Protective Effect of Pyrroloquinoline Quinone on TNF-α-induced Mitochondrial Injury in Chondrocytes.

Osteoarthritis (OA) is a degenerative disease characterized by matrix degradation and cell death leading to a gradual loss of articular cartilage integrity. As a bacterial synthesis of quinine, pyrroloquinoline quinone (PQQ) is a strong redox cofactor with a variety of biological benefits, including antioxidant, anti-inflammation-induced mitochondrial metabolism regulation. This study was designed to investigate the effect of PQQ on TNF-α-induced mitochondrial damage in chondrocytes. Chondrocytes isolated from C57BL/6 mice were exposed to TNF-α 50 ng/mL, TNF-α 50 ng/mL + PQQ 10 µmol/L for 24 h. Then, morphological study, functional study and mechanism study were taken. The results revealed TNF-α-induced chondrocyte mitochondrion damage could be reduced by application of PQQ, evidenced by elevated number of mitochondria, well-kept mtDNA integrity, preserved ATP level, reestablished mitochondrial membrane potential, and prevented mitochondrial function. The present work strongly suggests that the mitochondrion is an important target for OA chondrocyte damage induced by TNF-α and the PQQ protection from this damage ameliorates mitochondrial dysfunction induced by TNF-α. PQQ might be a potential chemical for OA intervention.

Patellofemoral MRI Alterations Following Single Bundle ACL Reconstruction with Hamstring Autografts Are Associated with Quadriceps Femoris Atrophy.

High incidence of patellofemoral pain and patellofemoral joint osteoarthritis was found following anterior cruciate ligament (ACL) reconstruction. The unstability of patellofemoral joint might be an important contribution factor. This study was designed to define the relationship between the unstability of patellofemoral joint and quadriceps femoris atrophy. Twenty patients underwent MRI scan before ACL reconstruction and every two weeks after surgery, until 12 weeks. The merchant's patellar congruence angle, lateral inclination angle, and quadriceps femoris muscle cross-sectional area were measured and the relationship between the changes of angles and the ratio of quadriceps femoris atrophy was studied by multiple regression analysis. Significant quadriceps femoris atrophy was observed after ACL reconstruction during the follow-up period of 12 weeks. The merchant's patellar congruence angle and lateral inclination angle significantly changed after surgery. The alterations of the merchant's patellar congruence angle were significantly correlated with the atrophy ratio of vastus medialis (coefficient=-15.76) and vastus lateralis (coefficient=8.35) during the follow-up period of 12 weeks. The alterations of lateral inclination angle were significantly correlated with the atrophy ratio of vastus medialis (coefficient=20.62), vastus lateralis (coefficient=-11.38) and rectus femoris (coefficient=-0.469) during the follow-up period 12 weeks. To sum up, ACL reconstruction can alleviate the dysfunction of patellofemoral joint to a certain extent. But, the unbalanced atrophy of quadriceps femoris once again destroyed the stability of patellofemoral joint following the operation, which might be one cause of patellofemoral joint pain and early onset of osteoarthritis after ACL reconstruction. So, rehabilitation training that focuses on quadriceps femoris especially the vastus medialis shortly following operation is suggested.