Age-related changes in proteoglycans of human intervertebral discs.

The age-related changes in glycosaminoglycan composition of human intervertebral discs were studied. A large number of tissue samples taken from 301 individuals at autopsy or at operation of prolapsed discs were investigated. It was found that the aging process is accompanied by a progressive decrease in GAGs content, both in annulus fibrosus and in nucleus pulposus. The GAG: collagen ratio significantly decreases. The KS and Ch-6-S were found to be the most abundant GAGs in both parts of the disc and their amounts decrease during the aging. A distinct, age-related increase of KS/Ch-S and Ch-6-S/Ch-4-S ratios was observed. Significant quantitative differences between the GAGs contents in normal and prolapsed discs were found. The nuclei pulposi of prolapsed discs contained less GAGs, especially KS and Ch-6-S, in comparison to normal tissue of the same age. Also, the age-related decline of GAGs: collagen ratio is more distinct in prolapsed discs. It seems that these differences in GAGs composition may be important in the mechanism of predisposition to disc prolapse.