title: Dexamethasone released from cochlear implant coatings combined with a protein repellent hydrogel layer inhibits fibroblast proliferation.
abstract: The insertion of cochlear implants into the inner ear often causes inflammation and fibrosis inside the scala tympani and thus growth of fibrous tissue on the implant surface. This deposition leads to the loss of function in both electrical and laser-based implants. The design of this study was to realize fibroblast growth inhibition by dexamethasone (Dex) released from the base material of the implant [polydimethylsiloxane (PDMS)]. To prevent cell and protein adhesion, the PDMS was coated with a hydrogel layer [star-shaped polyethylene glycol prepolymer (sPEG)]. Drug release rates were studied over 3 months, and surface characterization was performed. It was observed that the hydrogel slightly smoothened the surface roughened by the Dex crystals. The hydrogel coating reduced and prolonged the release of the drug over several months. Unmodified, sPEG-coated, Dex-loaded, and Dex/sPEG-equipped PDMS filaments were cocultivated in vitro with fluorescent fibroblasts, analyzed by fluorescent microscopy, and quantified by cell counting. Compared to the unmodified PDMS, cell growth on all modified filaments was averagely 95% ±standard deviation (SD) less, while cell growth on the bottom of the culture dishes containing Dex-loaded filaments was reduced by 70% ±SD. Both, Dex and sPEG prevented direct cell growth on the filament surfaces, while drug delivery was maintained for the duration of several months.
authors.affiliation: Department of Otolaryngology, Hannover Medical School, 30625, Hannover, Germany.
authors.forename: Antonina
authors.initials: A
authors.lastname: Wrzeszcz
authors.forename: Barbara
authors.initials: B
authors.lastname: Dittrich
authors.forename: Daniel
authors.initials: D
authors.lastname: Haamann
authors.forename: Pooyan
authors.initials: P
authors.lastname: Aliuos
authors.forename: Doris
authors.initials: D
authors.lastname: Klee
authors.forename: Ingo
authors.initials: I
authors.lastname: Nolte
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenarz
authors.forename: Günter
authors.initials: G
authors.lastname: Reuter
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003054:Cochlear Implants; D003692:Delayed-Action Preparations / Q000737:chemistry; D003907:Dexamethasone / Q000737:chemistry*; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing; D051379:Mice; D009757:Nylons / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000893:Anti-Inflammatory Agents; D020099:Coated Materials, Biocompatible; D003692:Delayed-Action Preparations; D004129:Dimethylpolysiloxanes; D020100:Hydrogels; D009757:Nylons; C085707:poly(dimethylsiloxane)-polyamide copolymer; D003907:Dexamethasone
keywords: cochlear implant; dexamethasone; drug release; fibroblast; hydrogel; polydimethylsiloxane