Analysis of Aging and Degeneration of the Human Intervertebral Disc

Abstract

These findings reveal that there is a high incidence of apoptosis in the intervertebral disc. Surviving cells are not synthetically inactive but are, rather, producing inappropriate matrix products during aging and degeneration. In certain instances it appears that the matrix surrounding the cell may form an isolation barrier, which may influence individual cell activity and intercellular communication. These results point to the need to 1) more fully understand the cause of disc cell death via apoptosis and to determine whether this programmed cell death can be reversed or halted, and 2) more fully understand the dynamic relation between disc cells and the surrounding extracellular matrix, which they produce and remodel. The factors regulating extracellular matrix-disc cell homeostasis in the disc are unknown, as is the relation between extracellular matrix and disc cell functional modulation. The morphologic findings of this study suggest that these issues are important considerations in disc cell biology. The identification of tartrate-resistant acid phosphatase activity in disc cells allows for a new area of study of disc extracellular matrix remodelling. In summary, these new perspectives provide new parameters with which to assess disc cell health and function.