Abstract
Study Design: Experimental in vivo study on New Zealand white rabbits.
Summary of Background Data: Bone Morphogenetic Protein 2 (BMP-2) is of increasing orthopaedic interest due to its osteo-inductive potency. Currently it is used in human and animal studies for posterolateral spinal fusions. However, little data is available concerning the pathophysiologic role of BMP-2 in normal and degenerated discs.
Methods: A recently established animal model was used to create mechanically induced disc degeneration of one single segment. In 6 animals, an external disc compression device was attached for 28 days. For comparison 8 animals underwent a sham operation.
Outcome Measures: The discs were analysed by a) immunohistology to determine protein content of BMP-2 and b) real time RT-PCR to quantify RNA content of BMP-2.
Results: Sham controls showed a homogeneous distribution of BMP-2 throughout the annulus fibrosus and cluster-like accumulation within the nucleus pulposus. Mechanically degenerated discs determined a reduction of positive cells with areas lacking BMP-2. Real time RT-PCR results demonstrated a statistically significant (7.92 times) upregulation of BMP-2 as compared with shams (p=0.033).
Conclusions: Mechanically induced disc degeneration is associated with a loss of BMP-2 protein. Disc cells respond with a stimulation of BMP-2 gene expression. This data confirms the role of BMP-2 in the pathophysiology of disc remodeling. It remains unclear if this mechanism of BMP-2 stimulation contributes to the disc reorganization alone or if it may also play a role in osteo-inductive processes like osteophyte formation or endplate sclerosis.
These abstracts were prepared by Mr. Brian J C Freeman FRCS (Tr & Orth). Correspondence should be addressed to him at The Centre for Spinal Studies and Surgery, University Hospital, Queens Medical Centre, Nottingham NG7 2UH.
