Bone injuries represent a significant healthcare burden, with autograft transplantation currently considered the gold standard treatment. However, autografts are limited by donor site morbidity, pain, and restricted availability. Bone tissue engineering offers a promising alternative by combining stem cells, biomaterial scaffolds, and bioactive cues to promote regeneration. External stimulation, such as magnetic fields, has also emerged as a strategy to enhance bone healing and tissue regeneration. In this study, a magnetic hydrogel model was developed to explore the therapeutic potential and mechanisms of magnetic field stimulation in bone repair. The effects of static and dynamic magnetic fields on mesenchymal stromal cells (MSCs) were first investigated, with a focus on osteogenic differentiation, mechanotransductive signaling and pathway activation. A magnetic hydrogel was then fabricated using gelatin methacryloyl (GelMA) combined with iron oxide magnetic nanoparticles (MNPs). MSCs were encapsulated either as dispersed cells or in spheroid form. The hydrogels were extensively characterised, demonstrating tunable mechanical properties, appropriate porosity, and long-term biocompatibility. To evaluate osteogenic potential, MSC-laden hydrogels were exposed to either static or dynamic magnetic fields for up to 28 days. Gene expression, mineralisation and hydrogel stiffness were assessed as markers of osteogenic activity and environmental remodeling. Stemness markers were also monitored to evaluate stem cell renewal capacity. Intermittent static magnetic field (SMF) exposure for 1 hour per day emerged as the most effective regime, enhancing osteogenic gene expression in 2D culture, and further evidenced within 3D cultures in combination with MNPs showing increased mineralisation. Incorporation of MNPs or application of intermittent SMF also led to stiffening of the hydrogel model over 28 days. In addition, intermittent SMF exposure supported stem cell population renewal over 28 days This thesis demonstrates that GelMA based magnetic hydrogels, particularly under intermittent SMFs can direct MSC osteogenesis. These findings support the development of smart biomaterials that integrate biophysical cues for next generation bone tissue engineering and regenerative medicine.
Emma L. Jackson (Thu,) studied this question.