Proteoglycans from osteoarthritic human articular cartilage influence type II collagen in vitro fibrillogenesis

Collagen fibrils were formed in the presence of dermatan sulfate (DSPG) and high density (HDPG) proteoglycans isolated from human adult knee femoral articular cartilage. Eroded cartilage had a higher percentage of DSPGs in the extracted proteoglycans than normal cartilage (p = .018). The dermatan sulfate proteoglycans (DS-PGI and DS-PGII) were detected in normal and osteoarthritic cartilage. DSPGs compared to HDPG inhibited in vitro collagen fibrillogenesis producing a longer lag phase (p less than .05) and a slower rate of fibril formation (p less than .05). DSPGs from eroded osteoarthritic cartilage alone or in combination with HDPG produced a longer lag phase than DSPGs from normal cartilage alone or in combination with HDPG (p less than .05). The inhibition of fibrillogenesis by DSPGs suggests that collagen fibril formation in vivo may be abnormal due to the influence of molecular changes in proteoglycan as well as an increased proportion of DSPGs occurring in osteoarthritic cartilage. Abnormal fibril formation may produce a weakened cartilage matrix, thus contributing to an accelerated process of cartilage degeneration in osteoarthritis.