Molecular markers in the evaluation of autologous chondrocyte implantation

Purpose: With the help of molecular markers, it has become possible to quantify cartilage repair and degradation in joints. In this study, we attempt to determine whether or not molecular markers in synovial fluid can be helpful in defining the repair process following autologous chondrocyte implantation (ACI). Type of Study: As part of a prospective clinical pilot study, 17 patients were evaluated before, as well as 6 weeks, 3, 6, and 12 months after the ACI. A synovial analysis was performed and molecular markers for bone and cartilage metabolism were determined. Methods: A number of parameters, including pyridinium crosslink (PY), deoxypyridinolin (DPD), n-telopeptide (NTX) from type I collagen, MMP-1, MMP-3; TIMP-1, PICP, proteoglycan, and YKL-40 were analyzed. The levels were referenced to the total protein concentration of the synovial fluid. The synovial analyses were compared with clinical parameters (Larson score) and magnetic resonance imaging (MRI) examinations. Results: The analysis of the data revealed differing trends for the various synovial markers over time. The most remarkable marker was found to be DPD, which increased continuously between surgery and week 12, only to disappear after the repair process had ceased I year after surgery. All molecular markers for cartilage degradation increased initially after surgery and dropped off below the original levels 3 to 6 months later. Conclusions: The evaluation revealed that the determination of marker levels can provide valuable information regarding the metabolism of bone and cartilage in a joint. They seem to provide a method for monitoring the repair process associated with the various treatment forms for chondral lesions.