Hydrogel Matrix Containing Microcarriers for Dexamethasone Delivery to Protect Against Cisplatin-Induced Hearing Loss

A functional hydrogel containing biopolymer microcarriers loaded with dexamethasone was developed to address the hearing loss that results from cisplatin ototoxicity. The drug delivery platform was tested both in vitro in the HEI-OC1 inner ear cell line and in vivo in a rat animal model. The newly described formula offered prolonged release of the contained dexamethasone for up to six days and transformed into a solid state at body temperature, thus counteracting its clearing through the Eustachian tube when injected into the middle ear. When tested in vitro, the inner ear cells exposed to cisplatin showed significantly higher viability at 48 hours when seeded on hydrogel containing dexamethasone-loaded microparticles than the cells treated with free dexamethasone. In the rat in vivo model, the ears of the rats treated with the hydrogel formulation presented better hearing thresholds after cisplatin administration than contralateral ears treated with free dexamethasone. The ears of the rats treated with microcarriers without inclusion in the functional hydrogel obtained better results than the dexamethasone treatment group but not as good as the hydrogel-containing microcarrier group. Histological assessment of the rats' inner ears showed better integrity of the structures and lower apoptosis in the microcarrier-treated groups than in the control group. Overall, the newly described microcarrier of dexamethasone offers better protection against cisplatin-induced hearing loss than free dexamethasone, especially when contained in a functional hydrogel formulation.