title: Allogeneic Articular Chondrocyte Transplantation Downregulates Interleukin 8 Gene Expression in the Degenerating Rabbit Intervertebral Disk In Vivo.
abstract: OBJECTIVE
  The aim of this study was to investigate whether repopulating the degenerating intervertebral disk (IVD) with articular chondrocytes will decrease inflammation in the degenerating rabbit IVD.
  
  
  METHODS
  This was a biologic study in a rabbit IVD-injury model in vivo. Dual cell tracking methods (infrared dye labeling and adenovirus transduction) were used to demonstrate the viability of allogeneic articular chondrocytes injected into degenerating rabbit IVDs. Interleukin 8 gene expression was determined via real-time polymerase chain reaction. Infiltrating inflammatory cells (macrophages, T cells, or neutrophils) were examined with immunohistochemistry. The IVDs were also examined by routine histology.
  
  
  RESULTS
  Articular chondrocytes labeled with infrared dye were detected in the degenerating IVDs at both 2 and 8 wks after injection. At the 2-wk time point, interleukin 8 gene expression was comparable in IVDs injected with chondrocytes and in intact disks as control (P = 0.647), whereas its expression in IVDs injected with saline increased 50-fold (P = 0.028). Transgene expression of red fluorescent protein, β-galactosidase, and human bone morphogenetic protein 7 diminished at 8 wks after injection. IVDs injected with chondrocytes overexpressing human bone morphogenetic protein 7 did not show lower interleukin 8 gene expression or improved histology. Macrophages were consistently detected by immunohistochemistry in the cartilage formed around the needle insertion sites in both the saline and chondrocyte groups, whereas neither T cells nor neutrophils were detected.
  
  
  CONCLUSIONS
  Allogeneic rabbit articular chondrocyte survived in the degenerating rabbit IVDs for at least 8 wks. Cell treatment resulted in reduced IVD inflammation but did not significantly improve IVD structure.
authors.affiliation: From the Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois (YZ, AC, PS, RW, HSA); Veterans Affairs Medical Center, Philadelphia, Pennsylvania (YZ); Department of Physical Medicine and Rehabilitation, Perelman School of Medicine, University of Pennsylvania, Philadelphia (YZ); Department of Orthopedic Surgery, University of Connecticut Health Center, Hartford (IM); Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois (E-YC); and Department of Orthopaedic Surgery and Rehabilitation Medicine, University of Chicago, Chicago, Illinois (T-CH).
authors.forename: Yejia
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ana
authors.initials: A
authors.lastname: Chee
authors.forename: Peng
authors.initials: P
authors.lastname: Shi
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Isaac
authors.initials: I
authors.lastname: Moss
authors.forename: Er-Yun
authors.initials: EY
authors.lastname: Chen
authors.forename: Tong-Chuan
authors.initials: TC
authors.lastname: He
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
mesh_terms: D064591:Allografts; D000818:Animals; D055419:Bone Morphogenetic Protein 7 / Q000235:genetics*; D017690:Cell Transplantation / Q000379:methods; D019902:Chondrocytes / Q000637:transplantation*; D004195:Disease Models, Animal; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006084:Graft Rejection; D006085:Graft Survival; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics*; D055959:Intervertebral Disc Degeneration / Q000235:genetics* / Q000601:surgery*; D011817:Rabbits; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity
chemical_list: C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D016209:Interleukin-8