The effect of bone morphogenetic protein-2 on rat intervertebral disc cells in vitro

• Published in: Spine (Philadelphia, Pa. 1976) Pa. 1976), 2003-08, Vol.28 (16), p.1773-1780
• Main Authors: Tim Yoon, S, Su Kim, Keun, Li, Jun, Soo Park, Jin, Akamaru, Tomoyuki, Elmer, William A, Hutton, William C
• Format: Article
• Language: English
• Subjects: Aggrecans; Animals; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins - pharmacology; Cell Division - drug effects; Cells, Cultured; Collagen Type I - genetics; Collagen Type II - genetics; Dose-Response Relationship, Drug; Extracellular Matrix Proteins; Gene Expression Regulation - drug effects; High Mobility Group Proteins - genetics; Humans; Intervertebral Disc - cytology; Intervertebral Disc - drug effects; Intervertebral Disc - metabolism; Lectins, C-Type; Osteocalcin - genetics; Proteoglycans - biosynthesis; Proteoglycans - genetics; Rats; Rats, Sprague-Dawley; Recombinant Proteins - pharmacology; RNA, Messenger - drug effects; RNA, Messenger - genetics; RNA, Messenger - metabolism; SOX9 Transcription Factor; Time Factors; Transcription Factors - genetics; Transforming Growth Factor beta
• ISSN: 0362-2436; 1528-1159
• DOI: 10.1097/01.BRS.0000083204.44190.34

An in vitro experiment to determine the molecular and cellular effect of recombinant human bone morphogenetic protein-2 on cultured rat intervertebral disc cells was performed. To determine the effect of recombinant human bone morphogenetic protein-2 on cell proliferation, production of sulfated-glycosaminoglycan, and the expression of genes specific for chondrocytes (Type II collagen, aggrecan, and Sox9) in cultured rat intervertebral disc cells. Intervertebral disc degeneration is associated with cellular and biochemical changes, which include decreased synthesis of cartilage specific gene products such as Type II collagen and aggrecan. Although bone morphogenetic protein-2 is known to induce chondrogenesis during new bone formation, the effects on intervertebral disc cells have not been characterized. Cells were isolated from the anulus fibrosus and transition zones of lumbar discs from Sprague-Dawley rats. The cells were grown in monolayer and treated with recombinant human bone morphogenetic protein-2 (0, 10, 100, 1000 ng/mL) in Dulbecco's Modified Eagle Medium/F-12 with 1% fetal bovine serum (day 0). On days 2, 4, and 7 after recombinant human bone morphogenetic protein-2 treatment, sulfated-glycosaminoglycan content in the media was quantified using 1,9-dimethylmethylene blue staining. The results were normalized according to culture duration and cell number. On day 7, mRNA was extracted for reverse transcriptase-polymerase chain reaction and real-time polymerase chain reaction to quantitate mRNAs of Type I collagen, Type II collagen, aggrecan, Sox9, osteocalcin, and glyceraldehyde phosphate dehydrogenase. Cell number was determined with a hemocytometer. Recombinant human bone morphogenetic protein-2 at 100 and 1000 ng/mL yielded a 17% and 42% increase in cell number on day 4, and a 59% and 79% on day 7, respectively. Recombinant human bone morphogenetic protein-2 at 10 ng/mL had no effect on cell number. Sulfated-glycosaminoglycan increase was greatest at day 7, increasing by 1.3-, 2.1-, and 3.6-fold with recombinant human bone morphogenetic protein-2 treatments of 10, 100, and 1000 ng/mL, respectively. Increases in mRNA levels of Type II collagen, aggrecan, Sox9, and osteocalcin were observed with recombinant human bone morphogenetic protein-2 concentrations of 100 and 1000 ng/mL on day 7 as determined by reverse transcriptase-polymerase chain reaction. No detectable increase in mRNA level of Type I collagen was observed with any levels of recombi