Recombinant human osteogenic protein-1 upregulates proteoglycan metabolism of human anulus fibrosus and nucleus pulposus cells

• Published in: Spine (Philadelphia, Pa. 1976) Pa. 1976), 2007-05, Vol.32 (12), p.1303-1309
• Main Authors: Imai, Yoshiyuki, Miyamoto, Kei, An, Howard S, Thonar, Eugene J-M A, Andersson, Gunnar B J, Masuda, Koichi
• Format: Article
• Language: English
• Subjects: Adolescent; Aged; Aged, 80 and over; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins - metabolism; Bone Morphogenetic Proteins - pharmacology; Cell Division - drug effects; Cell Division - physiology; Cells, Cultured; Humans; In Vitro Techniques; Intervertebral Disc - cytology; Intervertebral Disc - drug effects; Intervertebral Disc - metabolism; Intervertebral Disc Displacement - drug therapy; Intervertebral Disc Displacement - metabolism; Intervertebral Disc Displacement - pathology; Middle Aged; Proteoglycans - metabolism; Recombinant Proteins - metabolism; Recombinant Proteins - pharmacology; Up-Regulation - drug effects; Up-Regulation - physiology
• ISSN: 0362-2436; 1528-1159
• DOI: 10.1097/brs.0b013e3180593238

In vitro assessment of the effects of recombinant human osteogenic protein-1 (rhOP-1) on the proteoglycan metabolism of human intervertebral disc cells. To determine whether rhOP-1 is effective in stimulating the cell proliferation and proteoglycan metabolism of human intervertebral disc cells cultured in alginate beads. 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. 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. 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. 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.