Osmolarity Regulates Gene Expression in Intervertebral Disc Cells Quantifiedwith High Density Oligonucleotide Array Technology

INTRODUCTION: Cells of the intervertebral disc respond to mechanical and biophysical stimuli in their environment, including deformations, hydrostatic and osmotic pressures [1]. Previous studies have shown that fibrochondrocytes of the disc respond to altered osmotic pressure with changes in post-translational biosynthesis of proteoglycans (i.e., S-incorporation) [2, 3], as well as changes in gene expression for type II collagen and select proteoglycans [4]. In other cell types, a wide range of genes are transcriptionally activated following exposure to hypoor hyper-osmotic conditions [5]. We hypothesize that fibrochondrocytes of the intervertebral disc differentially respond to hypoand hyper-osmotic conditions with changes in gene expression for a large number of proteins. In this study, the gene expression profile of human intervertebral disc cells was quantified with gene array technology following exposure to varying osmolarity in alginate culture in vitro. The results of the study demonstrate that genes encoding a broad functional range of proteins are regulated by osmotic conditions in cells of the intervertebral disc.