PMC5138816_01
(a) Rat organ of Corti explant cultures treated with PA-infected HMEEC supernatants demonstrate severe HC damage and reduction in number compared to control group. Scale bars 10 mum. (b) Scanning electron micrograph of organ of Corti treated with PA-infected HMEECs supernatant shows severe hair bundle damage compared with control group. Scale bars 1 mum. (c) Rat organ of Corti treated with supernatants from MyD88 siRNA-transfected HMEECs shows no or little HC damage compared with supernatants from scrambled siRNA-transfected cells. Scale bars 10 mum. *P<0.001 or #
P>0.05. Yellow arrows indicate missing HCs and blue arrows denote dying HCs.
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fig1
The explant cultures treated with supernatant from uninfected HMEECs showed three rows of completely preserved outer (OHCs) and one row of inner (IHCs) hair cells (Figure 1a). In contrast, there was death of OHCs and IHCs in apical, middle and basal turns when explant cultures were treated with PA-infected HMEECs supernatants, both at 2- and 16-h (Figure 1a). Quantification of these data also confirmed significant reduction in the number of OHCs and IHCs in all turns of organ of Corti (Figure 1a). Abnormal bundle morphology in the treated explant cultures as compared to the control group was also observed in SEM analyses (Figure 1b). HMEECs transfected with MyD88 siRNA or uninfected cells showed little or no damage to OHCs and IHCs (Figure 1c). However, severe damage to HC stereocilia was evident when explants were treated with supernatants transfected with scrambled siRNA.