Accumulation of mitochondrial DNA with 4977-bp deletion in knee cartilage – an association with idiopathic osteoarthritis

Abstract

Since mitochondrial DNA (mtDNA) mutations have been established to associate with the aging process and some degenerative diseases, we investigated the correlation between idiopathic osteoarthritis (OA) and the 4977-bp mtDNA deletion. Cartilage were collected from six sites in knee joints removed from 18 aged patients with idiopathic OA, 10 aged non-OA cadavers, 3 young cadavers (YC), and lateral femoral condyle of 9 young patients. Histopathologic changes were examined and the common 4977-bp mtDNA deletions were analyzed in young and elderly cartilages obtained from different sites in the knee joint. The association of the 4977-bp deletion of mtDNA with idiopathic OA and aging was evaluated. The 4977-bp mtDNA deletion was detected in 17 of the 18 OA patients, 9 of the 10 aged non-OA cadavers, and 1 of the 3 YC. None of the nine specimens collected from the lateral femoral condyle of young patients had a detectable deletion of mtDNA. The 4977-bp mtDNA deletion was not significantly correlated with the severity of OA graded by the Mankin score. The frequencies of occurrence of the 4977-bp mtDNA deletion were significantly different between the OA group and the aged non-OA control group (P=0.004) and between the aged non-OA group and the young control group (P=0.002). The results suggest that accumulation of the 4977-bp deletion of mtDNA in knee cartilage increases with age and may play a role in the development of idiopathic OA in the knee joint.