Osteogenic protein-1 alleviates high glucose microenvironment-caused degenerative changes in nucleus pulposus cells

Background: Increasing evidence has indicated a close relationship between diabetes mellitus (DM) and disc degeneration. As a potential therapeutic growth factor, osteogenic protein-1 (OP-1) has lots of protective effects on the healthy disc cell9s biology.  Objective: This study was aimed to investigate the effects of OP-1 on degenerative changes of nucleus pulposus (NP) cells in a high glucose culture. Methods: Rat NP cells were cultured in the baseline medium or the high glucose (0.2 M) culture medium. OP-1 was added into the high glucose culture medium to investigate whether its has some protective effects against degenerative changes of NP cells in the high glucose culture. NP cell apoptosis ratio, caspase-3/9 activity, expression of apoptosis-related molecules (Bcl-2, Bax and caspase-3), matrix macromolecules (aggrecan and collagen II) and matrix remodeling enzymes (MMP-3, MMP-13 and ADAMTS-4), and immuno-staining of NP matrix proteins (aggrecan and collagen II) were evaluated. Results: Compared with the baseline culture, high glucose culture significantly increased NP cell apoptosis ratio, caspase-3/9 activity, up-regulated expression of Bax, caspase-3, MMP-3, MMP-13 and ADAMTS-4, down-regulated expression of Bcl-2, aggrecan and collagen II, and decreased staining intensity of aggrecan and collagen II. However, the results of these parameters were partly reversed by the addition of OP-1 in the high glucose culture. Conclusion: OP-1 can alleviate high glucose microenvironment-induced degenerative changes of NP cells. This study provides that OP-1 may be promising in retarding disc degeneration in DM patients.