title: Repair of osteochondral defect with tissue-engineered chondral plug in a rabbit model.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the macroscopic and histologic results of transplanting a tissue-engineered chondral plug made of atelocollagen sponge and PLLA mesh to treat osteochondral defects.
  
  
  METHODS
  Controlled experimental study.
  
  
  METHODS
  Twelve-week-old male Japanese white rabbits were used. Fresh articular cartilage slices were taken from the humeral head, and isolated chondrocytes were embedded in atelocollagen gel which does not have antigenic portions of collagen (2.0 x 10(6) cells/mL). They were seeded on the top of the atelocollagen sponge/PLLA mesh composite and cultured for 2 weeks. The culture medium was changed every 3 days and L-ascorbic acid (50 microg/mL) was added every 2 days. Culturing the composites for 2 weeks produced tissue-engineered chondral plugs. These tissue-engineered chondral plugs (4-mm diameter, 4-mm thick) were transplanted into the osteochondral defects (4 mm diameter, 4 mm deep) in the patellar grooves of the same rabbits from which the chondrocytes had been harvested (the experimental group). In the control group, the defects were treated with the plugs without chondrocytes. The rabbits were killed 4 and 12 weeks after transplantation. The repaired tissues were evaluated macroscopically and histologically, and analyzed immunohistochemically for expression of type II collagen.
  
  
  RESULTS
  Four weeks after transplantation in the experimental group, the defects were partially repaired with cartilage-like tissue with good subchondral bone formation. Twelve weeks after transplantation, the defects were repaired with hyaline cartilage-like tissue densely stained by Safranin O. Well-organized subchondral bone formation was also observed. In the control group, the defects were covered with only soft fibrous tissue at 4 and 12 weeks macroscopically. Immunohistochemically, type II collagen was detected in about 90% of the repaired area. Histologic scores in the experimental group were significantly higher than those in the control group at both 4 and 12 weeks after transplantation.
  
  
  CONCLUSIONS
  This study shows that the defects treated with tissue engineered chondral plug developed type II collagen in about 90% of the repaired area.
  
  
  CONCLUSIONS
  The transplantation of a tissue-engineered chondral plug will be one option for treating osteochondral defects. The next step in testing our hypothesis is to evaluate the repaired tissue biomechanically and biochemically over a longer period of time.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Ito
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ochi
authors.forename: Nobuo
authors.initials: N
authors.lastname: Adachi
authors.forename: Katsura
authors.initials: K
authors.lastname: Sugawara
authors.forename: Shinobu
authors.initials: S
authors.lastname: Yanada
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Ikada
authors.forename: Panjaphongse
authors.initials: P
authors.lastname: Ronakorn
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000166:cytology*; D002478:Cells, Cultured / Q000637:transplantation; D019902:Chondrocytes / Q000378:metabolism / Q000637:transplantation*; D003094:Collagen; D024043:Collagen Type II / Q000096:biosynthesis; D005269:Femur / Q000601:surgery* / Q000648:ultrastructure; D005781:Gelatin Sponge, Absorbable; D005782:Gels; D006811:Humerus; D008297:Male; D011091:Polyesters; D011817:Rabbits; D013526:Surgical Mesh; D023822:Tissue Engineering; D014945:Wound Healing
chemical_list: D024043:Collagen Type II; D005782:Gels; D011091:Polyesters; C059821:atelocollagen; C033616:poly(lactide); D003094:Collagen