Cartilage proteoglycan changes in experimental canine osteoarthritis.

Articular cartilage contains at least 2 proteoglycans (PGs) which aggregate with hyaluronate: one larger, richer in chondroitin sulphate (CSRPG); the other smaller, relatively richer in keratan sulphate (KSRPG). With maturation the ratio of CSRPG/KSRPG decreases. In order to test the hypothesis that osteoarthritic cartilage contains an increased amount of proteoglycans characteristic of immature cartilage, experimental osteoarthritis (OA) was induced in 11 dogs by transection of the anterior cruciate ligament. Proteoglycan populations were assessed by composite agarose polyacrylamide gel electrophoresis (CAPAGE). The OA cartilage had more proteoglycan and an increased proportion of the slower migrating band on CAPAGE, which corresponds to the CSRPG, supporting the hypothesis that OA cartilage contains an increased amount of proteoglycans characteristic of immature cartilage.