title: Bone morphogenetic protein (BMP)-2 enhances the expression of type II collagen and aggrecan in chondrocytes embedded in alginate beads.
abstract: OBJECTIVE
  For autologous chondrocyte transplantation (ACT) chondrocytes are expanded in vitro. During expansion these cells may dedifferentiate. This change in phenotype is characterized by a raised expression of type I collagen and a decrease in type II collagen expression. Since high expression of type II collagen is of central importance for the properties of hyaline cartilage, we investigated if the growth factor bone morphogenetic protein-2 (BMP-2) may modulate the chondrogenic phenotype in monolayer cell cultures and in three-dimensional culture systems.
  
  
  METHODS
  Chondrocytes from articular knee cartilage of 11 individuals (average age: 39.8 years) with no history of joint disease were isolated and seeded either in monolayer cultures or embedded in alginate beads in presence or absence of human recombinant BMP-2 (hr-BMP-2). Then, cells were harvested and analysis of the chondrogenic phenotype was performed using quantitative RT-PCR, immunocytochemistry and ELISA.
  
  
  RESULTS
  Addition of BMP-2 to chondrocytes expanded in two-dimensional (2D) cultures during the first subculture (P1) had no effect on mRNA amounts encoding type II collagen and interleukin-1beta (IL-1beta). In contrast, seeding chondrocytes in three-dimensional (3D) alginate cultures raised type II collagen expression significantly and addition of BMP-2 enhanced this effect.
  
  
  CONCLUSIONS
  We conclude that chondrocytes during expansion for ACT may benefit from BMP-2 activation only when seeded in an appropriate 3D culture system.
authors.affiliation: TETEC AG, Aspenhaustrasse 25, 72770 Reutlingen, Germany.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Gründer
authors.forename: Christoph
authors.initials: C
authors.lastname: Gaissmaier
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fritz
authors.forename: Reinout
authors.initials: R
authors.lastname: Stoop
authors.forename: Peter
authors.initials: P
authors.lastname: Hortschansky
authors.forename: Jürgen
authors.initials: J
authors.lastname: Mollenhauer
authors.forename: Wilhelm K
authors.initials: WK
authors.lastname: Aicher
mesh_terms: D000328:Adult; D000368:Aged; D053674:Aggrecans; D000464:Alginates; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000502:physiology*; D002358:Cartilage, Articular / Q000502:physiology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000502:physiology* / Q000637:transplantation; D024043:Collagen Type II / Q000032:analysis* / Q000235:genetics; D016207:Cytokines / Q000235:genetics / Q000502:physiology; D004339:Drug Compounding; D016326:Extracellular Matrix Proteins / Q000032:analysis* / Q000235:genetics; D005260:Female; D015870:Gene Expression; D006801:Humans; D007375:Interleukin-1 / Q000032:analysis; D007719:Knee Joint / Q000502:physiology*; D037181:Lectins, C-Type; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011509:Proteoglycans / Q000032:analysis* / Q000235:genetics; D011994:Recombinant Proteins; D023822:Tissue Engineering / Q000379:methods; D016212:Transforming Growth Factor beta
chemical_list: D053674:Aggrecans; D000464:Alginates; C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D024043:Collagen Type II; D016207:Cytokines; D016326:Extracellular Matrix Proteins; D007375:Interleukin-1; D037181:Lectins, C-Type; D011509:Proteoglycans; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2