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Objective: To evaluate plasma treatment for enhancing the biocompatibility of cochlear implant (CI) silicone surfaces, thus allowing colonization with human adipose-derived stem cells (hASCs) that are known to provide neurotrophic support. Methods: Silicone samples and CI electrode arrays were treated with 4 low-pressure plasmas of different characteristics. The hydrophilicity of plasma-treated and control surfaces as well as the adherence and morphology of hASCs were assessed. Finally, the insertion forces of electrode arrays were determined and the colonization potential of the electrode arrays with hASCs were tested. Results: The hydrophilicity of the silicone surfaces was significantly enhanced after plasma treatment, as was the adherence of hASCs. The characteristic morphology of hASCs was observed when grown on plasma-treated but not on untreated silicone surfaces. The insertion forces of plasma-treated electrode arrays were similar to those of untreated arrays, and the colonization of plasma-treated electrode arrays with hASCs was feasible. Conclusion: Plasma treatment of CI electrode arrays enhances their biocompatibility and allows for the colonization with hASCs that are known to produce neurotrophic factors. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Cochlear implant users with residual hearing often benefit greatly from simultaneous electric and acoustic stimulation. However, implantation can cause trauma to the inner ear, resulting in poorer hearing postoperatively. We investigated whether a single local injection of glucocorticoids can reduce hearing loss in long-term implanted guinea pigs. Methods: Three groups of animals underwent bilateral surgery. One ear was implanted with an electrode, and the contralateral ear received a cochleostomy only. A single dose of the glucocorticoids triamcinolone or dexamethasone, or of artificial perilymph was infused into cochleae via cochleostomy. Compound action potentials were measured before and after application and for 3 months postoperatively. Tissue growth was measured as the percentage of the total area of the scala tympani that was obliterated. Results: Ears subjected to cochleostomy only and treated with glucocorticoids demonstrated a mild hearing loss. In the implanted ears, both glucocorticoids preserved hearing at least temporarily. The volume of tissue growth within the scala tympani was not reduced, and there was no relation between the amount of tissue and hearing loss. Conclusions: Both glucocorticoids show a potential benefit for hearing preservation in implanted ears. Glucocorticoid therapy may be useful to protect residual hearing during cochlear implantation. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Multipotent stromal cells have become of increasing interest due to their potential to provide therapeutic approaches for autologous tissue repair. However, these cells are not well defined in the guinea pig, which represents an important model in hearing research. Adipose-tissue-derived stem cells (ADSC) and bone-marrow-derived stem cells (BMSC) were isolated from different donor sites, and growth curves were generated to judge the proliferation potential. Adipogenic, chondrogenic and osteogenic differentiation was induced and confirmed histologically. Finally, the capability of guinea pig ADSC to differentiate into neuron-like cells was investigated. With regard to the expansion potential, total cell number and doubling time, ADSC from the neck were the most suitable cells of the tested donor sites. Both ADSC and BMSC showed nearly identical behaviour and ability to undergo multilineage differentiation. Thus, we identified ADSC from the neck as a promising cell source for autologous cell-based approaches in hearing research using the guinea pig model. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objective: To evaluate long-term ipsilateral hearing preservation in patients who underwent cochlear implantation for the combined electric acoustic stimulation of the auditory system. Methods: This was a prospective observational study conducted at a tertiary referral center. Twenty-three subjects were implanted with the MED-EL C40+ standard or C40+ medium electrode using an atraumatic surgical protocol via an anterior-inferior cochleostomy approach. The desired insertion depth was 18–24 mm or 360°. All patients showed significant low-frequency hearing prior to surgery and monosyllabic word scores did not exceed 40% in the best aided condition. Pure-tone audiometry was performed prior to implantation and at distinct intervals after surgery. Results: Nine patients (39.1%) showed complete pure-tone audiometric hearing preservation (0–10 dB) over an average of 29 months. Seven subjects (30.4%) showed partial preservation of residual hearing (hearing loss 15–40 dB) until an average of 25 months. Delayed loss of residual hearing was observed in 5 cases (21.7%) and 2 patients (8.6%) completely lost residual hearing during or immediately after surgery. Freiburger Monosyllabic word understanding scores in a group of patients with complete hearing preservation increased from 13.1% preoperatively to 75% in the electric acoustic stimulation condition. Conclusion: This study documents that complete and partial preservation of ipsilateral hearing after cochlear implantation can be achieved in about 70% of cases over an average period of 27.25 months when using 360° electrode insertions. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]