COLLAGEN AND ELASTIN CROSSLINKS IN HUMAN INTERVERTEBRAL DISCS AND LIGAMENTUM FLAVUM: AGE, GENDER AND SPINAL LEVEL INFLUENCES

The collagen and elastin content and extent of collagen crosslinks were determined in human formalin-fixed and unfixed intervertebral discs and ligamentum flava. Tissue samples from cadaveric spinal discs (n = 77) and ligamentum flava (n = 364) were obtained from 24 formalin-fixed and 2 fresh spines. The mean age of all cases was 57±26 years. Spinal ligament and disc samples were harvested and analyzed for collagen, and crosslinks of pyridinoline, deoxypyridinoline, and elastin crosslinks isodesmosine and desmosine. Collagen and elastin crosslinks were extracted from hydrolyzed samples by cellulose partition chromatography, and analyzed by reverse-phase HPLC. Elastin crosslinks were only detected in 4 lumbar discs (mean 0.04±0.01 nmol/mg dry wt) but yielded results for all ligamentum flavum samples (mean 20.2±6.4 nmol/mg dry wt). For ligamentum flavum, the collagen and collagen crosslinks increased significantly with age (p < 0.05), whereas elastin content decreased significantly with age but only for the lumbar region (p < 0.05). Collagen and elastin content were significantly higher in females (p < 0.01) and collagen, pyridinoline and isodesmosine were significantly higher in the lumbar region (p < 0.01). Elastin detected in lumbar discs was significantly less than that found in ligamentum flavum. The collagen and elastin content and extent of collagen crosslinks in ligamentum matrix varied significantly depending on the age, gender and spinal region.