Therapeutic and protective effects of autologous serum in amikacin-induced ototoxicity.

Objective: Possible therapeutic and protective benefits of intratympanic autologous serum application in amikacin-induced ototoxicity were investigated. Methods: Twenty-four guinea pigs were separated equally into two groups: therapeutic (group A) and protective (group B). Transient evoked otoacoustic emissions were recorded before and after autologous serum application. Apoptotic cells were identified in the organ of Corti, spiral limbus and spiral ganglion by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling ('TUNEL') method. Results: Transient evoked otoacoustic emission responses at 1, 1.4 and 2.8 kHz improved without significance after autologous serum application in group A (p > 0.05). A significantly protective effect of autologous serum was determined at 4 kHz in group B (p < 0.05). There were significantly fewer apoptotic cells at the spiral limbus in the therapeutic and protective groups compared to the control group (p < 0.05). Conclusion: Autologous serum may offer protection against ototoxicity-induced hearing loss, but it cannot restore hearing. Immunohistochemically, autologous serum significantly decreases activation of the intrinsic pathway of pro-apoptotic signalling in mesenchymal cells compared to neurons and neurosensory cells.