Artificial round window niche for use in intratympanic drug delivery research to treat the inner ear

Introduction For the development of drug delivery systems such as round window niche implants (RNI) that can be placed in the round window niche (RWN) and deliver their active ingredients into the cochlea via the round window membrane (RWM), special test methods are required, since conventional methods of examining drug release from matrices work with very large volumes as well as complete rinsing of the test specimen.

Methods Using the CAD (Computer Aided Design) software Autodesk Inventor, a scala tympani (Sc.t.) was reconstructed in such a way that access to the scala was oriented upwards. A ring was planned around this opening, which served to place an artificial RWM (ThinCert​). In addition, the entire system was planned in a rectangle so that it could be placed stable. To keep the small RNI in the correct position on the larger membrane a stamp-shaped positioner was designed. All parts were converted to .stl files and stereolithographically printed in resin. The Sc.t was filled with artificial perilymph (AP) and closed at the apex.

Results The artificial RWN showed stable positioning and the Sc.t. was easily visualized and filled with AP without air. The membrane was well fixed and the RNI could be placed over the Sc.t. using the positioner. The eluate could be removed via the apical opening using a syringe.

Conclusion and Outlook An artificial RWN with downstream Sc.t., which can be used for future developments of drug application systems for local inner ear therapy, was created. The validation of the system by testing the release of dexamethasone from silicone-based RNI and the diffusion into the Sc.t. is currently carried out.

This study was funded by the Federal Ministry of Education and Research of Germany (BMBF) project “RESPONSE–Partnership for Innovation in Implant Technology” in the program “Zwanzig20– Partnership for Innovation”, Project ID 03ZZ0928L.

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Artikel online veröffentlicht:
12. Mai 2023