title: Structured three-dimensional co-culture of mesenchymal stem cells with chondrocytes promotes chondrogenic differentiation without hypertrophy.
abstract: OBJECTIVE
  This study investigated a novel approach to induce chondrogenic differentiation of human mesenchymal stem cells (hMSC). We hypothesized that a structured three-dimensional co-culture using hMSC and chondrocytes would provide chondroinductive cues to hMSC without inducing hypertrophy.
  
  
  METHODS
  In an effort to promote optimal chondrogenic differentiation of hMSC, we created bilaminar cell pellets (BCPs), which consist of a spherical population of hMSC encased within a layer of juvenile chondrocytes (JC). In addition to histologic analyses, we examined proteoglycan content and expression of chondrogenic and hypertrophic genes in BCPs, JC pellets, and hMSC pellets grown in the presence or absence of transforming growth factor-β (TGFβ) following 21 days of culture in either growth or chondrogenic media.
  
  
  RESULTS
  In either growth or chondrogenic media, we observed that BCPs and JC pellets produced more proteoglycan than hMSC pellets treated with TGFβ. BCPs and JC pellets also exhibited higher expression of the chondrogenic genes Sox9, aggrecan, and collagen 2A1, and lower expression of the hypertrophic genes matrix metalloproteinase-13, Runx2, collagen 1A1, and collagen 10A1 than hMSC pellets. Histologic analyses suggest that JC promote chondrogenic differentiation of cells in BCPs without hypertrophy. Furthermore, when cultured in hypoxic and inflammatory conditions intended to mimic the injured joint microenvironment, BCPs produced significantly more proteoglycan than either JC pellets or hMSC pellets.
  
  
  CONCLUSIONS
  The BCP co-culture promotes a chondrogenic phenotype without hypertrophy and, relative to pellet cultures of hMSCs or JCs alone, is more resistant to the adverse conditions anticipated at the site of articular cartilage repair.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143-0514, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Cooke
authors.forename: A A
authors.initials: AA
authors.lastname: Allon
authors.forename: T
authors.initials: T
authors.lastname: Cheng
authors.forename: A C
authors.initials: AC
authors.lastname: Kuo
authors.forename: H T
authors.initials: HT
authors.lastname: Kim
authors.forename: T P
authors.initials: TP
authors.lastname: Vail
authors.forename: R S
authors.initials: RS
authors.lastname: Marcucio
authors.forename: R A
authors.initials: RA
authors.lastname: Schneider
authors.forename: J C
authors.initials: JC
authors.lastname: Lotz
authors.forename: T
authors.initials: T
authors.lastname: Alliston
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D006801:Humans; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: D053674:Aggrecans; D050659:Core Binding Factor Alpha 1 Subunit; D011509:Proteoglycans; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D016212:Transforming Growth Factor beta; D003094:Collagen; D053509:Matrix Metalloproteinase 13