Differential vulnerability of outer and inner hair cells during and after oxygen-glucose deprivation in organotypic cultures of newborn rats.
Ischemia can contribute to the inner ear pathology and hearing loss. To determine the susceptibility of inner and outer hair cells (IHCs/OHCs) to ischemic and post-ischemic period, we used organotypic cultures of the organ of Corti isolated from P3 rats as an in vitro model of inner ear ischemia (oxygen-glucose deprivation, OGD). We identified the hair cells (HCs) by phalloidin staining. The cells with damaged cellular membrane integrity were identified by propidium iodide (PI)-exclusion assay. The cells with fragmented chromosomal DNA were detected by TUNEL assay. Organotypic cultures were subjected to a mild (3 h duration) or severe (4 h duration) OGD, followed by a recovery period of 21 h and 20 h, respectively. Mild OGD induced a loss of 10-20% HCs, whereas severe OGD induced loss of 35% HCs. We confirmed that OHCs are less vulnerable to OGD than IHCs. Of all missing OHCs, 80-90% was lost during the OGD period and 10-20% during the recovery period. In contrast, the loss of IHCs was equal during both experimental periods. The OGD period was mainly associated with PI-positive nuclei. TUNEL-positive nuclei were a minor fraction during the OGD period and increased during the recovery period, indicating the progression of DNA fragmentation. Our results implicate a differential susceptibility of IHCs and OHCs during and after ischemia-like insult, which may be of therapeutic consequence.
Amarjargal
N
N
Molecular Biology Research Laboratory, Department of Otorhinolaryngology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Andreeva
N
N
Gross
J
J
Haupt
H
H
Fuchs
J
J
Szczepek
A J
AJ
Mazurek
B
B
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D015687:Cell Hypoxia; D002463:Cell Membrane Permeability; D053938:DNA Fragmentation; D005947:Glucose / Q000378:metabolism*; D006199:Hair Cells, Auditory, Inner / Q000378:metabolism* / Q000473:pathology; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism* / Q000473:pathology; D006943:Hyperglycemia / Q000378:metabolism* / Q000473:pathology; D020287:In Situ Nick-End Labeling; D009924:Organ Culture Techniques; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013194:Staining and Labeling / Q000379:methods; D013997:Time Factors
D005947:Glucose; D010100:Oxygen