Long-Term Suppression of RUNX2 During MSC-Based Cartilage Formation Increases Cartilage Matrix Accumulation

The objective of this study was to evaluate the long-term effects of an autonomous RUNX2-supressing gene circuit on cartilage matrix accumulation and compressive mechanics in the tissues produced by MSC-derived chondrocytes (MdChs). Human mesenchymal stem cells (MSCs) were differentiated into chondrocytes and genetically modified using a lentiviral short hairpin RNA (shRNA) targeting RUNX2 (shRUNX2). Two configurations, low and high levels of shRUNX2 expression, were implemented. The influence on RUNX2 suppression, matrix protein secretion, and compressive mechanics was evaluated. Both low and high shRUNX2 suppressed RUNX2 expression, showing significant improvement in cartilage matrix accumulation with increased collagen type II and aggrecan deposition. High shRUNX2 more effectively suppresses RUNX2 gene expression and enhances sulfated glycosaminoglycan and matrix accumulation compared with the control and low shRUNX2 group. This study demonstrates the long-term effect of autonomous RUNX2 suppression in enhancing cartilage matrix accumulation and mechanical properties, providing a promising approach for advancing cartilage tissue engineering and repair strategies.