Surgical Transcanal Procedure for Injection of Cells and Substances into the Human Cochlear Modiolus

Area of Science:

• Regenerative Medicine
• Otolaryngology
• Neurosurgery

Background:

• Cochlear implants (CIs) improve hearing but are limited by spiral ganglion neuron (SGN) dysfunction.
• Regenerative medicine offers potential auditory nerve repair via local drug or cell delivery.
• This study focuses on a novel delivery method for potential auditory nerve regeneration therapies.

Purpose of the Study:

• To evaluate a minimally invasive technique for precise delivery of cell-sized beads into the cochlear modiolus.
• To assess the feasibility and accuracy of injecting simulated cell therapies into the human cochlea.
• To establish a foundation for future auditory nerve regeneration strategies.

Main Methods:

• Human temporal bones were used to establish and test an injection trajectory into the cochlear modiolus.
• A minimally invasive surgical approach involved cochleostomy and modiolus drilling.
• Cell-sized microbeads were injected using a syringe pump, followed by micro-CT and histological analysis.

Main Results:

• Accurate probe placement in the modiolus was achieved in 80% of specimens.
• Microbead injections demonstrated high retention rates (89-97%) within the modiolus with minimal leakage.
• The injection technique exhibited consistent trajectory and low variability.

Conclusions:

• A minimally invasive, precise injection method for delivering cell-sized beads into the cochlear modiolus is feasible.
• This technique supports future local delivery of drugs or cell therapies for hearing restoration.
• Further research is needed to confirm precision, reproducibility, and long-term outcomes.