A BIOCHEMICAL AND IMMUNOELECTRON MICROSCOPIC ANALYSIS OF CHONDROITIN SULFATE-RICH PROTEOGLYCANS IN HUMAN ALVEOLAR BONE

This study used biochemical and immunohistochemical methods to charact erize the chondroitin sulphate-rich proteoglycans from human alveolar bone obtained from an oral source. Proteoglycans were extracted from b one by a sequential 4 M guanidine HCl extraction process, and purified by DEAE-ion exchange chromatography. SDS-PAGE and Western blot analys is, using CS-56 monoclonal antibody, demonstrated one major proteoglyc an species with a core protein of 58 kDA, glycosaminoglycan chains of 45-66 kDa and a mean molecular weight of 205 kDa. This work confirmed the biochemistry of chondroitin sulphate-rich proteoglycans from a nov el source of adult human alveolar bone, and pointed towards a protoegl ycan with a high glutamate, glycine, aspartate, alanine, serine and le ucine content. Sections of alveolar bone were embedded in LR White res in, labelling was restricted to the osteocyte lacunae and canaliculi. Ultrastructural observations showed that the labelling was localized t o fine filamentous material in the walls of the osteocytes adn canalic uli. Sparse labelling was associated with the collagen fibres immediat ely subjacent to the lamina limitans, but no labelling was associated with the fibres immediately subjacent to the lamina limitans, but no l abelling of the mineralized matrix was observed. These findings also i ndicated subtle difference in the distribution of chondroitin sulphate compared with previously reported work, which may indicate species or age differences in the samples used in this study. Ultrastructural an alysis confirmed and extended observations of glycosaminoglycan locali zation at the osteocyte cell membrane of mature human alveolar bone.