Innervation of Cochlear Hair Cells by Human Induced Pluripotent Stem Cell-Derived Neurons In Vitro

Figure 3

Innervation of inner hair cells versus outer hair cells by stem cell-derived neurons. (a) The specific labeling of Prestin (grey) to the OHCs is depicted in the explant only control. (b–d) The hiPSC- and hESC-derived neural processes made contact with both the IHCs and the OHCs. The merged¹ images represent higher magnification images of the boxed inserts and depict the contacts made between the stem cell-derived neural processes and hair cells. Scale bar = 50 μm, relevant for all the images. (e) Total numbers of hair cells (inner and outer) were quantified in each group using antibodies against MyoVIIa (all hair cells) and Prestin (outer hair cells only). Data was compared to controls grown for one day in vitro. There was a significantly higher number of OHCs compared to IHCs in the explant only controls after 1 DIV (). At 10 DIV, there was a decline in the number of IHCs and OHCs present in the explants. There were no significant differences in the number of OHCs that the stem cell-derived neural processes contacted, when compared to the numbers of IHCs these cells contacted (iPS1 , ; iPS2: , ; and H9 , ). The iPS1-derived neurons made contact with significantly fewer OHCs compared to the hESC-derived neurons (). A Kruskal-Wallis one-way ANOVA was utilized to determine statistical significance between the groups compared. Values of were considered statistically significant and data presented as the mean ± SEM. OHCs: outer hair cells; IHCs: inner hair cells; DIV: days in vitro. The asterisks highlight the IHCs present in the cultures.