title: [Influence of in vivo or vitro microenvironment on the mechanical properties and histological structure of tissue engineered cartilage].
abstract: OBJECTIVE
  To investigate the influence of in vivo or vitro microenvironment on the mechanical properties and histological structure of tissue engineered cartilage, and to provide the appropriate parameters for cartilage construct in vitro.
  
  
  METHODS
  Human fetal articular chondrocytes were cultured and expanded in vitro, the passage 2 chondrocytes were seeded at the density of 6 x 10(7) cells/cm3 to cylindric dimensional scaffolds made by polyglycolic acid (PGA) and polylactic acid (PLA). These constructs were cultured in vitro for 4 weeks. After 4 weeks, part of samples were implanted subcutaneously into nude mice for 6 and 12 weeks, the others continued to be cultured in vitro. All specimens were harvested after 6 and 12 weeks, and evaluated by gross observation, histology, histochemistry, ultrastructure and mechanical test.
  
  
  RESULTS
  All specimens in vivo and vitro eventually formed good shape hyaline cartilage. The constructs in vivo group was white color with smooth surface, and had better mechanical properties than those in vitro, by TEM we can observe the thick and striated collagen fibers in regularly arranged collagen fibril which was similar to adult articular cartilage. The constructs in vitro group was yellow color with coarse surface, the appearance and ultrastructure was similar to fetal articular cartilage. Specimens implanted for 12 weeks in vivo had better compressive modulus(38.28 +/- 3.95) MPa and collagen diameter (41.58 +/- 2.78) nm than those cultured in vitro at the same time (4.12 +/- 0.63) MPa, (15.83 +/- 1.70) nm (P < 0. 01).
  
  
  CONCLUSIONS
  The structure and function of human tissue engineered cartilage became mature gradually from vitro to vivo, thick and striated collagen fibrils net similar to adult articular cartilage can be formed in constructs of vivo group,increased collagen cross-linking might be the reason that their mechanical properties been greatly improved.
authors.affiliation: Department of Plastic and Cosmetic Surgery, the First Peoples Hospital of Chenzhou, Chenzhou 423000, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Yan
authors.forename: Guang-Dong
authors.initials: GD
authors.lastname: Zhou
authors.forename: Yi-Lin
authors.initials: YL
authors.lastname: Cao
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002356:Cartilage / Q000502:physiology* / Q000648:ultrastructure; D002478:Cells, Cultured; D060833:Cellular Microenvironment; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds