title: Region-Specific Effect of the Decellularized Meniscus Extracellular Matrix on Mesenchymal Stem Cell-Based Meniscus Tissue Engineering.
abstract: BACKGROUND
  The meniscus is the most commonly injured knee structure, and surgical repair is often ineffective. Tissue engineering-based repair or regeneration may provide a needed solution. Decellularized, tissue-derived extracellular matrices (ECMs) have received attention for their potential use as tissue-engineered scaffolds. In considering meniscus-derived ECMs (mECMs) for meniscus tissue engineering, it is noteworthy that the inner and outer regions of the meniscus have different structural and biochemical features, potentially directing the differentiation of cells toward region-specific phenotypes.
  
  
  OBJECTIVE
  To investigate the applicability of mECMs for meniscus tissue engineering by specifically comparing region-dependent effects of mECMs on 3-dimensional constructs seeded with human bone marrow mesenchymal stem cells (hBMSCs).
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Bovine menisci were divided into inner and outer halves and were minced, treated with Triton X-100 and DNase, and extracted with urea. Then, hBMSCs (1 × 106cells/mL) were encapsulated in a photo-cross-linked 10% polyethylene glycol diacrylate scaffold containing mECMs (60 μg/mL) derived from either the inner or outer meniscus, with an ECM-free scaffold as a control. The cell-seeded constructs were cultured with chondrogenic medium containing recombinant human transforming growth factor β3 (TGF-β3) and were analyzed for expression of meniscus-associated genes as well as for the collagen (hydroxyproline) and glycosaminoglycan content as a function of time.
  
  
  RESULTS
  Decellularization was verified by the absence of 4',6-diamidino-2-phenylindole (DAPI)-stained cell nuclei and a reduction in the DNA content. Quantitative real-time polymerase chain reaction showed that collagen type I expression was significantly higher in the outer mECM group than in the other groups, while collagen type II and aggrecan expression was highest in the inner mECM group. The collagen (hydroxyproline) content was highest in the outer mECM group, while the glycosaminoglycan content was higher in both the inner and outer mECM groups compared with the control group.
  
  
  CONCLUSIONS
  These results showed that the inner mECM enhances the fibrocartilaginous differentiation of hBMSCs, while the outer mECM promotes a more fibroblastic phenotype. Our findings support the feasibility of fabricating bioactive scaffolds using region-specific mECM preparations for meniscus tissue engineering.
  
  
  CONCLUSIONS
  This is the first report to demonstrate the feasibility of applying region-specific mECMs for the engineering of meniscus implants capable of reproducing the biphasic, anatomic, and biochemical characteristics of the meniscus, features that should contribute to the feasibility of their clinical application.
authors.affiliation: Medicine for Sports and Performing Arts, Department of Health and Sport Sciences, Osaka University Graduate School of Medicine, Osaka, Japan.|Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Shimomura
authors.affiliation: Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Rothrauff
authors.affiliation: Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors.forename: Rocky S
authors.initials: RS
authors.lastname: Tuan
mesh_terms: D062088:Acellular Dermis; D005109:Extracellular Matrix / Q000637:transplantation*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry; D008592:Menisci, Tibial / Q000637:transplantation*; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D020959:Polyethylene / Q000737:chemistry; D023822:Tissue Engineering
chemical_list: D020100:Hydrogels; D020959:Polyethylene
keywords: extracellular matrix; meniscus tissue engineering; mesenchymal stem cells; scaffold