Arg-Gly-Asp Peptide-Functionalized Superparamagnetic γ-Fe₂O₃ Nanoparticles Enhance Osteoblast Migration In Vitro

Making osteoblast migration manageably target to injury sites has been the key challenging in cell therapy for bone and cartilage regeneration. Superparamagnetic materials, the magnetic guide for cell migration, have been applied to increase cell retention. However, additional targeting modifications are still needed to accelerate the low uptake efficiency and moving speed. Arg-Gly-Asp peptide (RGD)-functionalized magnetic nanoparticles showed cutting-edge competence in cell differentiation control and targeted drug delivery. However, more evidence was required to corroborate its role in osteoblast migration in bone repair. In the present study, RGD-modified γ-Fe₂O₃ nanoparticles (RGD-Fe₂O₃ NPs) were prefabricated with the grafting ratio of 33.3-37.4%. The RGD-Fe₂O₃ NPs unveiled excellent water dispersibility with uniform size distribution at 5-6 nm and negligibly low cytotoxicity. As a result, MC3T3-E1 osteoblasts treated with RGD-Fe₂O₃ NPs boosted its migration speed in a magnetic field compared with those incubated with unmodified Fe₂O₃ NPs. Furthermore, osteoblasts treated with RGD-Fe₂O₃ NPs exhibited more Fe uptake. The results exposed the fact that RGD-mediated specific cellular uptake presented higher efficiency than the non-RGD-mediated one, resulting from a stronger superparamagnetic force between the labeled cells and the magnetic field. These findings indicate that the RGD-functionalized Fe₂O₃ NPs can promote osteoblast migration in the magnetic field, providing a promising strategy in magnet-guided cell therapy for bone and cartilage regeneration.