title: Compressive properties of cartilage-like tissues repaired in vivo with scaffold-free, tissue engineered constructs.
abstract: BACKGROUND
  It is crucial to develop an effective methodology for restoring adequate compressive properties to osteoarthritic cartilage. We have developed a scaffold-free tissue engineered construct cultured from synovium-derived mesenchymal stem cells. However, the compressive properties of cartilage-like tissues repaired with the construct have not been fully determined.
  
  
  METHODS
  Synovium-derived mesenchymal stem cells were cultured in Dulbecco's modified Eagle's medium to produce the tissue engineered construct. Implantation of the construct into cylindrically-shaped partial defects in femoral cartilage in an experimental porcine model was performed. Six months after implantation, cartilage-like tissues repaired with the construct were subjected to static and cyclic compression tests using a micro-unconfined compression test apparatus developed in our laboratory.
  
  
  RESULTS
  The developed apparatus was validated in preliminary examinations. The repaired tissues exhibited rate-dependent viscoelastic properties; the compressive modulus was slightly lower than that of normal cartilage at a rate of 4 microm/s, while no difference was observed at a rate of 100 microm/s. In contrast, the repaired tissue without the construct exhibited rate-independent, non-viscoelastic properties. In the cyclic compression test, however, the compressive strain was significantly larger in both repaired tissues as compared with normal cartilage.
  
  
  CONCLUSIONS
  Although the quasi-static compressive properties of the repaired tissue with the construct, indicating rate-dependent and viscoelastic behaviors, are comparable to normal cartilage, the cyclic compressive strain increases more rapidly than in normal cartilage. It is suggested that the differences between the tissues and normal cartilage are attributable to the increased permeability of the extracellular matrix.
authors.affiliation: Biomechanics Laboratory, Department of Mechanical Engineering, Kogakuin University, 2665-1 Nakanomachi, Hachioji, Tokyo 192-0015, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Katakai
authors.forename: M
authors.initials: M
authors.lastname: Imura
authors.forename: W
authors.initials: W
authors.lastname: Ando
authors.forename: K
authors.initials: K
authors.lastname: Tateishi
authors.forename: H
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: N
authors.initials: N
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Fujie
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000601:surgery; D019902:Chondrocytes / Q000166:cytology* / Q000637:transplantation*; D020219:Chondrogenesis; D019245:Compressive Strength; D004548:Elasticity; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D013552:Swine; D013583:Synovial Membrane / Q000166:cytology; D023822:Tissue Engineering / Q000379:methods*; D014783:Viscosity