Gene expression profile analysis of human intervertebral disc degeneration

In this study, we used microarray analysis to investigate the biogenesis and progression of intervertebral disc degen-eration. The gene expression profiles of 37 disc tissue samples obtained from patients with herniated discs and de-generative disc disease collected by the National Cancer Institute Cooperative Tissue Network were analyzed. Differentially expressed genes between more and less degenerated discs were identified by significant analysis of microarray. A total of 555 genes were significantly overexpressed in more degenerated discs with a false discovery rate of < 3%. Functional annotation showed that these genes were significantly associated with membrane-bound vesicles, calcium ion binding and extracellular matrix. Protein-protein interaction analysis showed that these genes, including previously reported genes such as fibronectin, COL2A1 and -catenin, may play key roles in disc degener-ation. Unsupervised clustering indicated that the widely used morphology-based Thompson grading system was only marginally associated with the molecular classification of intervertebral disc degeneration. These findings indi-cate that detailed, systematic gene analysis may be a useful way of studying the biology of intervertebral disc degen-eration