Magnetic Nanocomposites and Fields for Bone and Cartilage Tissue Engineering Applications

Current stem cell research often relies on the use of growth factors to stimulate cell proliferation and differentiation for tissue engineering purposes. However, these growth factors are not only short-lived proteins but also expensive resources. Research in biodegradable magnetic nanocomposites is a promising rising field for biomedical applications due to the magnetic response properties of the materials that could provide external physical stimulations as an alternative. This project seeks to investigate the application potential of biodegradable magnetic nanocomposites for bone and cartilage tissue regeneration. Different weight percent of polyvinyl alcohol (PVA) was used to modify the surface of superparamagnetic nanoparticles to reduce aggregation and increase dispersibility in polymer solutions for the synthesis of magnetic nanocomposites. The results showed that 30 wt% of PVA coating was able to provide the best dispersibility compared to all other groups. Hydrogel-based magnetic nanocomposites were synthesized and the cytocompatibility of magnetic nanocomposite hydrogel with bone marrow-derived mesenchymal stem cells (BMSCs) was higher than pure hydrogel. However, both the hydrogel and magnetic nanocomposite hydrogel completely lost structural integrity within 24 hours of culture with BMSCs, which made it difficult for in vivo cell delivery. Another polymer, poly(glycerol sebacate) (PGS) was studied due to its reported elastomeric property. Initial study showed that magnetic PGS nanocomposites without any surface features had low cell adherence. Thus porous structures were created in magnetic PGS nanocomposites to increase cell adhesion. Different weight percent of magnetic nanoparticles (MNPs)-incorporated PGS nanocomposites were synthesized to investigate the effect of MNPs concentration on BMSC proliferation and differentiation behaviors with and without exposure to external electromagnetic field (EMF). The 3-week study showed that BMSCs cultured in magnetic PGS nanocomposite groups had slightly lower cell density but increased ALP activity, calcium deposition, protein and collagen secretion, indicating positive induction towards osteogenesis. This project presented promising porous magnetic PGS nanocomposite scaffolds for bone and cartilage tissue engineering applications