title: Chondrocyte death and cartilage degradation after autologous osteochondral transplantation surgery in a rabbit model.
abstract: BACKGROUND
  Autologous osteochondral transplantation surgery requires an impact force on the graft that may cause chondrocyte death and matrix degradation. This study attempted to determine the degree to which this occurs in a rabbit model shortly after the procedure.
  
  
  OBJECTIVE
  Impaction of a press-fit autologous osteochondral graft in vivo results in chondrocyte necrosis, apoptosis, and matrix degradation at early time points.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Twenty New Zealand White rabbits underwent unilateral osteochondral transplantation (OT) surgeries, and 10, bilateral sham surgeries. Fifteen animals were sacrificed at time zero (10 sham-0 limbs, 10 OT-0 limbs), and 15, 4 days after surgery (10 sham-4 limbs, 10 OT-4 limbs). Chondrocyte viability/necrosis was determined with cell vital staining. Chondrocyte apoptosis was determined by TUNEL, Bcl-2, and M30 assays. Cartilage matrix degradation was determined by routine light and polarized light microscopy and COL2-3/4C(short) immunohistochemistry. Statistical analysis was performed with a 2-way analysis of variance (P < .05).
  
  
  RESULTS
  There were significantly fewer viable cells in OT-4 than in sham-4. A similar difference in cell viability was found in OT-0 versus sham-0. There were more TUNEL-positive cells in OT-4 as compared with OT-0, sham-0, and sham-4; however, there was little or no staining of Bcl-2 and M30. Mankin scores were higher in both OT groups versus both sham groups at time zero and day 4. The OT-4 group had positive staining for COL2-3/4C(short) that corresponded with a loss of collagen birefringence at the superficial zone.
  
  
  CONCLUSIONS
  Osteochondral transplantation procedures performed by tamping a press-fit graft induce chondrocyte necrosis and matrix metalloproteinase-mediated cartilage matrix degradation. However, apoptosis was not found to a major contributor to cell death in this model.
  
  
  CONCLUSIONS
  Results of osteochondral transplantation procedures may be improved by atraumatic insertion and fixation techniques or by pharmacologic agents that can block these degradative processes.
authors.affiliation: Laboratory for Soft Tissue Research, Hospital for Special Surgery, New York, New York 10021, USA. GulottaL@HSS.edu
authors.forename: Lawrence V
authors.initials: LV
authors.lastname: Gulotta
authors.forename: Jonas R
authors.initials: JR
authors.lastname: Rudzki
authors.forename: David
authors.initials: D
authors.lastname: Kovacevic
authors.forename: Christopher C T
authors.initials: CC
authors.lastname: Chen
authors.forename: Dejan
authors.initials: D
authors.lastname: Milentijevic
authors.forename: Riley J
authors.initials: RJ
authors.lastname: Williams
mesh_terms: D000818:Animals; D017209:Apoptosis; D002356:Cartilage / Q000473:pathology* / Q000601:surgery; D017690:Cell Transplantation; D019902:Chondrocytes / Q000637:transplantation*; D023421:Models, Animal; D011817:Rabbits; D014182:Transplantation, Autologous