Local Administration of Magnesium Promotes Meniscal Healing Through Homing of Endogenous Stem Cells: A Proof-of-Concept Study

Background: Although many strategies have been developed to modify the biological and biomechanical environment of the meniscal suture repair to improve the chances of healing, the failure rates remain high. Thus, new methods to promote meniscal regeneration and repair are needed. Hypothesis: Administration of magnesium (via a repair using magnesium stitches) might enhance recruitment and adherence of endogenous stem cells to the site of the lesion, thereby promoting in situ meniscal regeneration and chondroprotective functions. Study Design: Controlled laboratory study. Methods: Synovial fluid–derived mesenchymal stem cells (SMSCs) were identified and isolated from the knees of rabbits with a meniscal injury of 4 weeks’ duration. An in vitro analysis of adherence and chemotaxis of SMSCs was performed. For the in vivo assay, rabbits (n = 120) with meniscal lesions were divided into 3 groups: repair with high-purity magnesium stitches (Mg group), repair with absorbable sutures (Control group), and no repair (Blank group). Healing of the regenerated tissue and degeneration of the articular cartilage were evaluated by gross and histological analysis at postoperative weeks 1, 3, 6, and 12. The mechanical properties of the repaired meniscus were also analyzed (tensile testing). Results: In vitro, magnesium promoted the adhesion and migration of SMSCs, which were identified and increased in the knee joints with meniscal lesions. Moreover, fibrochondrogenesis of SMSCs was stimulated by magnesium. Compared with the other groups, the Mg group had enhanced tissue regeneration, lower cartilage degeneration, and retained mechanical strength at 12 weeks after meniscal repair. Conclusion/Clinical Relevance: Magnesium could be used for in situ meniscal repair due to the potential capacity of magnesium to recruit endogenous stem cells and promote synthesis of fibrocartilaginous matrix.