The cochlea presents a hurdle for intravascular drug therapy because of the blood-labyrinthine barrier that tends to exclude entry of large molecules from its vasculature. Magnetic targeting of nanospheres through the cochlear round window membrane (RWM) may provide an entry for delivery of bioactive molecules for protection against or amelioration of acute sensorineural hearing loss. Multiple magnetite (Fe3O4) nanoparticles were encapsulated in biodegradable Poly(D,L-lactide-co-glycolide) (PLGA) providing high magnetic susceptibility and encapsulation of therapeutic payloads. These nanocomposites (MFNP) can be magnetically pulled through the RWM, enhance MRI and deliver payloads. It is important for pharmacokinetics to define the amounts of MFNP deliverable over time, under specific magnetic conditions. Hence, MFNP were conjugated with 99mTc and solutions placed on the RWM of anesthetized guinea pigs (n = 7). The RWM was parallel to the pole face of an external magnet, experimental ear up, for 45 minutes. Control animals (n = 7) were tested with the same solution, without magnets. Following euthanasia, the cochlear perilymph was aspirated and soft tissues collected for gamma scintigraphy. Significantly more MFNP were pulled into the cochlea by magnetic targeting in this preliminary study, 330% above controls. Calculations of quantitative delivery were performed such that if individual therapeutic molecular loading was known, delivery of drugs could be calculated. We conclude that magnetic targeting to the cochlea across the RWM is a viable means of therapeutic delivery.
Journal of Biomedical Nanotechnology (JBN) is a peer-reviewed multidisciplinary journal providing broad coverage in all research areas focused on the applications of nanotechnology in medicine, drug delivery systems, infectious disease, biomedical sciences, biotechnology, and all other related fields of life sciences.