title: Exogenous collagen-enhanced recruitment of mesenchymal stem cells during rabbit articular cartilage repair.
abstract: BACKGROUND
  Despite the well-known effect of type-I collagen in promoting cartilage repair, the mechanism still remains unknown. In this study we investigated this mechanism using a rabbit model of cartilage defects.
  
  
  METHODS
  5-mm-diameter full-thickness defects were created on both patellar grooves of 53 Japanese white rabbits (approximately 13 weeks old). The left defect was filled with collagen gel and the right defect was left empty. The rabbits were killed and examined morphometrically until the twenty-fourth postoperative week, by (1) evaluation of matrix production, (2) enumeration of the total number of cells engaged in cartilage repair, (3) enumeration of the proliferating cells, (4) localization of mesenchymal stem cells, and (v) localization of apoptotic cells.
  
  
  RESULTS
  We found that type-I collagen enhances cell recruitment, and thereby increases the number of proliferating cells. A considerable proportion of the proliferating cells were identified as bone marrow-derived mesenchymal stem cells. However, type-I collagen does not prevent the chondrocyte precursors from undergoing apoptotic disengagement from the chondrogenic lineage.
  
  
  CONCLUSIONS
  Type-I collagen promotes cartilage repair by enhancing recruitment of bone marrow-derived mesenchymal stem cells. Additional use of agent(s) that sustain mesenchymal stem cells along the chondrogenic path of differentiation may constitute an appropriate environment for cartilage repair.
authors.affiliation: Department of Orthopedic Surgery, Shiga University of Medical Science, Japan. mkubo@belle.shiga-med.ac.jp
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Kubo
authors.forename: Shinji
authors.initials: S
authors.lastname: Imai
authors.forename: Mineko
authors.initials: M
authors.lastname: Fujimiya
authors.forename: Eiji
authors.initials: E
authors.lastname: Isoya
authors.forename: Kosei
authors.initials: K
authors.lastname: Ando
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Mimura
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Matsusue
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D020219:Chondrogenesis / Q000187:drug effects; D024042:Collagen Type I / Q000008:administration & dosage* / Q000502:physiology; D048091:Guided Tissue Regeneration; D059630:Mesenchymal Stem Cells / Q000187:drug effects* / Q000502:physiology; D011817:Rabbits; D014945:Wound Healing / Q000187:drug effects
chemical_list: D024042:Collagen Type I