Intermittent Dynamic Compression Confers Anabolic Effects in Articular Cartilage

(1) Background: Mechanical loading is an essential part of the function and maintenance of the joint. Despite the importance of intermittent mechanical loading, this factor is rarely considered in preclinical models of cartilage, limiting their translatability. The aim of this study was to investigate the effects of intermittent dynamic compression on the extracellular matrix during long-term culture of bovine cartilage explants. (2) Methods: Bovine articular cartilage explants were cultured for 21 days and subjected to 20 min of 1 Hz cyclic compressive loading five consecutive days each week. Cartilage remodeling was investigated in the presence of IGF-1 or TGF-β1, as well as a TGF-β receptor 1 (ALK5) kinase inhibitor and assessed with biomarkers for type II collagen formation (PRO-C2) and fibronectin degradation (FBN-C). (3) Results: Compression of cartilage explants increased the release of PRO-C2 and FBN-C to the conditioned media and, furthermore, IGF-1 and compression synergistically increased PRO-C2 release. Inhibition of ALK5 blocked PRO-C2 and FBN-C release in dynamically compressed explants. (4) Conclusions: Dynamic compression of cartilage explants increases both type II collagen formation and fibronectin degradation, and IGF-1 interacts synergistically with compression, increasing the overall impact on cartilage formation. These data show that mechanical loading is important to consider in translational cartilage models