: Department of Cartilage Regeneration, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Kunikazu
authors: K
authors: Tsuji
authors: Center for Stem Cell and Regenerative Medicine, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Ichiro
authors: I
authors: Sekiya
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D020219:Chondrogenesis; D005260:Female; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000096:biosynthesis*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D011509:Proteoglycans / Q000096:biosynthesis / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D055647:Rats, Transgenic; D012038:Regeneration; D055114:X-Ray Microtomography; D000099158:Proteoglycan 4
chemical_list: D006023:Glycoproteins; D049452:Green Fluorescent Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; D000099158:Proteoglycan 4; C419197:PRG4 protein, human; C000597446:PRG4 protein, rat