Detection of abnormalities in the superficial zone of cartilage repaired using a tissue engineered construct derived from synovial stem cells

• Published in: European cells & materials 2012-09, Vol.24, p.292-307
• Main Authors: Ando, Wataru, Fujie, Hiromichi, Moriguchi, Yu, Nansai, Ryosuke, Shimomura, Kazunori, Hart, David A, Yoshikawa, Hideki, Nakamura, Norimasa
• Format: Article
• Language: English
• Subjects: animal model; Animals; Cartilage - anatomy & histology; Cartilage - metabolism; Cartilage - physiology; Cartilage tissue engineering; Fibrillar Collagens - ultrastructure; image analysis; Male; mechanical properties; mechanical test; Mesenchymal Stem Cell Transplantation; microstructure; Permeability; Proteoglycans - analysis; Swine; Synovial Membrane - cytology; Tissue Engineering
• ISSN: 1473-2262; 1473-2262
• DOI: 10.22203/ecm.v024a21

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.