Figure 2. Heat stress stimulates exosome release from inner ear tissue.

(A) Nanoparticle tracking analysis of conditioned media from utricles cultured under control conditions shows release of exosome-sized (~50–150 nm diameter) particles from control utricles. Heat shock resulted in a 2.4-fold increase in exosome release. Horizontal bars denote typical size ranges of exosomes and microvesicles. (B) Schematic of differential ultracentrifugation procedure used to isolate exosomes from utricle-conditioned culture medium. This process sequentially sediments extracellular components of decreasing size (tissue debris, gray; large vesicles, blue), with exosomes (red) isolated in the final pellet. (C) Isolated exosomes from utricle-conditioned media visualized by TEM were approximately 90 nm in diameter and displayed canonical cup-shaped morphology. Scale bars: 200 nm (top); 100 nm (enlarged inset).