title: Herniated intervertebral disk induces hypertrophy and ossification of ligamentum flavum.
abstract: METHODS
  In vitro experiment using degenerated human ligamentum flavum (LF) and herniated intervertebral disk (IVD).
  
  
  OBJECTIVE
  To investigate the role and effect of degenerated and herniated IVDs on LF hypertrophy and ossification.
  
  
  BACKGROUND
  Spinal stenosis is caused, in part, by hypertrophy and ossification of the LF, which are induced by aging and degenerative process. It is well known that degenerated IVDs spontaneously produce inflammatory cytokines. Therefore, we hypothesized that degenerated IVD may affect adjacent LF through secreted inflammatory cytokines.
  
  
  METHODS
  LF and herniated lumbar IVD tissues were obtained during surgical spinal procedures. LF fibroblasts were isolated by enzymatic digestion of LF tissue. LF cell cultures were treated with disk supernatant from herniated IVDs. Secreted cytokines from IVD tissue culture were detected by enzyme-linked immunosorbent assay. After analysis of cytotoxicity, DNA synthesis was measured. Reverse transcription-polymerase chain reaction for mRNA expressions of types I, II, III, V, and XI collagen and osteocalcin, and histochemical stains were performed.
  
  
  RESULTS
  Supernatant from tissue culture of herniated IVD showed increased production of interleukin-1α, interleukin-6, tumor necrosis factor-α, prostaglandin E2, and nitric oxide compared with disk tissue culture from traumatic condition. There was no cytotoxicity in LF cells treated with disk supernatant from herniated IVDs. There was significant increase in DNA synthesis, upregulation in mRNA expression of types III, XI collagen and osteocalcin, whereas variable expression pattern of type I and V, and strong positive stains for Von Kossa and alkaline phosphatase in LF cultures with disk supernatant.
  
  
  CONCLUSIONS
  Degenerated and herniated IVDs provide an important pathomechanism in hypertrophy and ossification of the LF through inflammatory cytokines.
authors.affiliation: *Brain Korea 21, Medical Science Graduated School †Department of Orthopaedic Surgery, Yonsei University College of Medicine ‡Department of Orthopaedic Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Kang
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Suk
authors.forename: Byung Ho
authors.initials: BH
authors.lastname: Lee
authors.forename: Hak-Sun
authors.initials: HS
authors.lastname: Kim
authors.forename: Kwang-Il
authors.initials: KI
authors.lastname: Lee
authors.forename: Si-Young
authors.initials: SY
authors.lastname: Park
authors.forename: Hwan-Mo
authors.initials: HM
authors.lastname: Lee
authors.forename: Seong-Hwan
authors.initials: SH
authors.lastname: Moon
mesh_terms: D000368:Aged; D000469:Alkaline Phosphatase / Q000378:metabolism; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D015232:Dinoprostone / Q000276:immunology / Q000378:metabolism; D006801:Humans; D006984:Hypertrophy / Q000276:immunology / Q000473:pathology; D007155:Immunologic Factors; D053582:Interleukin-1alpha / Q000276:immunology / Q000378:metabolism; D015850:Interleukin-6 / Q000276:immunology / Q000378:metabolism; D007403:Intervertebral Disc / Q000276:immunology / Q000473:pathology / Q000601:surgery; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000276:immunology* / Q000601:surgery; D017843:Ligamentum Flavum / Q000276:immunology / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D009999:Ossification, Heterotopic / Q000209:etiology / Q000276:immunology / Q000473:pathology*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013130:Spinal Stenosis / Q000276:immunology / Q000473:pathology / Q000601:surgery; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism
chemical_list: D016207:Cytokines; C508600:IL6 protein, human; D007155:Immunologic Factors; D053582:Interleukin-1alpha; D015850:Interleukin-6; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015675:Osteocalcin; D009569:Nitric Oxide; D003094:Collagen; D000469:Alkaline Phosphatase; D015232:Dinoprostone