Recombinant human osteogenic protein-1 upregulates proteoglycan metabolism of human anulus fibrosus and nucleus pulposus cells.
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.
Imai
Yoshiyuki
Y
Department of Orthopedic Surgery, Rush Medical College at Rush University Medical Center, Chicago, IL 60612, USA.
Miyamoto
Kei
K
An
Howard S
HS
Thonar
Eugene J-M A
EJ
Andersson
Gunnar B J
GB
Masuda
Koichi
K
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
C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D011509:Proteoglycans; D011994:Recombinant Proteins