title: Fabrication and in vitro evaluation of an articular cartilage extracellular matrix-hydroxyapatite bilayered scaffold with low permeability for interface tissue engineering.
abstract: BACKGROUND
  Osteochondral interface regeneration is challenging for functional and integrated cartilage repair. Various layered scaffolds have been used to reconstruct the complex interface, yet the influence of the permeability of the layered structure on cartilage defect healing remains largely unknown.
  
  
  METHODS
  We designed and fabricated a novel bilayered scaffold using articular cartilage extracellular matrix (ACECM) and hydroxyapatite (HAp), involving a porous, oriented upper layer and a dense, mineralised lower layer. By optimising the HAp/ACECM ratio, differing pore sizes and porosities were obtained simultaneously in the two layers. To evaluate the effects of permeability on cell behaviour, rabbit chondrocytes were seeded.
  
  
  RESULTS
  Morphological observations demonstrated that a gradual interfacial region was formed with pore sizes varying from 128.2 ± 20.3 to 21.2 ± 3.1 μm. The permeability of the bilayered scaffold decreased with increasing compressive strain and HAp content. Mechanical tests indicated that the interface was stable to bearing compressive and shear loads. Accordingly, the optimum HAp/ACECM ratio (7 w/v%) in the layer to mimic native calcified cartilage was found. Chondrocytes could not penetrate the interface and resided only in the upper layer, where they showed high cellularity and abundant matrix deposition.
  
  
  CONCLUSIONS
  Our findings suggest that a bilayered scaffold with low permeability, rather than complete isolation, represents a promising candidate for osteochondral interface tissue engineering.
authors.forename: Yongcheng
authors.initials: Y
authors.lastname: Wang
authors.forename: Haoye
authors.initials: H
authors.lastname: Meng
authors.forename: Xueling
authors.initials: X
authors.lastname: Yuan
authors.forename: Jiang
authors.initials: J
authors.lastname: Peng
authors.forename: Quanyi
authors.initials: Q
authors.lastname: Guo
authors.forename: Shibi
authors.initials: S
authors.lastname: Lu
authors.affiliation: Institute of Orthopaedics, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, China. way301@126.com.
authors.forename: Aiyuan
authors.initials: A
authors.lastname: Wang
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology*; D002470:Cell Survival / Q000187:drug effects; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D017886:Durapatite / Q000378:metabolism / Q000494:pharmacology*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D005240:Feasibility Studies; D055595:Mechanical Phenomena; D008903:Minerals / Q000378:metabolism; D010539:Permeability; D016062:Porosity; D011817:Rabbits; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds
chemical_list: D008903:Minerals; D017886:Durapatite