title: Detection of abnormalities in the superficial zone of cartilage repaired using a tissue engineered construct derived from synovial stem cells.
abstract: The present study investigated the surface structure and mechanical properties of repair cartilage generated from a tissue engineered construct (TEC) derived from synovial mesenchymal stem cells at six months post-implantation compared to those of uninjured cartilage. TEC-mediated repair tissue was cartilaginous with Safranin O staining, and had comparable macro-scale compressive properties with uninjured cartilage. However, morphological assessments revealed that the superficial zone of TEC-mediated tissue was more fibrocartilage-like, in contrast to the middle or deep zones that were more hyaline cartilage-like with Safranin O staining. Histological scoring of the TEC-mediated tissue was significantly lower in the superficial zone than in the middle and deep zones. Scanning electron microscopy showed a thick tangential bundle of collagen fibres at the most superficial layer of uninjured cartilage, while no corresponding structure was detected at the surface of TEC-mediated tissue. Immunohistochemical analysis revealed that PRG4 was localised in the superficial area of uninjured cartilage, as well as the TEC-mediated tissue. Friction testing showed that the lubrication properties of the two tissues was similar, however, micro-indentation analysis revealed that the surface stiffness of the TEC-repair tissue was significantly lower than that of uninjured cartilage. Permeability testing indicated that the TEC-mediated tissue exhibited lower water retaining capacity than did uninjured cartilage, specifically at the superficial zone. Thus, TEC-mediated tissue exhibited compromised mechanical properties at the superficial zone, properties which need improvement in the future for maintenance of long term repair cartilage integrity.
authors.affiliation: Department of Orthopaedics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Ando
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Fujie
authors.forename: Yu
authors.initials: Y
authors.lastname: Moriguchi
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Nansai
authors.forename: Kazunori
authors.initials: K
authors.lastname: Shimomura
authors.forename: David A
authors.initials: DA
authors.lastname: Hart
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Norimasa
authors.initials: N
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D002356:Cartilage / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D024022:Fibrillar Collagens / Q000648:ultrastructure; D008297:Male; D045164:Mesenchymal Stem Cell Transplantation; D010539:Permeability; D011509:Proteoglycans / Q000032:analysis; D013552:Swine; D013583:Synovial Membrane / Q000166:cytology*; D023822:Tissue Engineering; D000099158:Proteoglycan 4
chemical_list: D024022:Fibrillar Collagens; D011509:Proteoglycans; C419197:PRG4 protein, human; D000099158:Proteoglycan 4