title: Tissue-engineered intervertebral discs: MRI results and histology in the rodent spine.
abstract: OBJECTIVE
  Tissue-engineered intervertebral discs (TE-IVDs) represent a new experimental approach for the treatment of degenerative disc disease. Compared with mechanical implants, TE-IVDs may better mimic the properties of native discs. The authors conducted a study to evaluate the outcome of TE-IVDs implanted into the rat-tail spine using radiological parameters and histology.
  
  
  METHODS
  Tissue-engineered intervertebral discs consist of a distinct nucleus pulposus (NP) and anulus fibrosus (AF) that are engineered in vitro from sheep IVD chondrocytes. In 10 athymic rats a discectomy in the caudal spine was performed. The discs were replaced with TE-IVDs. Animals were kept alive for 8 months and were killed for histological evaluation. At 1, 5, and 8 months, MR images were obtained; T1-weighted sequences were used for disc height measurements, and T2-weighted sequences were used for morphological analysis. Quantitative T2 relaxation time analysis was used to assess the water content and T1ρ-relaxation time to assess the proteoglycan content of TE-IVDs.
  
  
  RESULTS
  Disc height of the transplanted segments remained constant between 68% and 74% of healthy discs. Examination of TE-IVDs on MR images revealed morphology similar to that of native discs. T2-relaxation time did not differ between implanted and healthy discs, indicating similar water content of the NP tissue. The size of the NP decreased in TE-IVDs. Proteoglycan content in the NP was lower than it was in control discs. Ossification of the implanted segment was not observed. Histological examination revealed an AF consisting of an organized parallel-aligned fiber structure. The NP matrix appeared amorphous and contained cells that resembled chondrocytes.
  
  
  CONCLUSIONS
  The TE-IVDs remained viable over 8 months in vivo and maintained a structure similar to that of native discs. Tissue-engineered intervertebral discs should be explored further as an option for the potential treatment of degenerative disc disease.
authors: Department of Neurological Surgery, Weill Cornell Brain and Spine Institute, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York;
authors: Peter
authors: P
authors: Grunert
authors: Harry H
authors: HH
authors: Gebhard
authors: Robby D
authors: RD
authors: Bowles
authors: Andrew R
authors: AR
authors: James
authors: Hollis G
authors: HG
authors: Potter
authors: Michael
authors: M
authors: Macielak
authors: Katherine D
authors: KD
authors: Hudson
authors: Marjan
authors: M
authors: Alimi
authors: Douglas J
authors: DJ
authors: Ballon
authors: Eric
authors: E
authors: Aronowitz
authors: Apostolos John
authors: AJ
authors: Tsiouris
authors: Lawrence J
authors: LJ
authors: Bonassar
authors: Roger
authors: R
authors: Härtl
mesh_terms: D000818:Animals; D019902:Chondrocytes / Q000473:pathology*; D004195:Disease Models, Animal; D007403:Intervertebral Disc / Q000473:pathology / Q000637:transplantation*; D055959:Intervertebral Disc Degeneration / Q000473:pathology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery; D008297:Male; D051381:Rats; D012756:Sheep; D023822:Tissue Engineering / Q000379:methods*