Using superparamagnetic iron oxide nanoparticles (SPIONs) and a recombinant adeno-associated virus vector (AAV2), minimally invasive magnetic targeting of brain-derived neurotrophic factor (BDNF) gene therapy to the inner ear has been reported to potentially reverse cochlear synaptopathy following NIHL [101]. The gene discussed is BDNF; the disease is noise induced hearing loss.