Human adipose-derived stem cells enhance the survival and neuritogenesis of auditory neurons.

Abstract

To evaluate the effect of human adipose-derived stem cells (ASCs) on auditory neurons with respect to a potential application in cochlear implantation. Spiral ganglions from rats were enzymatically dissociated and cocultured with or without ASCs in a coculture system. After 24 and 48 h, inserts with ASCs were removed and the dissociated neurons were fixed and stained. Then, a cell count of all dissociated cells and neurons was performed and the length of the neurites was evaluated. The potential effect of ASCs on the direction of neurite outgrowth was evaluated in a chemotaxis assay. For this, one chamber of the assay was filled with ASCs in medium and the other chamber filled with medium only. After 48 h, the growth direction of neurite outgrowth was evaluated. Cocultivation of auditory neurons with ASCs resulted in a marked and statistically significant increase in neurite outgrowth at 24 and 48 h after plating. Moreover, the number of surviving neurons and the percentage of neurons among the dissociated cells were higher in the coculture group compared with the control group during both observation periods. However, this difference was statistically significant only at one time point. A directional outgrowth of the neurons was not observed. ASCs appear to enhance the survival and the neuritogenesis of auditory neurons. This might be of particular interest for cochlear implantation, in which a proper function of the auditory nerve with a sufficient number of neurons and surviving peripheral processes is essential.