Correlation of synovial cytokine expression with quality of cells used for autologous chondrocyte implantation in human knees

The cell quality plays a decisive role in autologous chondrocyte implantation (ACI). Aim of the study was the analysis of in vivo interactions between synovial concentrations of cytokines and cell quality used for ACI. Knee lavage fluids of patients undergoing an ACI were examined for total protein content (TPC) and by ELISA for levels of basic fibroblast growth factor (bFGF), insulin-like growth factor 1, bone morphogenetic proteins 2 and 7 (BMP-2 and BMP-7). Cell quality following amplification for ACI was determined by surface expression of CD44, aggrecan, collagen type II and evaluation of cell characteristics. Data of 17 patients were supplemented by epidemiological parameters and clinical scores (IKDC, Lysholm, pain strength, subjective knee function). CD44 expression was positively associated with TPC and bFGF, and negatively linked to BMP-2 levels ( p < 0.01). In contrast, expression of collagen type II did not show any statistically significant correlations with synovial protein concentrations. TPC was positively associated with intraarticular bFGF levels and pain strength ( p < 0.01), both indicators for osteoarthritis (OA). Correlating with the negative relation of TPC and BMP-2, subjective knee function after 1 year was positively linked to intraarticular BMP-2 concentrations ( p < 0.001). Similarly, expression of collagen type II indicated a favorable clinical result reaching statistical significance in case of pain strength ( p < 0.01). Initially increased bFGF levels and CD44 expression indicated a worse clinical outcome after 1 year (IKDC, Lysholm Scores, pain strength). Surface expression of CD44 on chondrocytes used for ACI was negatively associated with synovial BMP-2 and positively to TPC and bFGF indicating catabolic synovial conditions. These correlations were also reflected by clinical outcome parameters.