Liposome-encapsulated hemoglobin alleviates hearing loss after transient cochlear ischemia: an experimental study in the gerbil.

The effects of liposome-encapsulated hemoglobin (LEH), an artificial oxygen carrier, were experimentally investigated in gerbils in the context of alleviation of hearing loss after transient cochlear ischemia. Animals were randomly assigned to receive 2 mL/kg of either LEH (P₅₀O₂=15 mmHg) or saline 1h after the experimental induction of 15 min of ischemia. Sequential recordings of auditory brainstem response (ABR) showed that administration of LEH prevented hearing loss due to cochlear ischemia. The mean ABR threshold at 32 kHz on day 1 was 21 ± 7 dB in the LEH group (n=6) and 45 ± 6 dB in the saline group (n=6). Thereafter, hearing impairment gradually improved up to day 7 in both groups. The animals were then subjected to histological study, which revealed that there was more substantial loss of the inner hair cells, but not the outer hair cells, in the saline group as compared to the LEH group. These results suggest that LEH is an efficient agent with regard to protection against hearing loss and underlying hair cell damager due to ischemic insult.
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