title: [A novel rabbit disc degeneration model induced by fibronectin fragment].
abstract: OBJECTIVE
  To establish a novel and useful rabbit model of lumbar disc degeneration using microinjection of fibronectin fragment (Fn-f).
  
  
  METHODS
  Thirty-two New Zealand white rabbits underwent injection of N-terminal 30 kDa Fn-f (experimental group) or phosphate buffered saline (PBS) (control group) into the central region of L1-2, L2-3, L3-4, L4-5 discs using a 32-gauge microsyringe. Two rabbits (blank group) with no treatments were sacrificed to examine the proteoglycan synthesis of neucleus pulposus (NP) using (35)S-sulfate incorporation assay. At the 4-, 8-, 12-, and 16-week time points, the discs were examined histologically, radiographically, and with proteoglycan synthesis.
  
  
  RESULTS
  Histology demonstrated a progressive loss of the cell numbers in NP and architecture destruction in NP and anulus fibrosus (AF) in Fn-f-injected discs over the 16-week study period. The NP regions in Fn-f-injected discs shrinked distinctly after the 4-week time point, and were not discernible with the inner AF by the 16-week time point. Protoglycan synthesis in Fn-f-injected discs decreased progressively (F = 263.241, P = 0.000). At each time point, the Fn-f-injected discs showed significantly decreased proteoglycan synthesis compared with controls (t = -27.010 - -2.833, P < 0.05). The DHI% of the Fn-f-injected discs at the 4-, 8-, 12-, and 16-week time points were 96.5% ± 1.7%, 85.6% ± 3.8%, 77.2% ± 3.5% and 65.5% ± 5.6%, respectively. Comparing with the DHI% of PBS-injected discs (97.4% ± 1.2%), the Fn-f-injected discs exihibited no significant differences in disc heights at the 4-week time point (P > 0.05), but significant decreases in disc heights at the 8-, 12-, and 16-week time points (t = -21.225 - -10.795, P < 0.01). Apparent anterior osteophytes formed at the 12-week time point and enlarged remarkablely by the 16-week time point in the experimental spines.
  
  
  CONCLUSIONS
  Fn-f can induce a progressively degenerative process in rabbit discs which is ethical, cost-effective, reproducible, and consistent with the spontaneous degeneration in human. And it seem to be a novel and useful model for the study of disc degeneration at the molecular level.
authors.affiliation: Department of Orthopedic Surgery, the Affiliated Hospital of Medical College, Qingdao University, Qingdao 266003, China.
authors.forename: Hai-fei
authors.initials: HF
authors.lastname: Liu
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.forename: Guang-xi
authors.initials: GX
authors.lastname: Qiao
authors.forename: Hao
authors.initials: H
authors.lastname: Tao
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Yan-ling
authors.initials: YL
authors.lastname: Hu
authors.forename: De-chun
authors.initials: DC
authors.lastname: Wang
authors.forename: You-gu
authors.initials: YG
authors.lastname: Hu
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005353:Fibronectins / Q000494:pharmacology*; D055959:Intervertebral Disc Degeneration / Q000139:chemically induced*; D008159:Lumbar Vertebrae; D011817:Rabbits; D011897:Random Allocation
chemical_list: D005353:Fibronectins