Chondrocyte number and proteoglycan synthesis in the aging and osteoarthritic human articular cartilage

Abstract

Objective: To correlate the number of chondrocytes in healthy and osteoarthritic human articular cartilage with age, and to evaluate the influence of donor age on total proteoglycan synthesis. Methods: Chondrocytes were isolated from human articular cartilage derived from hip joints with and without osteoarthritic lesions. The cell number was normalised to cartilage sample wet weight. In addition, the influence of age on chondrocyte numbers was assessed histomorphometrically. Chondrocytes were grown as monolayer cultures for seven days in a chemically defined serum-free basal medium. Total proteoglycan synthesis was measured by [³⁵S]sulphate incorporation into newly synthesised macromolecules. Results: Chondrocyte numbers in healthy cartilage decreased significantly with advancing age (r = −0.69, pConclusions: Under the experimental conditions employed, chondrocytes from healthy and osteoarthritic joints synthesised comparable amounts of cartilage macromolecules, independent of age or underlying osteoarthritic disease. Thus the decrease in chondrocyte number in aging and osteoarthritic joints could be a crucial factor in limiting tissue replenishment.