Age-related changes in collagen, pyridinoline, and deoxypyridinoline in normal human thoracic intervertebral discs.

Human thoracic discs were analyzed for collagen and collagen cross-links to determine the distribution due to segmental, age, and gender influences. Thoracic discs from 26 cadaveric spines (1 to 90 years old) were graded macroscopically, then separated into anular and nuclear samples. Only grade I (i.e., normal) disc samples were selected (n=209). Pyridinoline and deoxypyridinoline cross-links were initially separated by column chromatography and analyzed by reverse-phase high-pressure liquid chromatography. The collagen content was lower and the extent of pyridinoline and deoxypyridinoline were significantly higher in the nucleus compared with the anulus (p <.001). The collagen content and extent of pyridinoline were significantly lower with increasing age in the anulus and nucleus (p <.001). Young male discs had a significantly higher extent of pyridinoline compared with females (p <.001). Age, gender, and disc region differences were found to have a significant influence on the biochemical composition of the normal disc extracellular matrix.