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 a fibronectin fragment.
  
  
  METHODS
  Thirty-two rabbits underwent injection of N-terminal 30 kDa fibronectin fragment (Fn-f) (Group A, n=12; Group B, n=4) or phosphate buffered saline (PBS) (Group C, n=12; Group D, n=4) into the lumbar discs using a 32-gauge microsyringe. Two rabbits (Group E) with no treatment 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
  (1) Histology demonstrated a progressive loss of cell numbers in NP and architecture disorganization in NP and annulus fibrosus (AF) over the study period. (2) Radiology: comparing with the PBS-injected discs, the Fn-f-injected discs exhibited no significant differences in disc heights at the 4-week time point, but significant decreases in disc heights at the 8-, 12-, and 16-week time points (P<0.01). Apparent anterior osteophytes formed at the 12-week time point and enlarged remarkably by the 16-week time point in the Fn-f-injected spines. (3) Protoglycan synthesis in the Fn-f-injected discs decreased progressively (P<0.01). At each time point, the Fn-f-injected discs showed significantly decreased proteoglycan synthesis compared with controls (P<0.05 or P<0.01).
  
  
  CONCLUSIONS
  Fn-f induced a progressively degenerative process in rabbit discs, which was consistent with the spontaneous degeneration in human. Fn-f induced degeneration seemed 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, Shandong, 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: Bin
authors.initials: B
authors.lastname: Ning
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; D002452:Cell Count; D004195:Disease Models, Animal; D005353:Fibronectins / Q000494:pharmacology*; D007278:Injections, Spinal; D007403:Intervertebral Disc / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000473:pathology; D008845:Microinjections; D010446:Peptide Fragments / Q000494:pharmacology*; D011509:Proteoglycans / Q000096:biosynthesis; D011817:Rabbits; D011859:Radiography
chemical_list: D005353:Fibronectins; D010446:Peptide Fragments; D011509:Proteoglycans; C107678:fibroblast motility-stimulating factor