Figure 1. Exosomal HSP70–mediated protection of the mammalian inner ear.

The mammalian inner ear contains the vestibule, which houses the sensory epithelia for the perception of gravity and head movements, and the cochlea, which houses the sensory epithelia for the perception of sound. Sensory epithelium from the utricle, a subcompartment of the vestibule, contains hair cells that are surrounded by supporting cells and innervated by afferent neurons. In utricle explant experiments, heat shock induced supporting cells to release exosomes containing HSP70, which bound to TLR4-expressing hair cells and protected against aminoglycoside toxicity.