As a self-expanding stent and occlude, nitinol has become very mature, but it has been rarely reported as a ossicular chain reconstruction material.OBJECTIVE:
To explore the ototoxicity of nitinol after implanted into the acoustic vesicle of guinea pigs. METHODS: Fifty healthy guinea pigs with acute hearing were used in this study. One ear of each guinea pig was enrolled into the experimental group randomly, and the other ear of the guinea pigs was divided into control group I (titanium implantation group, 25 ears) and control group II (opened acoustic vesicle without implanting, 25 ears) equally. Five guinea pigs included in control I and control II groups were executed at days 7, 14, 28, 56, 112 after implantation randomly and respectively. The morphological observation to cochlea was carried by hematoxylineosin staining of cochlear slices. The apoptosis and deletion of hair cells were observed by acridine orange/propidium iodide fluorescent staining. The stereocilium arrangement was examined with scanning electron microscope. And the hair cell's organelle was observed by transmission electron microscope. The auditory function was evaluated by auditory brainstem response and distortion otoacoustic emission response at pre-implantation and pre-execute.RESULTS AND CONCLUSION:
Hematoxylin-eosin staining showed that there was no obvious change or morphological variation in the cochlear tissues and cells after nitinol and titanium implantation into the acoustic vesicle. No hair cell apoptosis was observed by acridine orange/propidium iodide fluorescent staining. The scanning electron microscopy showed that stereocilias were arranged normally. No abnormal changes in the stereocilia and the organella of hair cells were observed by transmission electron microscopy. There was no significant difference between auditory brainstem response threshold before and at days 7, 14, 28, 56 and 112 after implantation. Meanwhile, the through rate of distortion otoacoustic emission response was 100% in each group. These findings indicate that no significant influence on cochlear morphology and auditory function is found, suggesting no ototoxicity of the nitinol implantation into the acoustic vesicle of guinea pigs.