Sensorineural hearing loss due to aging, noise exposure, trauma or drug ototoxicity is irreversible because cochlear hair cells and neurons cannot regenerate. Recently, therapeutic strategies involving nanoparticles have been developed as innovative drug delivery systems. Thermodynamically stable liquid crystalline nanoparticles based on the polar lipid glycerol monooleate (GMO NP, cubosomes), nontoxic and able to encapsulate both hydrophilic and hydrophobic compounds, were produced and tested for biocompatibility in an immortalized Organ of Corti derived cell line (OC-k3), through cell viability and cytomorphological assays, and Western blot expression profiles of apoptotic markers. Overall, the GMO NP were biocompatible in OC-k3 at the doses and time tested, supporting previous data obtained in a neuronal cell line (PC12). The results encourage further tests on GMO NP-mediated drug release with improved target specificity and could be useful to develop innovative therapies against sensorineural hearing loss.