Age- and degeneration-related variations in cell density and glycosaminoglycan content in the human cervical intervertebral disc and its endplates

The first aim of this study was to quantify cell density in cervical intervertebral discs (IVDs) and endplates of varying age and degeneration grade. The second aim was to analyze glycosaminoglycan (GAG) content in cervical IVDs and their endplates.

Sixty cervical IVDs were excised from 30 human cadavers, not later than 24 hours post-mortem. Each sample underwent sectioning. Half of each sample underwent GAG content analysis using the dimethylmethylene blue binding assay. The other half underwent histological processing, histological degeneration grading, and cell density assessment using the Abercrombie method.

The nucleus pulposus (NP) (4218 ±417 cells/mm3) had significantly higher cell density than the anterior annulus fibrosus (AF) (3283 ±438 cells/mm3; p < 0.0001), and similar cell density (4464 ±551 cells/mm3; p = 0.36) to the posterior AF. Cell density was similar throughout the different regions of the endplate. The NP (619 ±178 µg/mg dry weight) had a significantly higher GAG content than both the anterior (428 ±199 µg/mg dry weight; p < 0.0001) and posterior AF (524 ±218 µg/mg dry weight; p < 0.0001).

In conclusion, this study introduces detailed 3D maps of cervical IVD and endplate cell density and GAG content. Furthermore, it shows that cervical IVDs and their endplates only slightly differ, in terms of cell density and GAG content, from lumbar IVDs.