Comparative rates of proteoglycan synthesis and size of proteoglycans in normal and osteoarthritic chondrocytes.

Normal human and osteoarthritic cells were isolated from cartilage with clostridial collagenase. The cells were grown in media as a suspension culture in the presence of 35SO4. Osteoarthritic cartilage of moderate histologic grade (4-8) yielded chondrocytes which incorporated 35SO4 at a rate 3-4 times greater than did normal chondrocytes. The rate of incorporation, however, decreased to normal levels with chondrocytes isolated from mild (grade 0-3) or more advanced (grade 9-13) stages of the disease. These results corroborate those obtained in earlier studies using organ cultures and show that when osteoarthritic cells are isolated from their matrix environment, they continue to synthesize macromolecules at an increased rate. Analysis of the material synthesized by the isolated cells on sizing column demonstrated an inverse relationship between the size of the 35SO4 containing molecules and the severity of the disease.