Jellyfish model for ototoxicity

Pharmacologic ototoxicity is well described in the medical literature, yet efficient screening models are lacking. Aurelia aurita ephyrae, transparent jellyfish with identifiable hair cells, could be an effective model. Structural changes readily manifest behaviorally, and hair cells are easily stained and observed. We treated ephyrae with various gentamicin concentrations, evaluated its motility, and quantified its hair cell loss.

Baseline pulsing per minute (P), swimming (S), and orientation (O) values were recorded from cultured ephyrae. Ephyrae were transferred into test tubes containing artificial seawater (ASW), gentamicin, or penicillin. P, S, and O were scored at 0, 24, and 48 hours. Ephyrae were formalin fixed, phalloidin stained, and imaged with confocal microscopy, and hair cells were then counted.

P was impaired by gentamicin in a dose-dependent fashion, whereas ASW controls maintained baseline P, S, and O values. Impairment of S and O occurred with 3.5 mmol/L gentamicin at 24 hours. For six experiments each using 40 ephyrae, at 24 hours, average P was reduced from 75.2 in ASW to 28.8, 12.3, and 1.9 for 1, 2, and 3.5 mmol/L gentamicin, respectively (p < 0.05 for all cases). Hair cell loss at 24 and 48 hours was significant (32% and 48% reduction compared with control, p < 0.05) and correlated with motility deficits. Deficits from penicillin exposure were not statistically significant.

The ephyra model demonstrated functional and histologic gentamicin-mediated impairments, showing promise as a screening tool for ototoxic agents. The changes in ephyra motility after gentamicin exposure correlated significantly with hair cell loss.