Use of organotypic cultures of Corti's organ to study the protective effects of antioxidant molecules on cisplatin-induced damage of auditory hair cells.
OBJECTIVE
Cisplatin causes the generation of reactive oxygen species (ROS), which interferes with the antioxidant defense system of Corti's organ and results in damage to the hair cells.


BACKGROUND
Cisplatin is a widely used chemotherapeutic agent with the dose-limiting side effect of ototoxicity. Evidence is accumulating that cisplatin interferes with the antioxidant defense system of Corti's organ.


METHODS
Organotypic explants of P-3 rat organ of Corti were the in vitro model system. Presence of intact auditory hair cells and stereocilia bundle integrity was assayed by phalloidin-FITC staining. Fluorescent dye probes detected H2O2 and intracellular thiol [e.g., glutathione (GSH)]. Spectrophotometric analysis determined antioxidant enzyme levels.


RESULTS
There was a rapid dose-dependent cisplatin cytotoxicity in the explants after 48 h of exposure. An accumulation of H2O2 and a reduction of GSH levels were observed within cisplatin-exposed hair cells. L-buthionine sulfoximine, an inhibitor of GSH formation, enhanced cisplatin ototoxicity, whereas N6-(2-phenylisopropyl) adenosine, an adenosine agonist, elevated antioxidant enzyme levels and ameliorated cisplatin toxicity. The following molecules protected hair cells from cisplatin-induced damage: GSH; glutathione diethyl ester (GSHe); ebselen (EBS); 4-methylthiobenzoic acid (MTBA); and D-methionine (D-MET). EBS, MTBA, and D-MET in vitro protection correlates with in vivo protection in rats.


CONCLUSIONS
Organotypic culture of Corti's organ has been validated as a model for studying cisplatin toxicity and for screening otoprotective molecules. Some of the events that contribute to cisplatin's ability to damage auditory hair cells are generation of ROS (e.g., H2O2), depletion of intracellular GSH, and interference with antioxidant enzymes within the cochlea. Agents that bolster the cochlea's antioxidant system can prevent cisplatin destruction of auditory hair cells. Identified protective agents may prove to be clinically useful in limiting or completely protecting from cisplatin ototoxicity.
Kopke
R D
RD
Department of Otolaryngology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Liu
W
W
Gabaizadeh
R
R
Jacono
A
A
Feghali
J
J
Spray
D
D
Garcia
P
P
Steinman
H
H
Malgrange
B
B
Ruben
R J
RJ
Rybak
L
L
Van de Water
T R
TR
D000704:Analysis of Variance; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism* / Q000633:toxicity*; D000975:Antioxidants / Q000378:metabolism*; D002945:Cisplatin / Q000378:metabolism* / Q000633:toxicity*; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D005260:Female; D016166:Free Radical Scavengers; D005609:Free Radicals; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000378:metabolism*; D009925:Organ of Corti / Q000187:drug effects* / Q000378:metabolism*; D020011:Protective Agents / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D000970:Antineoplastic Agents; D000975:Antioxidants; D016166:Free Radical Scavengers; D005609:Free Radicals; D020011:Protective Agents; D002945:Cisplatin