title: Optimal amount of basic fibroblast growth factor in gelatin sponges incorporating β-tricalcium phosphate with chondrocytes.
abstract: BACKGROUND
  A gelatin sponge with slowly releasing basic fibroblast growth factor (b-FGF) enhances chondrogenesis. This study investigated the optimal amount of b-FGF in gelatin sponges to fabricate engineered cartilage.
  
  
  METHODS
  b-FGF (0, 10, 100, 500, 1000, and 2000 μg/cm(3))-impregnated gelatin sponges incorporating β-tricalcium phosphate (β-TCP) were produced. Chondrocytes were isolated from the auricular cartilage of C57B6J mice and expanded. The expanded auricular chondrocytes (10×10(6) cells/cm(3)) were seeded onto the gelatin sponges, which served as scaffolds. The construct assembly was implanted in the subcutaneous space of mice through a syngeneic fashion. Thereafter, constructs were retrieved at 2, 4, or 6 weeks.
  
  
  RESULTS
  (1) Morphology: The size of implanted constructs was larger than the size of the scaffold with 500, 1000, and 2000 μg/cm(3) b-FGF-impregnated gelatin sponges incorporating β-TCP at 4 and 6 weeks after implantation. (2) The weight of the constructs increased roughly proportional to the increase in volume of the b-FGF-impregnated scaffold at 2, 4, and 6 weeks after implantation, except in the 2000 μg/cm(3) b-FGF-impregnated constructs group. (3) Histological examination: Extracellular matrix in the center of the constructs was observed in gelatin sponges impregnated with more than 100 μg/cm(3) b-FGF at 4 weeks after implantation. The areas of cells with an abundant extracellular matrix were positive for cartilage-specific marker type 2 collagen in the constructs. (4) Protein assay: Glycosaminoglycan and collagen type 2 expression were significantly increased at 4 and 6 weeks on implantation of gelatin sponges impregnated with more than 100 μg/cm(3) b-FGF. At 6 weeks after implantation, the ratio of type 2 collagen to type 1 collagen in constructs impregnated with 100 μg/cm(3) or more b-FGF was higher than that in mice auricular cartilage.
  
  
  CONCLUSIONS
  Gelatin sponges impregnated with more than 100 μg/cm(3) b-FGF incorporating β-TCP with chondrocytes (10×10(6) cells/cm(3)) can fabricate engineered cartilage at 4 weeks after implantation.
authors.affiliation: 1 Department of Pediatric Surgery, Graduate School of Medicine, University of Tokyo , Tokyo, Japan .
authors.forename: Yushi
authors.initials: Y
authors.lastname: Otani
authors.forename: Makoto
authors.initials: M
authors.lastname: Komura
authors.forename: Hiroko
authors.initials: H
authors.lastname: Komura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ishimaru
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Konishi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Komuro
authors.forename: Kazuto
authors.initials: K
authors.lastname: Hoshi
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takato
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tabata
authors.forename: Tadashi
authors.initials: T
authors.lastname: Iwanaka
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis; D002130:Calcium Phosphates / Q000737:chemistry; D002358:Cartilage, Articular / Q000166:cytology / Q000254:growth & development*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D020219:Chondrogenesis / Q000187:drug effects / Q000502:physiology; D003692:Delayed-Action Preparations / Q000008:administration & dosage* / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004867:Equipment Design; D019544:Equipment Failure Analysis; D016222:Fibroblast Growth Factor 2 / Q000008:administration & dosage* / Q000737:chemistry; D005781:Gelatin Sponge, Absorbable / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D066330:Printing, Three-Dimensional; D023822:Tissue Engineering / Q000295:instrumentation; D054457:Tissue Scaffolds
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D003692:Delayed-Action Preparations; C485817:beta-tricalcium phosphate; D016222:Fibroblast Growth Factor 2