In vitro investigation of electrospun PVDF-TrFE fiber mats to reduce connective tissue growth after cochlear implantation

Introduction Cochlear implant electrodes are frequently ensheathed by connective tissue as a consequence of surgical trauma and foreign body response, which can impair electrical stimulation. In this study, fiber mats fabricated by electrospinning with three different spinning times (15, 30 and 45 min) were evaluated for their suitability as surface modifications for cochlear implant electrodes to reduce connective tissue-induced insulation after implantation. Methods Their biocompatibility was assessed through incubation with an extract solution generated from the fiber mat using two different cell types and methods. The influence of the three different polymeric structures on electrical conductivity was examined by coating SEM-holders and measuring changes in impedance. In addition, the wetting behavior of the fiber mats was monitored over a period of 3 weeks. Cell proliferation was further investigated by directly seeding NIH/3T3 eGFP fibroblasts onto the fiber mats and analyzing their growth in a period of 7 days. Results and Discussion The fiber mats were considered biocompatible, although incubation with 100% extract resulted in decreased cell viability in NIH/3T3 fibroblasts. Impedance values increased with increasing fiber mat thickness. Wetting behavior was independent of mat thickness, occurring primarily within the first 24 h and reaching a plateau after 1–2 weeks of immersion in physiological sodium chloride solution. Although cell proliferation was reduced on the fiber mats compared to the conventional cell culture substrate after the 7 days of incubation, cell growth was delayed rather than completely inhibited. Overall, surface modification of cochlear implant electrodes with electrospun fiber mats shows potential to mitigate electrode insulation caused by connective tissue formation.