Figure 5.

Cisplatin impairs SC phagocytic activity. Utricles were treated with either neomycin or cisplatin until 50% of the HCs died. (a) SCs in neomycin-treated utricles exhibit robust phagocytic activity, as indicated by the number of SC constrictions. This activity is significantly reduced when HCs are killed by cisplatin. N=3–75 SC constrictions across 4–5 utricles per condition. *P<0.05 versus neomycin. (b) When 50% of the HCs have died, no SCs have died in control or neomycin-treated utricles; however, cisplatin-treated utricles exhibit a significant increase in SC death (determined by complete loss of EGFP signal). Bars represent mean±S.E.M. N=126–276 SCs across 4–5 utricles per condition. *P<0.05 versus control. (c) In a separate set of experiments, utricles were not live-imaged, but were cultured until 50% of the HCs died, then fixed and stained with phalloidin (white). In a single plane taken beneath the stereocilia bundles, scars (yellow arrowheads, inset) are visible in both the control and neomycin-treated utricles in spaces where tdTomato-positive HCs (red) are missing. In cisplatin-treated utricles, spaces missing tdTomato-positive HCs were often not covered by SC scars (blue arrowhead, inset). Scale bar=20 μm. Overall gain was increased on all inset images