Extracellular Matrix and Adhesion Molecule Gene Expression in the Normal and Injured Murine Intervertebral Disc.

OBJECTIVE:The aim of the study was to determine the transcription profile of the mouse nucleus pulposus and annulus fibrosus with an unbiased method. Furthermore, pathophysiological relevance of selected genes was demonstrated in the mouse tail intervertebral disc injury model. DESIGN:Paired normal mouse nucleus pulposus and annulus fibrosus tissue from C57BL/6j mice was examined by a polymerase chain reaction array. Key gene expression in the normal and injured intervertebral discs was confirmed by real-time polymerase chain reaction. RESULTS:Among the 84 genes studied, 63 were expressed higher in annulus fibrosus than in nucleus pulposus; only four genes were expressed higher in nucleus pulposus than in annulus fibrosus (n = 4, P ≤ 0.05). Real-time polymerase chain reaction confirmed that cadherin (cdh) 2 gene expression was higher in nucleus pulposus than in annulus fibrosus, and type I collagen (col1) gene expression was higher in the annulus fibrosus than in nucleus pulposus (n = 8, P < 0.01). One week after tail intervertebral disc injury, cdh2 gene expression decreased, while col1 expression increased (n = 8, P < 0.01). CONCLUSIONS:This is the first study to examine the relative expression of 84 genes in normal mouse nucleus pulposus and annulus fibrosus. Key genes in the normal and injured mouse intervertebral discs were confirmed with real-time polymerase chain reaction. This information should be useful for studying the mouse model of intervertebral disc degeneration and guide future cell therapy approaches.