Chondroitin sulfates and proteoglycans from normal and arthrosic human cartilage

The structure of chondroitin sulfates and proteoglycans extracted from human normal young and adult cartilages and also from human arthrosic cartilages are reported. The adult articular cartilage contains almost exclusively chondroitin 6-sulfate, whereas the normal young and the arthrosic cartilage chondroitin sulfates are hybrid polymers, containing 4-sulfated and 6-sulfated disaccharide units, distributed in a quite random way along the molecules. The young cartilage proteoglycans also differ from the adult cartilage proteoglycans by their contents of keratan sulfate, the relative proportion of nonaggregating proteoglycans and electrophoretic migration in agarose gel slabs. The proteoglycans from arthrosic cartilages are very similar to those from young normal cartilages. Such changes in composition could lead to alterations in the proportion and size of the aggregates they form in the cartilages, furnishing the conditions for the processes of growth and calcification to occur.