Cells of the anulus fibrosus and nucleus pulposus react to tissue degeneration differently. Decreased mRNA expression by nucleus pulposus cells and declining protein content of the matrix make the nucleus more vulnerable to degeneration than the anulus. The cells in the anulus fibrosus respond to early degeneration by upregulating biosynthetic processes. However, in heavily degenerated tissues, the decline in the synthesis of aggrecan and the increase in the concentrations of small proteoglycans may be responsible for the failure of the repair processes.

No abstract