Gene expression in human chondrocytes in late osteoarthritis is changed in both fibrillated and intact cartilage without evidence of generalised chondrocyte hypertrophy

Objectives: To investigate changes in gene expression in fibrillated and intact human osteoarthritis (OA) cartilage for evidence of an altered chondrocyte phenotype and hypertrophy. Methods: Paired osteochondral samples were taken from a high-load site and a low-load site from 25 OA joints and were compared with eight similar paired samples from age-matched controls. Gene expression of key matrix and regulatory genes was analysed by quantitative real-time reverse transcription-polymerase chain reaction on total RNA extracted from the cartilage. Results: There was a major change in chondrocyte gene expression in OA cartilage. SOX9 (38-fold) and aggrecan (4-fold) gene expression were both lower in OA (p