The Effect of Multipoint Injection Strategies of <scp>BMSCs</scp> on Repairing Cartilage Defects of the Knee Joint

Bone marrow-derived mesenchymal stem cells (BMSCs) are extensively utilised in tissue engineering and regenerative medicine due to their multipotent differentiation capabilities. However, the therapeutic efficacy of BMSCs is highly dependent on the transplantation route. This study aimed to compare the efficacy of commonly used BMSCs transplantation methods and identify the optimal delivery approach for cartilage repair. Our results demonstrated that all transplantation methods could significantly suppress pro-inflammatory factors, including IL-1β, iNOS, and MMP-9, while enhancing the activity of the key antioxidant enzyme superoxide dismutase (SOD). The intra-articular injection group exhibited the most substantial anti-inflammatory and antioxidant improvements. In vivo tracking experiments revealed that BMSCs from all groups were capable of homing to the cartilage defect site at 4 weeks post-modelling. Notably, the intra-articular injection group recruited the highest number of BMSCs to the defect area. Further histological analysis indicated that the joints treated with intra-articular injection displayed superior cartilage regeneration, characterised by a smooth tissue surface and coloration closely resembling adjacent native cartilage. In conclusion, while all tested BMSCs transplantation approaches contributed to cartilage repair, intra-articular injection demonstrated the most favourable therapeutic outcomes.