Arthroscopic Infrapatellar Fat Pad Release and Mesenchymal Stem Cell Mobilization

This prospective, single-center, paired-sample clinical laboratory study evaluated whether controlled mechanical release of the infrapatellar fat pad during knee arthroscopy increases the number of intra-articular cells with a mesenchymal stem cell immunophenotype. The study also evaluated whether the procedure is accompanied by immediate changes in the expression of selected genes associated with inflammation, immunomodulation, and tissue repair. Adults undergoing knee arthroscopy for meniscal pathology had a 20-mL intra-articular fluid sample collected before manipulation of any intra-articular structure. The infrapatellar fat pad was then gently and selectively shaved for approximately 1 minute using a motorized arthroscopic shaver with the suction turned off. A second 20-mL intra-articular fluid sample was collected immediately after the procedure and before further irrigation or continuation of the planned arthroscopic surgery. Paired pre-release and post-release samples were analyzed by flowcytometry to quantify cells with a mesenchymal stem cell immunophenotype. Quantitative real-time polymerase chain reaction was performed on the total cellular fraction to assess IL-1β, IL-6, IL-10, TGF-β, and CD24 gene expression. Comparisons were performed within each participant using the paired samples.