MRI Monitoring of USPIO-Labeled BMSCs Combined with Alginate Scaffold for Cartilage Defect Repair

Shanyu Lu ^1,2 Zhenyu Liu ^1,2 Meiling Qi ^1,2 Haocheng Zhen ³ Jing Luo ⁴ Yingchao Wang ^1,2 Le Chang ^1,2 Xiaolong Bai ^1,2 Yingguang Jiao ^1,2 Xinyao Chen ^1,2 Junping Zhen ^2*

• ¹ College of Medical Imaging, Shanxi Medical University, Taiyuan, Shanxi Province, China
• ² Department of Imaging, Second Hospital of Shanxi Medical University, Taiyuan, China
• ³ Shandong First Medical University, Tai'an, Shandong, China
• ⁴ Shanxi Key Laboratory for Immunomicroecology, Second Hospital of Shanxi Medical University, Taiyuan, China

Objective: This study aimed to evaluate the effectiveness of bone marrow mesenchymal stem cells (BMSCs) combined with sodium alginate scaffolds in repairing knee cartilage defects in New Zealand rabbits. Additionally, it assessed the potential of functional magnetic resonance imaging (fMRI) for non-invasive monitoring of the dynamic repair process.Methods: Rabbits were randomly divided into four groups: Group A (control), Group B (sodium alginate scaffold), Group C (BMSCs-sodium alginate scaffold), and Group D (USPIO-labeled BMSCs-sodium alginate scaffold). A cartilage defect model was created, and the respective materials were implanted into the defect regions. T2 mapping MRI was performed at weeks 1, 2, and 4 post-surgery to evaluate the repair process, followed by histological analysis to confirm the outcomes.Results: BMSCs significantly promoted cartilage defect repair and accelerated the degradation of sodium alginate scaffolds. Macroscopic and histological evaluations revealed repair tissue formation in Groups C and D by week 1, with most defect regions filled with new cartilage by week 4. T2 mapping analysis showed a gradual decline in T2 values in Group B, a more pronounced decrease in Group C, and consistently lower T2 values in Group D compared to Group C, with a slow upward trend over time.Conclusion: This study demonstrated that BMSCs exhibit significant regenerative potential for cartilage defect repair. USPIO labeling enables non-invasive, dynamic monitoring of the repair process without adverse effects on cell viability or differentiation. These findings provide experimental evidence supporting the application of BMSCs combined with magnetic labeling technology in cartilage regeneration.