title: Recombinant human osteogenic protein-1 upregulates proteoglycan metabolism of human anulus fibrosus and nucleus pulposus cells.
abstract: METHODS
  In vitro assessment of the effects of recombinant human osteogenic protein-1 (rhOP-1) on the proteoglycan metabolism of human intervertebral disc cells.
  
  
  OBJECTIVE
  To determine whether rhOP-1 is effective in stimulating the cell proliferation and proteoglycan metabolism of human intervertebral disc cells cultured in alginate beads.
  
  
  BACKGROUND
  OP-1 has been shown to stimulate the proteoglycan and collagen synthesis of rabbit intervertebral disc cells in vitro. In vivo, a single injection of rhOP-1 restored the disc height of a degenerated disc in the rabbit anular-puncture model. The effect of rhOP-1 on human intervertebral disc cells remains unknown.
  
  
  METHODS
  Human nucleus pulposus and anulus fibrosus cells were isolated from the discs of 4 cadaveric spines and one surgical specimen. After preculture for 7 days, alginate beads containing nucleus pulposus and anulus fibrosus cells were cultured for 21 days in media containing 10% fetal bovine serum with 0, 100, or 200 ng/mL rhOP-1 and supplements. The synthesis and accumulation of proteoglycans and the DNA content were biochemically assessed.
  
  
  RESULTS
  The addition of rhOP-1 to the media resulted in the prevention of a decreased cell number during culture. Treatment with rhOP-1, compared with the control condition (10% fetal bovine serum), significantly upregulated proteoglycan synthesis and accumulation in alginate beads in all cases tested. A longer exposure over 14 days to rhOP-1 resulted in a pronounced response. The retention of newly-synthesized proteoglycan was higher in the rhOP-1-treated cells than in the control.
  
  
  CONCLUSIONS
  rhOP-1 was effective in stimulating the cell proliferation and proteoglycan metabolism of human intervertebral disc cells in vitro. The results supported the hypothesis that an in vivo injection of rhOP-1 may increase the metabolic activity of disc cells or prevent apoptosis of disc cells in a degenerated disc. However, the requirement for a long exposure to rhOP-1 for human cells may suggest the need for a prolonged supply of rhOP-1 by a drug delivery system or by repeated injections.
authors.affiliation: Department of Orthopedic Surgery, Rush Medical College at Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Imai
authors.forename: Kei
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
authors.forename: Eugene J-M A
authors.initials: EJ
authors.lastname: Thonar
authors.forename: Gunnar B J
authors.initials: GB
authors.lastname: Andersson
authors.forename: Koichi
authors.initials: K
authors.lastname: Masuda
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000378:metabolism* / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D006801:Humans; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D007405:Intervertebral Disc Displacement / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D011509:Proteoglycans / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D011509:Proteoglycans; D011994:Recombinant Proteins