Aging and degeneration of the human intervertebral disc.

Human intervertebral discs undergo age-related degenerative changes that contribute to some of the most common causes of impairment and disability for middle aged and older persons: spine stiffness, neck pain, and back pain. Potential causes of the age-related degeneration of intervertebral discs include declining nutrition, loss of viable cells, cell senescence, post-translational modification of matrix proteins, accumulation of degraded matrix molecules, and fatigue failure of the matrix. The most important of these mechanisms appears to be decreasing nutrition of the central disc that allows accumulation of cell waste products and degraded matrix molecules, impairs cell nutrition, and causes a fall in pH levels that further compromises cell function and may cause cell death. Although aging changes of the disc appear to be inevitable, identification of activities and agents that accelerate these changes may help decrease the rate and severity of disc degeneration; and recent work suggests that methods can be developed that will regenerate disc tissue.