# The Effect of Multipoint Injection Strategies of BMSCs on Repairing Cartilage Defects of the Knee Joint

## TL;DR

This study compares different ways to inject bone marrow stem cells for knee cartilage repair and finds that injecting them directly into the joint works best.

## Contribution

The study identifies intra-articular injection as the optimal BMSCs delivery method for cartilage repair based on anti-inflammatory, antioxidant, and histological outcomes.

## Key findings

- Intra-articular injection showed the strongest anti-inflammatory and antioxidant effects.
- BMSCs injected intra-articularly migrated most effectively to the cartilage defect site.
- Joints treated with intra-articular injection showed superior cartilage regeneration.

## Abstract

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.