Magnetic targeting of growth factors using iron oxide nanoparticles

Growth factors play an important role in nerve regeneration and repair. A new drug delivery strategy termed `magnetic targeting` aims to enhance therapeutic efficiency by directing magnetic drug carriers specifically to selected neural cell populations and nervous tissues. Here, we covalently conjugated nerve growth factor to iron oxide nanoparticles (NGF-MNPs) and used controlled magnetic fields to deliver the NGF–MNP complexes to target sites. In order to actuate the magnetic fields a modular magnetic device was designed and fabricated. PC12 cells that were plated homogenously in culture were differentiated selectively only in targeted sites out of the entire dish, above the magnetic `hot spots`. To examine the ability to guide the NGF-MNPs towards specific targets in vivo we examined two model systems. First, we injected and directed magnetic carriers within the sciatic nerve. Second, we injected the MNPs intravenously and showed an accumulation of MNPs in mouse retina using an external magnet that was placed next to one of the eyes. We propose a novel approach to deliver drugs selectively to injured sites, thus, to promote an effective repair with minimal systemic side effects, overcoming significant challenges in regenerative therapeutics.