Superparamagnetic Nanoparticle Delivery to the Cochlea Through Round Window by External Magnetic Field: Feasibility...

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Otolaryngology

Background:

• Targeted drug delivery to the inner ear remains a significant challenge.
• Superparamagnetic iron oxide nanoparticles (SPIONs) offer potential for magnetically guided therapies.
• The round window (RW) is a key entry point for cochlear interventions.

Purpose of the Study:

• To assess the feasibility of delivering SPIONs into the cochlea via the RW using an external magnetic field.
• To evaluate the toxicity and efficacy of this SPION delivery method.
• To determine the long-term effects on hearing function.

Main Methods:

• SPIONs suspended in hyaluronic gel were applied to the punctured RW niche in Wistar rats.
• An external rare earth magnet (0.54 T) was used to mobilize SPIONs towards the cochlear apex.
• Hearing function was monitored using auditory brainstem responses (ABRs) and cochlear histology.

Main Results:

• SPIONs were successfully driven into the scala tympani, reaching the basal turn, second turn, and apex.
• Auditory thresholds remained unchanged one month post-administration, indicating preserved hearing function.
• Histological examination confirmed the presence and distribution of SPIONs within the cochlea.

Conclusions:

• External magnetic fields can effectively guide SPIONs into the cochlea through the round window.
• This non-invasive technique demonstrates feasibility and lack of immediate toxicity.
• SPIONs can be delivered to the cochlear apex while preserving hearing function for at least one month in rats.