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. i 2014 S. Karger AG, Basel