Immunohistochemical localization of the small proteoglycans decorin and biglycan in human intervertebral discs.

Immunohistochemistry was used to study the presence and distribution of the core proteins of the small proteoglycans decorin and biglycan in the various compartments of human intervertebral discs. Both proteoglycans could be found in the outer tendon-like parts of the annulus fibrosus, indicating their potential role in collagen network formation and biomechanical stress resistance. The loss of both proteoglycans in the annulus of individuals older than 50 years reflects a normal age-related change. In the nucleus pulposus, decorin could be found in fibrillar areas of the interterritorial matrix, thereby indicating co-localization of decorin with fibrils containing type II collagen. Biglycan was present in the extracellular matrix of the nucleus pulposus of adults. The pericellular immunoreactive rims observed around nucleus pulposus cells and giant chondrones indicated local biosynthetic activity for these small proteoglycans. The staining patterns in cartilage endplates resembled those found in human hyaline articular cartilage.