title: Genetic enhancement of matrix synthesis by articular chondrocytes: comparison of different growth factor genes in the presence and absence of interleukin-1.
abstract: OBJECTIVE
  To determine whether articular chondrocytes express growth factor genes delivered by adenoviral vectors and whether expression of these genes influences matrix synthesis in the presence and absence of interleukin-1 (IL-1).
  
  
  METHODS
  Monolayer cultures of rabbit articular chondrocytes were infected with recombinant adenovirus carrying genes encoding the following growth factors: insulin-like growth factor 1 (IGF-1), transforming growth factor beta1 (TGFbeta1), and bone morphogenetic protein 2 (BMP-2). As a control, cells were transduced with the lac Z gene. Cultures were also treated with each growth factor supplied as a protein. Levels of gene expression were noted, and the synthesis of proteoglycan, collagen, and noncollagenous proteins was measured by radiolabeling. Collagen was typed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The effects of growth factor gene transfer on proteoglycan synthesis in the presence of IL-1 were also measured.
  
  
  RESULTS
  The expression of all transgenes was high following adenoviral transduction. Proteoglycan synthesis was stimulated approximately 8-fold by the BMP-2 gene and 2-3-fold by the IGF-1 gene. The effects of BMP-2 and IGF-1 genes were additive upon cotransduction. Synthesis of collagen and noncollagenous proteins, in contrast, was most strongly stimulated by the IGF-1 gene. In each case, collagen typing confirmed the synthesis of type II collagen. IL-1 suppressed proteoglycan synthesis by 50-60%. IGF-1 and TGFbeta genes restored proteoglycan synthesis to control levels in the presence of IL-1. The BMP-2 gene, in contrast, elevated proteoglycan synthesis beyond control levels in the presence of IL-1.
  
  
  CONCLUSIONS
  Transfer of growth factor genes to articular chondrocytes can greatly increase matrix synthesis in vitro, even in the presence of the inflammatory cytokine IL-1. This result encourages the further development of gene therapy for the repair of damaged cartilage.
authors.affiliation: University of Pittsburgh School of Medicine, Pennsylvania, USA.
authors.forename: P
authors.initials: P
authors.lastname: Smith
authors.forename: F D
authors.initials: FD
authors.lastname: Shuler
authors.forename: H I
authors.initials: HI
authors.lastname: Georgescu
authors.forename: S C
authors.initials: SC
authors.lastname: Ghivizzani
authors.forename: B
authors.initials: B
authors.lastname: Johnstone
authors.forename: C
authors.initials: C
authors.lastname: Niyibizi
authors.forename: P D
authors.initials: PD
authors.lastname: Robbins
authors.forename: C H
authors.initials: CH
authors.lastname: Evans
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000235:genetics; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression; D005822:Genetic Vectors / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D007375:Interleukin-1 / Q000494:pharmacology; D011817:Rabbits; D016212:Transforming Growth Factor beta / Q000235:genetics
chemical_list: D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D016326:Extracellular Matrix Proteins; D007375:Interleukin-1; D016212:Transforming Growth Factor beta; D007334:Insulin-Like Growth Factor I