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Preliminary Characterization of Extracellular Vesicles From Auditory HEI-OC1 Cells.

  • Author(s): Kalinec, Gilda M
  • Cohn, Whitaker
  • Whitelegge, Julian P
  • Faull, Kym F
  • Kalinec, Federico
  • et al.


Isolate, purify, and characterize extracellular vesicles (EVs) obtained from auditory HEI-OC1 cells, and evaluate their suitability for intracochlear transport and delivery of pharmacological drugs and/or pro-resolution mediators of acute inflammatory processes.


HEI-OC1 EVs were isolated and purified using the exoEasy Maxi Kit, and their size was evaluated by nanoparticle tracking techniques. Bottom-up proteomics of the EVs, either freshly obtained or stored for up to 4 months at -20°C, was performed by LC-ESI-MS/MS. LC-ESI-MS/MS-MRM was used to measure the loading of dexamethasone inside EVs following co-incubation at room temperature for 1 hour with and without 5 minutes sonication.


Routinely, we were able to obtain purified fractions of >2 × 109 EVs/mL, with diameters varying between 50 and 800 nm. Bottom-up proteomics showed that among the most abundant EVs proteins, 19.2% were cytoplasmic, 17.2% were membrane localized, 12.3% were cytosolic, and 14.6% were nucleolar. No significant differences between fresh and stored EVs were detected. Importantly, co-incubation of HEI-OC1 EVs (1 × 108 EVs/mL) with dexamethasone (10 mM) resulted in the incorporation of 10.1 ± 1.9 nM dexamethasone per milliliter of EVs suspension.


Altogether, the results suggest that EVs from HEI-OC1 cells could be advantageously used as biological nanocarriers for the delivery of specific molecules and pharmacological drugs into the inner ear.

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