title: Long-Term Results of Cartilage Repair after Allogeneic Transplantation of Cartilaginous Aggregates Formed from Bone Marrow-Derived Cells for Large Osteochondral Defects in Rabbit Knees.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the long-term results of cartilage repair after allogeneic transplantation of cartilaginous aggregates formed from bone marrow-derived cells.
  
  
  METHODS
  Bone marrow cells were harvested from 12-day-old rabbits. The cells were subjected to a monolayer culture, and the spindle-shaped cells attached to the flask surface were defined as bone marrow-derived mesenchymal cells. After the monolayer culture, a 3-dimensional cartilaginous aggregate was formed using a bioreactor with chondrogenesis. We created osteochondral defects, measuring 5 mm in diameter and 4 mm in depth, at the femoral trochlea of 10-week-old rabbits. Two groups were established, the transplanted group in which the cartilaginous aggregate was transplanted into the defect, and the control group in which the defect was left untreated. Twenty-six and 52 weeks after surgery, the rabbits were sacrificed and their tissue repair status was evaluated macroscopically (International Cartilage Repair Society [ICRS] score) and histologically (O'Driscoll score).
  
  
  RESULTS
  The ICRS scores were as follows: at week 26, 7.2 ± 0.5 and 7.6 ± 0.8; at week 52, 7.6 ± 1.1 and 9.7 ± 0.7, for the transplanted and control groups, respectively. O'Driscoll scores were as follows: at week 26, 12.6 ± 1.9 and 10.1 ± 1.9; at week 52, 9.6 ± 3.0 and 14.0 ± 1.4, each for transplanted and control groups, respectively. No significant differences were observed between the groups.
  
  
  CONCLUSIONS
  This study demonstrates that allogeneic transplantation of cartilaginous aggregates formed from bone marrow-derived cells produces comparable long-term results based on macroscopic and histological outcome measures when compared with osteochondral defects that are left untreated.
authors.affiliation: Department of Rehabilitation, University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan ; Department of Orthopaedics Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Yoshioka
authors.affiliation: Department of Orthopaedics Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Mishima
authors.affiliation: Department of Orthopaedics Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan ; Department of Orthopaedics Surgery, Ibaraki Medical Center, Tokyo Medical University, Inashiki, Ibaraki, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Sakai
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Uemura
keywords: allogeneic transplantation; animal model; bone marrow–derived cells; cartilage repair; long-term study